Arjen Lindenholz

27 Clinical Vascular Imaging in the Brain at 7T 2 Figure 3. Intracranial vessel wall imaging at 3T and 7T. Intracranial vessel wall imaging of a 71-year-old male with a recent left sided ischemic infarction in the anterior circulation (not shown) resulting from symptomatic carotid artery disease. ( A ) A transverse 3T contrast-enhanced T1 Volume Isotropically Reconstructed Turbo Spin Echo Acquisition (VIRTA), repetition time 1500 ms, echo time 36 ms, acquired voxel size 0.6 × 0.6 × 1.0 mm 3 , reconstructed voxel size 0.5 × 0.5 × 0.5 mm 3 , field-of-view 200 x 167 × 45 mm 3 , scan duration 6 minutes 42 seconds. 14 Most of the arterial vessel walls of the circle of Willis are visible and appear to be normal (arrowheads). Blood is more suppressed than cerebrospinal fluid. ( B ) A transverse 7T post-contrast T1 Magnetization Preparation Inversion Recovery (MPIR) TSE acquisition, repetition time 3952 ms, echo time 37 ms, inversion time 1375 ms, acquired voxel size 0.8 × 0.8 × 0.8mm 3 , reconstructed voxel size 0.5 × 0.5 × 0.5 mm 3 , field-of-view 250 x 250 × 190 mm 3 , scan time 10 minutes 40 seconds. 9,21 The arterial vessel walls (arrowheads) are better seen due to an improved contrast with blood and cerebrospinal fluid, which is almost completely suppressed. Intracranial dissection may be hard to diagnose due to the small caliber of the involved arteries, and thus its diagnosis may highly benefit from the spontaneous bright signal on T1 high-resolution vessel wall images, as has already been investigated at 3T. 16,22 In addition, dissection often shows wall enhancement, and may present a visible flap and dual lumen. 16,22 Vasculitis, reversible vasoconstriction syndrome and moyamoya Central nervous system (CNS) vasculitis and reversible vasoconstriction syndrome (RCVS) often show clinical and lumenographic overlap, and at times only high- resolution vessel wall imaging with MRI may show distinguishing features between these two entities. 23,24 CNS vasculitis is characterized by short segments of vessel wall thickening, which is concentric more often than eccentric, and is associated with vessel wall enhancement, which may resolve after healing. 16,23-25 Compared to CNS vasculitis, RCVS shows longer segments of reversible wall thickening, continuous throughout the entire wall of the diseased vessel, with no or only mild enhancement. 24 Furthermore, high-resolution intracranial vessel wall imaging at 3T has been reported to be beneficial in differentiating moyamoya disease,