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Gordon S, Chan DLH, Bernard EJ, Eslick ME, Willowson KP, Roach PJ, Engel AF, Maher R, Clarke SJ, Agarwal V, Yasmin L, De Silva M, Mascall S, Conner A, Nevell D, Pavlakis N, Bailey DL. Single-centre experience with peptide receptor radionuclide therapy for neuroendocrine tumours (NETs): results using a theranostic molecular imaging-guided approach. J Cancer Res Clin Oncol 2023; 149:7717-7728. [PMID: 37004598 PMCID: PMC10374703 DOI: 10.1007/s00432-023-04706-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 03/17/2023] [Indexed: 04/04/2023]
Abstract
AIM To summarise our centre's experience managing patients with neuroendocrine tumours (NETs) in the first 5 years after the introduction of peptide receptor radionuclide therapy (PRRT) with [177Lu]Lu-DOTA-octreotate (LUTATE). The report emphasises aspects of the patient management related to functional imaging and use of radionuclide therapy. METHODS We describe the criteria for treatment with LUTATE at our centre, the methodology for patient selection, and the results of an audit of clinical measures, imaging results and patient-reported outcomes. Subjects are treated initially with four cycles of ~ 8 GBq of LUTATE administered as an outpatient every 8 weeks. RESULTS In the first 5 years offering LUTATE, we treated 143 individuals with a variety of NETs of which approx. 70% were gastroentero-pancreatic in origin (small bowel: 42%, pancreas: 28%). Males and females were equally represented. Mean age at first treatment with LUTATE was 61 ± 13 years with range 28-87 years. The radiation dose to the organs considered most at risk, the kidneys, averaged 10.6 ± 4.0 Gy in total. Median overall survival (OS) from first receiving LUTATE was 72.5 months with a median progression-free survival (PFS) of 32.3 months. No evidence of renal toxicity was seen. The major long-term complication seen was myelodysplastic syndrome (MDS) with a 5% incidence. CONCLUSIONS LUTATE treatment for NETs is a safe and effective treatment. Our approach relies heavily on functional and morphological imaging informing the multidisciplinary team of NET specialists to guide appropriate therapy, which we suggest has contributed to the favourable outcomes seen.
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Affiliation(s)
- S Gordon
- Sydney Vital Translational Cancer Research Centre, Sydney, Australia
| | - D L H Chan
- Department of Medical Oncology, Royal North Shore Hospital, Sydney, Australia
- Faculty of Medicine & Health, University of Sydney, Sydney, Australia
| | - E J Bernard
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, Sydney, NSW, 2065, Australia
| | - M E Eslick
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, Sydney, NSW, 2065, Australia
| | - K P Willowson
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, Sydney, NSW, 2065, Australia
| | - P J Roach
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, Sydney, NSW, 2065, Australia
| | - A F Engel
- Faculty of Medicine & Health, University of Sydney, Sydney, Australia
- Department of Colorectal Surgery, Royal North Shore Hospital, Sydney, Australia
| | - R Maher
- Department of Medical Imaging, Royal North Shore Hospital, Sydney, Australia
| | - S J Clarke
- Department of Medical Oncology, Royal North Shore Hospital, Sydney, Australia
- Faculty of Medicine & Health, University of Sydney, Sydney, Australia
| | - V Agarwal
- Sydney Vital Translational Cancer Research Centre, Sydney, Australia
| | - L Yasmin
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, Sydney, NSW, 2065, Australia
| | - M De Silva
- Department of Medical Oncology, Royal North Shore Hospital, Sydney, Australia
- Bill Walsh Translational Cancer Research Laboratory, University of Sydney, Sydney, Australia
| | - S Mascall
- Department of Medical Oncology, Royal North Shore Hospital, Sydney, Australia
| | - A Conner
- Department of Medical Oncology, Royal North Shore Hospital, Sydney, Australia
- Bill Walsh Translational Cancer Research Laboratory, University of Sydney, Sydney, Australia
| | - D Nevell
- Department of Anatomical Pathology, Royal North Shore Hospital, Sydney, Australia
| | - N Pavlakis
- Department of Medical Oncology, Royal North Shore Hospital, Sydney, Australia
- Bill Walsh Translational Cancer Research Laboratory, University of Sydney, Sydney, Australia
| | - D L Bailey
- Sydney Vital Translational Cancer Research Centre, Sydney, Australia.
- Faculty of Medicine & Health, University of Sydney, Sydney, Australia.
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, Sydney, NSW, 2065, Australia.
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Ashrafinia S, Dalaie P, Schindler TH, Pomper MG, Rahmim A. Standardized Radiomics Analysis of Clinical Myocardial Perfusion Stress SPECT Images to Identify Coronary Artery Calcification. Cureus 2023; 15:e43343. [PMID: 37700937 PMCID: PMC10493172 DOI: 10.7759/cureus.43343] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2023] [Indexed: 09/12/2023] Open
Abstract
PURPOSE Myocardial perfusion (MP) stress single-photon emission computed tomography (SPECT) is an established diagnostic test for patients suspected of coronary artery disease (CAD). Meanwhile, coronary artery calcification (CAC) scoring obtained from diagnostic CT is a highly sensitive test, offering incremental diagnostic information in identifying patients with significant CAD yet normal MP stress SPECT (MPSS) scans. However, after decades of wide utilization of MPSS, CAC is not commonly reimbursed (e.g. by the CMS), nor widely deployed in community settings. We studied the potential of complementary information deduced from the radiomics analysis of normal MPSS scans in predicting the CAC score. METHODS We collected data from 428 patients with normal (non-ischemic) MPSS (99mTc-sestamibi; consensus reading). A nuclear medicine physician verified iteratively reconstructed images (attenuation-corrected) to be free from fixed perfusion defects and artifactual attenuation. Three-dimensional images were automatically segmented into four regions of interest (ROIs), including myocardium and three vascular segments (left anterior descending [LAD]-left circumference [LCX]-right coronary artery [RCA]). We used our software package, standardized environment for radiomics analysis (SERA), to extract 487 radiomic features in compliance with the image biomarker standardization initiative (IBSI). Isotropic cubic voxels were discretized using fixed bin-number discretization (eight schemes). We first performed blind-to-outcome feature selection focusing on a priori usefulness, dynamic range, and redundancy of features. Subsequently, we performed univariate and multivariate machine learning analyses to predict CAC scores from i) selected radiomic features, ii) 10 clinical features, and iii) combined radiomics + clinical features. Univariate analysis invoked Spearman correlation with Benjamini-Hotchberg false-discovery correction. The multivariate analysis incorporated stepwise linear regression, where we randomly selected a 15% test set and divided the other 85% of data into 70% training and 30% validation sets. Training started from a constant (intercept) model, iteratively adding/removing features (stepwise regression), invoking the Akaike information criterion (AIC) to discourage overfitting. Validation was run similarly, except that the training output model was used as the initial model. We randomized training/validation sets 20 times, selecting the best model using log-likelihood for evaluation in the test set. Assessment in the test set was performed thoroughly by running the entire operation 50 times, subsequently employing Fisher's method to verify the significance of independent tests. RESULTS Unsupervised feature selection significantly reduced 8×487 features to 56. In univariate analysis, no feature survived the false-discovery rate (FDR) to directly correlate with CAC scores. Applying Fisher's method to the multivariate regression results demonstrated combining radiomics with the clinical features to enhance the significance of the prediction model across all cardiac segments. Conclusions: Our standardized and statistically robust multivariate analysis demonstrated significant prediction of the CAC score for all cardiac segments when combining MPSS radiomic features with clinical features, suggesting radiomics analysis can add diagnostic or prognostic value to standard MPSS for wide clinical usage.
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Affiliation(s)
- Saeed Ashrafinia
- Radiology, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Pejman Dalaie
- Radiology, Johns Hopkins University School of Medicine, Baltimore, USA
| | | | - Martin G Pomper
- Radiology, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Arman Rahmim
- Physics and Astronomy, University of British Columbia, Vancouver, CAN
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Di Domenico G, Di Biaso S, Longo L, Turra A, Tonini E, Longo M, Uccelli L, Bartolomei M. Validation of [Formula: see text]Tc and [Formula: see text]Lu quantification parameters for a Monte Carlo modelled gamma camera. EJNMMI Phys 2023; 10:27. [PMID: 37029829 PMCID: PMC10082889 DOI: 10.1186/s40658-023-00547-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 03/29/2023] [Indexed: 04/09/2023] Open
Abstract
PURPOSE Monte Carlo (MC) simulation in Nuclear Medicine is a powerful tool for modeling many physical phenomena which are difficult to track or measure directly. MC simulation in SPECT/CT imaging is particularly suitable for optimizing the quantification of activity in a patient, and, consequently, the absorbed dose to each organ. To do so, validating MC results with real data acquired with gamma camera is mandatory. The aim of this study was the validation of the calibration factor (CF) and the recovery coefficient (RC) obtained with SIMIND Monte Carlo code for modeling a Siemens Symbia Intevo Excel SPECT-CT gamma camera to ensure optimal [Formula: see text]Tc and [Formula: see text]Lu SPECT quantification. METHODS Phantom experiments using [Formula: see text]Tc and [Formula: see text]Lu have been performed to measure spatial resolution and sensitivity, as well as to evaluate the CF and RC from acquired data. The geometries used for 2D planar imaging were (1) Petri dish and (2) capillary source while for 3D volumetric imaging were (3) a uniform filled cylinder phantom and (4) a Jaszczack phantom with spheres of different volumes. The experimental results have been compared with the results obtained from Monte Carlo simulations performed in the same geometries. RESULTS Comparison shows good accordance between simulated and experimental data. The measured planar spatial resolution was 8.3[Formula: see text] mm for [Formula: see text]Tc and 11.8±0.6 mm for [Formula: see text]Lu. The corresponding data obtained by SIMIND for [Formula: see text]Tc was 7.8±0.1 mm, while for [Formula: see text]Lu was 12.4±0.4 mm. The CF was 110.1±5.5 cps/MBq for Technetium and 18.3±1.0 cps/MBq for Lutetium. The corresponding CF obtained by SIMIND for [Formula: see text]Tc was 107.3±0.3 cps/MBq, while for [Formula: see text]Lu 20.4±0.7 cps/MBq. Moreover, a complete curve RCs vs Volume (ml) both for Technetium and Lutetium was determined to correct the PVE for all volumes of clinical interest. In none of the cases, a RC coefficient equal to 100 was found. CONCLUSIONS The validation of quantification parameters shows that SIMIND can be used for simulating both gamma camera planar and SPECT images of Siemens Symbia Intevo using [Formula: see text]Tc and [Formula: see text]Lu radionuclides for different medical purposes and treatments.
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Affiliation(s)
- Giovanni Di Domenico
- Department of Physics and Earth Science, University of Ferrara, via Saragat 1, 44122 Ferrara, IT Italy
| | - Simona Di Biaso
- Department of Physics and Earth Science, University of Ferrara, via Saragat 1, 44122 Ferrara, IT Italy
| | - Lorenzo Longo
- Department of Physics and Earth Science, University of Ferrara, via Saragat 1, 44122 Ferrara, IT Italy
| | - Alessandro Turra
- Medical Physics Unit, University Hospital, 44124 Ferrara, IT Italy
| | - Eugenia Tonini
- Medical Physics Unit, University Hospital, 44124 Ferrara, IT Italy
| | | | - Licia Uccelli
- Nuclear Medicine Unit, University Hospital, 44124 Ferrara, IT Italy
- Department of Translational Medicine, University of Ferrara, via Fossato di Mortara, 70 c/o viale Eliporto, 44124 Ferrara, IT Italy
| | - Mirco Bartolomei
- Nuclear Medicine Unit, University Hospital, 44124 Ferrara, IT Italy
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Li Z, Le Roux PY, Callahan J, Hardcastle N, Hofman MS, Siva S, Yamamoto T. Quantitative assessment of ventilation-perfusion relationships with gallium-68 positron emission tomography/computed tomography imaging in lung cancer patients. Phys Imaging Radiat Oncol 2022; 22:8-12. [PMID: 35465222 PMCID: PMC9018442 DOI: 10.1016/j.phro.2022.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 11/30/2022] Open
Abstract
Voxel-wise correlations between gallium-68 (68Ga) positron emission tomography/computed tomography (PET/CT)-measured ventilation and perfusion varied widely among 19 patients with lung cancer (range: 0.26–0.88). 68Ga PET/CT-measured percent gas exchanging lung volume was moderately correlated with diffusing capacity of the lung for carbon monoxide (DLCO) as the reference standard, with the highest correlation coefficient of 0.59 (P < 0.01). 68Ga PET/CT ventilation/perfusion imaging may provide a reasonable surrogate for regional gas exchange.
Pulmonary functional imaging has demonstrated potential to improve thoracic radiotherapy. The purpose of this study was twofold: 1) to quantify ventilation/perfusion relationships in lung cancer patients using a new functional imaging approach, gallium-68 (68Ga)-positron emission tomography/computed tomography (PET/CT); and 2) to compare ventilation/perfusion matching with diffusing capacity of the lung for carbon monoxide (DLCO). Voxel-wise correlations between ventilation and perfusion varied widely among 19 patients (range: 0.26–0.88). 68Ga-PET/CT-measured percent gas exchanging lung volume was moderately correlated with DLCO (≤0.59). Our findings suggested that 68Ga-PET/CT ventilation/perfusion imaging provided complementary information and a reasonable surrogate for gas exchange in lung cancer patients.
