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Wu C, Hormuth DA, Christenson CD, Woodall RT, Abdelmalik MRA, Phillips WT, Hughes TJR, Brenner AJ, Yankeelov TE. Image-guided patient-specific optimization of catheter placement for convection-enhanced nanoparticle delivery in recurrent glioblastoma. Comput Biol Med 2024; 179:108889. [PMID: 39032243 DOI: 10.1016/j.compbiomed.2024.108889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 06/15/2024] [Accepted: 07/11/2024] [Indexed: 07/23/2024]
Abstract
BACKGROUND Proper catheter placement for convection-enhanced delivery (CED) is required to maximize tumor coverage and minimize exposure to healthy tissue. We developed an image-based model to patient-specifically optimize the catheter placement for rhenium-186 (186Re)-nanoliposomes (RNL) delivery to treat recurrent glioblastoma (rGBM). METHODS The model consists of the 1) fluid fields generated via catheter infusion, 2) dynamic transport of RNL, and 3) transforming RNL concentration to the SPECT signal. Patient-specific tissue geometries were assigned from pre-delivery MRIs. Model parameters were personalized with either 1) individual-based calibration with longitudinal SPECT images, or 2) population-based assignment via leave-one-out cross-validation. The concordance correlation coefficient (CCC) was used to quantify the agreement between the predicted and measured SPECT signals. The model was then used to simulate RNL distributions from a range of catheter placements, resulting in a ratio of the cumulative RNL dose outside versus inside the tumor, the "off-target ratio" (OTR). Optimal catheter placement) was identified by minimizing OTR. RESULTS Fifteen patients with rGBM from a Phase I/II clinical trial (NCT01906385) were recruited to the study. Our model, with either individual-calibrated or population-assigned parameters, achieved high accuracy (CCC > 0.80) for predicting RNL distributions up to 24 h after delivery. The optimal catheter placements identified using this model achieved a median (range) of 34.56 % (14.70 %-61.12 %) reduction on OTR at the 24 h post-delivery in comparison to the original placements. CONCLUSIONS Our image-guided model achieved high accuracy for predicting patient-specific RNL distributions and indicates value for optimizing catheter placement for CED of radiolabeled liposomes.
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Affiliation(s)
- Chengyue Wu
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA; Department of Breast Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA; Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA; Institute for Data Science in Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
| | - David A Hormuth
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, 78712, USA; Livestrong Cancer Institutes, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Chase D Christenson
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Ryan T Woodall
- Division of Mathematical Oncology, Beckman Research Institute, City of Hope National Medical Center, 1500 East Duarte Rd, Duarte, CA, 91010, USA
| | - Michael R A Abdelmalik
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
| | - William T Phillips
- Department of Radiology, UT Health San Antonio, San Antonio, TX, 78229, USA
| | - Thomas J R Hughes
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Andrew J Brenner
- Mays Cancer Center, UT Health San Antonio, San Antonio, TX, 78229, USA
| | - Thomas E Yankeelov
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Diagnostic Medicine, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Oncology, The University of Texas at Austin, Austin, TX, 78712, USA; Livestrong Cancer Institutes, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
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De Schepper S, Gnanasegaran G, De Vos W, Van de Casteele E, Dickson JC, Van den Wyngaert T. From SPECT/CT towards absolute quantification? - the case of unilateral condylar hyperplasia of the mandible. EJNMMI Phys 2024; 11:74. [PMID: 39177939 PMCID: PMC11343952 DOI: 10.1186/s40658-024-00676-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 08/05/2024] [Indexed: 08/24/2024] Open
Abstract
BACKGROUND Unilateral condylar hyperplasia (UCH) of the mandible is a rare condition characterized by asymmetric growth of the mandibular condyles. Bone scintigraphy with SPECT(/CT) is commonly used to diagnose UCH and guide treatment. Still, varying results have been reported using the traditional threshold of 55%:45% in relative tracer uptake. While absolute quantification of uptake on SPECT/CT could improve results, optimal correction and reconstruction settings are currently unknown. METHODS Three anthropomorphic phantoms representing UCH were developed from patient CT volumes and produced using 3D printing technology. Fillable spherical inserts of different sizes (Ø: 8-15 mm) were placed in the condylar positions representing symmetrical and asymmetrical distributions. Recovery coefficients were determined for SPECT/CT using various reconstruction corrections, including attenuation and scatter correction (ACSC), resolution modeling (RM), and partial volume correction (PVC) using phantom measurements. Uptake ratios between condyles and condyle to clivus were evaluated. Finally, the impact of these correction techniques on absolute activity and diagnostic accuracy was assessed in a retrospective patient cohort for the diagnostic threshold of 55%:45%. RESULTS The activity was only partially recovered in all spherical inserts (range: 22.5-64.9%). However, RM improved relative recovery by 20.2-62.3% compared to ACSC. In the symmetric phantoms, the 95% confidence interval (CI) of condyle ratios included the diagnostic threshold (57.6%:42.4%) for UCH when using ACSC potentially leading to false positives, but not for ACSCRM datasets. Partial volume corrections coefficients from the NEMA IQ phantom was positionally dependent, with improvements seen performing PVC using coefficients derived from anthropomorphic phantoms. Retrospective application in a patient cohort showed only a weak linear correlation (R²: 0.25-0.67) and large limits of agreement (9.6-12.5%) between different reconstructions. Up to 44% of patients were reclassified using the 55%:45% threshold. Using clinical outcome data, ACSCRM had highest sensitivity (91%; 95% CI 59-100%) and specificity (66%; 95% CI 47-81%), significantly improving specificity (P = 0.038). CONCLUSIONS Anthropomorphic phantoms were shown to be essential in determining optimal settings for acquisition, reconstruction, and analysis. SPECT/CT reconstructions with attenuation and scatter correction and resolution modeling are recommended and could improve specificity when using the 55%:45% threshold to assess condylar growth.
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Affiliation(s)
- Stijn De Schepper
- Department of Nuclear Medicine, Antwerp University Hospital, Drie Eikenstraat 655, Edegem, 2650, Belgium.
- Faculty of Medicine and Health Sciences (MICA - IPPON), University of Antwerp, Wilrijk, Belgium.
