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Am J Nucl Med Mol Imaging 2013;3(4):361-371
Original Article
Feasibility of simultaneous PET/MR of the carotid artery: first clinical experience
and comparison to PET/CT
Rasmus S Ripa, Andreas Knudsen, Anne Mette F Hag, Anne-Mette Lebech, Annika Loft, Sune H Keller, Adam E Hansen, Eric von
Benzon, Liselotte Højgaard, Andreas Kjær
Department of Clinical Physiology, Nuclear Medicine and PET, Rigshopitalet University Hospital & Cluster for Molecular Imaging,
Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Infectious Diseases,
Hvidovre University Hospital, Denmark; Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital,
Denmark
Received May 26, 2013; Accepted June 20, 2013; Epub July 10, 2013; Published July 15, 2013
Abstract: The study aimed at comparing PET/MR to PET/CT for imaging the carotid arteries in patients with known increased risk of
atherosclerosis. Six HIV-positive men underwent sequential PET/MR and PET/CT of the carotid arteries after injection of 400 MBq of
18F-FDG. PET/MR was performed a median of 131 min after injection. Subsequently, PET/CT was performed. Regions of interest
(ROI) were drawn slice by slice to include the carotid arteries and standardized uptake values (SUV) were calculated from both
datasets independently. Quantitative comparison of 18F-FDG uptake revealed a high congruence between PET data acquired using
the PET/MR system compared to the PET/CT system. The mean difference for SUVmean was -0.18 (p < 0.001) and -0.14 for SUVmax
(p < 0.001) indicating a small but significant bias towards lower values using the PET/MR system. The 95% limits of agreement were
-0.55 to 0.20 for SUVmean and -0.93 to 0.65 for SUVmax. The image quality of the PET/MR allowed for delineation of the carotid
vessel wall. The correlations between 18F-FDG uptake from ROI including both vessel wall and vessel lumen to ROI including only
the wall were strong (r = 0.98 for SUVmean and r = 1.00 for SUVmax) indicating that the luminal 18F-FDG content had minimal
influence on the values. The study shows for the first time that simultaneous PET/MR of the carotid arteries is feasible in patients
with increased risk of atherosclerosis. Quantification of 18F-FDG uptake correlated well between PET/MR and PET/CT despite
difference in method of PET attenuation correction, reconstruction algorithm, and detector technology. (ajnmmi1305002).
Keywords: Atherosclerosis, positron emission tomography, magnetic resonance imaging, PET/MR, hybrid scanners
Address correspondence to: Dr. Andreas Kjær, Department of Clinical Physiology, Nuclear Medicine & PET, KF-4012
Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark. E-mail: akjaer@sund.ku.dk
Original Article
Feasibility of simultaneous PET/MR of the carotid artery: first clinical experience
and comparison to PET/CT
Rasmus S Ripa, Andreas Knudsen, Anne Mette F Hag, Anne-Mette Lebech, Annika Loft, Sune H Keller, Adam E Hansen, Eric von
Benzon, Liselotte Højgaard, Andreas Kjær
Department of Clinical Physiology, Nuclear Medicine and PET, Rigshopitalet University Hospital & Cluster for Molecular Imaging,
Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Infectious Diseases,
Hvidovre University Hospital, Denmark; Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital,
Denmark
Received May 26, 2013; Accepted June 20, 2013; Epub July 10, 2013; Published July 15, 2013
Abstract: The study aimed at comparing PET/MR to PET/CT for imaging the carotid arteries in patients with known increased risk of
atherosclerosis. Six HIV-positive men underwent sequential PET/MR and PET/CT of the carotid arteries after injection of 400 MBq of
18F-FDG. PET/MR was performed a median of 131 min after injection. Subsequently, PET/CT was performed. Regions of interest
(ROI) were drawn slice by slice to include the carotid arteries and standardized uptake values (SUV) were calculated from both
datasets independently. Quantitative comparison of 18F-FDG uptake revealed a high congruence between PET data acquired using
the PET/MR system compared to the PET/CT system. The mean difference for SUVmean was -0.18 (p < 0.001) and -0.14 for SUVmax
(p < 0.001) indicating a small but significant bias towards lower values using the PET/MR system. The 95% limits of agreement were
-0.55 to 0.20 for SUVmean and -0.93 to 0.65 for SUVmax. The image quality of the PET/MR allowed for delineation of the carotid
vessel wall. The correlations between 18F-FDG uptake from ROI including both vessel wall and vessel lumen to ROI including only
the wall were strong (r = 0.98 for SUVmean and r = 1.00 for SUVmax) indicating that the luminal 18F-FDG content had minimal
influence on the values. The study shows for the first time that simultaneous PET/MR of the carotid arteries is feasible in patients
with increased risk of atherosclerosis. Quantification of 18F-FDG uptake correlated well between PET/MR and PET/CT despite
difference in method of PET attenuation correction, reconstruction algorithm, and detector technology. (ajnmmi1305002).
Keywords: Atherosclerosis, positron emission tomography, magnetic resonance imaging, PET/MR, hybrid scanners
Address correspondence to: Dr. Andreas Kjær, Department of Clinical Physiology, Nuclear Medicine & PET, KF-4012
Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark. E-mail: akjaer@sund.ku.dk
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