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Affiliation(s)
- Zhuorui Li
- Department of Biomedical Engineering, University of California Davis, Davis, CA, USA
| | - Pierre-Yves Le Roux
- Department of Nuclear Medicine, Brest University Hospital, EA3878 (GETBO), Brest, France
| | - Jason Callahan
- Molecular Imaging and Therapeutic Nuclear Medicine, Peter MacCallum Cancer Centre, Melbourne, Australia
| | - Nicholas Hardcastle
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Australia
| | - Michael S. Hofman
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Australia
| | - Shankar Siva
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Australia
- Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia
| | - Tokihiro Yamamoto
- Department of Radiation Oncology, University of California Davis School of Medicine, Sacramento, CA, USA
- Corresponding author at: Department of Radiation Oncology, University of California Davis School of Medicine, 4501 X St., Sacramento, CA 95817, USA.
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Kennedy J, Chicheportiche A, Keidar Z. Quantitative SPECT/CT for dosimetry of peptide receptor radionuclide therapy. Semin Nucl Med 2021; 52:229-242. [PMID: 34911637 DOI: 10.1053/j.semnuclmed.2021.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Neuroendocrine tumors (NETs) are uncommon malignancies of increasing incidence and prevalence. As these slow growing tumors usually overexpress somatostatin receptors (SSTRs), the use of 68Ga-DOTA-peptides (gallium-68 chelated with dodecane tetra-acetic acid to somatostatin), which bind to the SSTRs, allows for PET based imaging and selection of patients for peptide receptor radionuclide therapy (PRRT). PRRT with radiolabeled somatostatin analogues such as 177Lu-DOTATATE (lutetium-177-[DOTA,Tyr3]-octreotate), is mainly used for the treatment of metastatic or inoperable NETs. However, PRRT is generally administered at a fixed injected activity in order not to exceed dose limits in critical organs, which is suboptimal given the variability in radiopharmaceutical uptake among patients. Advances in SPECT (single photon emission computed tomography) imaging enable the absolute quantitative measure of the true radiopharmaceutical distribution providing for PRRT dosimetry in each patient. Personalized PRRT based on patient-specific dosimetry could improve therapeutic efficacy by optimizing effective tumor absorbed dose while limiting treatment related radiotoxicity.
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Affiliation(s)
- John Kennedy
- Department of Nuclear Medicine, Rambam Health Care Campus, Haifa, Israel; B. Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
| | - Alexandre Chicheportiche
- Department of Nuclear Medicine and Biophysics, Hadassah Medical Organization and Faculty of Medicine, Hebrew University of Jerusalem, Israel
| | - Zohar Keidar
- Department of Nuclear Medicine, Rambam Health Care Campus, Haifa, Israel; B. Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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Asl RG, Sabbaghi R, Ahangari HT, Hejazi P, Foroutan M. Prediction of Absorbed Dose to Normal Organs with Endocrine Tumors for I-131 by use of 99mTC Single Photon Emission Computed Tomography/Computed Tomography and Geant4 Application for Tomographic Emission Simulation. Indian J Nucl Med 2021; 36:273-281. [PMID: 34658551 PMCID: PMC8481846 DOI: 10.4103/ijnm.ijnm_6_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 04/30/2021] [Accepted: 05/07/2021] [Indexed: 11/04/2022] Open
Abstract
Introduction: This study aimed to predict the dose absorbed by normal organs with neuroendocrine tumors for 131I using single photon emission computed tomography/computed tomography (SPECT/CT) images and Geant4 application for tomographic emission (GATE) simulation. Materials and Methods: Four to 5 whole-body planar scan series, along with one SPECT/CT image, were taken from four patients following 99mTc-hynic-Tyr3-octreotide radiotracer injection. After image quantification, the residence time of each organ was calculated using the image analysis and the activity time curves. The energy deposit and dose conversion (S-value) were extracted from the GATE simulation for the target organs of each patient. Using the residence times and S-values, the mean absorbed dose for the target organs of each patient was calculated and compared with the data obtained from the standard method. Results: Very close agreement was obtained between the S-value of the self–organ irradiation. The mean percentage difference between the two methods (i.e. GATE and Medical Internal Radiation Dose [MIRD]) was 1.8%, while a weak agreement was observed for cross-organ irradiation. The percentage difference between the total absorbed doses by the organs was 2%. The percentage difference between the absorbed doses obtained for tumors and three considered normal organs estimated by the GATE method was slightly higher than the MIRD method (about 11% on average for tumors). Conclusion: Regardless of the small difference between the obtained results for the organs and absorbed doses of the tumors in the present study, patient-specific dosimetry by the GATE methods is useful and essential for therapeutic radionuclides such as 131I due to high cross-dose effects, especially for young adult patients, to ensure the radiation safety and increase the effectiveness of the treatment.
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Affiliation(s)
- Rohollah Ghahraman Asl
- Department of Medical Physics and Radiation Sciences, Faculty of Paramedicine, Sabzevar University of Medical Sciences, Sabzevar, Iran
| | - Rezvan Sabbaghi
- Department of Medical Physics, Faculty of medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Hadi Taleshi Ahangari
- Department of Medical Physics, Faculty of medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Payman Hejazi
- Department of Medical Physics, Faculty of medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Majid Foroutan
- Endocrinologist, Department of Internal Medicine, Faculty of Medicine, Semnan University of Medical Sciences, Semnan, Iran
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Tsuchitani T, Kitajima K, Takahashi Y, Kotoura N. Quantitative evaluation of single-photon emission computed tomography findings in lower extremity possible without computed tomography-based attenuation correction. Nucl Med Commun 2021; 42:1097-1103. [PMID: 34528929 DOI: 10.1097/mnm.0000000000001440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE For performing accurate quantitative analysis of single-photon emission computed tomography (SPECT)/computed tomography (CT) images, CT-based attenuation correction (CTAC) is considered to be necessary. However, the effect on quantitative values for an examined area close to the body surface, such as in the lower extremity, has yet to be elucidated. We performed the present investigation to determine the possibility of quantitative evaluation using a SPECT standalone device without CT. METHODS Validation was performed using clinical data of patients who underwent a lower extremity SPECT/CT examination, with grouping based on presence or absence of CTAC, scatter correction and resolution recovery. Using a reference group in which all types of correction were applied, standardized uptake values (SUVs), including maximum (SUVmax) and peak (SUVpeak), were examined in each group and compared. RESULTS As compared to the reference group, the difference in quantitative values became smaller in the order of the applied scatter correction and resolution recovery, applied resolution recovery, applied scatter correction, and neither scatter correction or resolution recovery applied groups, with no significant difference between the reference group and that with neither scatter correction or resolution recovery applied. A similar tendency was seen for both SUVmax and SUVpeak. CONCLUSIONS In bone SPECT quantitative examinations of the lower extremity, quantitative evaluation without CTAC is possible without the use of scatter correction or resolution recovery. Thus, quantitative evaluation can be performed with use of a standalone SPECT device without CT.
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Affiliation(s)
- Tatsuya Tsuchitani
- Department of Radiological Technology, Hyogo College of Medicine College Hospital
| | - Kazuhiro Kitajima
- Division of Nuclear Medicine and PET Center, Department of Radiology, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Yoshiyuki Takahashi
- Department of Radiological Technology, Hyogo College of Medicine College Hospital
| | - Noriko Kotoura
- Department of Radiological Technology, Hyogo College of Medicine College Hospital
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Morphis M, van Staden JA, du Raan H, Ljungberg M. Evaluation of Iodine-123 and Iodine-131 SPECT activity quantification: a Monte Carlo study. EJNMMI Phys 2021; 8:61. [PMID: 34410539 PMCID: PMC8377107 DOI: 10.1186/s40658-021-00407-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 08/10/2021] [Indexed: 01/18/2023] Open
Abstract
Purpose The quantitative accuracy of Nuclear Medicine images, acquired for both planar and SPECT studies, is influenced by the isotope-collimator combination as well as image corrections incorporated in the iterative reconstruction process. These factors can be investigated and optimised using Monte Carlo simulations. This study aimed to evaluate SPECT quantification accuracy for 123I with both the low-energy high resolution (LEHR) and medium-energy (ME) collimators and 131I with the high-energy (HE) collimator. Methods Simulated SPECT projection images were reconstructed using the OS-EM iterative algorithm, which was optimised for the number of updates, with appropriate corrections for scatter, attenuation and collimator detector response (CDR), including septal scatter and penetration compensation. An appropriate calibration factor (CF) was determined from four different source geometries (activity-filled: water-filled cylindrical phantom, sphere in water-filled (cold) cylindrical phantom, sphere in air and point-like source), investigated with different volume of interest (VOI) diameters. Recovery curves were constructed from recovery coefficients to correct for partial volume effects (PVEs). The quantitative method was evaluated for spheres in voxel-based digital cylindrical and patient phantoms. Results The optimal number of OS-EM updates was 60 for all isotope-collimator combinations. The CFpoint with a VOI diameter equal to the physical size plus a 3.0-cm margin was selected, for all isotope-collimator geometries. The spheres’ quantification errors in the voxel-based digital cylindrical and patient phantoms were less than 3.2% and 5.4%, respectively, for all isotope-collimator combinations. Conclusion The study showed that quantification errors of less than 6.0% could be attained, for all isotope-collimator combinations, if corrections for; scatter, attenuation, CDR (including septal scatter and penetration) and PVEs are performed. 123I LEHR and 123I ME quantification accuracies compared well when appropriate corrections for septal scatter and penetration were applied. This can be useful in departments that perform 123I studies and may not have access to ME collimators.
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Affiliation(s)
- Michaella Morphis
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa.
| | - Johan A van Staden
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
| | - Hanlie du Raan
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
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Kupitz D, Wissel H, Wuestemann J, Bluemel S, Pech M, Amthauer H, Kreissl MC, Grosser OS. Optimization of SPECT/CT imaging protocols for quantitative and qualitative 99mTc SPECT. EJNMMI Phys 2021; 8:57. [PMID: 34328565 PMCID: PMC8324619 DOI: 10.1186/s40658-021-00405-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 07/13/2021] [Indexed: 11/29/2022] Open
Abstract
Background The introduction of hybrid SPECT/CT devices enables quantitative imaging in SPECT, providing a methodological setup for quantitation using SPECT tracers comparable to PET/CT. We evaluated a specific quantitative reconstruction algorithm for SPECT data using a 99mTc-filled NEMA phantom. Quantitative and qualitative image parameters were evaluated for different parametrizations of the acquisition and reconstruction protocol to identify an optimized quantitative protocol. Results The reconstructed activity concentration (ACrec) and the signal-to-noise ratio (SNR) of all examined protocols (n = 16) were significantly affected by the parametrization of the weighting factor k used in scatter correction, the total number of iterations and the sphere volume (all, p < 0.0001). The two examined SPECT acquisition protocols (with 60 or 120 projections) had a minor impact on the ACrec and no significant impact on the SNR. In comparison to the known AC, the use of default scatter correction (k = 0.47) or object-specific scatter correction (k = 0.18) resulted in an underestimation of ACrec in the largest sphere volume (26.5 ml) by − 13.9 kBq/ml (− 16.3%) and − 7.1 kBq/ml (− 8.4%), respectively. An increase in total iterations leads to an increase in estimated AC and a decrease in SNR. The mean difference between ACrec and known AC decreased with an increasing number of total iterations (e.g., for 20 iterations (2 iterations/10 subsets) = − 14.6 kBq/ml (− 17.1%), 240 iterations (24i/10s) = − 8.0 kBq/ml (− 9.4%), p < 0.0001). In parallel, the mean SNR decreased significantly from 2i/10s to 24i/10s by 76% (p < 0.0001). Conclusion Quantitative SPECT imaging is feasible with the used reconstruction algorithm and hybrid SPECT/CT, and its consistent implementation in diagnostics may provide perspectives for quantification in routine clinical practice (e.g., assessment of bone metabolism). When combining quantitative analysis and diagnostic imaging, we recommend using two different reconstruction protocols with task-specific optimized setups (quantitative vs. qualitative reconstruction). Furthermore, individual scatter correction significantly improves both quantitative and qualitative results. Supplementary Information The online version contains supplementary material available at 10.1186/s40658-021-00405-3.
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Affiliation(s)
- Dennis Kupitz
- Department of Radiology and Nuclear Medicine, University Hospital Magdeburg, Magdeburg, Germany.
| | - Heiko Wissel
- Department of Radiology and Nuclear Medicine, University Hospital Magdeburg, Magdeburg, Germany
| | - Jan Wuestemann
- Department of Radiology and Nuclear Medicine, University Hospital Magdeburg, Magdeburg, Germany
| | - Stephanie Bluemel
- Department of Nuclear Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Maciej Pech
- Department of Radiology and Nuclear Medicine, University Hospital Magdeburg, Magdeburg, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, Magdeburg, Germany
| | - Holger Amthauer
- Department of Nuclear Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Michael C Kreissl
- Department of Radiology and Nuclear Medicine, University Hospital Magdeburg, Magdeburg, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, Magdeburg, Germany
| | - Oliver S Grosser
- Department of Radiology and Nuclear Medicine, University Hospital Magdeburg, Magdeburg, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, Magdeburg, Germany
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Atkova EL, Magomedov MM, Maydanova AA, Magomedova NM. [Modern methods in diagnostics of lacrimal system vertical part obliteration]. Vestn Otorinolaringol 2021; 86:97-103. [PMID: 34269032 DOI: 10.17116/otorino20218603197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A review of the literature is devoted to the description of modern diagnostic methods that are directed at detecting lacrimal pathway obstruction. The presented analysis is based on the study of data from Russian and foreign literary sources on both routine and high-tech lacrimal system examination methods, as well as on authors' experience in studying the diagnostic efficiency of imaging methods such as lacrimal scintigraphy, computed tomography with lacrimal pathway contrasting, and also single photon emission computed tomography. The article gives information about the advantages and disadvantages of the presented methods, highlights the questions of the prospects of their usage in practical dacryology.