| | | | - Wouter De Vos
- Department of Oral and Maxillofacial Surgery, Antwerp University Hospital, Antwerp, Belgium
- Faculty of Medicine and Health Sciences, University of Antwerp, Wilrijk, Belgium
| | - Elke Van de Casteele
- Department of Oral and Maxillofacial Surgery, Antwerp University Hospital, Antwerp, Belgium
- Faculty of Medicine and Health Sciences, University of Antwerp, Wilrijk, Belgium
| | - John C Dickson
- Institute of Nuclear Medicine, University College of London Hospitals NHS, London, UK
| | - Tim Van den Wyngaert
- Department of Nuclear Medicine, Antwerp University Hospital, Drie Eikenstraat 655, Edegem, 2650, Belgium
- Faculty of Medicine and Health Sciences (MICA - IPPON), University of Antwerp, Wilrijk, Belgium
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Saed M, Mahani H, Sadremomtaz A. Characterization of accurate 3D collimator-detector response function for single- and multi-lofthole collimated SPECT cameras. Jpn J Radiol 2024:10.1007/s11604-024-01624-1. [PMID: 38954193 DOI: 10.1007/s11604-024-01624-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 06/24/2024] [Indexed: 07/04/2024]
Abstract
PURPOSE Collimator-detector response function (CDRF) of a SPECT scanner refers to the image generated from a point source of activity. This research aims to characterize the CDRF of a breast-dedicated SPECT imager equipped with a lofthole collimator using GATE Monte Carlo simulation. MATERIALS AND METHODS To do so, a cylindrical multi-lofthole collimation system with lofthole apertures dedicated to breast imaging was modeled using the GATE Monte Carlo simulator. The dependency of the CDRF on the source-to-collimator distance of a single-lofthole as well as 8-lofthole collimations was assessed and then compared. In addition, the 3D-sensitivity map of the 8-lofthole collimation was derived. Finally, fair comparisons were conducted between the response of the 8-lofthole collimator and that of an 8-pinhole and also existing analytical derivations. In all cases, a data acquisition period of 5.0 min with an in-air 99mTc point source was considered. RESULTS For the single-lofthole collimator, 4.5 times increasing the magnification factor leads to a 16- and twofold improvement in the sensitivity and spatial resolution, respectively. In the single-lofthole collimator, the resolution and sensitivity are degraded as the source-to-aperture distance increases. For the cylindrical 8-lofthole collimator, the findings confirm that CDRF strongly depends on source-to-aperture distance and angle of photon incidence. For a 30 mm in-plane offset point, a 25% increase in sensitivity is observed compared to that of the center of the FOV. Increasing the angle from 0∘ to 34∘ results in a 50% reduction in sensitivity. Furthermore, the findings illustrate that spatial resolution follows a quadratic function as10 - 3 d 2 + 2 × 10 - 4 d + R 0 where d is an offset along the x-, y-, and z-axis, and R0 is the spatial resolution at the center of the FOV. CONCLUSION In conclusion, both spatial resolution and sensitivity of the lofthole collimation are considerably angle- and offset-dependent within the FOV of single- and multi-lofthole collimated SPECT imagers.
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Affiliation(s)
- Maryam Saed
- Department of Physics, Faculty of Science, University of Guilan, 41635-1914 Rasht, Iran
| | - Hojjat Mahani
- Radiation Applications Research School, Nuclear Science and Technology Research Institute, 14395-836 Tehran, Iran.
| | - Alireza Sadremomtaz
- Department of Physics, Faculty of Science, University of Guilan, 41635-1914 Rasht, Iran
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Feng Y, Worstell W, Kupinski M, Furenlid LR, Sabet H. Resolution recovery on list mode MLEM reconstruction for dynamic cardiac SPECT system. Biomed Phys Eng Express 2023; 10:10.1088/2057-1976/ad0f40. [PMID: 37995364 PMCID: PMC11162156 DOI: 10.1088/2057-1976/ad0f40] [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: 12/29/2022] [Accepted: 11/23/2023] [Indexed: 11/25/2023]
Abstract
The Dynamic Cardiac SPECT (DC-SPECT) system is being developed at the Massachusetts General Hospital, featuring a static cardio focus asymmetrical geometry enabling simultaneous high-resolution and high-sensitivity imaging. Among 14 design iterations of the DC-SPECT with varying number of detector heads, system sensitivity and resolution, the current version under development features 10 mm FWHM geometrical resolution (without resolution recovery) and 0.07% sensitivity at the center of the FOV, this is 1.5× resolution gain and 7× sensitivity gain compared to a conventional dual head gamma camera (0.01% sensitivity and 15-mm resolution). This work presents improvement in imaging resolution by implementing a spatially variant point spread function (SV-PSF) with list mode MLEM reconstruction. A resolution recovery method by PSF deconvolution is validated on list mode MLEM reconstruction for the DC-SPECT. A spatial invariant PSF is included as an additional test to show the influence of the PSF modelling accuracy on reconstructed image quality. We compare the MLEM reconstruction with and without PSF deconvolution; an analytic model is used for the calculation of system response, and the results are compared to the reconstruction with system modelling using Monte Carlo (MC) based methods. Results show that with PSF modelling applied, the quality of the reconstructed image is improved, and the DC-SPECT system can achieve a 4.5 mm central spatial resolution with average 795 counts/Mbq. Both the SV-PSF and the spatial-invariant PSF improve the image quality, and the reconstruction with SV-PSF generates line profiles closer to the ground truth. The results show substantial improvement over the GE Discovery 570c performance (7 mm spatial resolution with an average 460 counts/MBq, 5.8 mm resolution at the FOV center). The impact of PSF deconvolution is significant, improvement of the reconstructed image quality is evident in comparison to MC simulated system matrix with the same sampling size in the simulation.
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Affiliation(s)
- Yuemeng Feng
- Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States of America
| | | | - Matthew Kupinski
- Department of Radiology, and College of Optical Sciences, University of Arizona, Tucson, AZ, United States of America
| | - Lars R Furenlid
- Department of Radiology, and College of Optical Sciences, University of Arizona, Tucson, AZ, United States of America
| | - Hamid Sabet
- Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States of America
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Whitehead JF, Laeseke PF, Periyasamy S, Speidel MA, Wagner MG. In silico simulation of hepatic arteries: An open-source algorithm for efficient synthetic data generation. Med Phys 2023; 50:5505-5517. [PMID: 36950870 PMCID: PMC10517083 DOI: 10.1002/mp.16379] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 02/28/2023] [Accepted: 03/13/2023] [Indexed: 03/24/2023] Open
Abstract
BACKGROUND In silico testing of novel image reconstruction and quantitative algorithms designed for interventional imaging requires realistic high-resolution modeling of arterial trees with contrast dynamics. Furthermore, data synthesis for training of deep learning algorithms requires that an arterial tree generation algorithm be computationally efficient and sufficiently random. PURPOSE The purpose of this paper is to provide a method for anatomically and physiologically motivated, computationally efficient, random hepatic arterial tree generation. METHODS The vessel generation algorithm uses a constrained constructive optimization approach with a volume minimization-based cost function. The optimization is constrained by the Couinaud liver classification system to assure a main feeding artery to each Couinaud segment. An intersection check is included to guarantee non-intersecting vasculature and cubic polynomial fits are used to optimize bifurcation angles and to generate smoothly curved segments. Furthermore, an approach to simulate contrast dynamics and respiratory and cardiac motion is also presented. RESULTS The proposed algorithm can generate a synthetic hepatic arterial tree with 40 000 branches in 11 s. The high-resolution arterial trees have realistic morphological features such as branching angles (MAD with Murray's law= 1.2 ± 1 . 2 o $ = \;1.2 \pm {1.2^o}$ ), radii (median Murray deviation= 0.08 $ = \;0.08$ ), and smoothly curved, non-intersecting vessels. Furthermore, the algorithm assures a main feeding artery to each Couinaud segment and is random (variability = 0.98 ± 0.01). CONCLUSIONS This method facilitates the generation of large datasets of high-resolution, unique hepatic angiograms for the training of deep learning algorithms and initial testing of novel 3D reconstruction and quantitative algorithms designed for interventional imaging.
