First Experience of Imaging Large Vessel Vasculitis With Fully Integrated Positron Emission Tomography/MRI

Abstract

A 58-year-old woman with a history of infrarenal large vessel vasculitis (LVV) was admitted to our hospital with pain in the lower left abdomen. Considering the history of vasculitis, clinical symptoms, and slightly elevated parameters of inflammation (CRP: 0.5 mg/dL; norm, <0.5 mg/dL; blood sedimentation rate: 39 mm/hour; norm, <30 mm/hour), a [18F]-fluoro-desoxyglucose (FDG) positron emission tomography/MRI (PET/MR) scan was performed to identify suspected recurrent vasculitis. A whole-body integrated PET/MR system (Biograph mMR) was used combining MRI and PET into 1 imaging modality. This allows truly simultaneous acquisition and thus facilitates highly accurate spatial coregistration of PET and MRI data. The combined PET/MR acquisition was performed 140 minutes after injection of 417 MBq [18F]-FDG. A coronal T2w short τ inversion recovery sequence was performed to outline the extent of potential edema in the vessel wall. Whole-body contrast-enhanced magnetic resonance angiography (MRA) was performed to identify potential arterial stenosis or occlusions and to monitor a previously diagnosed aneurysm of the ascending aorta. The extent of the potential aortic inflammatory process was studied using an axial T1w fat-suppressed dark blood sequence before and after contrast media application. PET/MR revealed an extensive active inflammation of the infrarenal aortic wall, including the aortic bifurcation (Figures …