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Affiliation(s)
- E L Atkova
- Research Institute of Eye Diseases, Moscow, Russia
| | - M M Magomedov
- Pirogov Russian National Research Medical University, Moscow, Russia
| | - A A Maydanova
- Research Institute of Eye Diseases, Moscow, Russia.,Pirogov Russian National Research Medical University, Moscow, Russia
| | - N M Magomedova
- Pirogov Russian National Research Medical University, Moscow, Russia
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11
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Ramonaheng K, van Staden JA, du Raan H. The effect of calibration factors and recovery coefficients on 177Lu SPECT activity quantification accuracy: a Monte Carlo study. EJNMMI Phys 2021; 8:27. [PMID: 33738605 PMCID: PMC7973313 DOI: 10.1186/s40658-021-00365-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 02/08/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Different gamma camera calibration factor (CF) geometries have been proposed to convert SPECT data into units of activity concentration. However, no consensus has been reached on a standardised geometry. The CF is dependent on the selected geometry and is further affected by partial volume effects. This study investigated the effect of two CF geometries and their corresponding recovery coefficients (RCs) on the quantification accuracy of 177Lu SPECT images using Monte Carlo simulations. METHODS The CF geometries investigated were (i) a radioactive-sphere surrounded by non-radioactive water (sphere-CF) and (ii) a cylindrical phantom uniformly filled with radioactive water (cylinder-CF). Recovery coefficients were obtained using the sphere-CF and cylinder-CF, yielding the sphere-RC and cylinder-RC values, respectively, for partial volume correction (PVC). The quantification accuracy was evaluated using four different-sized spheres (15.6-65.4 ml) and a kidney model with known activity concentrations inside a cylindrical, torso and patient phantom. Images were reconstructed with the 3D OS-EM algorithm incorporating attenuation, scatter and detector-response corrections. Segmentation was performed using the physical size and a small cylindrical volume inside the cylinder for the sphere-CF and cylinder-CF, respectively. RESULTS The sphere quantification error (without PVC) was better for the sphere-CF (≤ - 5.54%) compared to the cylinder-CF (≤ - 20.90%), attributed to the similar geometry of the quantified and CF spheres. Partial volume correction yielded comparable results for the sphere-CF-RC (≤ 3.47%) and cylinder-CF-RC (≤ 3.53%). The accuracy of the kidney quantification was poorer (≤ 22.34%) for the sphere-CF without PVC compared to the cylinder-CF (≤ 2.44%). With PVC, the kidney quantification results improved and compared well for the sphere-CF-RC (≤ 3.50%) and the cylinder-CF-RC (≤ 3.45%). CONCLUSION The study demonstrated that upon careful selection of CF-RC combinations, comparable quantification errors (≤ 3.53%) were obtained between the sphere-CF-RC and cylinder-CF-RC, when all corrections were applied.
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Affiliation(s)
- Keamogetswe Ramonaheng
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa.
| | - Johannes A van Staden
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
| | - Hanlie du Raan
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
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12
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Marquis H, Deidda D, Gillman A, Willowson KP, Gholami Y, Hioki T, Eslick E, Thielemans K, Bailey DL. Theranostic SPECT reconstruction for improved resolution: application to radionuclide therapy dosimetry. EJNMMI Phys 2021; 8:16. [PMID: 33598750 PMCID: PMC7889770 DOI: 10.1186/s40658-021-00362-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 02/02/2021] [Indexed: 12/20/2022] Open
Abstract
Background SPECT-derived dose estimates in tissues of diameter less than 3× system resolution are subject to significant losses due to the limited spatial resolution of the gamma camera. Incorporating resolution modelling (RM) into the SPECT reconstruction has been proposed as a possible solution; however, the images produced are prone to noise amplification and Gibbs artefacts. We propose a novel approach to SPECT reconstruction in a theranostic setting, which we term SPECTRE (single photon emission computed theranostic reconstruction); using a diagnostic PET image, with its superior resolution, to guide the SPECT reconstruction of the therapeutic equivalent. This report demonstrates a proof in principle of this approach. Methods We have employed the hybrid kernelised expectation maximisation (HKEM) algorithm implemented in STIR, with the aim of producing SPECT images with PET-equivalent resolution. We demonstrate its application in both a dual 68Ga/177Lu IEC phantom study and a clinical example using 64Cu/67Cu. Results SPECTRE is shown to produce images comparable in accuracy and recovery to PET with minimal introduction of artefacts and amplification of noise. Conclusion The SPECTRE approach to image reconstruction shows improved quantitative accuracy with a reduction in noise amplification. SPECTRE shows great promise as a method of improving SPECT radioactivity concentrations, directly leading to more accurate dosimetry estimates in small structures and target lesions. Further investigation and optimisation of the algorithm parameters is needed before this reconstruction method can be utilised in a clinical setting.
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Affiliation(s)
- H Marquis
- Sydney Vital Translational Cancer Research Centre, Sydney, Australia.,Institute of Medical Physics, University of Sydney, Sydney, Australia
| | - D Deidda
- National Physical Laboratory, Teddington, UK
| | - A Gillman
- Australian e-Health Research Centre, CSIRO, Brisbane, Australia
| | - K P Willowson
- Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia
| | - Y Gholami
- Sydney Vital Translational Cancer Research Centre, Sydney, Australia.,Institute of Medical Physics, University of Sydney, Sydney, Australia.,Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - T Hioki
- Institute of Medical Physics, University of Sydney, Sydney, Australia
| | - E Eslick
- Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia
| | - K Thielemans
- Institute of Nuclear Medicine, University College London, London, UK
| | - D L Bailey
- Sydney Vital Translational Cancer Research Centre, Sydney, Australia. .,Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia. .,Faculty of Medicine and Health, University of Sydney, Sydney, Australia.
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13
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SPECT and SPECT/CT. Mol Imaging 2021. [DOI: 10.1016/b978-0-12-816386-3.00008-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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14
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Tomographic 99mTc radioactivity quantification in three-dimensional printed polymeric phantoms with bioinspired geometries. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2020.109130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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15
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Miyaji N, Miwa K, Tokiwa A, Ichikawa H, Terauchi T, Koizumi M, Onoguchi M. Phantom and clinical evaluation of bone SPECT/CT image reconstruction with xSPECT algorithm. EJNMMI Res 2020; 10:71. [PMID: 32601770 PMCID: PMC7324467 DOI: 10.1186/s13550-020-00659-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/10/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Two novel methods of image reconstruction, xSPECT Quant (xQ) and xSPECT Bone (xB), that use an ordered subset conjugate gradient minimizer (OSCGM) for SPECT/CT reconstruction have been proposed. The present study compares the performance characteristics of xQ, xB, and conventional Flash3D (F3D) reconstruction using images derived from phantoms and patients. METHODS A custom-designed body phantom for bone SPECT was scanned using a Symbia Intevo (Siemens Healthineers), and reconstructed xSPECT images were evaluated. The phantom experiments proceeded twice with different activity concentrations and sphere sizes. A phantom with 28-mm spheres containing a 99mTc-background and tumor-to-normal bone ratios (TBR) of 1, 2, 4, and 10 were generated, and convergence property against various TBR was evaluated across 96 iterations. A phantom with four spheres (13-, 17-, 22-, and 28-mm diameters), containing a 99mTc-background at TBR4, was also generated. The full width at half maximum of an imaged spinous process (10 mm), coefficients of variance (CV), contrast-to-noise ratio (CNR), and recovery coefficients (RC) were evaluated after reconstructing images of a spine using Flash 3D (F3D), xQ, and xB. We retrospectively analyzed images from 20 patients with suspected bone metastases (male, n = 13) which were acquired using [99mTc]Tc-(H)MDP SPECT/CT, then CV and standardized uptake values (SUV) at the 4th vertebral body (L4) were compared after xQ and xB reconstruction in a clinical setup. RESULTS Mean activity concentrations with various TBR converged according to increasing numbers of iterations. The spatial resolution of xB was considerably superior to xQ and F3D, and it approached almost the actual size regardless of the iteration numbers during reconstruction. The CV and RC were better for xQ and xB than for F3D. The CNR peaked at 24 iterations for xQ and 48 iterations for F3D and xB, respectively. The RC between xQ and xB significantly differed at lower numbers of iterations but were almost equivalent at higher numbers of iterations. The reconstructed xQ and xB images of the clinical patients showed a significant difference in the SUVmax and SUVpeak. CONCLUSIONS The reconstructed xQ and xB images were more accurate than those reconstructed conventionally using F3D. The xB for bone SPECT imaging offered essentially unchanged spatial resolution even when the numbers of iterations did not converge. The xB reconstruction further enhanced SPECT image quality using CT data. Our findings provide important information for understanding the performance characteristics of the novel xQ and xB algorithms.
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Affiliation(s)
- Noriaki Miyaji
- Department of Nuclear Medicine, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550 Japan
- Department of Quantum Medical Technology, Institute of Medical Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942 Japan
| | - Kenta Miwa
- Department of Radiological Sciences, School of Health Science, International University of Health and Welfare, 2600-1 Kitakanemaru, Ohtawara, Tochigi, 324-8501 Japan
| | - Ayaka Tokiwa
- Department of Radiological Sciences, School of Health Science, International University of Health and Welfare, 2600-1 Kitakanemaru, Ohtawara, Tochigi, 324-8501 Japan
| | - Hajime Ichikawa
- Department of Radiology, Toyohashi Municipal Hospital, 50, Aza Hachiken Nishi, Aotake–Cho, Toyohashi, Aichi 441-8570 Japan
| | - Takashi Terauchi
- Department of Nuclear Medicine, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550 Japan
| | - Mitsuru Koizumi
- Department of Nuclear Medicine, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550 Japan
| | - Masahisa Onoguchi
- Department of Quantum Medical Technology, Institute of Medical Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942 Japan
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16
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Ramonaheng K, van Staden JA, du Raan H. Validation of a Monte Carlo modelled gamma camera for Lutetium-177 imaging. Appl Radiat Isot 2020; 163:109200. [PMID: 32561041 DOI: 10.1016/j.apradiso.2020.109200] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/11/2020] [Accepted: 04/08/2020] [Indexed: 10/24/2022]
Abstract
This study validated a model of the Siemens Symbia T16 dual-head SPECT/CT gamma camera created using the Monte Carlo program SIMIND for 177Lu. The validation was done by comparing experimental and simulated gamma camera performance criteria tests for the 177Lu 208 keV photopeak with a medium-energy collimator. Results showed good agreement between the experimental and simulated values. These results illustrated that SIMIND could emulate the Symbia T16 successfully and therefore, can be used with confidence to model 177Lu images.
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Affiliation(s)
- K Ramonaheng
- Department of Medical Physics, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa.
| | - J A van Staden
- Department of Medical Physics, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
| | - H du Raan
- Department of Medical Physics, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
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17
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Si-Mohamed S, Moreau-Triby C, Tylski P, Tatard-Leitman V, Wdowik Q, Boccalini S, Dessouky R, Douek P, Boussel L. Head-to-head comparison of lung perfusion with dual-energy CT and SPECT-CT. Diagn Interv Imaging 2020; 101:299-310. [PMID: 32173289 DOI: 10.1016/j.diii.2020.02.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/10/2020] [Accepted: 02/11/2020] [Indexed: 02/06/2023]
Abstract
PURPOSE To compare the quantitative and qualitative lung perfusion data acquired with dual energy CT (DECT) to that acquired with a large field-of-view cadmium-zinc-telluride camera single-photon emission CT coupled to a CT system (SPECT-CT). MATERIALS AND METHODS A total of 53 patients who underwent both dual-layer DECT angiography and perfusion SPECT-CT for pulmonary hypertension or pre-operative lobar resection surgery were retrospectively included. There were 30 men and 23 women with a mean age of 65.4±17.5 (SD)years (range: 18-88years). Relative lobar perfusion was calculated by dividing the amount (of radiotracer or iodinated contrast agent) per lobe by the total amount in both lungs. Linear regression, Bland-Altman analysis, and Pearson's correlation coefficient were also calculated. Kappa test was used to test agreements in morphology and severity of perfusion defects assessed on SPECT-CT and on DECT iodine maps with a one-month interval. Wilcoxon rank sum test was used to compare the sharpness of perfusion defects and radiation dose among modalities. RESULTS Strong correlations for relative lobar perfusion using linear regression analysis and Pearson's correlation coefficient (r=0.93) were found. Bland-Altman analysis revealed a -0.10 bias, with limits of agreement between [-6.01; 5.81]. With respect to SPECT- CT as standard of reference, the sensitivity, specificity, PPV, NPV, accuracy for lobar perfusion defects were 89.4% (95%
CI: 82.6-93.4%), 96.5% (95% CI: 92.1-98.5%), 95.6% (95% CI:
90.9-97.8%), 91.4% (95% CI: 85.6-94.9%) and 93.0% (95% CI:
87.6-96.1%) respectively. High level of agreement was found for morphology and severity of perfusion defects between modalities (Kappa=0.84 and 0.86 respectively) and on DECT images among readers (Kappa=0.94 and 0.89 respectively). A significantly sharper delineation of perfusion defects was found on DECT images (P<0.0001) using a significantly lower equivalent dose of 4.1±2.3 (SD) mSv (range: 1.9-11.85mSv) compared to an equivalent dose of 5.3±1.1 (SD) mSv (range: 2.8-7.3mSv) for SPECT-CT, corresponding to a 21.2% dose reduction (P=0.0004). CONCLUSION DECT imaging shows strong quantitative correlations and qualitative agreements with SPECT-CT for the evaluation of lung perfusion.