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Affiliation(s)
- Joseph F Whitehead
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, USA
| | - Paul F Laeseke
- Department of Medicine, University of Wisconsin - Madison, Madison, Wisconsin, USA
| | - Sarvesh Periyasamy
- Department of Radiology, University of Wisconsin - Madison, Madison, Wisconsin, USA
| | - Michael A Speidel
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, USA
- Department of Medicine, University of Wisconsin - Madison, Madison, Wisconsin, USA
| | - Martin G Wagner
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, USA
- Department of Radiology, University of Wisconsin - Madison, Madison, Wisconsin, USA
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Mínguez Gabiña P, Monserrat Fuertes T, Jauregui I, Del Amo C, Rodeño Ortiz de Zarate E, Gustafsson J. Activity recovery for differently shaped objects in quantitative SPECT. Phys Med Biol 2023; 68:125012. [PMID: 37236207 DOI: 10.1088/1361-6560/acd982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 05/26/2023] [Indexed: 05/28/2023]
Abstract
Objective.The aim was to theoretically and experimentally investigate recovery in SPECT images with objects of different shapes. Furthermore, the accuracy of volume estimation by thresholding was studied for those shapes.Approach.Nine spheres, nine oblate spheroids, and nine prolate spheroids phantom inserts were used, of which the six smaller spheres were part of the NEMA IEC body phantom and the rest of the inserts were 3D-printed. The inserts were filled with99mTc and177Lu. When filled with99mTc, SPECT images were acquired in a Siemens Symbia Intevo Bold gamma camera and when filled with177Lu in a General Electric NM/CT 870 DR gamma camera. The signal rate per activity (SRPA) was determined for all inserts and represented as a function of the volume-to-surface ratio and of the volume-equivalent radius using VOIs defined according to the sphere dimensions and VOIs defined using thresholding. Experimental values were compared with theoretical curves obtained analytically (spheres) or numerically (spheroids), starting from the convolution of a source distribution with a point-spread function. Validation of the activity estimation strategy was performed using four 3D-printed ellipsoids. Lastly, the threshold values necessary to determine the volume of each insert were obtained.Main results.Results showed that SRPA values for the oblate spheroids diverted from the other inserts, when SRPA were represented as a function of the volume-equivalent radius. However, SRPA values for all inserts followed a similar behaviour when represented as a function of the volume-to-surface ratio. Results for ellipsoids were in agreement with those results. For the three types of inserts the volume could be accurately estimated using a threshold method for volumes larger than 25 ml.Significance.Determination of SRPA independently of lesion or organ shape should decrease uncertainties in estimated activities and thereby, in the long term, be beneficial to patient care.
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Affiliation(s)
- Pablo Mínguez Gabiña
- Department of Medical Physics and Radiation Protection, Gurutzeta-Cruces University Hospital/ Biocruces Bizkaia Health Research Institute, Plaza Cruces s/n, E-48903 Barakaldo, Spain
- Faculty of Engineering, Department of Applied Physics, UPV/EHU, Bilbao, Spain
| | - Teresa Monserrat Fuertes
- Department of Medical Physics and Radiation Protection, Central University Hospital of Asturias, Oviedo, Spain
- Faculty of Medicine and Nursing, Department of Surgery, Radiology and Physical Medicine, UPV/EHU, Bilbao, Spain
| | - Inés Jauregui
- 3D Printing and Bioprinting Laboratory, Biocruces Bizkaia Health Research Institute, Plaza Cruces s/n, E-48903 Barakaldo, Spain
| | - Cristina Del Amo
- 3D Printing and Bioprinting Laboratory, Biocruces Bizkaia Health Research Institute, Plaza Cruces s/n, E-48903 Barakaldo, Spain
| | - Emilia Rodeño Ortiz de Zarate
- Department of Nuclear Medicine, Gurutzeta-Cruces University Hospital/ Biocruces Bizkaia Health Research Institute, Plaza Cruces s/n, E-48903 Barakaldo, Spain
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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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Delker A, Schleske M, Liubchenko G, Berg I, Zacherl MJ, Brendel M, Gildehaus FJ, Rumiantcev M, Resch S, Hürkamp K, Wenter V, Unterrainer LM, Bartenstein P, Ziegler SI, Beyer L, Böning G. Biodistribution and dosimetry for combined [ 177Lu]Lu-PSMA-I&T/[ 225Ac]Ac-PSMA-I&T therapy using multi-isotope quantitative SPECT imaging. Eur J Nucl Med Mol Imaging 2023; 50:1280-1290. [PMID: 36629878 PMCID: PMC10027798 DOI: 10.1007/s00259-022-06092-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 12/22/2022] [Indexed: 01/12/2023]
Abstract
PURPOSE Quantitative SPECT for patient-specific dosimetry is a valuable tool in the scope of radionuclide therapy, although its clinical application for 225Ac-based treatments may be limited due to low therapeutic activities. Therefore, the aim of this study was to demonstrate the feasibility of clinical quantitative low-count SPECT imaging during [177Lu]Lu-PSMA-I&T/[225Ac]Ac-PSMA-I&T treatment. METHODS Eight prostate cancer patients (1000 MBq/8 MBq [177Lu]Lu-PSMA-I&T/[225Ac]Ac-PSMA-I&T) received a single-bed quantitative 177Lu/225Ac SPECT/CT acquisition (1 h) at 24 h post treatment (high-energy collimator, 16 projections p. head à 3.5 min, 128 × 128 pixel). The gamma peak at 440 keV (width: 10%) of the progeny 213Bi was imaged along with the peak at 208 keV (width: 15%) of 177Lu. Quantification included CT-based attenuation and window-based scatter correction plus resolution modelling. Gaussian post-filtering with a full-width-half-maximum of 30 mm and 40-45 mm was employed to match the signal-to-noise ratio of 225Ac and 177Lu, respectively. RESULTS Kidney (r = 0.96, p < 0.01) and lesion (r = 0.94, p < 0.01) SUV for [177Lu]Lu-PSMA-I&T and [225Ac]Ac-PSMA-I&T showed a strong and significant correlation. Kidney SUV were significantly higher (p < 0.01) for [225Ac]Ac-PSMA-I&T (2.5 ± 0.8 vs. 2.1 ± 0.9), while for [177Lu]Lu-PSMA-I&T lesion SUV were significantly higher (p = 0.03; 1.8 ± 1.1 vs. 2.1 ± 1.5). For absorbed dose estimates, significant differences regarding the kidneys remained, while no significant differences for lesion dosimetry were found. CONCLUSION Quantitative low-count SPECT imaging of the peak at 440 keV during [225Ac]Ac-PSMA-I&T therapy is feasible. Multi-isotope imaging for [177Lu]Lu-PSMA-I&T/[225Ac]Ac-PSMA-I&T therapy indicates accumulation of free 213Bi in the kidneys.
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Affiliation(s)
- Astrid Delker
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany.
| | - Mirjam Schleske
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Grigory Liubchenko
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Isabella Berg
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | | | - Matthias Brendel
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
- SyNergy, University of Munich, Munich, Germany
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
| | | | - Mikhail Rumiantcev
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Sandra Resch
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Kerstin Hürkamp
- Institute of Radiation Medicine, Helmholtz Zentrum München, German Research Center for Environmental Health GmbH, 85764, Neuherberg, Germany
| | - Vera Wenter
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Lena M Unterrainer
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Peter Bartenstein
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Sibylle I Ziegler
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Leonie Beyer
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Guido Böning
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
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Study of 99mTc absorption on micro-sized ion exchange resins to achieve high activity for SPECT. Appl Radiat Isot 2022; 186:110256. [DOI: 10.1016/j.apradiso.2022.110256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 04/20/2022] [Accepted: 04/21/2022] [Indexed: 11/30/2022]
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Frangos S, Michael K, Exadaktylou P, Giannoula E, Iakovou I. The Anger's camera. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00159-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Craig AJ, Murray I, Denis-Bacelar AM, Rojas B, Gear JI, Hossen L, Maenhout A, Khan N, Flux GD. Comparison of 90Y SIRT predicted and delivered absorbed doses using a PSF conversion method. Phys Med 2021; 89:1-10. [PMID: 34339928 PMCID: PMC8501309 DOI: 10.1016/j.ejmp.2021.07.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 06/23/2021] [Accepted: 07/19/2021] [Indexed: 12/24/2022] Open
Abstract
PURPOSE The aims of this study were to develop and apply a method to correct for the differences in partial volume effects of pre-therapy Technetium-99 m (99mTc)-MAA SPECT and post-therapy Yttrium-90 (90Y) bremsstrahlung SPECT imaging in selective internal radiation therapy, and to use this method to improve quantitative comparison of predicted and delivered 90Y absorbed doses. METHODS The spatial resolution of 99mTc SPECT data was converted to that of 90Y SPECT data using a function calculated from 99mTc and 90Y point spread functions. This resolution conversion method (RCM) was first applied to 99mTc and 90Y SPECT phantom data to validate the method, and then to clinical data to assess the power of 99mTc SPECT imaging to predict the therapeutic absorbed dose. RESULTS The maximum difference between absorbed doses to phantom spheres was 178%. This was reduced to 27% after the RCM was applied. The clinical data demonstrated differences within 38% for mean absorbed doses delivered to the normal liver, which were reduced to 20% after application of the RCM. Analysis of clinical data showed that therapeutic absorbed doses delivered to tumours greater than 100 cm3 were predicted to within 52%, although there were differences of up to 210% for smaller tumours, even after the RCM was applied. CONCLUSIONS The RCM was successfully verified using phantom data. Analysis of the clinical data established that the 99mTc pre-therapy imaging was predictive of the 90Y absorbed dose to the normal liver to within 20%, but had poor predictability for tumours smaller than 100 cm3.
