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Eyre K, Rafiee M, Coristine A, Delso G, Friedrich M, Chetrit M. COMPARISON OF POST-PROCESSING TECHNIQUES FOR OPTIMIZING THE QUALITY OF CARDIAC MAGNETIC RESONANCE T1 MAPPING IMAGES. Can J Cardiol 2022. [DOI: 10.1016/j.cjca.2022.08.131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Abstract
Purpose of Review The objective of this review is to document the advances in non-ionising imaging alternatives to CT for the head and neck. Recent Findings The main alternative to CT for imaging bone of the head and neck region is MRI, particularly techniques which incorporate gradient echo imaging (Black Bone technique) and ultra-short or zero-echo time imaging. Since these techniques can provide high resolution isometric voxels, they can be used to provide multi-planar reformats and, following post processing, 3D reconstructed images of the craniofacial skeleton. As expected, the greatest advancements in recent years have been focused on enhanced image processing techniques and attempts to address the difficulties encountered at air-bone interfaces. Summary This article will review the imaging techniques and recent advancements which are bringing non-ionising alternatives to CT imaging of the bone of the head and neck region into the realm of routine clinical application.
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Affiliation(s)
- Karen A. Eley
- Department of Radiology, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 218, Cambridge, CB2 0QQ UK
| | - Gaspar Delso
- MR Applications & Workflow, GE Healthcare, Barcelona, Spain
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Tanaka A, Sekine T, Ter Voert EEGW, Zeimpekis KG, Delso G, de Galiza Barbosa F, Warnock G, Kumita SI, Veit Haibach P, Huellner M. Reproducibility of Standardized Uptake Values Including Volume Metrics Between TOF-PET-MR and TOF-PET-CT. Front Med (Lausanne) 2022; 9:796085. [PMID: 35308500 PMCID: PMC8924656 DOI: 10.3389/fmed.2022.796085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 02/07/2022] [Indexed: 11/30/2022] Open
Abstract
Purpose To investigate the reproducibility of tracer uptake measurements, including volume metrics, such as metabolic tumor volume (MTV) and tumor lesion glycolysis (TLG) obtained by TOF-PET-CT and TOF-PET-MR. Materials and Methods Eighty consecutive patients with different oncologic diagnoses underwent TOF-PET-CT (Discovery 690; GE Healthcare) and TOF-PET-MR (SIGNA PET-MR; GE Healthcare) on the same day with single dose−18F-FDG injection. The scan order, PET-CT following or followed by PET-MR, was randomly assigned. A spherical volume of interest (VOI) of 30 mm was placed on the liver in accordance with the PERCIST criteria. For liver, the maximum and mean standard uptake value for body weight (SUV) and lean body mass (SUL) were obtained. For tumor delineation, VOI with a threshold of 40 and 50% of SUVmax was used (VOI40 and VOI50). The SUVmax, SUVmean, SUVpeak, MTV and TLG were calculated. The measurements were compared between the two scanners. Results In total, 80 tumor lesions from 35 patients were evaluated. There was no statistical difference observed in liver regions, whereas in tumor lesions, SUVmax, SUV mean, and SUVpeak of PET-MR were significantly underestimated (p < 0.001) in both VOI40 and VOI50. Among volume metrics, there was no statistical difference observed except TLG on VOI50 (p = 0.03). Correlation between PET-CT and PET-MR of each metrics were calculated. There was a moderate correlation of the liver SUV and SUL metrics (r = 0.63–0.78). In tumor lesions, SUVmax and SUVmean had a stronger correlation with underestimation in PET-MR on VOI 40 (SUVmax and SUVmean; r = 0.92 and 0.91 with slope = 0.71 and 0.72, respectively). In the evaluation of MTV and TLG, the stronger correlations were observed both on VOI40 (MTV and TLG; r = 0.75 and 0.92) and VOI50 (MTV and TLG; r = 0.88 and 0.95) between PET-CT and PET-MR. Conclusion PET metrics on TOF-PET-MR showed a good correlation with that of TOF-PET-CT. SUVmax and SUVpeak of tumor lesions were underestimated by 16% on PET-MRI. MTV with % threshold can be regarded as identical volumetric markers for both TOF-PET-CT and TOF-PET-MR.
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Affiliation(s)
- Aruki Tanaka
- Department of Radiology, Nippon Medical School Hospital, Tokyo, Japan
| | - Tetsuro Sekine
- Department of Radiology, Nippon Medical School Hospital, Tokyo, Japan.,Department of Radiology, Nippon Medical School Musashi Kosugi Hospital, Kanagawa, Japan.,Departments of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Edwin E G W Ter Voert
- Departments of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Konstantinos G Zeimpekis
- Departments of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland.,Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | | | - Felipe de Galiza Barbosa
- Departments of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Geoffrey Warnock
- Departments of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland.,PMOD Technologies Ltd., Zurich, Switzerland
| | | | - Patrick Veit Haibach
- Departments of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland.,Toronto Joint Department Medical Imaging, University Health Network, Sinai Health System, Women's College Hospital, Toronto, ON, Canada.,Department of Medical Imaging, University of Toronto, Toronto, ON, Canada
| | - Martin Huellner
- Departments of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
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Delso G, Torres-Espallardo I, Veit-Haibach P. Positron emission tomography. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00102-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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de Galiza Barbosa F, Delso G, Zeimpekis KG, Ter Voert E, Hüllner M, Stolzmann P, Veit-Haibach P. Evaluation and clinical quantification of neoplastic lesions and physiological structures in TOF-PET/MRI and non-TOF/MRI - a pilot study. Q J Nucl Med Mol Imaging 2021; 65:386-395. [PMID: 25964058 DOI: 10.23736/s1824-4785.17.02790-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
PURPOSE To clinically assess a new PET/MRI technology in which the PET--component features a new PET-- detector and time--of--flight (TOF) technology. Thus, we compared SUVmax/mean of neoplastic lesions and physiological structures between TOF-- and non--TOF--PET/MRI imaging. We qualitatively evaluated image quality derived from TOF-PET/MRI, non--TOF--PET/MRI reconstruction and FDG--PET/CT. Lastly we did clinical measurements to evaluate the PET-- detector sensitivity in order to better understand the background of our clinical results. MATERIALS AND METHODS Twenty--seven oncological patients were prospectively enrolled and evaluated with FDG-PET/CT and PET/MRI (15 M/ 12 F; mean age 56 ±10 y). Time between injection and PET/CT was 62.4 ±7.6 min, consecutive start of imaging of PET/MRI was 104.6 min±18.2 after injection. To assess the differences between TOF and non--TOF, all PET--images of the PET/MRI were reconstructed twice -with and without TOF. To compare lesion and tissue characterization between both reconstructions, malignant lesions as well as physiological structures were compared. Furthermore, PET image quality, artifacts, image sharpness, noise and lesion detectability were assessed as well. Count rates between both systems were also compared. RESULTS All malignant lesions and the majority of physiologic tissue (except the subcutaneous fat, spleen and blood pool) showed a good correlation concerning SUV (max and mean) measurements between PET/CT, non--TOF and TOF reconstructions. The general image quality was rated statistically significant superior in non--TOF (p<0.001) and TOF-reconstruction in PET/MRI (p<0.01) compared to PET/CT. Furthermore, TOF--PET/MRI was rated superior concerning image quality (p<0.05) compared to non--TOF PET/MRI. The ratio of emitted/received events between both systems (PET/CT and PET/MRI) was 2.78. CONCLUSIONS PET/MRI with TOF is reliable concerning SUV quantification and image quality. The technical promise of an improved sensitivity of the new PET--detector in this PET/MRI device could be confirmed in a clinical setting.
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Affiliation(s)
- F de Galiza Barbosa
- Department of Medical Radiology, Nuclear Medicine, University Hospital Zurich, Switzerland -
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Delso G, Farré L, Ortiz-Pérez JT, Prat S, Doltra A, Perea RJ, Caralt TM, Lorenzatti D, Vega J, Sotes S, Janich MA, Sitges M. Improving the robustness of MOLLI T1 maps with a dedicated motion correction algorithm. Sci Rep 2021; 11:18546. [PMID: 34535689 PMCID: PMC8448777 DOI: 10.1038/s41598-021-97841-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 08/25/2021] [Indexed: 01/03/2023] Open
Abstract
Myocardial tissue T1 constitutes a reliable indicator of several heart diseases related to extracellular changes (e.g. edema, fibrosis) as well as fat, iron and amyloid content. Magnetic resonance (MR) T1-mapping is typically achieved by pixel-wise exponential fitting of a series of inversion or saturation recovery measurements. Good anatomical alignment between these measurements is essential for accurate T1 estimation. Motion correction is recommended to improve alignment. However, in the case of inversion recovery sequences, this correction is compromised by the intrinsic contrast variation between frames. A model-based, non-rigid motion correction method for MOLLI series was implemented and validated on a large database of cardiac clinical cases (n = 186). The method relies on a dedicated similarity metric that accounts for the intensity changes caused by T1 magnetization relaxation. The results were compared to uncorrected series and to the standard motion correction included in the scanner. To automate the quantitative analysis of results, a custom data alignment metric was defined. Qualitative evaluation was performed on a subset of cases to confirm the validity of the new metric. Motion correction caused noticeable (i.e. > 5%) performance degradation in 12% of cases with the standard method, compared to 0.3% with the new dedicated method. The average alignment quality was 85% ± 9% with the default correction and 90% ± 7% with the new method. The results of the qualitative evaluation were found to correlate with the quantitative metric. In conclusion, a dedicated motion correction method for T1 mapping MOLLI series has been evaluated on a large database of clinical cardiac MR cases, confirming its increased robustness with respect to the standard method implemented in the scanner.
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Affiliation(s)
- Gaspar Delso
- MR Applications & Workflow, GE Healthcare, Barcelona, Spain
| | | | | | | | | | | | | | | | - Julián Vega
- Hospital Clínic de Barcelona, Barcelona, Spain
| | - Santi Sotes
- Hospital Clínic de Barcelona, Barcelona, Spain
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Delso G, Suryanarayanan K, Ortiz-Perez JT, Prat S, Doltra A, Perea RJ, Caralt TM, Lorenzatti D, Vega J, Sotes S, Sitges M, Janich MA. Validation of a deep learning reconstruction framework for 3D delayed myocardial enhancement imaging. Eur Heart J Cardiovasc Imaging 2021. [DOI: 10.1093/ehjci/jeaa356.300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: None.
Introduction
Myocardial delayed enhancement (MDE) MRI plays an important role in the identification of several cardiac conditions, both ischemic and non-ischemic (e.g. myocarditis, IDC, amyloidosis). 3D imaging offers increased resolution, full heart coverage and better depiction of complex pathologies, but its image quality is limited by long acquisition times.
Deep learning (DL) models enable advanced reconstruction algorithms that yield regularized images in practical computation times. In this study we evaluate a novel 3D-DL reconstruction to overcome the trade-off between reconstructed quality and acquisition time on MDE data.
Methods
A group of 14 subjects referred for CMR (5 F / 9 M, 59 ± 11 y.o., 78 ± 13 kg) were scanned with a 3D MDE sequence prototype: SPGR with IR preparation, fat & spatial saturation, respiratory navigator, ARC 2x, FOV 40x40cm, ST 1.4-2.4mm, matrix 280²-320², FA 20deg, BW 62.5 kHz, TE 2.1 ± 0.1ms, TI based on a CINE IR scout. All were retrospectively reconstructed using a 3D DL algorithm, trained on a database of over 700 datasets to reconstruct high-quality images with adjustable noise reduction.
The images were compared with standard 3D Cartesian reconstruction by two experienced cardiologists, to identify alterations in morphology or contrast distribution. Noise was estimated using the intensity standard deviation on a blood pool ROI. Feature preservation was estimated using the structural similarity index (SSI).
Results
The new method improved perceived image quality without loss of structural information or resolution (fig 1). Quantitative analysis (fig 2) confirmed these results: The average coefficient of variation in the blood was 0.08 ± 0.02 in the reference and 0.05 ± 0.02 with the new method; Given a target image noise level, DL reconstruction yielded up to 10% better SSI, compared to anisotropic filtering.
The clinical review didn’t reveal diagnostically significant alterations of structure or uptake pattern. A perceived reduction of sharpness was initially reported but individual examination of landmarks (e.g. pulmonary and coronary arteries) confirmed that no relevant features were being lost with the new reconstruction.
Discussion
The 3D MDE images obtained with DL reconstruction improved the trade-off between image noise -estimated by the blood pool intensity deviation- and feature preservation -estimated by SSI-.
Consistent improvement of image quality without morphological alterations of diagnostic relevance indicates that the new method can be considered for clinical practice. The next step in the validation process will require testing the robustness over a large set of cases with heterogeneous acquisition settings.
Conclusion
We presented the preliminary evaluation of a deep learning reconstruction method with 3D myocardial delayed enhancement data. The results show systematic improvement of overall image quality without loss of relevant diagnostic information.
Abstract Figure.