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Affiliation(s)
- S Si-Mohamed
- Department of Radiology, Hospices Civils de Lyon, 69500 Bron, France; Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, 69621 Lyon, France.
| | - C Moreau-Triby
- Department of Nuclear Medicine, Hospices Civils de Lyon, 69500 Bron, France
| | - P Tylski
- Medical Physics and Radioprotection, Hospices Civils de Lyon, 69500 Bron, France
| | - V Tatard-Leitman
- Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, 69621 Lyon, France
| | - Q Wdowik
- Department of Radiology, Hospices Civils de Lyon, 69500 Bron, France
| | - S Boccalini
- Department of Radiology, Hospices Civils de Lyon, 69500 Bron, France
| | - R Dessouky
- Department of Radiology, Faculty of Medicine, Zagazig University, 44519 Zagazig, Egypt
| | - P Douek
- Department of Radiology, Hospices Civils de Lyon, 69500 Bron, France; Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, 69621 Lyon, France
| | - L Boussel
- Department of Radiology, Hospices Civils de Lyon, 69500 Bron, France; Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, 69621 Lyon, France
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18
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Frezza A, Desport C, Uribe C, Zhao W, Celler A, Després P, Beauregard JM. Comprehensive SPECT/CT system characterization and calibration for 177Lu quantitative SPECT (QSPECT) with dead-time correction. EJNMMI Phys 2020; 7:10. [PMID: 32060777 PMCID: PMC7021856 DOI: 10.1186/s40658-020-0275-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/26/2020] [Indexed: 12/31/2022] Open
Abstract
Background Personalization of 177Lu-based radionuclide therapy requires implementation of dosimetry methods that are both accurate and practical enough for routine clinical use. Quantitative single-photon emission computed tomography/computed tomography (QSPECT/CT) is the preferred scanning modality to achieve this and necessitates characterizing the response of the camera, and calibrating it, over the full range of therapeutic activities and system capacity. Various methods to determine the camera calibration factor (CF) and the deadtime constant (τ) were investigated, with the aim to design a simple and robust protocol for quantitative 177Lu imaging. Methods The SPECT/CT camera was equipped with a medium energy collimator. Multiple phantoms were used to reproduce various attenuation conditions: rod sources in air or water-equivalent media, as well as a Jaszczak phantom with inserts. Planar and tomographic images of a wide range of activities were acquired, with multiple energy windows for scatter correction (double or triple energy window technique) as well as count rate monitoring over a large spectrum of energy. Dead time was modelled using the paralysable model. CF and τ were deduced by curve fitting either separately in two steps (CF determined first using a subset of low-activity acquisitions, then τ determined using the full range of activity) or at once (both CF and τ determined using the full range of activity). Total or segmented activity in the SPECT field of view was computed. Finally, these methods were compared in terms of accuracy to recover the known activity, in particular when planar-derived parameters were applied to the SPECT data. Results The SPECT camera was shown to operate as expected on a finite count rate range (up to ~ 350 kcps over the entire energy spectrum). CF and τ from planar (sources in air) and SPECT segmented Jaszczak data yielded a very good agreement (CF < 1% and τ < 3%). Determining CF and τ from a single curve fit made dead-time-corrected images less prone to overestimating recovered activity. Using triple-energy window scatter correction while acquiring one or more additional energy window(s) to enable wide-spectrum count rate monitoring (i.e. ranging 55–250 or 18–680 keV) yielded the most consistent results across the various geometries. The final, planar-derived calibration parameters for our system were a CF of 9.36 ± 0.01 cps/MBq and a τ of 0.550 ± 0.003 μs. Using the latter, the activity in a Jaszczak phantom could be quantified by QSPECT with an accuracy of 0.02 ± 1.10%. Conclusions Serial planar acquisitions of sources in air using an activity range covering the full operational capacity of the SPECT/CT system, with multiple energy windows for wide-spectrum count rate monitoring, and followed by simultaneous determination of CF and τ using a single equation derived from the paralysable model, constitutes a practical method to enable accurate dead-time-corrected QSPECT imaging in a post-177Lu radionuclide therapy setting.
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Affiliation(s)
- Andrea Frezza
- Cancer Research Center, Université Laval, Quebec City, QC, Canada.,Department of Physics, Engineering Physics and Optics, Université Laval, Quebec City, QC, Canada.,Oncology Division, CHU de Québec - Université Laval Research Center, Quebec City, QC, Canada
| | - Corentin Desport
- Cancer Research Center, Université Laval, Quebec City, QC, Canada.,Department of Physics, Engineering Physics and Optics, Université Laval, Quebec City, QC, Canada.,Oncology Division, CHU de Québec - Université Laval Research Center, Quebec City, QC, Canada
| | - Carlos Uribe
- Functional Imaging Department, BC Cancer, Vancouver, BC, Canada
| | - Wei Zhao
- Medical Imaging Research Group, Department of Radiology, University of British Columbia, Vancouver, BC, Canada
| | - Anna Celler
- Medical Imaging Research Group, Department of Radiology, University of British Columbia, Vancouver, BC, Canada
| | - Philippe Després
- Cancer Research Center, Université Laval, Quebec City, QC, Canada.,Department of Physics, Engineering Physics and Optics, Université Laval, Quebec City, QC, Canada.,Oncology Division, CHU de Québec - Université Laval Research Center, Quebec City, QC, Canada.,Department of Radiation Oncology, CHU de Québec - Université Laval, Quebec City, QC, Canada
| | - Jean-Mathieu Beauregard
- Cancer Research Center, Université Laval, Quebec City, QC, Canada. .,Oncology Division, CHU de Québec - Université Laval Research Center, Quebec City, QC, Canada. .,Department of Radiology and Nuclear Medicine, Université Laval, Quebec City, QC, Canada. .,Department of Medical Imaging, CHU de Québec - Université Laval, 11 côte du Palais, Quebec City, QC, G1R 2J6, Canada.
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Abstract
The continuous development of SPECT over the past 50 years has led to improved image quality and increased diagnostic confidence. The most influential developments include the realization of hybrid SPECT/CT devices, as well as the implementation of attenuation correction and iterative image reconstruction techniques. These developments have led to a preference for SPECT/CT devices over SPECT-only systems and to the widespread adoption of the former, strengthening the role of SPECT/CT as the workhorse of Nuclear Medicine imaging. New trends in the ongoing development of SPECT/CT are diverse. For example, whole-body SPECT/CT images, consisting of acquisitions from multiple consecutive bed positions in the manner of PET/CT, are increasingly performed. Additionally, in recent years, some interesting approaches in detector technology have found their way into commercial products. For example, some SPECT cameras dedicated to specific organs employ semiconductor detectors made of cadmium telluride or cadmium zinc telluride, which have been shown to increase the obtainable image quality by offering a higher sensitivity and energy resolution. However, the advent of quantitative SPECT/CT which, like PET, can quantify the amount of tracer in terms of Bq/mL or as a standardized uptake value could be regarded as most important development. It is a major innovation that will lead to increased diagnostic accuracy and confidence, especially in longitudinal studies and in the monitoring of treatment response. The current work comprises two main aspects. At first, physical and technical fundamentals of SPECT image formation are described and necessary prerequisites of quantitative SPECT/CT are reviewed. Additionally, the typically achievable quantitative accuracy based on reports from the literature is given. Second, an extensive list of studies reporting on clinical applications of quantitative SPECT/CT is provided and reviewed.
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Affiliation(s)
- Philipp Ritt
- Clinic of Nuclear Medicine, University Hospital Erlangen, Ulmenweg 18, 91054, Erlangen, Germany.
| | - Torsten Kuwert
- Clinic of Nuclear Medicine, University Hospital Erlangen, Ulmenweg 18, 91054, Erlangen, Germany
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20
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Brady SL, Shulkin BL. Analysis of quantitative [I-123] mIBG SPECT/CT in a phantom and in patients with neuroblastoma. EJNMMI Phys 2019; 6:31. [PMID: 31889238 PMCID: PMC6937351 DOI: 10.1186/s40658-019-0267-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 12/02/2019] [Indexed: 11/13/2022] Open
Abstract
Purpose To determine the accuracy of quantitative SPECT, intersystem and interpatient standardized uptake value (SUV) calculation consistency for a manufacturer-independent quantitative SPECT/CT reconstruction algorithm, and the range of SUVs of normal and neoplastic tissue. Methods A NEMA body phantom with 6 spheres (ranging 10–37 mm) was filled with a known activity-to-volume ratio and used to determine the contrast recovery coefficient (CRC) for each visible sphere, and the measured SUV accuracy of those spheres and background water solution. One hundred eleven 123I-metaiodobenzylguanidine ([I-123] mIBG) SPECT/CT examinations from 43 patients were reconstructed using SUV SPECT® (HERMES Medical Solutions Inc.); 42 examinations were acquired using a GE Infinia Hawkeye 4 SPECT/CT, and 69 were acquired on a Siemens Symbia Intevo SPECT/CT. Inter scanner SUV analysis of 9 regions of normal [I-123] mIBG tissue uptake was conducted. Intrapatient mean SUV variability was calculated by measuring normal liver uptake within patients scanned on both cameras. The intensity of uptake by neoplastic tissue in the images was quantified using maximum SUV and, if present, compared over time. Results The phantom results of the visible spheres and background resulted in accuracy calculations better than 5–10% with CRC correction. Interscanner SUV variability showed no statistical difference (average p value 0.559; range 0.066–1.0) among the 9 normal tissues analyzed. Intrapatient liver mean SUV varied ≤ 16% as calculated for 28 patients (87 examinations) studied on both scanners. In one patient, a thoracic tumor evaluated over 10 time points (18 months) underwent a 74% (3.1/12.0) reduction in maximum SUV with treatment. Conclusion The results demonstrate quantitative accuracy to better than 10%, and both consistent SUV calculation between 2 different SPECT/CT scanners for 9 tissues, and low intrapatient measurement variability for quantitative SPECT/CT analysis in a pediatric population with neuroblastoma. Quantitative SPECT/CT offers the opportunity for objective analysis of tumor response using [I-123] mIBG by normalizing the uptake to injected dose and patient weight, as is done for PET.
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Affiliation(s)
- Samuel L Brady
- Department of Radiology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, 45229, USA
| | - Barry L Shulkin
- Department of Diagnostic Imaging MS 220, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105-3678, USA.
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21
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Tran-Gia J, Salas-Ramirez M, Lassmann M. What You See Is Not What You Get: On the Accuracy of Voxel-Based Dosimetry in Molecular Radiotherapy. J Nucl Med 2019; 61:1178-1186. [PMID: 31862802 DOI: 10.2967/jnumed.119.231480] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 12/11/2019] [Indexed: 11/16/2022] Open
Abstract
Improvements in quantitative SPECT/CT have aroused growing interest in voxel-based dosimetry for radionuclide therapies, because it promises visualization of absorbed doses at a voxel level. In this work, SPECT/CT-based voxel-level dosimetry of a 3-dimensional (3D) printed 2-compartment kidney phantom was performed, and the resulting absorbed dose distributions were examined. Additionally, the potential of the PETPVC partial-volume correction tool was investigated. Methods: Both kidney compartments (70% cortex, 30% medulla) were filled with different activity concentrations, and SPECT/CT imaging was performed. The images were reconstructed using varying settings (iterations, subsets, and postfiltering). On the basis of these activity concentration maps, absorbed dose distributions were calculated with precalculated 177Lu voxel S values and an empiric kidney half-life. An additional set of absorbed doses was calculated after applying PETPVC for partial-volume correction of the SPECT reconstructions. Results: SPECT/CT imaging blurs the 2 discrete suborgan absorbed dose values into a continuous distribution. Although this effect is slightly improved by applying more iterations, it is enhanced by additional postfiltering. By applying PETPVC, the absorbed dose values are separated into 2 peaks. Although this leads to a better agreement between SPECT/CT-based and nominal values, considerable discrepancies remain. In contrast to the calculated nominal absorbed doses of 7.8 and 1.6 Gy (in the cortex and medulla, respectively), SPECT/CT-based voxel-level dosimetry resulted in mean absorbed doses of 3.0-6.6 Gy (cortex) and 2.7-5.1 Gy (medulla). PETPVC led to improved ranges of 6.1-8.9 Gy (cortex) and 2.1-5.4 Gy (medulla). Conclusion: Our study showed that 177Lu quantitative SPECT/CT imaging leads to voxel-based dose distributions largely differing from the real organ distribution. SPECT/CT imaging and reconstruction deficiencies might directly translate into unrealistic absorbed dose distributions, thus questioning the reliability of SPECT-based voxel-level dosimetry. Therefore, SPECT/CT reconstructions should be adapted to ensure an accurate quantification of the underlying activity and, therefore, absorbed dose in a volume of interest of the expected object size (e.g., organs, organ substructures, lesions, or voxels). As an example, PETPVC largely improves the match between SPECT/CT-based and nominal dose distributions. In conclusion, the concept of voxel-based dosimetry should be treated with caution. Specifically, one should remember that the absorbed dose distribution is mainly a convolved version of the underlying SPECT reconstruction.