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Affiliation(s)
- Allison J. Craig
- Joint Department of Physics, Royal Marsden NHSFT, Sutton, United Kingdom,The Institute of Cancer Research, London, United Kingdom,Corresponding author.
| | - Iain Murray
- Joint Department of Physics, Royal Marsden NHSFT, Sutton, United Kingdom,The Institute of Cancer Research, London, United Kingdom
| | | | - Bruno Rojas
- Joint Department of Physics, Royal Marsden NHSFT, Sutton, United Kingdom,The Institute of Cancer Research, London, United Kingdom
| | - Jonathan I. Gear
- Joint Department of Physics, Royal Marsden NHSFT, Sutton, United Kingdom,The Institute of Cancer Research, London, United Kingdom
| | - Lucy Hossen
- Royal Brompton & Harefield NHSFT, London, United Kingdom
| | | | - Nasir Khan
- Chelsea & Westminster NHSFT, London, United Kingdom
| | - Glenn D. Flux
- Joint Department of Physics, Royal Marsden NHSFT, Sutton, United Kingdom,The Institute of Cancer Research, London, United Kingdom
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12
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Woodall RT, Hormuth Ii DA, Wu C, Abdelmalik MRA, Phillips WT, Bao A, Hughes TJR, Brenner AJ, Yankeelov TE. Patient specific, imaging-informed modeling of rhenium-186 nanoliposome delivery via convection-enhanced delivery in glioblastoma multiforme. Biomed Phys Eng Express 2021; 7. [PMID: 34050041 DOI: 10.1088/2057-1976/ac02a6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 05/18/2021] [Indexed: 12/25/2022]
Abstract
Convection-enhanced delivery of rhenium-186 (186Re)-nanoliposomes is a promising approach to provide precise delivery of large localized doses of radiation for patients with recurrent glioblastoma multiforme. Current approaches for treatment planning utilizing convection-enhanced delivery are designed for small molecule drugs and not for larger particles such as186Re-nanoliposomes. To enable the treatment planning for186Re-nanoliposomes delivery, we have developed a computational fluid dynamics approach to predict the distribution of nanoliposomes for individual patients. In this work, we construct, calibrate, and validate a family of computational fluid dynamics models to predict the spatio-temporal distribution of186Re-nanoliposomes within the brain, utilizing patient-specific pre-operative magnetic resonance imaging (MRI) to assign material properties for an advection-diffusion transport model. The model family is calibrated to single photon emission computed tomography (SPECT) images acquired during and after the infusion of186Re-nanoliposomes for five patients enrolled in a Phase I/II trial (NCT Number NCT01906385), and is validated using a leave-one-out bootstrapping methodology for predicting the final distribution of the particles. After calibration, our models are capable of predicting the mid-delivery and final spatial distribution of186Re-nanoliposomes with a Dice value of 0.69 ± 0.18 and a concordance correlation coefficient of 0.88 ± 0.12 (mean ± 95% confidence interval), using only the patient-specific, pre-operative MRI data, and calibrated model parameters from prior patients. These results demonstrate a proof-of-concept for a patient-specific modeling framework, which predicts the spatial distribution of nanoparticles. Further development of this approach could enable optimizing catheter placement for future studies employing convection-enhanced delivery.
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Affiliation(s)
- Ryan T Woodall
- Biomedical Engineering, The University of Texas at Austin, Austin, Texas, United States of America
| | - David A Hormuth Ii
- Oden Institute for Computational Engineering and Sciences,The University of Texas at Austin, Austin, Texas, United States of America.,Oncology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Chengyue Wu
- Oden Institute for Computational Engineering and Sciences,The University of Texas at Austin, Austin, Texas, United States of America
| | - Michael R A Abdelmalik
- Oden Institute for Computational Engineering and Sciences,The University of Texas at Austin, Austin, Texas, United States of America.,Mechanical Engineering, Eindhoven University of Technology, The Netherlands
| | - William T Phillips
- Departments of Radiology at UT Health San Antonio, San Antonio, Texas, United States of America
| | - Ande Bao
- Department of Radiation Oncology, Seidman Cancer Center, University Hospitals, Cleveland Medical Center, Cleveland, Ohio, United States of America.,School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Thomas J R Hughes
- Oden Institute for Computational Engineering and Sciences,The University of Texas at Austin, Austin, Texas, United States of America.,Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas, United States of America
| | - Andrew J Brenner
- Mays Cancer Center at UT Health San Antonio, San Antonio, Texas, United States of America
| | - Thomas E Yankeelov
- Biomedical Engineering, The University of Texas at Austin, Austin, Texas, United States of America.,Oden Institute for Computational Engineering and Sciences,The University of Texas at Austin, Austin, Texas, United States of America.,Diagnostic Medicine, The University of Texas at Austin, Austin, Texas, United States of America.,Oncology, The University of Texas at Austin, Austin, Texas, United States of America.,Livestrong Cancer Institutes, The University of Texas at Austin, Austin, Texas, United States of America.,Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
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13
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Monserrat Fuertes T, González García F, Peinado Montes M, Domínguez Grande M, Martín Fernández N, Gómez de Iturriaga Piña A, Mínguez Gabiña P. Description of the methodology for dosimetric quantification in treatments with 177Lu-DOTATATE. Rev Esp Med Nucl Imagen Mol 2021. [DOI: 10.1016/j.remnie.2021.03.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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14
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Monserrat Fuertes T, González García FM, Peinado Montes MÁ, Domínguez Grande ML, Martín Fernández N, Gómez de Iturriaga Piña A, Mínguez Gabiña P. Description of the methodology for dosimetric quantification in treatments with 177Lu-DOTATATE. Rev Esp Med Nucl Imagen Mol 2021; 40:167-178. [PMID: 33811003 DOI: 10.1016/j.remn.2021.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/22/2021] [Accepted: 02/24/2021] [Indexed: 11/28/2022]
Abstract
Implementation of dosimetry calculations in the daily practice of Nuclear Medicine Departments is, at this time, a controversial issue, partly due to the lack of a standardized methodology that is accepted by all interested parties (patients, nuclear medicine physicians and medical physicists). However, since the publication of RD 601/2019 there is a legal obligation to implement it, despite the fact that it is a complex and high resource consumption procedure. The aim of this article is to review the theoretical bases of in vivo dosimetry in treatments with 177Lu-DOTATATE. The exposed methodology is the one proposed by the MIRD Committee (Medical Internal Radiation Dose) of the SNMMI (Society of Nuclear Medicine & Molecular Imaging). According to this method, the absorbed dose is obtained as the product of 2factors: the time-integrated activity of the radiopharmaceutical present in a source region and a geometrical factor S. This approach, which a priori seems simple, in practice requires several SPECT/CT acquisitions, several measurements of the whole body activity and taking several blood samples, as well as hours of image processing and computation. The systematic implementation of these calculations, in all the patients we treat, will allow us to obtain homogeneous data to correlate the absorbed doses in the lesions with the biological effect of the treatment. The final purpose of the dosimetry calculations is to be able to maximize the therapeutic effect in the lesions, controlling the radiotoxicity in the organs at risk.
