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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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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, 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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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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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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Abstract
Among the proposed system architectures capable of delivering positron emission tomography/magnetic resonance (PET/MR) datasets, tri-modality systems open an interesting field in which the synergies between these modalities can be exploited to address some of the problems encountered in standalone systems. In this paper we present a feasibility study of the correction of dental streak artifacts in computed tomography (CT)-based attenuation correction images using complementary MR data. The frequency and severity of metal artifacts in oncology patients was studied by inspecting the CT scans of 152 patients examined at our hospital. A prospective correction algorithm using CT and MR information to automatically locate and edit the region affected by metal artifacts was developed and tested retrospectively on data from 15 oncology patients referred for a PET/CT scan. In datasets without malignancies, the activity in Waldeyer's ring was used to measure the maximum uptake variation when the proposed correction was applied. The measured bias ranged from 10% to 30%. In datasets with malignancies on the slices affected by artifacts, the correction led to lesion uptake variations of 6.1% for a lesion 3 cm away from the implant, 1.5% for a lesion 7 cm away and <1% for a lesion 8 cm away.
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Affiliation(s)
- G Delso
- GE Healthcare, Waukesha, WI, USA.
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Delso G, Martinez-Möller A, Bundschuh RA, Nekolla SG, Ziegler SI, Schwaiger M. Preliminary study of the detectability of coronary plaque with PET. Phys Med Biol 2011; 56:2145-60. [PMID: 21389354 DOI: 10.1088/0031-9155/56/7/016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The evaluation of coronary plaque vulnerability could be of great diagnostic value in cardiology. Positron emission tomography (PET) is a good candidate due to its ability to quantify micromolar concentrations of targeted drugs. However, the detectability of sub-voxel targets such as coronary plaque is limited by partial volume effects and by cardiorespiratory motion. The goal of this paper is to investigate the impact of these factors in the detectability of plaque uptake. Radioactive markers were implanted on the epicardium of a pig and in vivo scans were performed. This was complemented with phantom measurements to determine the minimum detectable uptake as a function of background activity. Simulations were used to evaluate the effect of cardiorespiratory motion on the reconstructed lesions. Despite cardiorespiratory motion of up to 7 mm, the markers were detectable in the in vivo scans even after the injection of background. A lower limit of 250 Bq was found for a target to be detectable. Motion reduced the contrast of the reconstructed lesions to 23% of their static counterpart. Respiratory gating improved this to 49% of the static value. The results suggest that coronary plaque evaluation with PET is possible, provided that sufficient plaque-to-myocardium uptake contrast (50 to 100) can be achieved. This requirement increases exponentially for lesions with uptake below 250 Bq. The described experiments provide a means of estimating the minimum uptake and contrast required to ensure the detectability of plaque lesions.
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Affiliation(s)
- G Delso
- Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar, TU München, Ismaninger Str. 22, 81675 München, Germany.
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Delso G, Martinez-Möller A, Bundschuh RA, Ladebeck R, Candidus Y, Faul D, Ziegler SI. Evaluation of the attenuation properties of MR equipment for its use in a whole-body PET/MR scanner. Phys Med Biol 2010; 55:4361-74. [DOI: 10.1088/0031-9155/55/15/011] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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