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Affiliation(s)
- Johannes Tran-Gia
- Department of Nuclear Medicine, University of Würzburg, Würzburg, Germany
| | | | - Michael Lassmann
- Department of Nuclear Medicine, University of Würzburg, Würzburg, Germany
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Adusumilli P, Nejadhamzeeigilani H, Pitts K, McDermott G, Scarsbrook AF, Vaidyanathan S, Patel CN, Chowdhury FU. Protocol-driven multidetector SPECT/CT: integration of hybrid imaging into the routine workflow of whole-body bone scintigraphy in oncology patients. Clin Radiol 2019; 75:79.e1-79.e7. [PMID: 31601386 DOI: 10.1016/j.crad.2019.09.128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 09/06/2019] [Indexed: 10/25/2022]
Abstract
AIM To analyse the additional clinical value of protocol-driven and selective use of multidetector single-photon-emission tomography/computed tomography (SPECT/CT) in oncology patients undergoing whole-body bone scintigraphy (BS) and to analyse reporter confidence in diagnosis with and without SPECT/CT. MATERIALS AND METHODS During a 2-year period, 2,954 whole-body BS examinations were performed in oncology patients, with 444 (15%) undergoing additional protocol-driven SPECT/CT. Retrospective evaluation of planar BS and SPECT/CT images was performed by two experienced dual-trained nuclear medicine radiologists. The BS and SPECT/CT images were graded blindly using a five-point scale designed to evaluate the likelihood of a lesion being benign or malignant. Interpretation was applied on a per-patient basis. RESULTS There was a 74.5% increase in definitive diagnostic classification and a 26.6% reduction in equivocal findings with SPECT/CT when compared to BS alone (p<0001). Of cases initially classified as "probably benign" on BS, 5.1% (10/193) were reclassified to "probably malignant" (1%) or "malignant" (4.1%) using the SPECT/CT data. The highest impact in reporter confidence was seen with SPECT/CT in the interpretation of lesions within the pelvis (34%), ribs (23%), lumbar spine (22%), and thoracic spine (21%). CONCLUSION Protocol-driven, selective use of SPECT/CT imaging to augment planar BS reduces equivocal findings and improves reporter confidence whilst minimising the impact on patient and reporting workflows.
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Affiliation(s)
- P Adusumilli
- Department of Clinical Radiology, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | | | - K Pitts
- Department of Nuclear Medicine, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - G McDermott
- Department of Medical Physics, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - A F Scarsbrook
- Department of Clinical Radiology, Leeds Teaching Hospitals NHS Trust, Leeds, UK; Department of Nuclear Medicine, Leeds Teaching Hospitals NHS Trust, Leeds, UK; Leeds Institute of Health Research, University of Leeds, Leeds, UK
| | - S Vaidyanathan
- Department of Clinical Radiology, Leeds Teaching Hospitals NHS Trust, Leeds, UK; Department of Nuclear Medicine, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - C N Patel
- Department of Clinical Radiology, Leeds Teaching Hospitals NHS Trust, Leeds, UK; Department of Nuclear Medicine, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - F U Chowdhury
- Department of Clinical Radiology, Leeds Teaching Hospitals NHS Trust, Leeds, UK; Department of Nuclear Medicine, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
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Bailey DL, Roach PJ. A Brief History of Lung Ventilation and Perfusion Imaging Over the 50-Year Tenure of the Editors of Seminars in Nuclear Medicine. Semin Nucl Med 2019; 50:75-86. [PMID: 31843063 DOI: 10.1053/j.semnuclmed.2019.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The ventilation/perfusion lung scan has been in continuous use for approximately half a century, the same lifetime as Seminars in Nuclear Medicine. Remarkably, the founding Editors-in-Chief have continued to guide the journal over this entire period. In this Feschrift issue celebrating their enormous contribution, we review the history of the lung scan, its highs and lows, the transition from planar to SPECT/CT V/Q scans, and the future that is in store in this age of multimodality functional imaging. We concur with the published view of one of the retiring editors (LMF) that V/Q scintigraphy is indeed alive and well and has a definite future in clinical medicine.
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Affiliation(s)
- Dale L Bailey
- Royal North Shore Hospital, Department of Nuclear Medicine, Sydney, Australia; University of Sydney, Faculty of Medicine & Health, Sydney, Australia.
| | - Paul J Roach
- Royal North Shore Hospital, Department of Nuclear Medicine, Sydney, Australia; University of Sydney, Faculty of Medicine & Health, Sydney, Australia
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Ryu H, Meikle SR, Willowson KP, Eslick EM, Bailey DL. Performance evaluation of quantitative SPECT/CT using NEMA NU 2 PET methodology. ACTA ACUST UNITED AC 2019; 64:145017. [DOI: 10.1088/1361-6560/ab2a22] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Willowson KP, Eslick E, Ryu H, Poon A, Bernard EJ, Bailey DL. Feasibility and accuracy of single time point imaging for renal dosimetry following 177Lu-DOTATATE ('Lutate') therapy. EJNMMI Phys 2018; 5:33. [PMID: 30569328 PMCID: PMC6300448 DOI: 10.1186/s40658-018-0232-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 11/19/2018] [Indexed: 12/16/2022] Open
Abstract
Background This study aims to assess both feasibility and accuracy of renal dosimetry imaging protocols in patients receiving Lutate therapy for neuroendocrine tumours (NETs), when data acquisition over multiple days is not possible on all cycles. Method Patients who had received a full 4 cycles of Lutate therapy with complete imaging at each cycle were included. Imaging consisted of quantitative SPECT/CT of the kidneys at 4, 24 and 96–120 h post injection. Renal absorbed dose was calculated for each data set, and in addition, five alternative methods were explored for comparison. Method 1: a patient average clearance time (t1/2 average) derived from the first half of contributing patient data was used to estimate absorbed dose for subsequent patients based on 4 h imaging alone; method 2: t1/2 average was applied to subsequent patients on 24 h imaging alone; method 3: a patient-specific clearance rate (t1/2 patient) was determined from complete image data of cycle 1 and applied subsequently to remaining cycles using 4 h image data alone; method 4: t1/2 patient was applied to 24 h imaging alone in subsequent cycles; method 5: the 120 h data was estimated on subsequent cycles based on the cycle 1 fraction of injected activity (%IA) at 24 and 120 h. Results Twenty treatments from 18 patients, resulting in 80 cycles of therapy, were analysed. The measured average renal absorbed dose per cycle of treatment was 0.38 ± 0.19 Gy/GBq when derived from full imaging data. The use of t1/2 average applied to a single time point led to large deviations of dose estimates from true values (on average 59% and 30%, when using 4 h data and 24 h data, respectively). The use of complete image data on cycle 1 and the derivation of t1/2 patient led to improved dose estimates, with an average deviation from true values of 13% and 2% when using 4 h data only and 24 h data only, respectively. The use of a 120 h %IA derived from cycle 1 led to an average deviation from true dose estimates of 14%. Conclusion In instances where demands on both patients and facilities make multiple time point data acquisition impractical, renal dosimetry is best derived through complete imaging at cycle 1 only followed by a single 24 h imaging time point on subsequent cycles, assuming no significant changes in renal function during the time course of therapy.
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Affiliation(s)
- Kathy P Willowson
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia. .,Institute of Medical Physics, The University of Sydney, Camperdown, NSW, 2006, Australia.
| | - Enid Eslick
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia
| | - Hyunju Ryu
- Faculty of Health Sciences, The University of Sydney, Lidcombe, NSW, 2141, Australia
| | - Aurora Poon
- Department of Molecular Imaging and Therapy, The Austin Hospital, Heidelberg, VIC, 3084, Australia
| | - Elizabeth J Bernard
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia
| | - Dale L Bailey
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia.,Faculty of Health Sciences, The University of Sydney, Lidcombe, NSW, 2141, Australia
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Karimi Ghodoosi E, D'Alessandria C, Li Y, Bartel A, Köhner M, Höllriegl V, Navab N, Eiber M, Li WB, Frey E, Ziegler S. The effect of attenuation map, scatter energy window width, and volume of interest on the calibration factor calculation in quantitative 177Lu SPECT imaging: Simulation and phantom study. Phys Med 2018; 56:74-80. [DOI: 10.1016/j.ejmp.2018.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 11/07/2018] [Accepted: 11/15/2018] [Indexed: 10/27/2022] Open
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Willowson KP, Ryu H, Jackson P, Singh A, Eslick E, Bailey DL. A Comparison of 2D and 3D Kidney Absorbed Dose Measures in Patients Receiving 177Lu-DOTATATE. ASIA OCEANIA JOURNAL OF NUCLEAR MEDICINE & BIOLOGY 2018; 6:113-119. [PMID: 29998144 PMCID: PMC6038968 DOI: 10.22038/aojnmb.2018.26105.1182] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Objective(s): To investigate and compare quantitative accuracy of kidney absorbed dose measures made from both 2D and 3D imaging in patients receiving 177Lu-DOTATATE (Lutate) for treatment of neuroendocrine tumours (NETs). Methods: Patients receiving Lutate therapy underwent both whole body planar imaging and SPECT/CT imaging over the kidneys at time points 0.5, 4, 24, and 96-120 hours after injection. Planar data were corrected for attenuation using transmission data, and were converted to units of absolute activity via two methods, using either a calibration standard in the field of view or relative to pre-voiding image total counts. Hand drawn regions of interest were used to generate time activity curves and kidney absorbed dose estimates in OLINDA-EXM. Fully quantitative SPECT data were generated using CT-derived corrections for both scatter and attenuation, before correction for dead time and application of a camera specific sensitivity factor to convert data to units of absolute activity. Volumes of interest were defined for kidney using the co-registered x-ray CT, before time activity curves and absorbed dose measures were generated in OLINDA-EXM, both with and without corrections made to the model for patient specific kidney volumes. Quantitative SPECT data were also used to derive dose maps through dose kernel convolution (DKC), which was treated as the gold standard. Results: A total of 50 studies were analysed, corresponding to various cycles of treatment from 21 patients. Planar absorbed dose estimates were consistently higher than SPECT derived estimates by, on average, a factor of 3. Conclusion: Quantitative SPECT is considered the gold standard approach for organ specific dosimetry however often relies on in house software. As such planar methods for estimating absorbed dose are much more widely available, and in particular, are often the only source of reference in previously published data. For the case of Lutate dosimetry, planar measures may lead to a three-fold increase in measures of kidney absorbed dose.
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Affiliation(s)
- Kathy P Willowson
- Institute of Medical Physics, School of Physics, University of Sydney, Camperdown, NSW Australia
| | - HyunJu Ryu
- Faculty of Health Sciences, University of Sydney, Cumberland, NSW Australia
| | - Price Jackson
- Department of Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, VIC Australia
| | - Anita Singh
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW Australia
| | - Enid Eslick
- Institute of Medical Physics, School of Physics, University of Sydney, Camperdown, NSW Australia
| | - Dale L Bailey
- Faculty of Health Sciences, University of Sydney, Cumberland, NSW Australia.,Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW Australia
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Tran-Gia J, Lassmann M. Characterization of Noise and Resolution for Quantitative 177Lu SPECT/CT with xSPECT Quant. J Nucl Med 2018; 60:50-59. [DOI: 10.2967/jnumed.118.211094] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 06/14/2018] [Indexed: 12/29/2022] Open
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Halty A, Badel JN, Kochebina O, Sarrut D. Image-based SPECT calibration based on the evaluation of the Fraction of Activity in the Field of View. EJNMMI Phys 2018; 5:11. [PMID: 29766354 PMCID: PMC5953912 DOI: 10.1186/s40658-018-0209-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 03/16/2018] [Indexed: 11/27/2022] Open
Abstract
Background SPECT quantification is important for dosimetry in targeted radionuclide therapy (TRT) and the calibration of SPECT images is a crucial stage for image quantification. The current standardized calibration protocol (MIRD 23) uses phantom acquisitions to derive a global calibration factor in specific conditions. It thus requires specific acquisitions for every clinical protocols. We proposed an alternative and complementary image-based calibration method that allows to determine a calibration factor adapted to each patient, radionuclide, and acquisition protocol and that may also be used as an additional independent calibration. Results The proposed method relies on a SPECT/CT acquisition of a given region of interest and an initial whole-body (WB) planar image. First, the conjugate view of WB planar images is computed after scatter and attenuation correction. 3D SPECT images are reconstructed with scatter, attenuation, and collimator-detector response (CDR) corrections and corrected from apparent dead-time. The field of view (FOV) of the SPECT image is then projected on the corrected WB planar image. The fraction of activity located in the area corresponding to the SPECT FOV is then calculated based on the counts on the corrected WB planar image. The Fraction of Activity in Field Of View (FAF) is then proposed to compute the calibration factor as the total number of counts in the SPECT image divided by this activity. Quantification accuracy was compared with the standard calibration method both with phantom experiments and on patient data. Both standard and image-based calibrations give good accuracy on large region of interest on phantom experiments (less than 7% of relative difference compared to ground truth). Apparent dead-time correction allows to reduce the uncertainty associated with standard calibration from 2.5 to 1%. The differences found between both methods were lower than the uncertainty range of the standard calibration (<3%). In patient data, although no ground truth was available, both methods give similar calibration factor (average difference 3.64%). Conclusions A calibration factor may be computed directly from the acquired SPECT image providing that a WB planar image is also available and if both acquisitions are performed before biological elimination. This method does not require to perform phantom acquisition for every different acquisition conditions and may serve to double check the calibration with an independent factor.