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Affiliation(s)
- T Monserrat Fuertes
- Servicio de Radiofísica y Protección Radiológica, Hospital Universitario Central de Asturias, Oviedo, Asturias, España; Departamento de Cirugía, Radiología y Medicina Física, UPV/EHU, Leioa, Bizkaia, España.
| | - F M González García
- Servicio de Medicina Nuclear, Hospital Universitario Central de Asturias, Oviedo, Asturias, España
| | - M Á Peinado Montes
- Servicio de Radiofísica y Protección Radiológica, Hospital Universitario Central de Asturias, Oviedo, Asturias, España
| | - M L Domínguez Grande
- Servicio de Medicina Nuclear, Hospital Universitario Central de Asturias, Oviedo, Asturias, España
| | - N Martín Fernández
- Servicio de Medicina Nuclear, Hospital Universitario Central de Asturias, Oviedo, Asturias, España
| | - A Gómez de Iturriaga Piña
- Departamento de Cirugía, Radiología y Medicina Física, UPV/EHU, Leioa, Bizkaia, España; Servicio de Oncología Radioterápica, Hospital Universitario Gurutzeta-Cruces/Instituto de Investigación Sanitaria BioCruces, Barakaldo, Bizkaia, España
| | - P Mínguez Gabiña
- Unidad de Protección Radiológica y Radiofísica, Hospital Universitario Gurutzeta-Cruces/Instituto de Investigación Sanitaria BioCruces, Barakaldo, Bizkaia, España
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15
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Hosny T, Khalil MM, Elfiky AA, Elshemey WM. Image quality characteristics of myocardial perfusion SPECT imaging using state-of-the-art commercial software algorithms: evaluation of 10 reconstruction methods. AMERICAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 2020; 10:375-386. [PMID: 33329938 PMCID: PMC7724275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 10/02/2020] [Indexed: 06/12/2023]
Abstract
Myocardial perfusion imaging (MPI) is widely used as standard of care in patients with coronary artery disease. The availability of hybrid SPECT/CT imaging system and associated advanced reconstruction algorithms serve to improve diagnostic accuracy and enhances image quality of MPI. The aim of this work was to evaluate the relative performance of iterative reconstruction algorithms correcting for different combinations of image degrading factors versus filtered back projection on the quality of myocardial perfusion SPECT imaging. A standard cardiac phantom containing myocardial defects of different sizes and compositions was used to simulate myocardial perfusion SPECT/CT clinical studies. A clinically relevant activity was determined to avoid discordance with real data acquisition. Acquisition parameters including time per projection, angular rotation increment, and iterative reconstruction number of iterations and subsets were varied. The reconstruction was carried out applying different algorithms including 10 variants of analytical (e.g FBP) and iterative reconstructions with and without resolution recovery. Typical figures of merit were used to evaluate the image quality of MPI reconstructed with ten different reconstruction methods. OSEM-RR showed remarkable improvement of image quality of MPI in terms of SNR, CNR and defect contrast percentage compared to FBP algorithm. Full correction scheme IR-RR (i.e. IRACSCRR) provides clinically acceptable image quality of MPI compared to FBP.
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Affiliation(s)
- Taher Hosny
- Department of Biophysics, Faculty Science, Cairo UniversityCairo, Egypt
| | - Magdy M Khalil
- Department of Physics, Faculty of Science, Helwan UniversityCairo, Egypt
| | - Abdo A Elfiky
- Department of Biophysics, Faculty Science, Cairo UniversityCairo, Egypt
| | - Wael M Elshemey
- Department of Biophysics, Faculty Science, Cairo UniversityCairo, Egypt
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16
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Ouahman M, Errifai R, Asmi H, Bouzekraoui Y, Douama S, Bentayeb F, Bonutti F. Collimator and Energy Window Evaluation in Ga-67 Imaging by Monte Carlo Simulation. Mol Imaging Radionucl Ther 2020; 29:118-123. [PMID: 33094575 PMCID: PMC7583743 DOI: 10.4274/mirt.galenos.2020.21549] [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] [Indexed: 12/01/2022] Open
Abstract
Objectives: Gallium-67 (Ga-67) imaging is affected by collimator penetration and scatter components owing to the high-energy (HE) gamma-ray emissions. The characterization of penetration and scatter distribution is essential for the optimization of low-energy high-resolution (LEHR), medium energy (ME), and HE collimators and for the development of an effective correction technique. We compared the image quality that can be achieved by 3 collimators for different energy windows using the SIMIND Monte Carlo code. Methods: Simulation experiments were conducted for LEHR, ME, and HE collimators for Ga-67 point source placed at 12-cm distance from the detector surface using the Monte Carlo SIMIND simulation code. Their spectra point spread functions as well as the original, penetration, scattering, and X-rays curves were drawn and analyzed. The parameters full-width at half maximum and full-width at tenth maximum were also investigated. Results: The original, penetration, and scatter curves within 10% for LEHR were 34.46%, 33.52%, 17.29%, and 14.72%, respectively. Similarly, the original, penetration, scatter, and X-rays within 10% for ME and HE were 83.06%, 10.25%, 6.69%, and 0% and 81.44%, 11.51%, 7.05%, and 0%, respectively. The trade-off between spatial resolution and sensitivity was achieved by using the ME collimator at 185 photopeak of Ga-67. Conclusion: The Monte Carlo simulation outcomes can be applied for optimal collimator designing and for the development of new correction method in Ga-67 imaging.