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Affiliation(s)
- G Delso
- GE Healthcare, Barcelona, Spain
| | | | | | - S Prat
- Hospital Clinic de Barcelona, Barcelona, Spain
| | - A Doltra
- Hospital Clinic de Barcelona, Barcelona, Spain
| | - RJ Perea
- Hospital Clinic de Barcelona, Barcelona, Spain
| | - TM Caralt
- Hospital Clinic de Barcelona, Barcelona, Spain
| | | | - J Vega
- Hospital Clinic de Barcelona, Barcelona, Spain
| | - S Sotes
- Hospital Clinic de Barcelona, Barcelona, Spain
| | - M Sitges
- Hospital Clinic de Barcelona, Barcelona, Spain
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Delso G, Ortiz-Perez JT, Prat S, Doltra A, Perea RJ, Caralt TM, Lorenzatti D, Vega J, Sotes S, Sitges M, Janich MA. Improving the robustness of MOLLI T1 maps with a dedicated motion correction algorithm. Eur Heart J Cardiovasc Imaging 2021. [DOI: 10.1093/ehjci/jeaa356.316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: None.
Introduction
Myocardial T1 mapping constitutes a reliable indicator of heart diseases related to changes of myocardial extracellular content (e.g. oedema, fibrosis) as well as fat, iron and amyloid content.
T1-mapping techniques rely on fitting a model to a series of MRI measurements. Alignment between these measurements is required for accurate T1 estimation. This is limited by triggering accuracy and patient motion. Image registration is often applied to improve the alignment. In the case of MOLLI series, registration is compromised by contrast variation between the images.
We present the validation of a new registration method, designed to account for the contrast properties of MOLLI data.
Methods
A cohort of 186 patients referred for a CMR was included in this study (115 M / 71 F; weight 75 ± 15 Kg; age 55 ± 16). Scans on a 3.0T MR included a MOLLI sequence with target parameters: 2D bSSFP, 160x148, pFOV 0.8-1.0, 1.4x1.4mm², ST 8mm, TE 1.4ms, TR 3.0ms, FA 35deg, NEX 1, BW 100kHz, 2x ASSET, 5(3)3.
Cartesian 2D reconstruction followed by motion correction was applied retrospectively. A new correction algorithm was implemented, based on a similarity criterion that accounted for T1 relaxation: It consisted of an iterative approach alternating polarity estimation, T1 fitting, relaxation simulation and frame registration. The coefficient of determination (R²) was used as a quality measure. A representative subset of the results was reviewed by two experienced cardiologists.
Results
All reconstructions (totalling 1133 2D MOLLI series) yielded qualitatively correct T1 maps. Results with the new method were compared to conventional motion correction and no correction.
The number of pixels with R²>0.95 was 85%±9% with standard motion correction and 90%±7% with the new dedicated method. In terms of improvement w.r.t. uncorrected data, the standard method yielded +3%±8% and the new one +9%±8%. Motion correction caused noticeable performance degradation in 12% of cases with the standard method, compared to 0.2% with the proposed method.
The relative performance of the different methods can be appreciated in Figure 3.
Discussion
Despite T1 mapping techniques constituting a reliable diagnostic tool in cardiac imaging, they remain sensitive to patient motion and triggering inaccuracies, making them vulnerable to arrhythmia episodes.
Improving the similarity criterion by accounting for T1 relaxation significantly decreased the incidence of misregistration and subsequent T1 inaccuracies. Using the R² of the voxel-wise T1 fit as a surrogate of alignment allowed to confirm the increased robustness of the new, dedicated motion correction method for MOLLI series.
Conclusion
We have demonstrated a new reconstruction pipeline with built-in registration, optimized for MOLLI T1-mapping. Using a large database of clinical data, the new method has been shown to improve the robustness to motion of cardiac T1 mapping.
Abstract Figure.
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Affiliation(s)
- G Delso
- GE Healthcare, Barcelona, Spain
| | | | - S Prat
- Hospital Clinic de Barcelona, Barcelona, Spain
| | - A Doltra
- Hospital Clinic de Barcelona, Barcelona, Spain
| | - RJ Perea
- Hospital Clinic de Barcelona, Barcelona, Spain
| | - TM Caralt
- Hospital Clinic de Barcelona, Barcelona, Spain
| | | | - J Vega
- Hospital Clinic de Barcelona, Barcelona, Spain
| | - S Sotes
- Hospital Clinic de Barcelona, Barcelona, Spain
| | - M Sitges
- Hospital Clinic de Barcelona, Barcelona, Spain
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Morales Ferez X, Mill J, Delso G, Sitges M, Doltra A, Loncaric F, Camara O, Bijnens B. 4D flow magnetic resonance imaging to assess left atrial haemodynamics in healthy and hypertrophic subjects. Eur Heart J Cardiovasc Imaging 2021. [DOI: 10.1093/ehjci/jeaa356.288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): - University, research centre and hospital foundation grants for the contracting of new research staff (FI 2020) - Spanish Ministry of Economy and Competitiveness Retos investigacion project
Introduction
The assessment of the left atrium (LA) haemodynamics is key to better understand the development of LA-related pathological processes. In this regard 4D flow magnetic resonance imaging (MRI) can provide complementary information to standard Doppler echocardiographic studies and identify complex blood flow patterns. Yet, until recently, the left atrium (LA) has been largely left aside in 4D flow MRI studies.
Purpose
We aimed at assessing the LA haemodynamics of healthy and hypertrophic cardiomyopathy (HCM) subjects with a qualitative visualization of flow patterns and deriving quantitative indices related to ventricular dysfunction from pulmonary veins (PV) and mitral valve (MV) velocity profiles.
Methods
Segmentation was performed directly over 4D flow angiograms. A total of 20 cases were processed, 11 healthy and 9 HCM subjects. 4D velocity matrices were masked with the segmented mask to isolate LA haemodynamics. Velocity profiles were then obtained in the PV and MV and integrated over planes perpendicular to the lumen of the vessels to create velocity spectrograms. Fourier spectral analysis was applied to the velocity curves to highlight differences that might go unnoticed in the time domain. In addition, the Q-Criterion was computed for vortex identification, visually inspecting both cohorts across the whole cardiac cycle.
Results
Fourier spectral analysis of the velocity curves suggested that overall, healthy patients have higher dynamic range of the velocity curves. It can be observed in Figure 1, that the usual E/A MV velocity pattern is preserved in 10 of the 11 healthy subjects while 5 of the HCM patients present significant alterations of said curve. In fact, patients 4, 6, 7 and 8 seem to present a 3 peaked MV velocity curve. The vortex analysis identified 3 main types of vortices in healthy subjects: a ‘filling’ systolic vortex (10/11) arising near the most dominant PV (usually the left superior PV) as seen in Figure 2; a conduit phase vortex (7/11), similar in nature to the preceding systolic vortex; and an E-wave vortex (9/11) attached to the LA ostium. Four of the HCM patients (out of the five with altered MV velocity profile) also showed a systolic vortex, but with more complex blood flow patterns and emerging far from the PVs. One of such vortices is shown in Figure 2, composed of two distinct eddies near the MV. The E-wave vortex was also observed but was less predominant than in healthy subjects (3/9).
Conclusions
4D Flow analysis of the LA is feasible and might hold promise in the understanding of the complex haemodynamics in ventricular dysfunction.
Abstract Figure. Velocity Spectrograms and Vortices
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Affiliation(s)
- X Morales Ferez
- University Pompeu Fabra, Physense, BCN Medtech, Department of Information and Communications Technologies, Barcelona, Spain
| | - J Mill
- University Pompeu Fabra, Physense, BCN Medtech, Department of Information and Communications Technologies, Barcelona, Spain
| | - G Delso
- GE Healthcare Spain, Barcelona, Spain
| | - M Sitges
- Cardiovascular Institute, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain, Institut d"investigacions biomèdiques august pi i sunyer (IDIBAPS), Barcelona, Spain
| | - A Doltra
- Cardiovascular Institute, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain, Institut d"investigacions biomèdiques august pi i sunyer (IDIBAPS), Barcelona, Spain
| | - F Loncaric
- Cardiovascular Institute, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain, Institut d"investigacions biomèdiques august pi i sunyer (IDIBAPS), Barcelona, Spain
| | - O Camara
- University Pompeu Fabra, Physense, BCN Medtech, Department of Information and Communications Technologies, Barcelona, Spain
| | - B Bijnens
- Institut d"investigacions biomèdiques august pi i sunyer (IDIBAPS), Barcelona, Spain, La Institució Catalana de Recerca i Estudis Avançats, (ICREA), Barcelona, Spain
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Zeimpekis KG, Geiger J, Wiesinger F, Delso G, Kellenberger CJ. Three-dimensional magnetic resonance imaging ultrashort echo-time cones for assessing lung density in pediatric patients. Pediatr Radiol 2021; 51:57-65. [PMID: 32860525 PMCID: PMC7796870 DOI: 10.1007/s00247-020-04791-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 05/18/2020] [Accepted: 07/29/2020] [Indexed: 12/18/2022]
Abstract
BACKGROUND MRI of lung parenchyma is challenging because of the rapid decay of signal by susceptibility effects of aerated lung on routine fast spin-echo sequences. OBJECTIVE To assess lung signal intensity in children on ultrashort echo-time sequences in comparison to a fast spin-echo technique. MATERIALS AND METHODS We conducted a retrospective study of lung MRI obtained in 30 patients (median age 5 years, range 2 months to 18 years) including 15 with normal lungs and 15 with cystic fibrosis. On a fast spin-echo sequence with radial readout and an ultrashort echo-time sequence, both lungs were segmented and signal intensities were extracted. We compared lung-to-background signal ratios and histogram analysis between the two patient cohorts using non-parametric tests and correlation analysis. RESULTS On ultrashort echo-time the lung-to-background ratio was age-dependent, ranging from 3.15 to 1.33 with high negative correlation (Rs = -0.86). Signal in posterior dependent portions of the lung was 18% and 11% higher than that of the anterior lung for age groups 0-2 and 2-18 years, respectively. The fast spin-echo sequence showed no variation of signal ratios by age or location, with a median of 0.99 (0.98-1.02). Histograms of ultrashort echo-time slices between controls and children with aggravated cystic fibrosis with mucus plugging and wall thickening exhibited significant discrepancies that differentiated between normal and pathological lungs. CONCLUSION Signal intensity of lung on ultrashort echo-time is higher than that on fast spin-echo sequences, is age-dependent and shows a gravity-dependent anterior to posterior gradient. This signal variation appears similar to lung density described on CT.
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Affiliation(s)
- Konstantinos G. Zeimpekis
- grid.412004.30000 0004 0478 9977Department of Nuclear Medicine, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland ,grid.5801.c0000 0001 2156 2780Department of Information Technology and Electrical Engineering, ETH, Zürich, Switzerland
| | - Julia Geiger
- grid.412341.10000 0001 0726 4330Department of Diagnostic Imaging, University Children’s Hospital Zürich, Zürich, Switzerland ,grid.412341.10000 0001 0726 4330Children’s Research Center, University Children’s Hospital Zürich, Zürich, Switzerland
| | | | - Gaspar Delso
- grid.418143.b0000 0001 0943 0267GE Healthcare, Waukesha, WI USA
| | - Christian J. Kellenberger
- grid.412341.10000 0001 0726 4330Department of Diagnostic Imaging, University Children’s Hospital Zürich, Zürich, Switzerland ,grid.412341.10000 0001 0726 4330Children’s Research Center, University Children’s Hospital Zürich, Zürich, Switzerland
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Ando T, Kemp B, Warnock G, Sekine T, Kaushik S, Wiesinger F, Delso G. Zero Echo Time MRAC on FDG-PET/MR Maintains Diagnostic Accuracy for Alzheimer's Disease; A Simulation Study Combining ADNI-Data. Front Neurosci 2020; 14:569706. [PMID: 33324141 PMCID: PMC7725704 DOI: 10.3389/fnins.2020.569706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 11/03/2020] [Indexed: 11/13/2022] Open
Abstract
Aim Attenuation correction using zero-echo time (ZTE) - magnetic resonance imaging (MRI) (ZTE-MRAC) has become one of the standard methods for brain-positron emission tomography (PET) on commercial PET/MR scanners. Although the accuracy of the net tracer-uptake quantification based on ZTE-MRAC has been validated, that of the diagnosis for dementia has not yet been clarified, especially in terms of automated statistical analysis. The aim of this study was to clarify the impact of ZTE-MRAC on the diagnosis of Alzheimer's disease (AD) by performing simulation study. Methods We recruited 27 subjects, who underwent both PET/computed tomography (CT) and PET/MR (GE SIGNA) examinations. Additionally, we extracted 107 subjects from the Alzheimer Disease Neuroimaging Initiative (ADNI) dataset. From the PET raw data acquired on PET/MR, three FDG-PET series were generated, using two vendor-provided MRAC methods (ZTE and Atlas) and CT-based AC. Following spatial normalization to Montreal Neurological Institute (MNI) space, we calculated each patient's specific error maps, which correspond to the difference between the PET image corrected using the CTAC method and the PET images corrected using the MRAC methods. To simulate PET maps as if ADNI data had been corrected using MRAC methods, we multiplied each of these 27 error maps with each of the 107 ADNI cases in MNI space. To evaluate the probability of AD in each resulting image, we calculated a cumulative t-value using a fully automated method which had been validated not only in the original ADNI dataset but several multi-center studies. In the method, PET score = 1 is the 95% prediction limit of AD. PET score and diagnostic accuracy for the discrimination of AD were evaluated in simulated images using the original ADNI dataset as reference. Results Positron emission tomography score was slightly underestimated both in ZTE and Atlas group compared with reference CTAC (-0.0796 ± 0.0938 vs. -0.0784 ± 0.1724). The absolute error of PET score was lower in ZTE than Atlas group (0.098 ± 0.075 vs. 0.145 ± 0.122, p < 0.001). A higher correlation to the original PET score was observed in ZTE vs. Atlas group (R 2: 0.982 vs. 0.961). The accuracy for the discrimination of AD patients from normal control was maintained in ZTE and Atlas compared to CTAC (ZTE vs. Atlas. vs. original; 82.5% vs. 82.1% vs. 83.2% (CI 81.8-84.5%), respectively). Conclusion For FDG-PET images on PET/MR, attenuation correction using ZTE-MRI had superior accuracy to an atlas-based method in classification for dementia. ZTE maintains the diagnostic accuracy for AD.