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Affiliation(s)
- Adrien Halty
- Univ Lyon, INSA-Lyon, Université Lyon 1, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, 69008, France. .,Univ Lyon, Centre Léon Bérard, Lyon, 69008, France.
| | | | - Olga Kochebina
- Univ Lyon, INSA-Lyon, Université Lyon 1, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, 69008, France
| | - David Sarrut
- Univ Lyon, INSA-Lyon, Université Lyon 1, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, 69008, France.,Univ Lyon, Centre Léon Bérard, Lyon, 69008, France
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Determination of gamma camera calibration factors for quantitation of therapeutic radioisotopes. EJNMMI Phys 2018; 5:8. [PMID: 29717385 PMCID: PMC5930296 DOI: 10.1186/s40658-018-0208-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 02/23/2018] [Indexed: 01/23/2023] Open
Abstract
Background Camera calibration, which translates reconstructed count map into absolute activity map, is a prerequisite procedure for quantitative SPECT imaging. Both planar and tomographic scans using different phantom geometries have been proposed for the determination of the camera calibration factor (CF). However, there is no consensus on which approach is the best. The aim of this study is to evaluate all these calibration methods, compare their performance, and propose a practical and accurate calibration method for SPECT quantitation of therapeutic radioisotopes. Twenty-one phantom experiments (Siemens Symbia SPECT/CT) and 12 Monte Carlo simulations (GATE v6.1) using three therapy isotopes (131I, 177Lu, and 188Re) have been performed. The following phantom geometries were used: (1) planar scans of point source in air (PS), (2) tomographic scans of insert(s) filled with activity placed in non-radioactive water (HS + CB), (3) tomographic scans of hot insert(s) in radioactive water (HS + WB), and (4) tomographic scans of cylinders uniformly filled with activity (HC). Tomographic data were reconstructed using OSEM with CT-based attenuation correction and triple energy window (TEW) scatter correction, and CF was determined using total counts in the reconstructed image, while for planar scans, the photopeak counts, corrected for scatter and background with TEW, were used. Additionally, for simulated data, CF obtained from primary photons only was analyzed. Results For phantom experiments, CF obtained from PS and HS + WB agreed to within 6% (below 3% if experiments performed on the same day are considered). However, CF from HS + CB exceeded those from PS by 4–12%. Similar trend was found in simulation studies. Analysis of CFs from primary photons helped us to understand this discrepancy. It was due to underestimation of scatter by the TEW method, further enhanced by attenuation correction. This effect becomes less important when the source is distributed over the entire phantom volume (HS + WB and HC). Conclusions Camera CF could be determined using planar scans of a point source, provided that the scatter and background contributions are removed, for example using the clinically available TEW method. This approach is simple and yet provides CF with sufficient accuracy (~ 5%) to be used in clinics for radiotracer quantification.
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Dittmann H, Kopp D, Kupferschlaeger J, Feil D, Groezinger G, Syha R, Weissinger M, la Fougère C. A Prospective Study of Quantitative SPECT/CT for Evaluation of Lung Shunt Fraction Before SIRT of Liver Tumors. J Nucl Med 2018; 59:1366-1372. [DOI: 10.2967/jnumed.117.205203] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 01/05/2018] [Indexed: 12/26/2022] Open
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Wieder H, Czernin J, Navar BN, Israel O, Beyer T, Freudenberg LS. Variations of clinical SPECT/CT operations. Nuklearmedizin 2017; 51:154-60. [DOI: 10.3413/nukmed-0467-12-01] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 03/14/2012] [Indexed: 02/05/2023]
Abstract
SummaryAim: This survey gathers information about clinical SPECT/CT operations worldwide to help guide standardization of clinical SPECT/ CT imaging. Methods: An international, webbased survey of SPECT/CT users was initiated in 12/2010 through an e-mail distribution. Users were asked 71 questions related to (A) demographics, (B) SPECT/CT operations/utilization and (C) variations in imaging protocols. Results: Collected responses originated from 117 imaging centers in the Americas (66%), Europe (20%), Asia-Pacific (11%) and the Middle-East (3%), with the majority of responding sites representing public health care institutions (69%). Most sites operate 1–2 SPECT/CT-systems (74%), typically installed in Nuclear Medicine departments (84%) with extensive prior SPECT-only experience (82%). Only 14% of SPECT/CTs are installed in Radiology departments. Clinical SPECT/CT imaging is performed either as routine (51%) or ad-hoc “add-on” procedure (49%) with a high inter-site and inter-examination variability. The main application of the integrated CT is to provide anatomical localization of the tracer uptake rather than to produce contrast enhanced or other high-quality CT images. Consequently, in only 22% of the sites a CT contrast injector is installed. Only 6% of centers use SPECT/CT devices for stand-alone CT procedures. Conclusion: An international survey among clinical SPECT/CT users revealed that SPECT/CT is a not a routine component of nuclear medicine procedures. The majority of the centers responding do not fully utilize the diagnostic potential of the CT components. Significant variations in standard imaging protocols were observed. These findings illustrate the need for training and standardization and underscore the need for revisiting the role of SPECT/CT in diagnostic imaging.
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Tran-Gia J, Lassmann M. Optimizing Image Quantification for 177Lu SPECT/CT Based on a 3D Printed 2-Compartment Kidney Phantom. J Nucl Med 2017; 59:616-624. [PMID: 29097409 DOI: 10.2967/jnumed.117.200170] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/16/2017] [Indexed: 01/18/2023] Open
Abstract
The aim of this work was to find an optimal setup for activity determination of 177Lu-based SPECT/CT imaging reconstructed with 2 commercially available methods (xSPECT Quant and Flash3D). For this purpose, 3-dimensional (3D)-printed phantoms of different geometries were manufactured, different partial-volume correction (PVC) methods were applied, and the accuracy of the activity determination was evaluated. Methods: A 2-compartment kidney phantom (70% cortical and 30% medullary compartment), a sphere, and an ellipsoid of equal volumes were 3D printed, filled with 177Lu, and scanned with a SPECT/CT system. Reconstructions were performed with xSPECT and Flash3D. Different PVC methods were applied to find an optimal quantification setup: method 1 was a geometry-specific recovery coefficient based on the 3D printing model, method 2 was a geometry-specific recovery coefficient based on the low-dose CT scan, method 3 was an enlarged volume of interest including spilled-out counts, method 4 was activity concentration in the peak milliliter applied to the entire CT-based volume, and method 5 was a fixed threshold of 42% of the maximum in a large volume containing the object of interest. Additionally, the influence of postreconstruction gaussian filtering was investigated. Results: Although the recovery coefficients of sphere and ellipsoid differed by only 0.7%, a difference of 31.7% was observed between the sphere and the renal cortex phantoms. Without postfiltering, the model-based recovery coefficients (methods 1 and 2) resulted in the best accuracies (xSPECT, 1.5%; Flash3D, 10.3%), followed by the enlarged volume (method 3) (xSPECT, 8.5%; Flash3D, 13.0%). The peak-milliliter method (method 4) showed large errors only for sphere and ellipsoid (xSPECT, 23.4%; Flash3D, 21.6%). Applying a 42% threshold (method 5) led to the largest quantification errors (xSPECT, 32.3%; Flash3D, 46.7%). After postfiltering, a general increase in the errors was observed. Conclusion: In this work, 3D printing was used as a prototyping technique for a geometry-specific investigation of SPECT/CT reconstruction parameters and PVC methods. The optimal setup for activity determination was found to be an unsmoothed SPECT/CT reconstruction in combination with a recovery coefficient based on the low-dose CT. The difference between spheric and renal recovery coefficients suggests that the typically applied volume-dependent but only sphere-based recovery coefficient lookup tables should be replaced by a more geometry-specific alternative.
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Affiliation(s)
- Johannes Tran-Gia
- Department of Nuclear Medicine, University of Würzburg, Würzburg, Germany
| | - Michael Lassmann
- Department of Nuclear Medicine, University of Würzburg, Würzburg, Germany
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Matsutomo N, Matsumoto S, Yamamoto T, Sato E. Validation of a calibration method using the cross-calibration factor and system planar sensitivity in quantitative single-photon emission computed tomography imaging. Radiol Phys Technol 2017; 10:439-445. [PMID: 28822095 DOI: 10.1007/s12194-017-0416-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 08/14/2017] [Accepted: 08/15/2017] [Indexed: 11/28/2022]
Abstract
The present study aimed to validate the absolute quantitative accuracy of a calibration method for single-photon emission computed tomography (SPECT) using cross-calibration factor (CCF)- and system sensitivity-based calibration methods. The CCF obtained with different reconstruction parameters was evaluated using a cylindrical phantom (diameter 20 cm, height 20 cm). SPECT images were acquired with a positron emission tomography/computed tomography (CT) phantom. Subsequently, they were reconstructed by using ordered subset expectation maximization with resolution recovery, scatter, and CT-based attenuation correction. All reconstructed SPECT counts were converted to activity concentrations based on the CCF and system planar sensitivity. We placed 12 circular regions of interest, 37 mm in diameter, on the phantom background, and the converted activity concentration and relative measurement error were assessed. The CCF obtained using a cylindrical phantom was affected by the iterative update number and post-smoothing filter function. The activity concentration calibrated using the CCF showed over- and underestimation. However, the activity concentration obtained from the system planar sensitivity was similar to that gained using the phantom. The values obtained using the system planar sensitivity were within 10% of the activity concentrations obtained with the phantom. These findings demonstrated that the calibration method using system planar sensitivity provides accurate quantification within 10% of the true activity concentration. Further clinical examination is required to validate the present results.
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Affiliation(s)
- Norikazu Matsutomo
- Department of Medical Radiological Technology, Faculty of Health Sciences, Kyorin University, 5-4-1 Shimorenjaku, Mitaka-shi, Tokyo, 181-8612, Japan.
| | - Saki Matsumoto
- Department of Radiology, Kyorin University Hospital, 6-20-2 Shinkawa, Mitaka-shi, Tokyo, 181-8611, Japan
| | - Tomoaki Yamamoto
- Department of Medical Radiological Technology, Faculty of Health Sciences, Kyorin University, 5-4-1 Shimorenjaku, Mitaka-shi, Tokyo, 181-8612, Japan
| | - Eisuke Sato
- Department of Medical Radiological Technology, Faculty of Health Sciences, Kyorin University, 5-4-1 Shimorenjaku, Mitaka-shi, Tokyo, 181-8612, Japan
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Löfgren J, Mortensen J, Rasmussen SH, Madsen C, Loft A, Hansen AE, Oturai P, Jensen KE, Mørk ML, Reichkendler M, Højgaard L, Fischer BM. A Prospective Study Comparing 99mTc-Hydroxyethylene-Diphosphonate Planar Bone Scintigraphy and Whole-Body SPECT/CT with 18F-Fluoride PET/CT and 18F-Fluoride PET/MRI for Diagnosing Bone Metastases. J Nucl Med 2017; 58:1778-1785. [PMID: 28798033 DOI: 10.2967/jnumed.116.189183] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 07/11/2017] [Indexed: 12/24/2022] Open
Abstract
We prospectively evaluated and compared the diagnostic performance of 99mTc-hydroxyethylene-diphosphonate (99mTc-HDP) planar bone scintigraphy (pBS), 99mTc-HDP SPECT/CT, 18F-NaF PET/CT, and 18F-NaF PET/MRI for the detection of bone metastases. Methods: One hundred seventeen patients with histologically proven malignancy referred for clinical pBS were prospectively enrolled. pBS and whole-body SPECT/CT were performed followed by 18F-NaF PET/CT within 9 d. 18F-NaF PET/MRI was also performed in 46 patients. Results: Bone metastases were confirmed in 16 patients and excluded in 101, which was lower than expected. The number of equivocal scans was significantly higher for pBS than for SPECT/CT and PET/CT (18 vs. 5 and 6, respectively; P = 0.004 and 0.01, respectively). When equivocal readings were excluded, no statistically significant difference in sensitivity, specificity, positive predictive value, negative predictive value, or overall accuracy were found when comparing the different imaging techniques. In the per-patient analysis, equivocal scans were either assumed positive for metastases ("pessimistic analysis") or assumed negative for metastases ("optimistic analysis"). The percentages of misdiagnosed patients for the pessimistic analysis were 21%, 15%, 9%, and 7% for pBS, SPECT/CT, PET/CT, and PET/MRI, respectively. Corresponding figures for the optimistic analysis were 9%, 12%, 5%, and 7%. In those patients identified as having bone metastases according to the reference standard, SPECT/CT, 18F-NaF PET/CT, and PET/MRI detected additional lesions compared with pBS in 31%, 63%, and 71%, respectively. Conclusion:18F-NaF PET/CT and whole-body SPECT/CT resulted in a significant reduction of equivocal readings compared with pBS, which implies an improved diagnostic confidence. However, the clinical benefit of using, for example, 18F-NaF PET/CT or PET/MRI as compared with SPECT/CT and pBS in this patient population with a relatively low prevalence of bone metastases (14%) is likely limited. This conclusion is influenced by the low prevalence of patients with osseous metastases. There may well be significant differences in the sensitivity of SPECT/CT, PET/CT, and PET/MRI compared with pBS, but a larger patient population or a patient population with a higher prevalence of bone metastases would have to be studied to demonstrate this.
