Jeffrey M. Lau MD, PhD, Presenter: Nothing to Disclose

Richard Laforest PhD, Abstract Co-Author: Nothing to Disclose

Jie Zheng PhD, Abstract Co-Author: Nothing to Disclose

Xingyu Nie BS, Abstract Co-Author: Nothing to Disclose

Agus Priatna PhD, Abstract Co-Author: Research Consultant, Siemens AG Employee, Siemens AG

Pamela K. Woodard MD, Abstract Co-Author: Research support, Siemens AG Research support, Astellas Group Consultant, BIOTRONIK GmbH & Co KG

David Duane Faul PhD, Abstract Co-Author: Employee, Siemens AG

Robert J. Gropler MD, Abstract Co-Author: Advisory Board, Bracco Group Advisory Board, GlaxoSmithKline plc Advisory Board, Pfizer Inc Advisory Board, Bayer AG Research grant, GlaxoSmithKline plc Research grant, Pfizer Inc Research grant, Clinical Data, Inc Research grant, Lantheus Medical Imaging, Inc

Carotid atherosclerosis is a prevalent disease with significant morbidity and mortality. The current reference standard, carotid ultrasonography, assesses anatomy only, and does not identify whether the lesions are metabolically active. In this pilot study, we investigate the feasibility of carotid atherosclerosis evaluation using simultaneous acquisition Positron Emission Tomography/Magnetic Resonance (PET/MR).

15 patients undergoing clinical 18F-FDG PET/CT for oncologic purposes were recruited. Carotid PET/MR was performed within 120 mins after 444-703 MBq 18F-FDG injection. Multi-contrast MRI was performed during a 15 minute continuous list-mode acquisition using T1, T2, PD, and gradient-echo (GR) weighted images. The sequences performed were turbo spin-echo (TSE) sequences with an interpolated resolution of 0.25 x 0.25 x 0.8mm. In addition, a SPACE (Sampling Perfection with Application optimized Contrast using different flip angle Evolutions) sequence was used to obtain 3D isotropic (0.8 mm) black blood carotid wall images. PET attenuation correction µ-map was a dual echo VIBE Dixon sequence. PET images were reconstructed with 3D-OSEM (Ordered Subset Estimation Maximization) with 3 iterations, 21 subsets and post-Gaussian filter of 4 mm. Each patient’s bilateral common carotid arteries and vertebral arteries were divided into 12 segments for scoring for the presence of plaque, lipid pool, hemorrhage, calcification, and 18F-FDG activity. The method of delineating between fibrous plague, lipid pool, hemorrhage, thrombus, calcification and other vascular pathologies is based on published differential signal patterns on MR T1, T2, and PD sequences.

29/180 (16%) examined segments showed positive PET activity, 48/180 (26%) showed fibrous plague, and 16/180 (9%) segments showed lipid pool. Positive PET/MR correlation was seen more frequently with lipid pool (10/16, 63%) versus fibrous (22/48, 46%), suggesting that lipid pool lesions are more likely to be metabolically active than fibrous plagues (z=1.16, P=0.12).

We demonstrate that a clinical carotid 18F-FDG PET/MR exam is feasible, quick, and has the potential to provide both anatomic and metabolic information about carotid atherosclerotic plaque.

The complementary PET/MR information may prove significant in patient risk-stratification and assignment of medical or procedural intervention.

Lau, J, Laforest, R, Zheng, J, Nie, X, Priatna, A, Woodard, P, Faul, D, Gropler, R, 18F-FDG PET/MR Carotid Plaque Imaging: Early Experience.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14004906.html