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Affiliation(s)
- Takahiro Ando
- Department of Radiology, Nippon Medical School, Tokyo, Japan
| | - Bradley Kemp
- Department of Radiology, Mayo Clinic, Rochester, MN, United States
| | - Geoffrey Warnock
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,PMOD Technologies Ltd., Zurich, Switzerland
| | - Tetsuro Sekine
- Department of Radiology, Nippon Medical School, Tokyo, Japan.,Department of Radiology, Nippon Medical School Musashi-Kosugi Hospital, Kawasaki, Japan.,Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
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Abstract
Artificial intelligence (AI) is an overarching term for a multitude of technologies which are currently being discussed and introduced in several areas of medicine and in medical imaging specifically. There is, however, limited literature and information about how AI techniques can be integrated into the design of clinical imaging trials. This article will present several aspects of AI being used in trials today and how imaging departments and especially nuclear medicine departments can prepare themselves to be at the forefront of AI-driven clinical trials. Beginning with some basic explanation on AI techniques currently being used and existing challenges of its implementation, it will also cover the logistical prerequisites which have to be in place in nuclear medicine departments to participate successfully in AI-driven clinical trials.
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Affiliation(s)
| | | | - Joshua D Kaggie
- Department of Radiology, University of Cambridge, Cambridge, UK
| | | | - Ur Metser
- Joint Department of Medical Imaging, University Health Network, Toronto, CA
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Eley KA, Delso G. Automated 3D MRI rendering of the craniofacial skeleton: using ZTE to drive the segmentation of black bone and FIESTA-C images. Neuroradiology 2020; 63:91-98. [PMID: 32772120 PMCID: PMC7803710 DOI: 10.1007/s00234-020-02508-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/28/2020] [Indexed: 11/29/2022]
Abstract
Purpose Automated bone segmentation from MRI datasets would have a profound impact on clinical utility, particularly in the craniofacial skeleton where complex anatomy is coupled with radiosensitive organs. Techniques such as gradient echo black bone (GRE-BB) and short echo time (UTE, ZTE) have shown potential in this quest. The objectives of this study were to ascertain (1) whether the high-contrast of zero echo time (ZTE) could drive segmentation of high-resolution GRE-BB data to enhance 3D-output and (2) if these techniques could be extrapolated to ZTE driven segmentation of a routinely used non bone-specific sequence (FIESTA-C). Methods Eleven adult volunteers underwent 3T MRI examination with sequential acquisition of ZTE, GRE-BB and FIESTA-C imaging. Craniofacial bone segmentation was performed using a fully automated segmentation algorithm. Segmentation was completed individually for GRE-BB and a modified version of the algorithm was subsequently implemented, wherein the bone mask yielded by ZTE segmentation was used to initialise segmentation of GRE-BB. The techniques were subsequently applied to FIESTA-C datasets. The resulting 3D reconstructions were evaluated for areas of unexpected bony defects and discrepancies. Results The automated segmentation algorithm yielded acceptable 3D outputs for all GRE-BB datasets. These were enhanced with the modified algorithm using ZTE as a driver, with improvements in areas of air/bone interface and dense muscular attachments. Comparable results were obtained with ZTE+FIESTA-C. Conclusion Automated 3D segmentation of the craniofacial skeleton is enhanced through the incorporation of a modified segmentation algorithm utilising ZTE. These techniques are transferrable to FIESTA-C imaging which offers reduced acquisition time and therefore improved clinical utility.
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Affiliation(s)
- Karen A Eley
- Department of Radiology, University of Cambridge School of Clinical Medicine, Box 218, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0QQ, UK.
| | - Gaspar Delso
- Department of Radiology, University of Cambridge School of Clinical Medicine, Box 218, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0QQ, UK
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14
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Wadhwa P, Thielemans K, Efthimiou N, Wangerin K, Keat N, Emond E, Deller T, Bertolli O, Deidda D, Delso G, Tohme M, Jansen F, Gunn RN, Hallett W, Tsoumpas C. PET image reconstruction using physical and mathematical modelling for time of flight PET-MR scanners in the STIR library. Methods 2020; 185:110-119. [PMID: 32006678 DOI: 10.1016/j.ymeth.2020.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/15/2019] [Accepted: 01/14/2020] [Indexed: 10/25/2022] Open
Abstract
This work demonstrates how computational and physical modelling of the positron emission tomography (PET) image acquisition process for a state-of-the-art integrated PET and magnetic resonance imaging (PET-MR) system can produce images comparable to the manufacturer. The GE SIGNA PET/MR scanner is manufactured by General Electric and has time-of-flight (TOF) capabilities of about 390 ps. All software development took place in the Software for Tomographic Image Reconstruction (STIR: http://stir.sf.net) library, which is a widely used open source software to reconstruct data as exported from emission tomography scanners. The new software developments will be integrated into STIR, providing the opportunity for researchers worldwide to establish and expand their image reconstruction methods. Furthermore, this work is of particular significance as it provides the first validation of TOF PET image reconstruction for real scanner datasets using the STIR library. This paper presents the methodology, analysis, and critical issues encountered in implementing an independent reconstruction software package. Acquired PET data were processed via several appropriate algorithms which are necessary to produce an accurate and precise quantitative image. This included mathematical, physical and anatomical modelling of the patient and simulation of various aspects of the acquisition. These included modelling of random coincidences using 'singles' rates per crystals, detector efficiencies and geometric effects. Attenuation effects were calculated by using the STIR's attenuation correction model. Modelling all these effects within the system matrix allowed the reconstruction of PET images which demonstrates the metabolic uptake of the administered radiopharmaceutical. These implementations were validated using measured phantom and clinical datasets. The developments are tested using the ordered subset expectation maximisation (OSEM) and the more recently proposed kernelised expectation maximisation (KEM) algorithm which incorporates anatomical information from MR images into PET reconstruction.
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Affiliation(s)
- Palak Wadhwa
- Biomedical Imaging Science Department, School of Medicine, University of Leeds, UK; Invicro, London, UK.
| | - Kris Thielemans
- Institute of Nuclear Medicine, University College London, UK
| | - Nikos Efthimiou
- PET Research Centre, Faculty of Health Sciences, University of Hull, UK
| | | | | | - Elise Emond
- Institute of Nuclear Medicine, University College London, UK
| | | | | | - Daniel Deidda
- Biomedical Imaging Science Department, School of Medicine, University of Leeds, UK; National Physical Laboratory, Teddington, UK
| | | | | | | | | | | | - Charalampos Tsoumpas
- Biomedical Imaging Science Department, School of Medicine, University of Leeds, UK; Invicro, London, UK.
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Sgard B, Khalifé M, Bouchut A, Fernandez B, Soret M, Giron A, Zaslavsky C, Delso G, Habert MO, Kas A. ZTE MR-based attenuation correction in brain FDG-PET/MR: performance in patients with cognitive impairment. Eur Radiol 2019; 30:1770-1779. [DOI: 10.1007/s00330-019-06514-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/28/2019] [Accepted: 10/15/2019] [Indexed: 10/25/2022]
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Schawkat K, Sah BR, Ter Voert EE, Delso G, Wurnig M, Becker AS, Leibl S, Schneider PM, Reiner CS, Huellner MW, Veit-Haibach P. Role of intravoxel incoherent motion parameters in gastroesophageal cancer: relationship with 18F-FDG-positron emission tomography, computed tomography perfusion and magnetic resonance perfusion imaging parameters. Q J Nucl Med Mol Imaging 2019; 65:178-186. [PMID: 31496202 DOI: 10.23736/s1824-4785.19.03153-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Identification of pretherapeutic predictive markers in gastro-esophageal cancer is essential for individual-oriented treatment. This study evaluated the relationship of multimodality parameters derived from intravoxel incoherent motion method (IVIM), 18F-FDG-positron emission tomography (PET), computed tomography (CT) perfusion and dynamic contrast enhanced magnetic resonance imaging (MRI) in patients with gastro-esophageal cancer and investigated their histopathological correlation. METHODS Thirty-one consecutive patients (28 males; median age 63.9 years; range 37-84 years) with gastro-esophageal adenocarcinoma (N.=22) and esophageal squamous cell carcinoma (N.=9) were analyzed. IVIM parameters: pseudodiffusion (D*), perfusion fraction (fp), true diffusion (D) and the threshold b-value (bval); PET-parameters: SUV<inf>max</inf>, metabolic tumor volume (MTV) and total lesion glycolysis (TLG); CT perfusion parameters: blood flow (BF), blood volume (BV) and mean transit time (MTT); and MR perfusion parameters: time to enhance, positive enhancement integral, time-to-peak (TTP), maximum-slope-of-increase, and maximum-slope-of-decrease were determined, and correlated to each other and to histopathology. RESULTS IVIM and PET parameters showed significant negative correlations: MTV and bval (r<inf>s</inf> =-0.643, P=0.002), TLG and bval (r<inf>s</inf>=-0.699, P<0.01) and TLG and fp (r<inf>s</inf>=-0.577, P=0.006). Positive correlation was found for TLG and D (r<inf>s</inf>=0.705, P=0.000). Negative correlation was found for bval and staging (r<inf>s</inf>=0.590, P=0.005). Positive correlation was found for positive enhancement interval and BV (r<inf>s</inf>=0.547, P=0.007), BF and regression index (r<inf>s</inf>=0.753, P=0.005) and for time-to-peak and staging (r<inf>s</inf>=0.557, P=0.005). CONCLUSIONS IVIM parameters (bval, fp, D) provide quantitative information and correlate with PET parameters (MTV, TLG) and staging. IVIM might be a useful tool for additional characterization of gastro-esophageal cancer.
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Affiliation(s)
- Khoschy Schawkat
- Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland - .,University of Zurich, Zurich, Switzerland -
| | - Bert-Ram Sah
- Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland.,Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Edwin E Ter Voert
- University of Zurich, Zurich, Switzerland.,Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Gaspar Delso
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Moritz Wurnig
- Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Anton S Becker
- Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Sebastian Leibl
- Department of Pathology, University Hospital Zurich, Zurich, Switzerland
| | - Paul M Schneider
- Center for Visceral, Thoracic and Specialized Tumor Surgery, Hirslanden Medical Center, Zurich, Switzerland
| | - Cäcilia S Reiner
- Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Martin W Huellner
- University of Zurich, Zurich, Switzerland.,Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Patrick Veit-Haibach
- Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland.,Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,University of Toronto, Toronto, ON, Canada.,Toronto Joint Department of Medical Imaging, University Hospital of Zurich, Toronto General Hospital, Zurich, Switzerland
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Delso G, Gillett D, Bashari W, Matys T, Mendichovszky I, Gurnell M. Clinical Evaluation of 11C-Met-Avid Pituitary Lesions Using a ZTE-Based AC Method. IEEE Trans Radiat Plasma Med Sci 2019. [DOI: 10.1109/trpms.2018.2886838] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Rezaei A, Schramm G, Willekens SMA, Delso G, Van Laere K, Nuyts J. A Quantitative Evaluation of Joint Activity and Attenuation Reconstruction in TOF PET/MR Brain Imaging. J Nucl Med 2019; 60:1649-1655. [PMID: 30979823 DOI: 10.2967/jnumed.118.220871] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 04/04/2019] [Indexed: 11/16/2022] Open
Abstract
Time-of-flight (TOF) PET data provide an effective means for attenuation correction (AC) when no (or incomplete or inaccurate) attenuation information is available. Since MR scanners provide little information on photon attenuation of different tissue types, AC in hybrid PET/MR scanners has always been challenging. In this contribution, we aim at validating the activity reconstructions of the maximum-likelihood ordered-subsets activity and attenuation (OSAA) reconstruction algorithm on a patient brain data set. We present a quantitative comparison of joint reconstructions with the current clinical gold standard-ordered-subsets expectation maximization-using CT-based AC in PET/CT, as well as the current state of the art in PET/MR, that is, zero time echo (ZTE)-based AC. Methods: The TOF PET emission data were initially used in a preprocessing stage to estimate crystal maps of efficiencies, timing offsets, and timing resolutions. Applying these additional corrections during reconstructions, OSAA, ZTE-based, and the vendor-provided atlas-based AC techniques were analyzed and compared with CT-based AC. In our initial study, we used the CT-based estimate of the expected scatter and later used the ZTE-based and OSAA attenuation estimates to compute the expected scatter contribution of the data during reconstructions. In all reconstructions, a maximum-likelihood scaling of the single-scatter simulation estimate to the emission data was used for scatter correction. The reconstruction results were analyzed in the 86 segmented regions of interest of the Hammers atlas. Results: Our quantitative analysis showed that, in practice, a tracer activity difference of +0.5% (±2.1%) and +0.1% (±2.3%) could be expected for the state-of-the-art ZTE-based and OSAA AC methods, respectively, in PET/MR compared with the clinical gold standard in PET/CT. Conclusion: Joint activity and attenuation estimation methods can provide an effective solution to the challenging AC problem for brain studies in hybrid TOF PET/MR scanners. With an accurate TOF-based (timing offsets and timing resolutions) calibration, and similar to the results of the state-of-the-art method in PET/MR, regional errors of joint TOF PET reconstructions are within a few percentage points.