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Affiliation(s)
- Mina Ouahman
- Mohammed V-Rabat University Faculty of Science, Laboratory of High Energy Physics Modelisation Simulation, Rabat, Morocco
| | - Rachid Errifai
- Mohammed V-Rabat University Faculty of Science, Laboratory of High Energy Physics Modelisation Simulation, Rabat, Morocco
| | - Hicham Asmi
- Mohammed V-Rabat University Faculty of Science, Laboratory of High Energy Physics Modelisation Simulation, Rabat, Morocco
| | - Youssef Bouzekraoui
- Mohammed V-Rabat University Faculty of Science, Laboratory of High Energy Physics Modelisation Simulation, Rabat, Morocco
| | - Sanae Douama
- Mohammed V-Rabat University Faculty of Science, Laboratory of High Energy Physics Modelisation Simulation, Rabat, Morocco
| | - Farida Bentayeb
- Mohammed V-Rabat University Faculty of Science, Laboratory of High Energy Physics Modelisation Simulation, Rabat, Morocco
| | - Faustino Bonutti
- Academic Hospital of Udine, Clinic of Medical Physics, Udine, Italy
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17
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Image-based dosimetry for 225Ac-PSMA-I&T therapy using quantitative SPECT. Eur J Nucl Med Mol Imaging 2020; 48:1260-1261. [PMID: 32959113 PMCID: PMC8041692 DOI: 10.1007/s00259-020-05024-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 08/31/2020] [Indexed: 11/17/2022]
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18
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Chun SY, Nguyen MP, Phan TQ, Kim H, Fessler JA, Dewaraja YK. Algorithms and Analyses for Joint Spectral Image Reconstruction in Y-90 Bremsstrahlung SPECT. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:1369-1379. [PMID: 31647425 PMCID: PMC7263381 DOI: 10.1109/tmi.2019.2949068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Quantitative yttrium-90 (Y-90) SPECT imaging is challenging due to the nature of Y-90, an almost pure beta emitter that is associated with a continuous spectrum of bremsstrahlung photons that have a relatively low yield. This paper proposes joint spectral reconstruction (JSR), a novel bremsstrahlung SPECT reconstruction method that uses multiple narrow acquisition windows with accurate multi-band forward modeling to cover a wide range of the energy spectrum. Theoretical analyses using Fisher information and Monte-Carlo (MC) simulation with a digital phantom show that the proposed JSR model with multiple acquisition windows has better performance in terms of covariance (precision) than previous methods using multi-band forward modeling with a single acquisition window, or using a single-band forward modeling with a single acquisition window. We also propose an energy-window subset (ES) algorithm for JSR to achieve fast empirical convergence and maximum-likelihood based initialization for all reconstruction methods to improve quantification accuracy in early iterations. For both MC simulation with a digital phantom and experimental study with a physical multi-sphere phantom, our proposed JSR-ES, a fast algorithm for JSR with ES, yielded higher recovery coefficients (RCs) on hot spheres over all iterations and sphere sizes than all the other evaluated methods, due to fast empirical convergence. In experimental study, for the smallest hot sphere (diameter 1.6cm), at the 20th iteration the increase in RCs with JSR-ES was 66 and 31% compared with single wide and narrow band forward models, respectively. JSR-ES also yielded lower residual count error (RCE) on a cold sphere over all iterations than other methods for MC simulation with known scatter, but led to greater RCE compared with single narrow band forward model at higher iterations for experimental study when using estimated scatter.
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19
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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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Dietze MMA, van der Velden S, Lam MGEH, Viergever MA, de Jong HWAM. Fast quantitative reconstruction with focusing collimators for liver SPECT. EJNMMI Phys 2018; 5:28. [PMID: 30511121 PMCID: PMC6277405 DOI: 10.1186/s40658-018-0228-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 08/09/2018] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Generation of a SPECT scan during procedure may aid in the optimization of treatments as liver radioembolization by offering image-guided dosimetry. This, however, requires both shortened acquisition times and fast quantitative reconstruction. Focusing collimators increase sensitivity and thus may speed up imaging. Monte Carlo-based iterative reconstruction has shown to provide quantitative results for parallel hole collimators but may be slow. The purpose of this work is to develop fast Monte Carlo-based reconstruction for focusing collimators and to evaluate the impact of reconstruction and collimator choice on quantitative accuracy of liver dosimetry by means of simulations. RESULTS The developed fast Monte Carlo simulator was found to accurately generate projections compared to a full Monte Carlo simulation, providing projections in several seconds instead of several days. Monte Carlo-based scatter correction was superior to other scatter correction methods in describing recovered activity and reached similar noise levels as dual-energy window scatter correction. Although truncation artifacts were present in the cone beam collimator (50 cm), the region inside the field of view (FOV) could be reconstructed without loss of accuracy. Provided the object to image is inside the FOV, the focusing collimator with 50 cm focal distance could retrieve the same noise levels as a parallel hole collimator in 68% of the total scanning time, the multifocal collimator in 73% of the time, and the 100-cm focal distance collimator in 84% of the time. CONCLUSION Focusing collimators combined with Monte Carlo-based reconstruction have the ability to enable quantitative imaging of the FOV in a significantly shorter timeframe. The proposed approach to the forward projector will additionally make it possible to reconstruct within minutes. These are crucial steps in moving toward real-time dosimetry during interventions.
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Affiliation(s)
- Martijn M. A. Dietze
- Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 Utrecht, GA Netherlands
- Image Sciences Institute, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 Utrecht, GA Netherlands
| | - Sandra van der Velden
- Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 Utrecht, GA Netherlands
- Image Sciences Institute, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 Utrecht, GA Netherlands
| | - Marnix G. E. H. Lam
- Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 Utrecht, GA Netherlands
| | - Max A. Viergever
- Image Sciences Institute, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 Utrecht, GA Netherlands
| | - Hugo W. A. M. de Jong
- Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 Utrecht, GA Netherlands
- Image Sciences Institute, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 Utrecht, GA Netherlands
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21
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Evaluation of quantitative 123I and 131I SPECT with Monte Carlo-based down-scatter compensation. Nucl Med Commun 2018; 39:1097-1102. [PMID: 30222722 DOI: 10.1097/mnm.0000000000000920] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Quantitative I and I single-photon emission computed tomography (SPECT) is hampered by down-scatter from the high-energy peaks. This paper presents a down-scatter compensation method, where down-scatter generated in the patient and gamma camera collimator and detector is modelled using Monte Carlo simulation in the ordered subsets expectation maximization SPECT reconstruction algorithm. MATERIALS AND METHODS The new down-scatter compensation method was compared with conventional triple energy window (TEW) scatter compensation and Gaussian convolution-based forced detection Monte Carlo methods. The comparison was made with the NEMA-IEC phantom using six spherical inserts (diameters from 10 to 37 mm) and a lung compartment. The phantom was filled with I and I solutions to known sphere-to-background concentration ratios. Spherical volumes of interest with the same diameter as the inserts were drawn on the images, and recovery coefficients for the spheres were calculated in addition to lung-to-background ratio. RESULTS The new down-scatter compensation method provided higher recovery coefficients than the TEW scatter compensation or Gaussian convolution-based forced detection Monte Carlo algorithm for both isotopes. Background activity concentration could be accurately estimated with the new down-scatter compensation method and with the TEW scatter compensation, whereas activity concentration of the spheres was severely underestimated even with the new method. CONCLUSION Down-scatter compensation with Monte Carlo-simulation effectively reduces down-scatter effects in I and I SPECT imaging.
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22
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McKnight BN, Viola-Villegas NT. 89 Zr-ImmunoPET companion diagnostics and their impact in clinical drug development. J Labelled Comp Radiopharm 2018; 61:727-738. [PMID: 29341222 PMCID: PMC6050145 DOI: 10.1002/jlcr.3605] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 12/14/2017] [Accepted: 01/05/2018] [Indexed: 12/27/2022]
Abstract
Therapeutic monoclonal antibodies have been used in cancer treatment for 30 years, with around 24 mAb and mAb:drug conjugates approved by the FDA to date. Despite their specificity, efficacy has remained limited, which, in part, derails nascent initiatives towards precision medicine. An image-guided approach to reinforce treatment decisions using immune positron emission tomography (immunoPET) companion diagnostic is warranted. This review provides a general overview of current translational research using Zr-89 immunoPET and opportunities for utilizing and harnessing this tool to its full potential. Patient case studies are cited to illustrate immunoPET probes as tools for profiling molecular signatures. Discussions on its utility in reinforcing clinical decisions as it relates to histopathological tumor assessment and standard diagnostic methods, and its potential as predictive biomarkers, are presented. We finally conclude with an overview of practical considerations to its utility in the clinic.