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Affiliation(s)
- Johan Löfgren
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jann Mortensen
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sine H Rasmussen
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Claus Madsen
- Department of Clinical Physiology and Nuclear Medicine, Herlev Hospital, University of Copenhagen, Copenhagen, Denmark; and
| | - Annika Loft
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Adam E Hansen
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Peter Oturai
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Karl Erik Jensen
- Department of Radiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Mette Louise Mørk
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Michala Reichkendler
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Liselotte Højgaard
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Barbara M Fischer
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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Hutton BF, Ben-Haim S. What are the necessary corrections for dynamic cardiac SPECT? J Nucl Cardiol 2017; 24:1347-1349. [PMID: 27349428 DOI: 10.1007/s12350-016-0580-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Accepted: 05/23/2016] [Indexed: 11/26/2022]
Affiliation(s)
- Brian F Hutton
- Institute of Nuclear Medicine, University College London and UCL Hospitals, London, United Kingdom
- Centre for Medical Radiation Physics, University of Wollongong, NSW, Australia
| | - Simona Ben-Haim
- Institute of Nuclear Medicine, University College London and UCL Hospitals, London, United Kingdom.
- Institute of Nuclear Medicine, Chaim Sheba Medical Center, 5265601, Tel-Hashomer, Israel.
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D’Arienzo M, Cozzella M, Fazio A, De Felice P, Iaccarino G, D’Andrea M, Ungania S, Cazzato M, Schmidt K, Kimiaei S, Strigari L. Quantitative 177 Lu SPECT imaging using advanced correction algorithms in non-reference geometry. Phys Med 2016; 32:1745-1752. [DOI: 10.1016/j.ejmp.2016.09.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/09/2016] [Accepted: 09/16/2016] [Indexed: 11/25/2022] Open
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Rui X, Jin Y, FitzGerald PF, Wu M, Alessio AM, Kinahan PE, De Man B. Fast analytical approach of application specific dose efficient spectrum selection for diagnostic CT imaging and PET attenuation correction. Phys Med Biol 2016; 61:7787-7811. [PMID: 27754977 DOI: 10.1088/0031-9155/61/21/7787] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Computed tomography (CT) has been used for a variety of applications, two of which include diagnostic imaging and attenuation correction for PET or SPECT imaging. Ideally, the x-ray tube spectrum should be optimized for the specific application to minimize the patient radiation dose while still providing the necessary information. In this study, we proposed a projection-based analytic approach for the analysis of contrast, noise, and bias. Dose normalized contrast to noise ratio (CNRD), inverse noise normalized by dose (IND) and bias are used as evaluation metrics to determine the optimal x-ray spectrum. Our simulation investigated the dose efficiency of the x-ray spectrum ranging from 40 kVp to 200 kVp. Water cylinders with diameters of 15 cm, 24 cm, and 35 cm were used in the simulation to cover a variety of patient sizes. The effects of electronic noise and pre-patient copper filtration were also evaluated. A customized 24 cm CTDI-like phantom with 13 mm diameter inserts filled with iodine (10 mg ml-1), tantalum (10 mg ml-1), water, and PMMA was measured with both standard (1.5 mGy) and ultra-low (0.2 mGy) dose to verify the simulation results at tube voltages of 80, 100, 120, and 140 kVp. For contrast-enhanced diagnostic imaging, the simulation results indicated that for high dose without filtration, the optimal kVp for water contrast is approximately 100 kVp for a 15 cm water cylinder. However, the 60 kVp spectrum produces the highest CNRD for bone and iodine. The optimal kVp for tantalum has two selections: approximately 50 and 100 kVp. The kVp that maximizes CNRD increases when the object size increases. The trend in the CTDI phantom measurements agrees with the simulation results, which also agrees with previous studies. Copper filtration improved the dose efficiency for water and tantalum, but reduced the iodine and bone dose efficiency in a clinically-relevant range (70-140 kVp). Our study also shows that for CT-based attenuation correction applications for PET or SPECT, a higher-kVp spectrum with copper filtration is preferable. This method is developed based on filter back projection and does not require image reconstruction or Monte Carlo dose estimates; thus, it could potentially be used for patient-specific and task-based on-the-fly protocol optimization.
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Affiliation(s)
- Xue Rui
- Image Reconstruction Laboratory, GE Global Research Center, Niskayuna, NY, USA
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Abstract
The synergy of functional and anatomic information in hybrid systems has undoubtedly enhanced the diagnostic potential of radionuclide imaging in recent years, contributing to the advancement of SPECT/CT in clinical practice. Since the introduction of commercial SPECT/CT in the late 1990 s, the field has seen rapid expansion and development toward multidetector CT subsystems, establishing the role of SPECT/CT as a routine imaging tool. It is, however, important to discuss possible challenges and technical limitations of such systems and how these influence imaging outcomes. In particular, the issues of patient motion and spatial misalignment of the SPECT and CT modalities, data corrections such as those for photon attenuation, and the choice of CT acquisition protocols in relation to radiation exposure are discussed in the article.
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Affiliation(s)
- Lefteris Livieratos
- Nuclear Medicine Department, Guy's & St Thomas' Hospitals, London, UK; Imaging Sciences and Biomedical Engineering, King's College London, London, UK.
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Gamma camera calibration and validation for quantitative SPECT imaging with 177Lu. Appl Radiat Isot 2016; 112:156-64. [DOI: 10.1016/j.apradiso.2016.03.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 02/09/2016] [Accepted: 03/07/2016] [Indexed: 11/21/2022]
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Quantitative SPECT/CT Imaging of (177)Lu with In Vivo Validation in Patients Undergoing Peptide Receptor Radionuclide Therapy. Mol Imaging Biol 2016; 17:585-93. [PMID: 25475521 DOI: 10.1007/s11307-014-0806-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE The purpose of this study is to extend an established SPECT/CT quantitation protocol to (177)Lu and validate it in vivo using urine samples, thus providing a basis for 3D dosimetry of (177)Lu radiotherapy and improvement over current planar methods which improperly account for anatomical variations, attenuation, and overlapping organs. PROCEDURES In our quantitation protocol, counts in images reconstructed using an ordered subset-expectation maximization algorithm are converted to kilobecquerels per milliliter using a calibration factor derived from a phantom experiment. While varying reconstruction parameters, we tracked the ratio of image to true activity concentration (recovery coefficient, RC) in hot spheres and a noise measure in a homogeneous region. The optimal parameter set was selected as the point where recovery in the largest three spheres (16, 8, and 4 ml) stagnated, while the noise continued to increase. Urine samples were collected following 12 SPECT/CT acquisitions of patients undergoing [(177)Lu]DOTATATE therapy, and activity concentrations were measured in a well counter. Data was reconstructed using parameters chosen in the phantom experiment, and estimated activity concentration from the images was compared to the urine values to derive RCs. RESULTS In phantom data, our chosen parameter set yielded RCs in 16, 8, and 4 ml spheres of 80.0, 74.1, and 64.5 %, respectively. For patients, the mean bladder RC was 96.1 ± 13.2% (range, 80.6-122.4 %), with a 95 % confidence interval between 88.6 and 103.6 %. The mean error of SPECT/CT concentrations was 10.1 ± 8.3% (range, -19.4-22.4 %). CONCLUSIONS Our results show that quantitative (177)Lu SPECT/CT in vivo is feasible but could benefit from improved reconstruction methods. Quantifying bladder activity is analogous to determining the amount of activity in the kidneys, an important task in dosimetry, and our results provide a useful benchmark for future efforts.
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Ichikawa H, Miwa K, Matsutomo N, Watanabe Y, Kato T, Shimada H. [Development of a Novel Body Phantom with Bone Equivalent Density for Evaluation of Bone SPECT]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2015; 71:1235-1240. [PMID: 26685836 DOI: 10.6009/jjrt.2015_jsrt_71.12.1235] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We developed a custom-designed phantom for bone single photon emission computed tomography (SPECT)-specific radioactivity distribution and linear attenuation coefficient. The aim of this study was to evaluate the accuracy of the phantom. The lumbar phantom consisted of the trunk of a body phantom (background) containing a cylinder (vertebral body), a sphere (tumor), and a T-shaped container (processus). The vertebral body, tumor, and processus phantoms contained a K(2)HPO(4) solution of bone equivalent density and 50, 300 and 50 kBq/mL of (99m)Tc, respectively. The body phantom contained 8 kBq/mL of (99m)Tc solution. SPECT images were acquired using low-energy high-resolution collimation, a 128 × 128 matrix and 120 projections over 360° with a dwell time of 15 sec/view × 4 times. Thereafter, CT images were acquired at 130 kV and 70 ref mAs using adaptive dose modulation. The SPECT data were reconstructed with ordered subset expectation maximization with three-dimensional, scatter, and CT-based attenuation correction. Count ratio, linear attenuation coefficient (LAC), and full-width at half-maximum (FWHM) were measured. Count ratios between the background, the vertebral body, and the tumor in SPECT images were 463.8: 2888.0: 15150.3 (1: 6.23: 32.7). The LAC of the background and vertebral body in the CT-derived attenuation map were 0.155 cm⁻¹ and 0.284 cm⁻¹, respectively, and the FWHM measured from the processus was 15.27 mm. The precise counts and LAC indicated that the phantom was accurate and could serve as a tool for evaluating acquisition, reconstruction parameters, and quantitation in bone SPECT images.
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Klausen TL, Mortensen J, de Nijs R, Andersen FL, Højgaard L, Beyer T, Holm S. Intravenous contrast-enhanced CT can be used for CT-based attenuation correction in clinical (111)In-octreotide SPECT/CT. EJNMMI Phys 2015; 2:3. [PMID: 26501805 PMCID: PMC4545801 DOI: 10.1186/s40658-015-0108-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 01/14/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND CT-based attenuation correction (CT-AC) using contrast-enhancement CT impacts (111)In-SPECT image quality and quantification. In this study we assessed and evaluated the effect. METHODS A phantom (5.15 L) was filled with an aqueous solution of In-111. Three SPECT/CT scans were performed: (A) no IV contrast, (B) with 100-mL IV contrast, and (C) with 200-mL IV contrast added. Scan protocol included a localization CT, a low-dose CT (LD), and a full-dose CT (FD). Phantom, LD and FD scan series were performed at 90, 120, and 140 kVp. Phantom data were evaluated looking at mean counts in a central volume. Ten patients referred for (111)In-octreotide scintigraphy were scanned according to our clinical (111)In-SPECT/CT protocol including a topogram, a LD (140 kVp), and a FD (120 kVp). The FD/contrast-enhanced CT was acquired in both arterial (FDAP) and venous phase (FDVP) following a mono-phasic IV injection of 125-mL Optiray (4.5 mL/s). For patient data, we report image quality, Krenning scores, and mean/max values for liver and tumor regions. RESULTS Phantoms: in uncorrected emission data, mean counts (average ± SD) decreased with increasing IV concentration: (A) 119 ± 9, (B) 113 ± 8, and (C) 110 ± 9. For all attenuation correction (AC) scans, the mean values increased with increasing iodine concentration. PATIENTS there were no visible artifacts in single photon emission computed tomography (SPECT) following CT-AC with contrast-enhanced CT. The average score of image quality was 4.1 ± 0.3, 3.8 ± 0.4, and 4.2 ± 0.4 for LD, arterial phase, and venous phase, respectively. A total of 16 lesions were detected. The Krenning scores of 13/16 lesions were identical across all scan series. The max pixel values for the 16 lesions showed generally lower values for LD than for contrast-enhanced CT. CONCLUSIONS In (111)In-SPECT/CT imaging of phantoms and patients, the use of IV CT contrast did neither degrade the SPECT image quality nor affect the clinical Krenning score. Reconstructed counts in healthy liver tissues were unaffected, and there was a generally lower count value in lesions following CT-AC based on the LD non-enhanced images. Overall, for clinical interpretation, no separate low-dose CT is required for CT-AC in (111)In-SPECT/CT.
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Affiliation(s)
- Thomas Levin Klausen
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
| | - Jann Mortensen
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
| | - Robin de Nijs
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
| | - Flemming Littrup Andersen
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
| | - Liselotte Højgaard
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
| | - Thomas Beyer
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark. .,Center for Medical Physics and Biomedical Engineering, General Hospital Vienna, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090, Vienna, Austria.
| | - Søren Holm
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
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Bailey DL, Hennessy TM, Willowson KP, Henry EC, Chan DLH, Aslani A, Roach PJ. In vivo quantification of (177)Lu with planar whole-body and SPECT/CT gamma camera imaging. EJNMMI Phys 2015; 2:20. [PMID: 26501821 PMCID: PMC4573647 DOI: 10.1186/s40658-015-0123-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 08/25/2015] [Indexed: 11/24/2022] Open
Abstract
Background Advances in gamma camera technology and the emergence of a number of new theranostic radiopharmaceutical pairings have re-awakened interest in in vivo quantification with single-photon-emitting radionuclides. We have implemented and validated methodology to provide quantitative imaging of 177Lu for 2D whole-body planar studies and for 3D tomographic imaging with single-photon emission computed tomography (SPECT)/CT. Methods Whole-body planar scans were performed on subjects to whom a known amount of [177Lu]-DOTA-octreotate had been administered for therapy. The total radioactivity estimated from the images was compared with the known amount of the radionuclide therapy administered. In separate studies, venous blood samples were withdrawn from subjects after administration of [177Lu]-DOTA-octreotate while a SPECT acquisition was in progress and the concentration of the radionuclide in the venous blood sample compared with that estimated from large blood pool structures in the SPECT reconstruction. The total radioactivity contained within an internal SPECT calibration standard was also assessed. Results In the whole-body planar scans (n = 28), the estimated total body radioactivity was accurate to within +4.6 ± 5.9 % (range −17.1 to +11.2 %) of the correct value. In the SPECT reconstructions (n = 12), the radioactivity concentration in the cardiac blood pool was accurate to within −4.0 ± 7.8 % (range −16.1 to +7.5 %) of the true value and the internal standard measurements (n = 89) were within 2.0 ± 8.5 % (range −16.3 to +24.2 %) of the known amount of radioactivity contained. Conclusions In our hands, state-of-the-art hybrid SPECT/CT gamma cameras were able to provide accurate estimates of in vivo radioactivity to better than, on average, ±10 % for use in biodistribution and radionuclide dosimetry calculations.