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Affiliation(s)
- Ahmadreza Rezaei
- KU Leuven - University of Leuven, Department of Imaging and Pathology, Division of Nuclear Medicine & Molecular Imaging (NMMI), Medical Imaging Research Center (MIRC), B-3000, Leuven, Belgium; and
| | - Georg Schramm
- KU Leuven - University of Leuven, Department of Imaging and Pathology, Division of Nuclear Medicine & Molecular Imaging (NMMI), Medical Imaging Research Center (MIRC), B-3000, Leuven, Belgium; and
| | - Stefanie M A Willekens
- KU Leuven - University of Leuven, Department of Imaging and Pathology, Division of Nuclear Medicine & Molecular Imaging (NMMI), Medical Imaging Research Center (MIRC), B-3000, Leuven, Belgium; and
| | - Gaspar Delso
- MR Applications and Workflow, GE Healthcare, Waukesha, Wisconsin
| | - Koen Van Laere
- KU Leuven - University of Leuven, Department of Imaging and Pathology, Division of Nuclear Medicine & Molecular Imaging (NMMI), Medical Imaging Research Center (MIRC), B-3000, Leuven, Belgium; and
| | - Johan Nuyts
- KU Leuven - University of Leuven, Department of Imaging and Pathology, Division of Nuclear Medicine & Molecular Imaging (NMMI), Medical Imaging Research Center (MIRC), B-3000, Leuven, Belgium; and
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Messerli M, de Galiza Barbosa F, Marcon M, Muehlematter UJ, Stolzmann P, Warschkow R, Delso G, ter Voert EEGW, Huellner MW, Frauenfelder T, Veit-Haibach P. Value of PET/MRI for assessing tumor resectability in NSCLC-intra-individual comparison with PET/CT. Br J Radiol 2019; 92:20180379. [PMID: 30209954 PMCID: PMC6435071 DOI: 10.1259/bjr.20180379] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 08/22/2018] [Accepted: 09/05/2018] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVE The purpose of this study was to compare the diagnostic accuracy of positron emission tomography (PET)/MRI with PET/CT for determining tumor resectability of non-small cell lung cancer (NSCLC). METHODS Sequential trimodality PET/CT/MRI was performed in 36 patients referred with the clinical question of resectability assessment in NSCLC. PET/CT and PET/MR images including T1 weighted sequence (T1-Dixon) and respiration gated T2 weighted sequence (T2-Propeller) were evaluated for resectability-defining factors; i.e. longest diameter of the tumor, minimal tumor distance to the carina, mediastinal invasion, invasion of the carina, pleural infiltration, pericardial infiltration, diaphragm infiltration, presence of additional nodules. RESULTS There was no significant difference of maximal axial diameter measurements of the primary lung tumors and narrow limits of agreement in Bland-Altman analysis ranging from -11.1 mm to + 11.8 mm for T2-Propeller and from -14.3 mm to + 13.8 mm for T1-Dixon sequence. A high agreement of PET/MR with PET/CT for the different resectability-defining factors was observed (k from 0.769 to 1.000). There was an excellent agreement of T2-Propeller sequence and CT for additional pulmonary nodule detection (k of 0.829 and 0.833), but only a moderate and good agreement using T1-Dixon sequence (k of 0.484 and 0.722). CONCLUSION In NSCLC the use of PET/MRI, including a dedicated pulmonary MR imaging protocol, provides a comparable diagnostic value for determination of tumor resectability compared to PET/CT. ADVANCES IN KNOWLEDGE Our findings suggest that whole body PET/MRI can safely be used for the local staging of NSCLC patients. Further studies are warranted to determine whether it is feasible to integrate an imaging sequence in a whole body PET/MRI setting with the potential advantage of detection of liver or brain metastases.
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Affiliation(s)
- Michael Messerli
- Department of Nuclear Medicine, University Hospital Zurich/University of Zurich, Zurich, Switzerland
| | - Felipe de Galiza Barbosa
- Department of Nuclear Medicine, University Hospital Zurich/University of Zurich, Zurich, Switzerland
| | - Magda Marcon
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich/University Zurich, Zurich, Switzerland
| | | | - Paul Stolzmann
- Department of Nuclear Medicine, University Hospital Zurich/University of Zurich, Zurich, Switzerland
| | - René Warschkow
- Departmentof Surgery, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | | | - Edwin EGW ter Voert
- Department of Nuclear Medicine, University Hospital Zurich/University of Zurich, Zurich, Switzerland
| | - Martin W Huellner
- Department of Nuclear Medicine, University Hospital Zurich/University of Zurich, Zurich, Switzerland
| | - Thomas Frauenfelder
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich/University Zurich, Zurich, Switzerland
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Kralik SF, Supakul N, Wu IC, Delso G, Radhakrishnan R, Ho CY, Eley KA. Black bone MRI with 3D reconstruction for the detection of skull fractures in children with suspected abusive head trauma. Neuroradiology 2018; 61:81-87. [DOI: 10.1007/s00234-018-2127-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 10/30/2018] [Indexed: 10/27/2022]
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ter Voert EEGW, Muehlematter UJ, Delso G, Pizzuto DA, Müller J, Nagel HW, Burger IA. Quantitative performance and optimal regularization parameter in block sequential regularized expectation maximization reconstructions in clinical 68Ga-PSMA PET/MR. EJNMMI Res 2018; 8:70. [PMID: 30054750 PMCID: PMC6063806 DOI: 10.1186/s13550-018-0414-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 06/27/2018] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND In contrast to ordered subset expectation maximization (OSEM), block sequential regularized expectation maximization (BSREM) positron emission tomography (PET) reconstruction algorithms can run until full convergence while controlling image quality and noise. Recent studies with BSREM and 18F-FDG PET reported higher signal-to-noise ratios and higher standardized uptake values (SUV). In this study, we investigate the optimal regularization parameter (β) for clinical 68Ga-PSMA PET/MR reconstructions in the pelvic region applying time-of-flight (TOF) BSREM in comparison to TOF OSEM. Two-minute emission data from the pelvic region of 25 patients who underwent 68Ga-PSMA PET/MR were retrospectively reconstructed. Reference OSEM reconstructions had 28 subsets and 2 iterations. BSREM reconstructions were performed with 15 β values between 150 and 1200. Regions of interest (ROIs) were drawn around lesions and in uniform background. Background SUVmean (average) and SUVstd (standard deviation), and lesion SUVmax (average of 5 hottest voxels) were calculated. Differences were analyzed using the Wilcoxon matched pairs signed-rank test. RESULTS A total of 40 lesions were identified in the pelvic region. Background noise (SUVstd) and lesions SUVmax decreased with increasing β. Image reconstructions with β values lower than 400 have higher (p < 0.01) background noise, compared to the reference OSEM reconstructions, and are therefore less useful. Lesions with low activity on images reconstructed with β values higher than 600 have a lower (p < 0.05) SUVmax compared to the reference. These reconstructions are likely visually appealing due to the lower background noise, but the lower SUVmax could possibly render small low-uptake lesions invisible. CONCLUSIONS In our study, we showed that PET images reconstructed with TOF BSREM in combination with the 68Ga-PSMA tracer result in lower background noise and higher SUVmax values in lesions compared to TOF OSEM. Our study indicates that a β value between 400 and 550 might be the optimal compromise between high SUVmax and low background noise.
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Affiliation(s)
- Edwin E. G. W. ter Voert
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091 Zurich, Switzerland
- University of Zurich, Rämistrasse 71, CH-8006 Zurich, Switzerland
| | - Urs J. Muehlematter
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091 Zurich, Switzerland
| | - Gaspar Delso
- GE Healthcare, 3000 N Grandview Blvd, Waukesha, WI 53188 USA
| | - Daniele A. Pizzuto
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091 Zurich, Switzerland
- Institute of Nuclear Medicine, Università Cattolica del Sacro Cuore, Largo Francesco Vito 1, 00168 Rome, Italy
| | - Julian Müller
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091 Zurich, Switzerland
| | - Hannes W. Nagel
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091 Zurich, Switzerland
| | - Irene A. Burger
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091 Zurich, Switzerland
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Delso G, Kemp B, Kaushik S, Wiesinger F, Sekine T. Improving PET/MR brain quantitation with template-enhanced ZTE. Neuroimage 2018; 181:403-413. [PMID: 30010010 DOI: 10.1016/j.neuroimage.2018.07.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 06/20/2018] [Accepted: 07/12/2018] [Indexed: 10/28/2022] Open
Abstract
PURPOSE The impact of MR-based attenuation correction on PET quantitation accuracy is an ongoing cause of concern for advanced brain research with PET/MR. The purpose of this study was to evaluate a new, template-enhanced zero-echo-time attenuation correction method for PET/MR scanners. METHODS 30 subjects underwent a clinically-indicated 18F-FDG-PET/CT, followed by PET/MR on a GE SIGNA PET/MR. For each patient, a 42-s zero echo time (ZTE) sequence was used to generate two attenuation maps: one with the standard ZTE segmentation-based method; and another with a modification of the method, wherein pre-registered anatomical templates and CT data were used to enhance the segmentation. CT data, was used as gold standard. Reconstructed PET images were qualified visually and quantified in 68 volumes-of-interest using a standardized brain atlas. RESULTS Attenuation maps were successfully generated in all cases, without manual intervention or parameter tuning. One patient was excluded from the quantitative analysis due to the presence of multiple brain metastases. The PET bias with template-enhanced ZTE attenuation correction was measured to be -0.9% ± 0.9%, compared with -1.4% ± 1.1% with regular ZTE attenuation correction. In terms of absolute bias, the new method yielded 1.1% ± 0.7%, compared with 1.6% ± 0.9% with regular ZTE. Statistically significant bias reduction was obtained in the frontal region (from -2.0% to -1.0%), temporal (from -1.2% to -0.2%), parietal (from -1.9% to -1.1%), occipital (from -2.0% to -1.1%) and insula (from -1.4% to -1.1%). CONCLUSION These results indicate that the co-registration of pre-recorded anatomical templates to ZTE data is feasible in clinical practice and can be effectively used to improve the performance of segmentation-based attenuation correction.
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Affiliation(s)
| | - Bradley Kemp
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | | | - Tetsuro Sekine
- Department of Radiology, Nippon Medical School, Tokyo, Japan
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Sah BR, Ghafoor S, Burger IA, Ter Voert EEGW, Sekine T, Delso G, Huellner M, Dedes KJ, Boss A, Veit-Haibach P. Feasibility of 18F-FDG Dose Reductions in Breast Cancer PET/MRI. J Nucl Med 2018; 59:1817-1822. [PMID: 29880506 DOI: 10.2967/jnumed.118.209007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/27/2018] [Indexed: 12/16/2022] Open
Abstract
The goal of this study was to determine the level of clinically acceptable 18F-FDG dose reduction in time-of-flight PET/MRI in patients with breast cancer. Methods: Twenty-six consecutive women with histologically proven breast cancer were analyzed (median age, 51 y; range, 34-83 y). Simulated dose-reduced PET images were generated by unlisting the list-mode data on PET/MRI. The acquired 20-min PET frame was reconstructed in 5 ways: a reconstruction of the first 2 min with 3 iterations and 28 subsets for reference, and reconstructions simulating 100%, 20%, 10%, and 5% of the original dose. General image quality and artifacts, image sharpness, image noise, and lesion detectability were analyzed using a 4-point scale. Qualitative parameters were compared using the nonparametric Friedman test for multiple samples and the Wilcoxon signed-rank test for paired samples. Different groups of independent samples were compared using the Mann-Whitney U test. Results: Overall, 355 lesions (71 lesions with 5 different reconstructions each) were evaluated. The 20-min reconstruction with 100% injected dose showed the best results in all categories. For general image quality and artifacts, image sharpness, and noise, the reconstructions with a simulated dose of 20% and 10% were significantly better than the 2-min reconstructions (P ≤ 0.001). Furthermore, 20%, 10%, and 5% reconstructions did not yield results different from those of the 2-min reconstruction for detectability of the primary lesion. For 10% of the injected dose, a calculated mean dose of 22.6 ± 5.5 MBq (range, 17.9-36.9 MBq) would have been applied, resulting in an estimated whole-body radiation burden of 0.5 ± 0.1 mSv (range, 0.4-0.7 mSv). Conclusion: Ten percent of the standard dose of 18F-FDG (reduction of ≤90%) results in clinically acceptable PET image quality in time-of-flight PET/MRI. The calculated radiation exposure would be comparable to the effective dose of a single digital mammogram. A reduction of radiation burden to this level might justify partial-body examinations with PET/MRI for dedicated indications.