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Affiliation(s)
- Brooke N. McKnight
- Cancer Biology, Wayne State University School of Medicine, Detroit, MI 48201
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Tilley S, Jacobson M, Cao Q, Brehler M, Sisniega A, Zbijewski W, Stayman JW. Penalized-Likelihood Reconstruction With High-Fidelity Measurement Models for High-Resolution Cone-Beam Imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:988-999. [PMID: 29621002 PMCID: PMC5889122 DOI: 10.1109/tmi.2017.2779406] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We present a novel reconstruction algorithm based on a general cone-beam CT forward model, which is capable of incorporating the blur and noise correlations that are exhibited in flat-panel CBCT measurement data. Specifically, the proposed model may include scintillator blur, focal-spot blur, and noise correlations due to light spread in the scintillator. The proposed algorithm (GPL-BC) uses a Gaussian Penalized-Likelihood objective function, which incorporates models of blur and correlated noise. In a simulation study, GPL-BC was able to achieve lower bias as compared with deblurring followed by FDK as well as a model-based reconstruction method without integration of measurement blur. In the same study, GPL-BC was able to achieve better line-pair reconstructions (in terms of segmented-image accuracy) as compared with deblurring followed by FDK, a model-based method without blur, and a model-based method with blur but not noise correlations. A prototype extremities quantitative cone-beam CT test-bench was used to image a physical sample of human trabecular bone. These data were used to compare reconstructions using the proposed method and model-based methods without blur and/or correlation to a registered CT image of the same bone sample. The GPL-BC reconstructions resulted in more accurate trabecular bone segmentation. Multiple trabecular bone metrics, including trabecular thickness (Tb.Th.) were computed for each reconstruction approach as well as the CT volume. The GPL-BC reconstruction provided the most accurate Tb.Th. measurement, 0.255 mm, as compared with the CT derived value of 0.193 mm, followed by the GPL-B reconstruction, the GPL-I reconstruction, and then the FDK reconstruction (0.271 mm, 0.309 mm, and 0.335 mm, respectively).
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24
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Segars WP, Tsui BMW, Jing Cai, Fang-Fang Yin, Fung GSK, Samei E. Application of the 4-D XCAT Phantoms in Biomedical Imaging and Beyond. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:680-692. [PMID: 28809677 PMCID: PMC5809240 DOI: 10.1109/tmi.2017.2738448] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The four-dimensional (4-D) eXtended CArdiac-Torso (XCAT) series of phantoms was developed to provide accurate computerized models of the human anatomy and physiology. The XCAT series encompasses a vast population of phantoms of varying ages from newborn to adult, each including parameterized models for the cardiac and respiratory motions. With great flexibility in the XCAT's design, any number of body sizes, different anatomies, cardiac or respiratory motions or patterns, patient positions and orientations, and spatial resolutions can be simulated. As such, the XCAT phantoms are gaining a wide use in biomedical imaging research. There they can provide a virtual patient base from which to quantitatively evaluate and improve imaging instrumentation, data acquisition, techniques, and image reconstruction and processing methods which can lead to improved image quality and more accurate clinical diagnoses. The phantoms have also found great use in radiation dosimetry, radiation therapy, medical device design, and even the security and defense industry. This review paper highlights some specific areas in which the XCAT phantoms have found use within biomedical imaging and other fields. From these examples, we illustrate the increasingly important role that computerized phantoms and computer simulation are playing in the research community.
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Dewaraja YK, Chun SY, Srinivasa RN, Kaza RK, Cuneo KC, Majdalany BS, Novelli PM, Ljungberg M, Fessler JA. Improved quantitative 90 Y bremsstrahlung SPECT/CT reconstruction with Monte Carlo scatter modeling. Med Phys 2017; 44:6364-6376. [PMID: 28940483 DOI: 10.1002/mp.12597] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 09/13/2017] [Accepted: 09/15/2017] [Indexed: 01/07/2023] Open
Abstract
PURPOSE In 90 Y microsphere radioembolization (RE), accurate post-therapy imaging-based dosimetry is important for establishing absorbed dose versus outcome relationships for developing future treatment planning strategies. Additionally, accurately assessing microsphere distributions is important because of concerns for unexpected activity deposition outside the liver. Quantitative 90 Y imaging by either SPECT or PET is challenging. In 90 Y SPECT model based methods are necessary for scatter correction because energy window-based methods are not feasible with the continuous bremsstrahlung energy spectrum. The objective of this work was to implement and evaluate a scatter estimation method for accurate 90 Y bremsstrahlung SPECT/CT imaging. METHODS Since a fully Monte Carlo (MC) approach to 90 Y SPECT reconstruction is computationally very demanding, in the present study the scatter estimate generated by a MC simulator was combined with an analytical projector in the 3D OS-EM reconstruction model. A single window (105 to 195-keV) was used for both the acquisition and the projector modeling. A liver/lung torso phantom with intrahepatic lesions and low-uptake extrahepatic objects was imaged to evaluate SPECT/CT reconstruction without and with scatter correction. Clinical application was demonstrated by applying the reconstruction approach to five patients treated with RE to determine lesion and normal liver activity concentrations using a (liver) relative calibration. RESULTS There was convergence of the scatter estimate after just two updates, greatly reducing computational requirements. In the phantom study, compared with reconstruction without scatter correction, with MC scatter modeling there was substantial improvement in activity recovery in intrahepatic lesions (from > 55% to > 86%), normal liver (from 113% to 104%), and lungs (from 227% to 104%) with only a small degradation in noise (13% vs. 17%). Similarly, with scatter modeling contrast improved substantially both visually and in terms of a detectability index, which was especially relevant for the low uptake extrahepatic objects. The trends observed for the phantom were also seen in the patient studies where lesion activity concentrations and lesion-to-liver concentration ratios were lower for SPECT without scatter correction compared with reconstruction with just two MC scatter updates: in eleven lesions the mean uptake was 4.9 vs. 7.1 MBq/mL (P = 0.0547), the mean normal liver uptake was 1.6 vs. 1.5 MBq/mL (P = 0.056) and the mean lesion-to-liver uptake ratio was 2.7 vs. 4.3 (P = 0.0402) for reconstruction without and with scatter correction respectively. CONCLUSIONS Quantitative accuracy of 90 Y bremsstrahlung imaging can be substantially improved with MC scatter modeling without significant degradation in image noise or intensive computational requirements.
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Affiliation(s)
- Yuni K Dewaraja
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Se Young Chun
- School of Electrical and Computer Engineering, Ulsan National Institute of Science and Technology, Ulsan, Korea
| | - Ravi N Srinivasa
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Ravi K Kaza
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Kyle C Cuneo
- Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Bill S Majdalany
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Paula M Novelli
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michael Ljungberg
- Department of Medical Radiation Physics, Lund University, Lund, Sweden
| | - Jeffrey A Fessler
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA
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Myronakis ME, Cai W, Dhou S, Cifter F, Hurwitz M, Segars PW, Berbeco RI, Lewis JH. A graphical user interface for XCAT phantom configuration, generation and processing. Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/aa5767] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Zeraatkar N, Farahani MH, Rahmim A, Sarkar S, Ay MR. Design and assessment of a novel SPECT system for desktop open-gantry imaging of small animals: A simulation study. Med Phys 2016; 43:2581. [DOI: 10.1118/1.4947127] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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Chun SY. The Use of Anatomical Information for Molecular Image Reconstruction Algorithms: Attenuation/Scatter Correction, Motion Compensation, and Noise Reduction. Nucl Med Mol Imaging 2016; 50:13-23. [PMID: 26941855 DOI: 10.1007/s13139-016-0399-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 01/11/2016] [Accepted: 01/13/2016] [Indexed: 01/05/2023] Open
Abstract
PET and SPECT are important tools for providing valuable molecular information about patients to clinicians. Advances in nuclear medicine hardware technologies and statistical image reconstruction algorithms enabled significantly improved image quality. Sequentially or simultaneously acquired anatomical images such as CT and MRI from hybrid scanners are also important ingredients for improving the image quality of PET or SPECT further. High-quality anatomical information has been used and investigated for attenuation and scatter corrections, motion compensation, and noise reduction via post-reconstruction filtering and regularization in inverse problems. In this article, we will review works using anatomical information for molecular image reconstruction algorithms for better image quality by describing mathematical models, discussing sources of anatomical information for different cases, and showing some examples.