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Affiliation(s)
- Dale L Bailey
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia. .,Faculty of Health Sciences, University of Sydney, Cumberland, NSW, Australia. .,Sydney Medical School, University of Sydney, Camperdown, NSW, Australia. .,NETwork, Sydney Vital, St Leonards, Sydney, NSW, Australia.
| | - Thomas M Hennessy
- Institute of Medical Physics, University of Sydney, Camperdown, NSW, Australia
| | - Kathy P Willowson
- Institute of Medical Physics, University of Sydney, Camperdown, NSW, Australia
| | - E Courtney Henry
- Institute of Medical Physics, University of Sydney, Camperdown, NSW, Australia
| | - David L H Chan
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia.,NETwork, Sydney Vital, St Leonards, Sydney, NSW, Australia
| | - Alireza Aslani
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia
| | - Paul J Roach
- Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia.,Sydney Medical School, University of Sydney, Camperdown, NSW, Australia
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Rowe SP, Vicente E, Anizan N, Wang H, Leal JP, Lodge MA, Frey EC, Wahl RL. Repeatability of Radiotracer Uptake in Normal Abdominal Organs with ¹¹¹In-Pentetreotide Quantitative SPECT/CT. J Nucl Med 2015; 56:985-8. [PMID: 25977467 DOI: 10.2967/jnumed.115.155358] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 04/15/2015] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED With an increasing emphasis on quantitation of SPECT imaging and its use in dosimetry to guide therapies, it is desirable to understand the repeatability in normal-organ SPECT uptake values (SPECT-UVs). We investigated the variability of normal abdominal organ uptake in repeated (111)In-pentetreotide SPECT studies. METHODS Nine patients with multiple (111)In-pentetreotide SPECT/CT studies for clinical purposes were evaluated. Volumes of interest were drawn for the abdominal organs and applied to SPECT-UVs. The variability of those values was assessed. RESULTS The average SPECT-UV for the liver (1.7 ± 0.6) was much lower than for the kidneys (right, 8.0 ± 2.4; left, 7.5 ± 1.7). Interpatient and intrapatient variability was similar (intraclass correlation coefficients, 0.40-0.59) for all organs. The average coefficients of variation for each organ for each patient were obtained and averaged across all patients (0.26 for liver, 0.22 for right kidney, and 0.20 for left kidney). The coefficients of variation for the organs across all scans were 0.33 (liver), 0.30 (right kidney), and 0.22 (left kidney). CONCLUSION Variability across all patients and all scans for the liver was higher than reported with (18)F-FDG PET, though left kidney variability was similar to PET liver variability and left kidney uptake may be able to serve as an internal metric for determining the quantifiability of an (111)In-pentetreotide SPECT study.
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Affiliation(s)
- Steven P Rowe
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Esther Vicente
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Nadège Anizan
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hao Wang
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jeffrey P Leal
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Martin A Lodge
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Eric C Frey
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Richard L Wahl
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Estimation of radioactivity in single-photon emission computed tomography for sentinel lymph node biopsy in a torso phantom study. Nucl Med Commun 2015; 36:646-50. [PMID: 25738561 DOI: 10.1097/mnm.0000000000000294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The number of lymph nodes to be removed is determined from residual counts. Advance estimation of residual radioactivity in lymphatic nodes before a biopsy is useful for reducing surgical operation time. The purpose of this study was to estimate the total radioactivity of a small hotspot in single-photon emission computed tomography (SPECT) of a torso phantom. METHODS A cross-calibration study was performed to convert counts in SPECT images to radioactivity. A simulation study was performed to estimate the size of the volume of interest (VOI) covering a hotspot corrupted with full-width at half-maximum between 8 and 16 mm. The estimation of total radioactivity was validated in a torso phantom study using small sources. RESULTS True radioactivity was approximately equal to integrated values of hotspots using the VOI with a diameter of 40 mm in our simulation study. The difference was less than 18% in cases of more than 9.4 kBq. CONCLUSION The total radioactivity in small sources simulating a typical sentinel node was estimated from SPECT images using a VOI of 40 mm in a torso phantom study. Because the difference from actual values was less than 10% on average when radioactivities were more than 9.4 kBq, the total radioactivity of a lymph node can be estimated in a clinical examination.
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Anizan N, Wang H, Zhou XC, Wahl RL, Frey EC. Factors affecting the repeatability of gamma camera calibration for quantitative imaging applications using a sealed source. Phys Med Biol 2015; 60:1325-37. [PMID: 25592130 DOI: 10.1088/0031-9155/60/3/1325] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Several applications in nuclear medicine require absolute activity quantification of single photon emission computed tomography images. Obtaining a repeatable calibration factor that converts voxel values to activity units is essential for these applications. Because source preparation and measurement of the source activity using a radionuclide activity meter are potential sources of variability, this work investigated instrumentation and acquisition factors affecting repeatability using planar acquisition of sealed sources. The calibration factor was calculated for different acquisition and geometry conditions to evaluate the effect of the source size, lateral position of the source in the camera field-of-view (FOV), source-to-camera distance (SCD), and variability over time using sealed Ba-133 sources. A small region of interest (ROI) based on the source dimensions and collimator resolution was investigated to decrease the background effect. A statistical analysis with a mixed-effects model was used to evaluate quantitatively the effect of each variable on the global calibration factor variability. A variation of 1 cm in the measurement of the SCD from the assumed distance of 17 cm led to a variation of 1-2% in the calibration factor measurement using a small disc source (0.4 cm diameter) and less than 1% with a larger rod source (2.9 cm diameter). The lateral position of the source in the FOV and the variability over time had small impacts on calibration factor variability. The residual error component was well estimated by Poisson noise. Repeatability of better than 1% in a calibration factor measurement using a planar acquisition of a sealed source can be reasonably achieved. The best reproducibility was obtained with the largest source with a count rate much higher than the average background in the ROI, and when the SCD was positioned within 5 mm of the desired position. In this case, calibration source variability was limited by the quantum noise.
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Affiliation(s)
- N Anizan
- Department of Radiology, Johns Hopkins University, Baltimore, MD, USA
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Midgley SM. A method for estimating radiation interaction coefficients for tissues from single energy CT. Phys Med Biol 2014; 59:7479-99. [PMID: 25393760 DOI: 10.1088/0031-9155/59/23/7479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
A parametric model for the x-ray linear attenuation coefficient is used to describe the compositional dependence of Hounsfield numbers measured by medical CT scanners. Measurements with materials of known density and composition, that span and evenly sample the compositional range of tissues, are written as linear simultaneous equations and solved for model coefficients. An algorithm is identified for this purpose. Results are expressed as atomic cross-sections in units of barn per electron divided by the attenuation coefficient for water. With the CT scanner characterised, a virtual CT scan can be simulated to predict HN for tissues based upon their known density and composition. Similar calculations using the tabulations and mixture rule deliver attenuation coefficients and mass energy absorption coefficients for mono-energetic radiation 10 keV to 20 MeV. Results are presented for measurements with a radiotherapy CT simulator, the RMI-467 phantom with tissue substitute materials, plus common polymer materials and silicon. Published measurements with earlier generations of the phantom and tissue substitutes using different CT scanners are also considered. Measured atomic cross-sections differ from expectations for mono-energetic radiation due to the use of a filtered spectrum and energy integrating detection system. The cross-sections for different CT scanners are similar, without large variations with kVp. Results are presented showing the relationship between predicted HN for tissues, electron density and photon interaction coefficients for healthy tissues and mono-energetic radiation. A strategy is suggested for accommodating strongly attenuating materials such as calculi and metallic implants.
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Affiliation(s)
- S M Midgley
- School of Physics, Monash University, Clayton, Victoria 3080, Australia. William Buckland Radiotherapy Centre, Alfred Hospital, Melbourne, VIC, 3181, Australia
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Liu H, Guo M, Hu Z, Shi P, Hu H. Nonlinear dual reconstruction of SPECT activity and attenuation images. PLoS One 2014; 9:e106951. [PMID: 25225796 PMCID: PMC4167322 DOI: 10.1371/journal.pone.0106951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 08/08/2014] [Indexed: 11/22/2022] Open
Abstract
In single photon emission computed tomography (SPECT), accurate attenuation maps are needed to perform essential attenuation compensation for high quality radioactivity estimation. Formulating the SPECT activity and attenuation reconstruction tasks as coupled signal estimation and system parameter identification problems, where the activity distribution and the attenuation parameter are treated as random variables with known prior statistics, we present a nonlinear dual reconstruction scheme based on the unscented Kalman filtering (UKF) principles. In this effort, the dynamic changes of the organ radioactivity distribution are described through state space evolution equations, while the photon-counting SPECT projection data are measured through the observation equations. Activity distribution is then estimated with sub-optimal fixed attenuation parameters, followed by attenuation map reconstruction given these activity estimates. Such coupled estimation processes are iteratively repeated as necessary until convergence. The results obtained from Monte Carlo simulated data, physical phantom, and real SPECT scans demonstrate the improved performance of the proposed method both from visual inspection of the images and a quantitative evaluation, compared to the widely used EM-ML algorithms. The dual estimation framework has the potential to be useful for estimating the attenuation map from emission data only and thus benefit the radioactivity reconstruction.
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Affiliation(s)
- Huafeng Liu
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, China
| | - Min Guo
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, China
| | - Zhenghui Hu
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, China
| | - Pengcheng Shi
- B. Thomas Golisano College of Computing and Information Sciences, Rochester Institute of Technology, Rochester, New York, United States of America
| | - Hongjie Hu
- Department of Radiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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Thompson JD, Hogg P, Manning DJ, Szczepura K, Chakraborty DP. A free-response evaluation determining value in the computed tomography attenuation correction image for revealing pulmonary incidental findings: a phantom study. Acad Radiol 2014; 21:538-45. [PMID: 24594424 DOI: 10.1016/j.acra.2014.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 01/08/2014] [Accepted: 01/08/2014] [Indexed: 11/28/2022]
Abstract
RATIONALE AND OBJECTIVES The purpose of this study was to compare lesion-detection performance when interpreting computed tomography (CT) images that are acquired for attenuation correction when performing single photon emission computed tomography/computed tomography (SPECT/CT) myocardial perfusion studies. In the United Kingdom, there is a requirement that these images be interpreted; thus, it is necessary to understand observer performance on these images. MATERIALS AND METHODS An anthropomorphic chest phantom with inserted spherical lesions of different sizes and contrasts was scanned on five different SPECT/CT systems using site-specific CT protocols for SPECT/CT myocardial perfusion imaging. Twenty-one observers (0-4 years of CT experience) searched 26 image slices (17 abnormal, containing 1-3 lesions, and 9 normal, containing no lesions) for each CT acquisition. The observers marked and rated perceived lesions under the free-response paradigm. Four analyses were conducted using jackknife alternative free-response receiver operating characteristic (JAFROC) analysis: (1) 20-pixel acceptance radius (AR) with all 21 readers, abbreviated to 20/ALL analysis, (2) 40-pixel AR with 21 readers (40/ALL), (3) 20-pixel AR with 14 readers experienced in CT (20/EXP), and (4) 20-pixel AR with 7 readers with no CT experience (20/NOT). The significance level of the test was set so as to conservatively control the overall probability of a type I error to <0.05. RESULTS The mean JAFROC figure of merit (FOM) for the five CT acquisitions for the 20/ALL study were 0.602, 0.639, 0.372, 0.475, and 0.719 with a significant difference in lesion-detection performance evident between all individual treatment pairs (P < .0001) with the exception of the 1-2 pairing, which was not significant (these differed only in milliamp seconds). System 5, which had the highest performance, had the smallest slice thickness and the largest matrix size. For the other analyses, the system orderings remained unchanged, and the significance of FOM difference findings remained identical to those for 20/ALL, with one exception: for 20/EXP analysis the 1-2 difference became significant with the higher milliamp seconds superior. Improved detection performance was associated with a smaller slice thickness, increased matrix size, and, to a lesser extent, increased tube charge. CONCLUSIONS Protocol variations for CT-based attenuation correction (AC) in SPECT/CT imaging have a measurable impact on lesion-detection performance. The results imply that z-axis resolution and matrix size had the greatest impact on lesion detection, with a weaker but detectable dependence on the product of milliamp and seconds.
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Affiliation(s)
- John D Thompson
- University of Salford, Directorate of Radiography, 6th Floor Allerton Building, Frederick Road Campus, Greater Manchester, M6 6PU, UK; University Hospitals of Morecambe Bay NHS Foundation Trust, Nuclear Medicine, Furness General Hospital, Dalton Lane, Barrow-in-Furness, Cumbria, LA14 4LF, UK.
| | - Peter Hogg
- University of Salford, Directorate of Radiography, 6th Floor Allerton Building, Frederick Road Campus, Greater Manchester, M6 6PU, UK
| | - David J Manning
- Lancaster Medical School, Faculty of Health & Medicine, Furness College, Lancaster University, Lancaster LA1 4YG, UK
| | - Katy Szczepura
- University of Salford, Directorate of Radiography, 6th Floor Allerton Building, Frederick Road Campus, Greater Manchester, M6 6PU, UK
| | - Dev P Chakraborty
- Medical Image Interpretation Assessment Laboratory, University of Pittsburgh, Presby South Tower, Room 4771, 200 Lothrop Street, Pittsburgh, PA 15213, USA
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