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Affiliation(s)
- Bert-Ram Sah
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland .,Department of Cancer Imaging, King`s College London, London, United Kingdom.,Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Soleen Ghafoor
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Irene A Burger
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland.,Cancer Center Zurich, Zurich, Switzerland
| | - Edwin E G W Ter Voert
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Tetsuro Sekine
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland
| | - Gaspar Delso
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland.,GE Healthcare, Waukesha, Wisconsin
| | - Martin Huellner
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Konstantin J Dedes
- Cancer Center Zurich, Zurich, Switzerland.,Department of Gynaecology, University Hospital of Zurich, Zurich, Switzerland
| | - Andreas Boss
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland
| | - Patrick Veit-Haibach
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland.,Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Switzerland.,University of Zurich, Zurich, Switzerland.,Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada; and.,University of Toronto, Toronto, Ontario, Canada
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Sah BR, Leissing CA, Delso G, Ter Voert EE, Krieg S, Leibl S, Schneider PM, Reiner CS, Hüllner MW, Veit-Haibach P. Evaluation of multifunctional imaging parameters in gastro-oesophageal cancer using F-18-FDG-PET/CT with integrated perfusion CT. Q J Nucl Med Mol Imaging 2018:S1824-4785.18.03067-4. [PMID: 29745630 DOI: 10.23736/s1824-4785.18.03067-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Positron emission tomography (PET) / computed tomography (CT) is among the most frequently used imaging modalities for initial staging of gastro-oesophageal (GE) cancer, whereas CT-perfusion (CTP) provides different multiparametric information. This proof of concept study compares CTP- and PET-parameters in patients with GE cancer to evaluate correlations and a possible prognostic value of a combined PET/CTP imaging procedure. METHODS A total of 31 patients with F-18-FDG-PET/CT and CTP studies were prospectively analysed. Patients had adenocarcinoma (n = 22) and oesophageal squamous cell carcinoma (SCC, n = 9). Imaging was performed before start of treatment. CTP parameters [blood flow (BF), blood volume (BV), mean transit time (MTT)] and metabolic parameters [(maximum and mean standardised uptake values and standard deviation (SUVmax, SUVmean, SUVsd), metabolic tumour volume (MTV) and tumour lesion glycolysis (TLG)], as well as flow metabolic product [FMP (BF × SUVmax)] were determined and their relationship was compared. Additionally their association to clinical parameters (differentiation grading, staging, HER2-status, follow-up status) and to histopathological regression (post-neoadjuvant regression grading) was evaluated. RESULTS Correlation between parameters of both modalities was significant between MTT and MTV (r = 0.375, p = 0.038); no other significant correlation was found. Patients with complete histopathological regression showed significantly lower BF and BV than patients with nearly complete or partial response. TLG and regression grading showed significant correlation with staging. All other quantitative parameters for CTP and PET data did not correlate significantly with histopathological regression grading, differentiation or staging. CONCLUSIONS The combination of PET and CTP parameters (FMP) showed no significant prognostic value. Significant correlations were only found between MTT and MTV, which indicates a possible perfusional/metabolic coupling. Therefore, pre-therapeutic CTP and PET- parameters provide complementary information about the pre-therapeutic tumour status and are not interchangeable. Only CTP parameters might be able to predict complete histopathological regression. On the other hand, only PET parameters are correlated with staging.
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Affiliation(s)
- Bert-Ram Sah
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Suisse - .,Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Suisse - .,Department of Cancer Imaging, King's College London, London, UK - .,University of Zurich, Zurich, Suisse -
| | - Christian A Leissing
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Suisse.,University of Zurich, Zurich, Suisse
| | - Gaspar Delso
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Suisse.,GE Healthcare, Waukesha, WI, USA
| | - Edwin E Ter Voert
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Suisse
| | | | - Sebastian Leibl
- Department of Pathology, University Hospital of Zurich, Zurich, Suisse
| | - Paul M Schneider
- Department of Surgery, University Hospital of Zurich, Center for Visceral, Thoracic and Specialized Tumor Surgery, Hirslanden Medical Center, Zurich, Suisse
| | - Cäcilia S Reiner
- Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Suisse.,University of Zurich, Zurich, Suisse
| | - Martin W Hüllner
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Suisse.,University of Zurich, Zurich, Suisse
| | - Patrick Veit-Haibach
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Suisse.,Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich, Suisse.,Joint Department of Medical Imaging, University of Toronto, Toronto, ON, Canada
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Sekine T, Delso G, Zeimpekis KG, de Galiza Barbosa F, Ter Voert EEGW, Huellner M, Veit-Haibach P. Reduction of 18F-FDG Dose in Clinical PET/MR Imaging by Using Silicon Photomultiplier Detectors. Radiology 2017; 286:249-259. [PMID: 28914600 DOI: 10.1148/radiol.2017162305] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Purpose To determine the level of clinically acceptable reduction in injected fluorine 18 (18F) fluorodeoxyglucose (FDG) dose in time-of-flight (TOF)-positron emission tomography(PET)/magnetic resonance (MR) imaging by using silicon photomultiplier (SiPM) detectors compared with TOF-PET/computed tomography (CT) using Lu1.8Y0.2SiO5(Ce), or LYSO, detectors in patients with different body mass indexes (BMIs). Materials and Methods Patients were enrolled in this study as part of a larger prospective study with a different purpose than evaluated in this study (NCT02316431). All patients gave written informed consent prior to inclusion into the study. In this study, 74 patients with different malignant diseases underwent sequential whole-body TOF-PET/CT and TOF-PET/MR imaging. PET images with simulated reduction of injected 18F-FDG doses were generated by unlisting the list-mode data from PET/MR imaging. Two readers rated the image quality of whole-body data sets, as well as the image quality in each body compartment, and evaluated the conspicuity of malignant lesions. Results The image quality with 70% or 60% of the injected dose of 18F-FDG at PET/MR imaging was comparable to that at PET/CT. With 50% of the injected dose, comparable image quality was maintained among patients with a BMI of less than 25 kg/m2. PET images without TOF reconstruction showed higher artifact scores and deteriorated sharpness than those with TOF reconstruction. Conclusion Sixty percent of the usually injected 18F-FDG dose (reduction of up to 40%) in patients with a BMI of more than 25 kg/m2 results in clinically adequate PET image quality in TOF-PET/MR imaging performed by using SiPM detectors. Additionally, in patients with a BMI of less than 25 kg/m2, 50% of the injected dose may safely be used. © RSNA, 2017 Online supplemental material is available for this article.
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Affiliation(s)
- Tetsuro Sekine
- From the Departments of Nuclear Medicine (T.S., K.G.Z., F.d.G.B., E.E.G.W.t.V., M.H., P.V.), Neuroradiology (M.H.), and Diagnostic and Interventional Radiology (P.V.), University Hospital Zurich, Ramistrasse 100, 8091 Zurich, Switzerland; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D.); and University of Zurich, Zurich, Switzerland (E.E.G.W.t.V., M.H., P.V.)
| | - Gaspar Delso
- From the Departments of Nuclear Medicine (T.S., K.G.Z., F.d.G.B., E.E.G.W.t.V., M.H., P.V.), Neuroradiology (M.H.), and Diagnostic and Interventional Radiology (P.V.), University Hospital Zurich, Ramistrasse 100, 8091 Zurich, Switzerland; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D.); and University of Zurich, Zurich, Switzerland (E.E.G.W.t.V., M.H., P.V.)
| | - Konstantinos G Zeimpekis
- From the Departments of Nuclear Medicine (T.S., K.G.Z., F.d.G.B., E.E.G.W.t.V., M.H., P.V.), Neuroradiology (M.H.), and Diagnostic and Interventional Radiology (P.V.), University Hospital Zurich, Ramistrasse 100, 8091 Zurich, Switzerland; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D.); and University of Zurich, Zurich, Switzerland (E.E.G.W.t.V., M.H., P.V.)
| | - Felipe de Galiza Barbosa
- From the Departments of Nuclear Medicine (T.S., K.G.Z., F.d.G.B., E.E.G.W.t.V., M.H., P.V.), Neuroradiology (M.H.), and Diagnostic and Interventional Radiology (P.V.), University Hospital Zurich, Ramistrasse 100, 8091 Zurich, Switzerland; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D.); and University of Zurich, Zurich, Switzerland (E.E.G.W.t.V., M.H., P.V.)
| | - Edwin E G W Ter Voert
- From the Departments of Nuclear Medicine (T.S., K.G.Z., F.d.G.B., E.E.G.W.t.V., M.H., P.V.), Neuroradiology (M.H.), and Diagnostic and Interventional Radiology (P.V.), University Hospital Zurich, Ramistrasse 100, 8091 Zurich, Switzerland; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D.); and University of Zurich, Zurich, Switzerland (E.E.G.W.t.V., M.H., P.V.)
| | - Martin Huellner
- From the Departments of Nuclear Medicine (T.S., K.G.Z., F.d.G.B., E.E.G.W.t.V., M.H., P.V.), Neuroradiology (M.H.), and Diagnostic and Interventional Radiology (P.V.), University Hospital Zurich, Ramistrasse 100, 8091 Zurich, Switzerland; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D.); and University of Zurich, Zurich, Switzerland (E.E.G.W.t.V., M.H., P.V.)
| | - Patrick Veit-Haibach
- From the Departments of Nuclear Medicine (T.S., K.G.Z., F.d.G.B., E.E.G.W.t.V., M.H., P.V.), Neuroradiology (M.H.), and Diagnostic and Interventional Radiology (P.V.), University Hospital Zurich, Ramistrasse 100, 8091 Zurich, Switzerland; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D.); and University of Zurich, Zurich, Switzerland (E.E.G.W.t.V., M.H., P.V.)
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Sekine T, Barbosa FDG, Delso G, Burger IA, Stolzmann P, Ter Voert EE, Huber GF, Kollias SS, von Schulthess GK, Veit-Haibach P, Huellner MW. Local resectability assessment of head and neck cancer: Positron emission tomography/MRI versus positron emission tomography/CT. Head Neck 2017; 39:1550-1558. [PMID: 28500749 DOI: 10.1002/hed.24783] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 11/28/2016] [Accepted: 02/08/2017] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The purpose of this study was to compare the diagnostic accuracy of positron emission tomography (PET)/MRI with PET/CT for local resectability of head and neck cancer. METHODS Sequential contrast-enhanced PET/CT-MRI was performed in 58 patients referred for the staging or restaging of head and neck cancer. Tumors were assessed with PET/CT and PET/MRI for the presence of resectability-defining factors: T4b status (mediastinal invasion, invasion of the prevertebral space, and vascular encasement), and another 8 findings that would imply obstacles for surgical cure (invasion of the laryngeal cartilage, invasion of the preepiglottic fat pad, perineural spread, orbital invasion, bone infiltration, skull base invasion, dural infiltration, and invasion of the brachial plexus). RESULTS The sensitivity/specificity/accuracy of local resectability-defining factors of PET/CT and PET/MRI was 0.92/0.99/0.98 and 0.98/0.99/0.99 (P = .727), respectively, per lesion, and 0.96/0.87/0.91 and 0.96/0.90/0.93 (P = .687), respectively, per patient. CONCLUSION Both contrast-enhanced PET/MRI and contrast-enhanced PET/CT can serve as reliable examinations for defining local resectability of head and neck cancer.