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Affiliation(s)
- Se Young Chun
- School of Electrical and Computer Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
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Tilley S, Siewerdsen JH, Stayman JW. Model-based iterative reconstruction for flat-panel cone-beam CT with focal spot blur, detector blur, and correlated noise. Phys Med Biol 2015; 61:296-319. [PMID: 26649783 DOI: 10.1088/0031-9155/61/1/296] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
While model-based reconstruction methods have been successfully applied to flat-panel cone-beam CT (FP-CBCT) systems, typical implementations ignore both spatial correlations in the projection data as well as system blurs due to the detector and focal spot in the x-ray source. In this work, we develop a forward model for flat-panel-based systems that includes blur and noise correlation associated with finite focal spot size and an indirect detector (e.g. scintillator). This forward model is used to develop a staged reconstruction framework where projection data are deconvolved and log-transformed, followed by a generalized least-squares reconstruction that utilizes a non-diagonal statistical weighting to account for the correlation that arises from the acquisition and data processing chain. We investigate the performance of this novel reconstruction approach in both simulated data and in CBCT test-bench data. In comparison to traditional filtered backprojection and model-based methods that ignore noise correlation, the proposed approach yields a superior noise-resolution tradeoff. For example, for a system with 0.34 mm FWHM scintillator blur and 0.70 FWHM focal spot blur, using the correlated noise model instead of an uncorrelated noise model increased resolution by 42% (with variance matched at 6.9 × 10(-8) mm(-2)). While this advantage holds across a wide range of systems with differing blur characteristics, the improvements are greatest for systems where source blur is larger than detector blur.
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Affiliation(s)
- Steven Tilley
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
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Banari Bahnamiri S. Investigation of Collimator Influential Parameter on SPECT Image Quality: a Monte Carlo Study. J Biomed Phys Eng 2015; 5:39-48. [PMID: 25973410 PMCID: PMC4417619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Indexed: 11/17/2022]
Abstract
BACKGROUND Obtaining high quality images in Single Photon Emission Tomography (SPECT) device is the most important goal in nuclear medicine. Because if image quality is low, the possibility of making a mistake in diagnosing and treating the patient will rise. Studying effective factors in spatial resolution of imaging systems is thus deemed to be vital. One of the most important factors in SPECT imaging in nuclear medicine is the use of an appropriate collimator for a certain radiopharmaceutical feature in order to create the best image as it can be effective in the quantity of Full Width at Half Maximum (FWHM) which is the main parameter in spatial resolution. METHOD In this research, the simulation of the detector and collimator of SPECT imaging device, Model HD3 made by Philips Co. and the investigation of important factors on the collimator were carried out using MCNP-4c code. RESULTS The results of the experimental measurments and simulation calculations revealed a relative difference of less than 5% leading to the confirmation of the accuracy of conducted simulation MCNP code calculation. CONCLUSION This is the first essential step in the design and modelling of new collimators used for creating high quality images in nuclear medicine.
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Chun SY, Dewaraja YK, Fessler JA. Alternating direction method of multiplier for tomography with nonlocal regularizers. IEEE TRANSACTIONS ON MEDICAL IMAGING 2014; 33:1960-1968. [PMID: 25291351 PMCID: PMC4465786 DOI: 10.1109/tmi.2014.2328660] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The ordered subset expectation maximization (OSEM) algorithm approximates the gradient of a likelihood function using a subset of projections instead of using all projections so that fast image reconstruction is possible for emission and transmission tomography such as SPECT, PET, and CT. However, OSEM does not significantly accelerate reconstruction with computationally expensive regularizers such as patch-based nonlocal (NL) regularizers, because the regularizer gradient is evaluated for every subset. We propose to use variable splitting to separate the likelihood term and the regularizer term for penalized emission tomographic image reconstruction problem and to optimize it using the alternating direction method of multiplier (ADMM). We also propose a fast algorithm to optimize the ADMM parameter based on convergence rate analysis. This new scheme enables more sub-iterations related to the likelihood term. We evaluated our ADMM for 3-D SPECT image reconstruction with a patch-based NL regularizer that uses the Fair potential function. Our proposed ADMM improved the speed of convergence substantially compared to other existing methods such as gradient descent, EM, and OSEM using De Pierro's approach, and the limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm.
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Chun SY, Fessler JA, Dewaraja YK. Post-reconstruction non-local means filtering methods using CT side information for quantitative SPECT. Phys Med Biol 2014; 58:6225-40. [PMID: 23956327 DOI: 10.1088/0031-9155/58/17/6225] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Quantitative SPECT techniques are important for many applications including internal emitter therapy dosimetry where accurate estimation of total target activity and activity distribution within targets are both potentially important for dose–response evaluations. We investigated non-local means (NLM) post-reconstruction filtering for accurate I-131 SPECT estimation of both total target activity and the 3D activity distribution. We first investigated activity estimation versus number of ordered-subsets expectation–maximization (OSEM) iterations. We performed simulations using the XCAT phantom with tumors containing a uniform and a non-uniform activity distribution, and measured the recovery coefficient (RC) and the root mean squared error (RMSE) to quantify total target activity and activity distribution, respectively. We observed that using more OSEM iterations is essential for accurate estimation of RC, but may or may not improve RMSE. We then investigated various post-reconstruction filtering methods to suppress noise at high iteration while preserving image details so that both RC and RMSE can be improved. Recently, NLM filtering methods have shown promising results for noise reduction. Moreover, NLM methods using high-quality side information can improve image quality further. We investigated several NLM methods with and without CT side information for I-131 SPECT imaging and compared them to conventional Gaussian filtering and to unfiltered methods. We studied four different ways of incorporating CT information in the NLM methods: two known (NLM CT-B and NLM CT-M) and two newly considered (NLM CT-S and NLM CT-H). We also evaluated the robustness of NLM filtering using CT information to erroneous CT. NLM CT-S and NLM CT-H yielded comparable RC values to unfiltered images while substantially reducing RMSE. NLM CT-S achieved −2.7 to 2.6% increase of RC compared to no filtering and NLM CT-H yielded up to 6% decrease in RC while other methods yielded lower RCs than them: Gaussian filtering (up to 11.8% decrease in RC), NLM method without CT (up to 9.5% decrease in RC), and NLM CT-M and NLM CT-B (up to 19.4% decrease in RC). NLM CT-S and NLM CT-H achieved 8.2 to 33.9% and −0.9 to 36% decreased RMSE on tumors compared to no filtering respectively while other methods yielded less reduced or increased RMSE: Gaussian filtering (up to 7.9% increase in RMSE), NLM method without CT (up to 18.3% increase in RMSE), and NLM CT-M and NLM CT-B (up to 31.5% increase in RMSE). NLM CT-S and NLM CT-H also yielded images with tumor shapes that better-matched the true shapes than other methods. All NLM methods using CT information were robust to small misregistration between SPECT and CT, but NLM CT-S and NLM CT-H were more sensitive than NLM CT-M and NLM CT-B to missing CT information.
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Affiliation(s)
- Se Young Chun
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109, USA.
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