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Affiliation(s)
- Tetsuro Sekine
- Department of Nuclear Medicine, University Hospital Zurich / University of Zurich, Zurich, Switzerland.,Department of Radiology, Nippon Medical School, Tokyo, Japan
| | - Felipe de Galiza Barbosa
- Department of Nuclear Medicine, University Hospital Zurich / University of Zurich, Zurich, Switzerland
| | - Gaspar Delso
- Department of Nuclear Medicine, University Hospital Zurich / University of Zurich, Zurich, Switzerland.,GE Healthcare, Waukesha, Wisconsin
| | - Irene A Burger
- Department of Nuclear Medicine, University Hospital Zurich / University of Zurich, Zurich, Switzerland
| | - Paul Stolzmann
- Department of Nuclear Medicine, University Hospital Zurich / University of Zurich, Zurich, Switzerland
| | - Edwin E Ter Voert
- Department of Nuclear Medicine, University Hospital Zurich / University of Zurich, Zurich, Switzerland
| | - Gerhard F Huber
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Zurich / University of Zurich, Zurich, Switzerland
| | - Spyros S Kollias
- Clinic of Neuroradiology, University Hospital Zurich / University of Zurich, Zurich, Switzerland
| | - Gustav K von Schulthess
- Department of Nuclear Medicine, University Hospital Zurich / University of Zurich, Zurich, Switzerland
| | - Patrick Veit-Haibach
- Department of Nuclear Medicine, University Hospital Zurich / University of Zurich, Zurich, Switzerland.,Institute of Diagnostic and Interventional Radiology, University Hospital Zurich / University of Zurich, Zurich, Switzerland
| | - Martin W Huellner
- Department of Nuclear Medicine, University Hospital Zurich / University of Zurich, Zurich, Switzerland
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Anderla A, Sladojevic S, Delso G, Culibrk D, Mirkovic M, Stefanovic D. Suppression of Metal Artefacts in CT Using Virtual Singorams and Corresponding MR Images. CURR SCI INDIA 2017. [DOI: 10.18520/cs/v112/i07/1505-1511] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Grant AM, Deller TW, Khalighi MM, Maramraju SH, Delso G, Levin CS. NEMA NU 2-2012 performance studies for the SiPM-based ToF-PET component of the GE SIGNA PET/MR system. Med Phys 2017; 43:2334. [PMID: 27147345 DOI: 10.1118/1.4945416] [Citation(s) in RCA: 177] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
PURPOSE The GE SIGNA PET/MR is a new whole body integrated time-of-flight (ToF)-PET/MR scanner from GE Healthcare. The system is capable of simultaneous PET and MR image acquisition with sub-400 ps coincidence time resolution. Simultaneous PET/MR holds great potential as a method of interrogating molecular, functional, and anatomical parameters in clinical disease in one study. Despite the complementary imaging capabilities of PET and MRI, their respective hardware tends to be incompatible due to mutual interference. In this work, the GE SIGNA PET/MR is evaluated in terms of PET performance and the potential effects of interference from MRI operation. METHODS The NEMA NU 2-2012 protocol was followed to measure PET performance parameters including spatial resolution, noise equivalent count rate, sensitivity, accuracy, and image quality. Each of these tests was performed both with the MR subsystem idle and with continuous MR pulsing for the duration of the PET data acquisition. Most measurements were repeated at three separate test sites where the system is installed. RESULTS The scanner has achieved an average of 4.4, 4.1, and 5.3 mm full width at half maximum radial, tangential, and axial spatial resolutions, respectively, at 1 cm from the transaxial FOV center. The peak noise equivalent count rate (NECR) of 218 kcps and a scatter fraction of 43.6% are reached at an activity concentration of 17.8 kBq/ml. Sensitivity at the center position is 23.3 cps/kBq. The maximum relative slice count rate error below peak NECR was 3.3%, and the residual error from attenuation and scatter corrections was 3.6%. Continuous MR pulsing had either no effect or a minor effect on each measurement. CONCLUSIONS Performance measurements of the ToF-PET whole body GE SIGNA PET/MR system indicate that it is a promising new simultaneous imaging platform.
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Affiliation(s)
- Alexander M Grant
- Department of Bioengineering, Stanford University, Stanford, California 94305-5128 and Department of Radiology, Stanford University, Stanford, California 94305-5128
| | | | | | | | - Gaspar Delso
- GE Healthcare and University Hospital of Zurich, Zurich 8006, Switzerland
| | - Craig S Levin
- Department of Bioengineering, Stanford University, Stanford, California 94305-5128; Department of Radiology, Stanford University, Stanford, California 94305-5128; Department of Electrical Engineering, Stanford University, Stanford, California 94305-5128; and Department of Physics, Stanford University, Stanford, California 94305-5128
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Ter Voert EEGW, Veit-Haibach P, Ahn S, Wiesinger F, Khalighi MM, Levin CS, Iagaru AH, Zaharchuk G, Huellner M, Delso G. Clinical evaluation of TOF versus non-TOF on PET artifacts in simultaneous PET/MR: a dual centre experience. Eur J Nucl Med Mol Imaging 2017; 44:1223-1233. [PMID: 28124091 DOI: 10.1007/s00259-017-3619-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 01/04/2017] [Indexed: 12/12/2022]
Abstract
PURPOSE Our objective was to determine clinically the value of time-of-flight (TOF) information in reducing PET artifacts and improving PET image quality and accuracy in simultaneous TOF PET/MR scanning. METHODS A total 65 patients who underwent a comparative scan in a simultaneous TOF PET/MR scanner were included. TOF and non-TOF PET images were reconstructed, clinically examined, compared and scored. PET imaging artifacts were categorized as large or small implant-related artifacts, as dental implant-related artifacts, and as implant-unrelated artifacts. Differences in image quality, especially those related to (implant) artifacts, were assessed using a scale ranging from 0 (no artifact) to 4 (severe artifact). RESULTS A total of 87 image artifacts were found and evaluated. Four patients had large and eight patients small implant-related artifacts, 27 patients had dental implants/fillings, and 48 patients had implant-unrelated artifacts. The average score was 1.14 ± 0.82 for non-TOF PET images and 0.53 ± 0.66 for TOF images (p < 0.01) indicating that artifacts were less noticeable when TOF information was included. CONCLUSION Our study indicates that PET image artifacts are significantly mitigated with integration of TOF information in simultaneous PET/MR. The impact is predominantly seen in patients with significant artifacts due to metal implants.
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Affiliation(s)
- Edwin E G W Ter Voert
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland.
- University of Zurich, Zurich, Switzerland.
| | - Patrick Veit-Haibach
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
- Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland
| | | | | | | | - Craig S Levin
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University, Stanford, CA, USA
| | - Andrei H Iagaru
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Stanford University, Stanford, CA, USA
| | - Greg Zaharchuk
- Department of Radiology, Neuroradiology, Stanford University, Stanford, CA, USA
| | - Martin Huellner
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
- Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
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Svirydenka H, Delso G, De Galiza Barbosa F, Huellner M, Davison H, Fanti S, Veit-Haibach P, Ter Voert EEGW. The Effect of Susceptibility Artifacts Related to Metallic Implants on Adjacent-Lesion Assessment in Simultaneous TOF PET/MR. J Nucl Med 2017; 58:1167-1173. [PMID: 28062597 DOI: 10.2967/jnumed.116.180802] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 11/30/2016] [Indexed: 12/30/2022] Open
Abstract
Metalic implants may affect attenuation correction (AC) in PET/MR imaging. The purpose of this study was to evaluate the effect of susceptibility artifacts related to metallic implants on adjacent metabolically active lesions in clinical simultaneous PET/MR scanning for both time-of-flight (TOF) and non-TOF reconstructed PET images. Methods: We included 27 patients without implants but with confirmed 18F-FDG-avid lesions adjacent to common implant locations. In all patients, a clinically indicated whole-body 18F-FDG PET/MR scan was acquired. Baseline non-TOF and TOF PET images were reconstructed. Reconstruction was repeated after the introduction of artificial signal voids in the AC map to simulate metallic implants in standard anatomic areas. All reconstructed images were qualitatively and quantitatively assessed and compared with the baseline images. Results: In total, 51 lesions were assessed. In 40 and 50 of these cases (non-TOF and TOF, respectively), the detectability of the lesions did not change; in 9 and 1 cases, the detectability changed; and in 2 non-TOF cases, the lesions were no longer visible after the introduction of metallic artifacts. The inclusion of TOF information significantly reduced artifacts due to simulated implants in the femoral head, sternum, and spine (P = 0.01, 0.01, and 0.03, respectively). It also improved image quality in these locations (P = 0.02, 0.01, and 0.01, respectively). The mean percentage error was -3.5% for TOF and -4.8% for non-TOF reconstructions, meaning that the inclusion of TOF information reduced the percentage error in SUVmax by 28.5% (P < 0.01). Conclusion: Qualitatively, there was a significant reduction of artifacts in the femoral head, sternum, and spine. There was also a significant qualitative improvement in image quality in these locations. Furthermore, our study indicated that simulated susceptibility artifacts related to metallic implants have a significant effect on small, moderately 18F-FDG-avid lesions near the implant site that possibly may go unnoticed without TOF information. On larger, highly 18F-FDG-avid lesions, the metallic implants had only a limited effect. The largest significant quantitative difference was found in artifacts of the sternum. There was only a weak inverse correlation between lesions affected by artifacts and distance from the implant.
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Affiliation(s)
- Hanna Svirydenka
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,Department of Nuclear Medicine, Sant'Orsola Hospital, University of Bologna, Bologna, Italy
| | | | | | - Martin Huellner
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Helen Davison
- Department of Medical Physics, Royal United Hospitals Bath NHS Foundation Trust, Bath, United Kingdom
| | - Stefano Fanti
- Department of Nuclear Medicine, Sant'Orsola Hospital, University of Bologna, Bologna, Italy
| | - Patrick Veit-Haibach
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland; and.,University of Zurich, Zurich, Switzerland
| | - Edwin E G W Ter Voert
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland .,University of Zurich, Zurich, Switzerland
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ter Voert EEGW, Delso G, de Galiza Barbosa F, Huellner M, Veit-Haibach P. The Effect of Defective PET Detectors in Clinical Simultaneous [18F]FDG Time-of-Flight PET/MR Imaging. Mol Imaging Biol 2016; 19:626-635. [DOI: 10.1007/s11307-016-1023-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Wu B, Warnock G, Zaiss M, Lin C, Chen M, Zhou Z, Mu L, Nanz D, Tuura R, Delso G. An overview of CEST MRI for non-MR physicists. EJNMMI Phys 2016; 3:19. [PMID: 27562024 PMCID: PMC4999387 DOI: 10.1186/s40658-016-0155-2] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 08/06/2016] [Indexed: 01/16/2023] Open
Abstract
The search for novel image contrasts has been a major driving force in the magnetic resonance (MR) research community, in order to gain further information on the body’s physiological and pathological conditions. Chemical exchange saturation transfer (CEST) is a novel MR technique that enables imaging certain compounds at concentrations that are too low to impact the contrast of standard MR imaging and too low to directly be detected in MRS at typical water imaging resolution. For this to be possible, the target compound must be capable of exchanging protons with the surrounding water molecules. This property can be exploited to cause a continuous buildup of magnetic saturation of water, leading to greatly enhanced sensitivity. The goal of the present review is to introduce the basic principles of CEST imaging to the general molecular imaging community. Special focus has been given to the comparison of state-of-the-art CEST methods reported in the literature with their positron emission tomography (PET) counterparts.
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Affiliation(s)
- B Wu
- GE Healthcare, Waukesha (WI), USA
| | - G Warnock
- PMOD Technologies Ltd., Zurich, Switzerland
| | - M Zaiss
- German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - C Lin
- GE Healthcare, Waukesha (WI), USA
| | - M Chen
- Peking Hospital, Beijing, China
| | - Z Zhou
- GE Healthcare, Waukesha (WI), USA
| | - L Mu
- University of Zurich, Zurich, Switzerland
| | - D Nanz
- University Hospital of Zurich, Zurich, Switzerland
| | - R Tuura
- Children's Hospital Zurich, Zurich, Switzerland
| | - G Delso
- GE Healthcare, Waukesha (WI), USA.
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Abstract
Simultaneous PET/MRI was introduced into the commercial market only a few years ago, and its availability is currently gaining momentum with the introduction of a second-generation PET/MRI system from an additional vendor. Furthermore, there is still an increasing interest in its potential in clinical and research applications. Despite very early technical infancy problems, which meanwhile have been solved, there are still different limitations that have to be worked around in daily routine responsibly by the physicists and physicians. This article gives an overview over the most common technical, logistical, and clinical limitations; artifacts; and pitfalls, without any claim for completeness. The readers will not only learn the background of the limitation but also partly learn about possible solutions. At the end of each paragraph, the readers will find a short summary for an easier overview of the topics discussed.
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Affiliation(s)
- Gaspar Delso
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland; GE Healthcare, Waukesha, WI
| | - Edwin ter Voert
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | | | - Patrick Veit-Haibach
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland; Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland.
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Levin CS, Maramraju SH, Khalighi MM, Deller TW, Delso G, Jansen F. Design Features and Mutual Compatibility Studies of the Time-of-Flight PET Capable GE SIGNA PET/MR System. IEEE Trans Med Imaging 2016; 35:1907-1914. [PMID: 26978664 DOI: 10.1109/tmi.2016.2537811] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A recent entry into the rapidly evolving field of integrated PET/MR scanners is presented in this paper: a whole body hybrid PET/MR system (SIGNA PET/MR, GE Healthcare) capable of simultaneous acquisition of both time-of-flight (TOF) PET and high resolution MR data. The PET ring was integrated into an existing 3T MR system resulting in a (patient) bore opening of 60 cm diameter, with a 25 cm axial FOV. PET performance was evaluated both on the standalone PET ring and on the same detector integrated into the MR system, to assess the level of mutual interference between both subsystems. In both configurations we obtained detector performance data. PET detector performance was not significantly affected by integration into the MR system. The global energy resolution was within 2% (10.3% versus 10.5%), and the system coincidence time resolution showed a maximum change of < 3% (385 ps versus 394 ps) when measured outside MR and during simultaneous PET/MRI acquisitions, respectively. To evaluate PET image quality and resolution, the NEMA IQ phantom was acquired with MR idle and with MR active. Impact of PET on MR IQ was assessed by comparing SNR with PET acquisition on and off. B0 and B1 homogeneities were acquired before and after the integration of the PET ring inside the magnet. In vivo brain and whole body head-to-thighs data were acquired to demonstrate clinical image quality.
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Delso G, Khalighi M, Ter Voert E, Barbosa F, Sekine T, Hüllner M, Veit-Haibach P. Effect of Time-of-Flight Information on PET/MR Reconstruction Artifacts: Comparison of Free-breathing versus Breath-hold MR-based Attenuation Correction. Radiology 2016; 282:229-235. [PMID: 27355899 DOI: 10.1148/radiol.2016152509] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Purpose To evaluate the magnitude and anatomic extent of the artifacts introduced on positron emission tomographic (PET)/magnetic resonance (MR) images by respiratory state mismatch in the attenuation map. Materials and Methods The method was tested on 14 patients referred for an oncologic examination who underwent PET/MR imaging. The acquisition included standard PET and MR series for each patient, and an additional attenuation correction series was acquired by using breath hold. PET data were reconstructed with and without time-of-flight (TOF) information, first by using the standard free-breathing attenuation map and then again by using the additional breath-hold map. Two-tailed paired t testing and linear regression with 0 intercept was performed on TOF versus non-TOF and free-breathing versus breath-hold data for all detected lesions. Results Fluorodeoxyglucose-avid lesions were found in eight of the 14 patients included in the study. The uptake differences (maximum standardized uptake values) between PET reconstructions with free-breathing versus breath-hold attenuation ranged, for non-TOF reconstructions, from -18% to 26%. The corresponding TOF reconstructions yielded differences from -15% to 18%. Conclusion TOF information was shown to reduce the artifacts caused at PET/MR by respiratory mismatch between emission and attenuation data. © RSNA, 2016 Online supplemental material is available for this article.
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Affiliation(s)
- Gaspar Delso
- From the Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D., M.K.); the Departments of Nuclear Medicine (E.t.V., F.B., T.S., M.H., P.V.H.), Neuroradiology (M.H.) and Medical Radiology (P.V.H.), University Hospital of Zurich; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); and University of Zurich, Zurich, Switzerland (E.t.V., M.H., P.V.H.)
| | - Mohammed Khalighi
- From the Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D., M.K.); the Departments of Nuclear Medicine (E.t.V., F.B., T.S., M.H., P.V.H.), Neuroradiology (M.H.) and Medical Radiology (P.V.H.), University Hospital of Zurich; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); and University of Zurich, Zurich, Switzerland (E.t.V., M.H., P.V.H.)
| | - Edwin Ter Voert
- From the Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D., M.K.); the Departments of Nuclear Medicine (E.t.V., F.B., T.S., M.H., P.V.H.), Neuroradiology (M.H.) and Medical Radiology (P.V.H.), University Hospital of Zurich; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); and University of Zurich, Zurich, Switzerland (E.t.V., M.H., P.V.H.)
| | - Felipe Barbosa
- From the Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D., M.K.); the Departments of Nuclear Medicine (E.t.V., F.B., T.S., M.H., P.V.H.), Neuroradiology (M.H.) and Medical Radiology (P.V.H.), University Hospital of Zurich; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); and University of Zurich, Zurich, Switzerland (E.t.V., M.H., P.V.H.)
| | - Tetsuro Sekine
- From the Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D., M.K.); the Departments of Nuclear Medicine (E.t.V., F.B., T.S., M.H., P.V.H.), Neuroradiology (M.H.) and Medical Radiology (P.V.H.), University Hospital of Zurich; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); and University of Zurich, Zurich, Switzerland (E.t.V., M.H., P.V.H.)
| | - Martin Hüllner
- From the Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D., M.K.); the Departments of Nuclear Medicine (E.t.V., F.B., T.S., M.H., P.V.H.), Neuroradiology (M.H.) and Medical Radiology (P.V.H.), University Hospital of Zurich; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); and University of Zurich, Zurich, Switzerland (E.t.V., M.H., P.V.H.)
| | - Patrick Veit-Haibach
- From the Applied Science Laboratory, GE Healthcare, Waukesha, Wis (G.D., M.K.); the Departments of Nuclear Medicine (E.t.V., F.B., T.S., M.H., P.V.H.), Neuroradiology (M.H.) and Medical Radiology (P.V.H.), University Hospital of Zurich; Department of Radiology, Nippon Medical School, Tokyo, Japan (T.S.); and University of Zurich, Zurich, Switzerland (E.t.V., M.H., P.V.H.)
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Sekine T, Ter Voert EEGW, Warnock G, Buck A, Huellner M, Veit-Haibach P, Delso G. Clinical Evaluation of Zero-Echo-Time Attenuation Correction for Brain 18F-FDG PET/MRI: Comparison with Atlas Attenuation Correction. J Nucl Med 2016; 57:1927-1932. [PMID: 27339875 DOI: 10.2967/jnumed.116.175398] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 05/31/2016] [Indexed: 12/19/2022] Open
Abstract
Accurate attenuation correction (AC) on PET/MR is still challenging. The purpose of this study was to evaluate the clinical feasibility of AC based on fast zero-echo-time (ZTE) MRI by comparing it with the default atlas-based AC on a clinical PET/MR scanner. METHODS We recruited 10 patients with malignant diseases not located on the brain. In all patients, a clinically indicated whole-body 18F-FDG PET/CT scan was acquired. In addition, a head PET/MR scan was obtained voluntarily. For each patient, 2 AC maps were generated from the MR images. One was atlas-AC, derived from T1-weighted liver acquisition with volume acceleration flex images (clinical standard). The other was ZTE-AC, derived from proton-density-weighted ZTE images by applying tissue segmentation and assigning continuous attenuation values to the bone. The AC map generated by PET/CT was used as a silver standard. On the basis of each AC map, PET images were reconstructed from identical raw data on the PET/MR scanner. All PET images were normalized to the SPM5 PET template. After that, these images were qualified visually and quantified in 67 volumes of interest (VOIs; automated anatomic labeling, atlas). Relative differences and absolute relative differences between PET images based on each AC were calculated. 18F-FDG uptake in all 670 VOIs and generalized merged VOIs were compared using a paired t test. RESULTS Qualitative analysis shows that ZTE-AC was robust to patient variability. Nevertheless, misclassification of air and bone in mastoid and nasal areas led to the overestimation of PET in the temporal lobe and cerebellum (%diff of ZTE-AC, 2.46% ± 1.19% and 3.31% ± 1.70%, respectively). The |%diff| of all 670 VOIs on ZTE was improved by approximately 25% compared with atlas-AC (ZTE-AC vs. atlas-AC, 1.77% ± 1.41% vs. 2.44% ± 1.63%, P < 0.01). In 2 of 7 generalized VOIs, |%diff| on ZTE-AC was significantly smaller than atlas-AC (ZTE-AC vs. atlas-AC: insula and cingulate, 1.06% ± 0.67% vs. 2.22% ± 1.10%, P < 0.01; central structure, 1.03% ± 0.99% vs. 2.54% ± 1.20%, P < 0.05). CONCLUSION The ZTE-AC could provide more accurate AC than clinical atlas-AC by improving the estimation of head-skull attenuation. The misclassification in mastoid and nasal areas must be addressed to prevent the overestimation of PET in regions near the skull base.
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Affiliation(s)
- Tetsuro Sekine
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland .,Department of Radiology, Nippon Medical School, Tokyo, Japan
| | | | - Geoffrey Warnock
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,Institute of Pharmacology & Toxicology, University of Zurich, Zurich, Switzerland.,PMOD Technologies Ltd., Zurich, Switzerland
| | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Martin Huellner
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Patrick Veit-Haibach
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.,Division of Diagnostic and Interventional Radiology, Department of Medical Radiology, University Hospital Zurich, Zurich, Switzerland; and
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Abstract
The aim of this article is to provide Radiologists and Nuclear Medicine physicians the basic information required to understand how PET/MR scanners work, what are their limitations and how to evaluate their performance. It will cover the operational principles of standalone PET and MR imaging, as well as the technical challenges of creating a hybrid system and how they have been solved in the now commercially available scanners. Guidelines will be provided to interpret the main performance figures of hybrid PET/MR systems.
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Affiliation(s)
- Gaspar Delso
- Department of Nuclear Medicine, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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de Galiza Barbosa F, Delso G, Ter Voert EEGW, Huellner MW, Herrmann K, Veit-Haibach P. Multi-technique hybrid imaging in PET/CT and PET/MR: what does the future hold? Clin Radiol 2016; 71:660-72. [PMID: 27108800 DOI: 10.1016/j.crad.2016.03.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/11/2016] [Accepted: 03/22/2016] [Indexed: 12/19/2022]
Abstract
Integrated positron-emission tomography and computed tomography (PET/CT) is one of the most important imaging techniques to have emerged in oncological practice in the last decade. Hybrid imaging, in general, remains a rapidly growing field, not only in developing countries, but also in western industrialised healthcare systems. A great deal of technological development and research is focused on improving hybrid imaging technology further and introducing new techniques, e.g., integrated PET and magnetic resonance imaging (PET/MRI). Additionally, there are several new PET tracers on the horizon, which have the potential to broaden clinical applications in hybrid imaging for diagnosis as well as therapy. This article aims to highlight some of the major technical and clinical advances that are currently taking place in PET/CT and PET/MRI that will potentially maintain the position of hybrid techniques at the forefront of medical imaging technologies.
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Affiliation(s)
- F de Galiza Barbosa
- Department of Nuclear Medicine, University Hospital Zurich, Switzerland; University of Zurich, Switzerland
| | - G Delso
- Department of Nuclear Medicine, University Hospital Zurich, Switzerland; GE Healthcare, Waukesha, WI, USA
| | - E E G W Ter Voert
- Department of Nuclear Medicine, University Hospital Zurich, Switzerland; University of Zurich, Switzerland
| | - M W Huellner
- Department of Nuclear Medicine, University Hospital Zurich, Switzerland; University of Zurich, Switzerland; Department of Neuroradiology, University Hospital Zurich, Switzerland
| | - K Herrmann
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, United States; Department of Nuclear Medicine, Universitätsklinikum Würzburg, Oberdürrbacher, Str. 6, Würzburg, Germany
| | - P Veit-Haibach
- Department of Nuclear Medicine, University Hospital Zurich, Switzerland; University of Zurich, Switzerland; Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland.
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Sekine T, Burgos N, Warnock G, Huellner M, Buck A, Ter Voert EEGW, Cardoso MJ, Hutton BF, Ourselin S, Veit-Haibach P, Delso G. Multi-Atlas-Based Attenuation Correction for Brain 18F-FDG PET Imaging Using a Time-of-Flight PET/MR Scanner: Comparison with Clinical Single-Atlas- and CT-Based Attenuation Correction. J Nucl Med 2016; 57:1258-64. [PMID: 27013697 DOI: 10.2967/jnumed.115.169045] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 02/25/2016] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED In this work, we assessed the feasibility of attenuation correction (AC) based on a multi-atlas-based method (m-Atlas) by comparing it with a clinical AC method (single-atlas-based method [s-Atlas]), on a time-of-flight (TOF) PET/MRI scanner. METHODS We enrolled 15 patients. The median patient age was 59 y (age range, 31-80). All patients underwent clinically indicated whole-body (18)F-FDG PET/CT for staging, restaging, or follow-up of malignant disease. All patients volunteered for an additional PET/MRI scan of the head (no additional tracer being injected). For each patient, 3 AC maps were generated. Both s-Atlas and m-Atlas AC maps were generated from the same patient-specific LAVA-Flex T1-weighted images being acquired by default on the PET/MRI scanner during the first 18 s of the PET scan. An s-Atlas AC map was extracted by the PET/MRI scanner, and an m-Atlas AC map was created using a Web service tool that automatically generates m-Atlas pseudo-CT images. For comparison, the AC map generated by PET/CT was registered and used as a gold standard. PET images were reconstructed from raw data on the TOF PET/MRI scanner using each AC map. All PET images were normalized to the SPM5 PET template, and (18)F-FDG accumulation was quantified in 67 volumes of interest (VOIs; automated anatomic labeling atlas). Relative (%diff) and absolute differences (|%diff|) between images based on each atlas AC and CT-AC were calculated. (18)F-FDG uptake in all VOIs and generalized merged VOIs were compared using the paired t test and Bland-Altman test. RESULTS The range of error on m-Atlas in all 1,005 VOIs was -4.99% to 4.09%. The |%diff| on the m-Atlas was improved by about 20% compared with s-Atlas (s-Atlas vs. m-Atlas: 1.49% ± 1.06% vs. 1.21% ± 0.89%, P < 0.01). In generalized VOIs, %diff on m-Atlas in the temporal lobe and cerebellum was significantly smaller (s-Atlas vs. m-Atlas: temporal lobe, 1.49% ± 1.37% vs. -0.37% ± 1.41%, P < 0.01; cerebellum, 1.55% ± 1.97% vs. -1.15% ± 1.72%, P < 0.01). CONCLUSION The errors introduced using either s-Atlas or m-Atlas did not exceed 5% in any brain region investigated. When compared with the clinical s-Atlas, m-Atlas is more accurate, especially in regions close to the skull base.
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Affiliation(s)
- Tetsuro Sekine
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland Department of Radiology, Nippon Medical School, Tokyo, Japan
| | - Ninon Burgos
- Translational Imaging Group, Centre for Medical Image Computing, University College London, NW1 2HE, London, United Kingdom
| | - Geoffrey Warnock
- Institute of Pharmacology & Toxicology, University of Zurich, Zurich, Switzerland PMOD Technologies Ltd., Zurich, Switzerland
| | - Martin Huellner
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | | | - M Jorge Cardoso
- Translational Imaging Group, Centre for Medical Image Computing, University College London, NW1 2HE, London, United Kingdom Dementia Research Centre, Institute of Neurology, University College London, WC1N 3AR London, United Kingdom
| | - Brian F Hutton
- Institute of Nuclear Medicine, University College London, NW1 2BU London, United Kingdom Centre for Medical Radiation Physics, University of Wollongong, NSW 2522 Wollongong, Australia
| | - Sebastien Ourselin
- Translational Imaging Group, Centre for Medical Image Computing, University College London, NW1 2HE, London, United Kingdom Dementia Research Centre, Institute of Neurology, University College London, WC1N 3AR London, United Kingdom
| | - Patrick Veit-Haibach
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland Division of Diagnostic and Interventional Radiology, Department of Medical Radiology, University Hospital Zurich, Zurich, Switzerland; and
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Khalighi MM, Delso G, Tohme M, Iagaru A, Zaharchuk G. Dynamic brain PET/MR using TOF reconstruction. EJNMMI Phys 2016; 2:A60. [PMID: 26956320 PMCID: PMC4798706 DOI: 10.1186/2197-7364-2-s1-a60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Zeimpekis K, Huellner M, De Galiza Barbosa F, Ter Voert E, Davison H, Delso G, Veit-Haibach P. Clinical evaluation of PET image quality as a function of acquisition time in a new TOF-PET/MR compared to TOF-PET/CT - initial results. EJNMMI Phys 2016; 2:A76. [PMID: 26956337 PMCID: PMC4798667 DOI: 10.1186/2197-7364-2-s1-a76] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
| | | | | | | | - Helen Davison
- Nuclear Medicine, University Hospital Zurich, Switzerland
| | - Gaspar Delso
- Nuclear Medicine, University Hospital Zurich, Switzerland
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Teuho J, Johansson J, Linden J, Hansen AE, Holm S, Keller SH, Delso G, Veit-Haibach P, Magota K, Saunavaara V, Tolvanen T, Teräs M, Iida H. Effect of Attenuation Correction on Regional Quantification Between PET/MR and PET/CT: A Multicenter Study Using a 3-Dimensional Brain Phantom. J Nucl Med 2016; 57:818-24. [PMID: 26823565 DOI: 10.2967/jnumed.115.166165] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 01/04/2016] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED A spatial bias in brain PET/MR exists compared with PET/CT, because of MR-based attenuation correction. We performed an evaluation among 4 institutions, 3 PET/MR systems, and 4 PET/CT systems using an anthropomorphic brain phantom, hypothesizing that the spatial bias would be minimized with CT-based attenuation correction (CTAC). METHODS The evaluation protocol was similar to the quantification of changes in neurologic PET studies. Regional analysis was conducted on 8 anatomic volumes of interest (VOIs) in gray matter on count-normalized, resolution-matched, coregistered data. On PET/MR systems, CTAC was applied as the reference method for attenuation correction. RESULTS With CTAC, visual and quantitative differences between PET/MR and PET/CT systems were minimized. Intersystem variation between institutions was +3.42% to -3.29% in all VOIs for PET/CT and +2.15% to -4.50% in all VOIs for PET/MR. PET/MR systems differed by +2.34% to -2.21%, +2.04% to -2.08%, and -1.77% to -5.37% when compared with a PET/CT system at each institution, and these differences were not significant (P ≥ 0.05). CONCLUSION Visual and quantitative differences between PET/MR and PET/CT systems can be minimized by an accurate and standardized method of attenuation correction. If a method similar to CTAC can be implemented for brain PET/MRI, there is no reason why PET/MR should not perform as well as PET/CT.
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Affiliation(s)
- Jarmo Teuho
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland
| | - Jarkko Johansson
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland
| | - Jani Linden
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland
| | - Adam Espe Hansen
- Department of Clinical Physiology, Nuclear Medicine, and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Søren Holm
- Department of Clinical Physiology, Nuclear Medicine, and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sune H Keller
- Department of Clinical Physiology, Nuclear Medicine, and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Gaspar Delso
- PET/CT-MR Center, University Hospital Zurich, Zurich, Switzerland
| | | | - Keiichi Magota
- Section of Nuclear Medicine, Department of Radiology, Hokkaido University Hospital, Sapporo, Japan
| | - Virva Saunavaara
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland
| | - Tuula Tolvanen
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland
| | - Mika Teräs
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland Department of Medical Physics, Turku University Hospital, Turku, Finland; and
| | - Hidehiro Iida
- National Cerebral and Cardiovascular Center, Osaka, Japan
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Beyer T, Lassen ML, Boellaard R, Delso G, Yaqub M, Sattler B, Quick HH. Investigating the state-of-the-art in whole-body MR-based attenuation correction: an intra-individual, inter-system, inventory study on three clinical PET/MR systems. MAGMA 2016; 29:75-87. [PMID: 26739263 DOI: 10.1007/s10334-015-0505-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 09/21/2015] [Accepted: 10/23/2015] [Indexed: 01/19/2023]
Abstract
OBJECTIVE We assess inter- and intra-subject variability of magnetic resonance (MR)-based attenuation maps (MRμMaps) of human subjects for state-of-the-art positron emission tomography (PET)/MR imaging systems. MATERIALS AND METHODS Four healthy male subjects underwent repeated MR imaging with a Siemens Biograph mMR, Philips Ingenuity TF and GE SIGNA PET/MR system using product-specific MR sequences and image processing algorithms for generating MRμMaps. Total lung volumes and mean attenuation values in nine thoracic reference regions were calculated. Linear regression was used for comparing lung volumes on MRμMaps. Intra- and inter-system variability was investigated using a mixed effects model. RESULTS Intra-system variability was seen for the lung volume of some subjects, (p = 0.29). Mean attenuation values across subjects were significantly different (p < 0.001) due to different segmentations of the trachea. Differences in the attenuation values caused noticeable intra-individual and inter-system differences that translated into a subsequent bias of the corrected PET activity values, as verified by independent simulations. CONCLUSION Significant differences of MRμMaps generated for the same subjects but different PET/MR systems resulted in differences in attenuation correction factors, particularly in the thorax. These differences currently limit the quantitative use of PET/MR in multi-center imaging studies.
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Affiliation(s)
- Thomas Beyer
- Center for Medical Physics and Biomedical Engineering, General Hospital Vienna, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090, Vienna, Austria.
| | - Martin L Lassen
- Center for Medical Physics and Biomedical Engineering, General Hospital Vienna, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090, Vienna, Austria
| | - Ronald Boellaard
- Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands. .,Department of Nuclear Medicine and Molecular Imaging, University Medical Centre Groningen, Groningen, The Netherlands.
| | - Gaspar Delso
- Department of Medical Imaging, University Hospital of Zurich, Zurich, Switzerland.,GE Healthcare, Waukesha, WI, USA
| | - Maqsood Yaqub
- Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands
| | - Bernhard Sattler
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig, Germany
| | - Harald H Quick
- Institute of Medical Physics, University of Erlangen-Nürnberg, Erlangen, Germany.,High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
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Affiliation(s)
| | | | | | | | | | | | - Gaspar Delso
- University Hospital; Zurich Switzerland
- GE Healthcare; Waukesha Wisconsin USA
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Delso G, Khalighi M, Hofbauer M, Porto M, Veit-Haibach P, von Schulthess G. Preliminary evaluation of image quality in a new clinical ToF-PET/MR scanner. EJNMMI Phys 2015; 1:A41. [PMID: 26501629 PMCID: PMC4544605 DOI: 10.1186/2197-7364-1-s1-a41] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
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Delso G, Deller T, Khalighi M, Veit-Haibach P, von Schulthess G. Dynamic comparison of PET imaging performance between state-of-the-art ToF-PET/CT and ToF-PET/MR scanners. EJNMMI Phys 2015; 1:A75. [PMID: 26501666 PMCID: PMC4545837 DOI: 10.1186/2197-7364-1-s1-a75] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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48
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Monnier F, Fayad H, Bert J, Lapuyade-Lahorgue J, Hatt M, Veit-Haibach P, Delso G, Visvikis D. Generation of pseudo-CT from a single MRI for PET/MR attenuation correction purposes. EJNMMI Phys 2015; 1:A74. [PMID: 26501665 PMCID: PMC4545960 DOI: 10.1186/2197-7364-1-s1-a74] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Affiliation(s)
| | | | | | | | | | - Patrick Veit-Haibach
- Nuclear Medicine Department, University Hospital Zurich, Kragujevac, Switzerland
| | - Gaspar Delso
- Nuclear Medicine Department, University Hospital Zurich, Kragujevac, Switzerland
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Sekine T, Buck A, Delso G, Ter Voert EEGW, Huellner M, Veit-Haibach P, Warnock G. Evaluation of Atlas-Based Attenuation Correction for Integrated PET/MR in Human Brain: Application of a Head Atlas and Comparison to True CT-Based Attenuation Correction. J Nucl Med 2015; 57:215-20. [PMID: 26493207 DOI: 10.2967/jnumed.115.159228] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 10/07/2015] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Attenuation correction (AC) for integrated PET/MR imaging in the human brain is still an open problem. In this study, we evaluated a simplified atlas-based AC (Atlas-AC) by comparing (18)F-FDG PET data corrected using either Atlas-AC or true CT data (CT-AC). METHODS We enrolled 8 patients (median age, 63 y). All patients underwent clinically indicated whole-body (18)F-FDG PET/CT for staging, restaging, or follow-up of malignant disease. All patients volunteered for an additional PET/MR of the head (additional tracer was not injected). For each patient, 2 AC maps were generated: an Atlas-AC map registered to a patient-specific liver accelerated volume acquisition-Flex MR sequence and using a vendor-provided head atlas generated from multiple CT head images and a CT-based AC map. For comparative AC, the CT-AC map generated from PET/CT was superimposed on the Atlas-AC map. PET images were reconstructed from the list-mode raw data from the PET/MR imaging scanner using each AC map. All PET images were normalized to the SPM5 PET template, and (18)F-FDG accumulation was quantified in 67 volumes of interest (VOIs; automated anatomic labeling atlas). Relative difference (%diff) between images based on Atlas-AC and CT-AC was calculated, and averaged difference images were generated. (18)F-FDG uptake in all VOIs was compared using Bland-Altman analysis. RESULTS The range of error in all 536 VOIs was -3.0%-7.3%. Whole-brain (18)F-FDG uptake based on Atlas-AC was slightly underestimated (%diff = 2.19% ± 1.40%). The underestimation was most pronounced in the regions below the anterior/posterior commissure line, such as the cerebellum, temporal lobe, and central structures (%diff = 3.69% ± 1.43%, 3.25% ± 1.42%, and 3.05% ± 1.18%), suggesting that Atlas-AC tends to underestimate the attenuation values of the skull base bone. CONCLUSION When compared with the gold-standard CT-AC, errors introduced using Atlas-AC did not exceed 8% in any brain region investigated. Underestimation of (18)F-FDG uptake was minor (<4%) but significant in regions near the skull base.
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Affiliation(s)
- Tetsuro Sekine
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland University of Zurich, Zurich, Switzerland Department of Radiology, Nippon Medical School, Tokyo, Japan
| | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland University of Zurich, Zurich, Switzerland
| | - Gaspar Delso
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland University of Zurich, Zurich, Switzerland GE Healthcare, Waukesha, Wisconsin
| | - Edwin E G W Ter Voert
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland University of Zurich, Zurich, Switzerland
| | - Martin Huellner
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland University of Zurich, Zurich, Switzerland Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland; and
| | - Patrick Veit-Haibach
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland University of Zurich, Zurich, Switzerland Division of Diagnostic and Interventional Radiology, Department of Medical Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Geoffrey Warnock
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland University of Zurich, Zurich, Switzerland
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Huellner MW, de Galiza Barbosa F, Husmann L, Pietsch CM, Mader CE, Burger IA, Stolzmann P, Delso G, Frauenfelder T, von Schulthess GK, Veit-Haibach P. TNM Staging of Non–Small Cell Lung Cancer: Comparison of PET/MR and PET/CT. J Nucl Med 2015; 57:21-6. [DOI: 10.2967/jnumed.115.162040] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 10/06/2015] [Indexed: 12/25/2022] Open
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