Added Value of Vessel Wall Magnetic Resonance Imaging in the Differentiation of Moyamoya Vasculopathies in a Non-Asian Cohort

Abstract

Background and Purpose Although studies have evaluated the differential imaging of moyamoya disease and atherosclerosis, none have investigated the added value of vessel-wall MRI. The current study evaluates the added diagnostic value of vessel-wall MRI in differentiating moyamoya disease (MMD), atherosclerotic-moyamoya syndrome (A-MMS) and vasculitic-moyamoya syndrome (V-MMS) with a multi-contrast protocol. Methods We retrospectively reviewed the carotid artery territories of patients with clinically defined vasculopathies (MMD, atherosclerosis, vasculitis) and steno-occlusive intracranial carotid disease. Two neuroradiologists, blinded to clinical data reviewed the luminal imaging of each carotid, evaluating collateral extent and making a presumed diagnosis with diagnostic confidence. After three weeks, the two readers reviewed the luminal imaging+vessel-wall MRI for presence, pattern and intensity of post-contrast enhancement, T2 signal characteristics, pattern of involvement, presumed diagnosis and confidence. Results Ten A-MMS, three V-MMS and eight MMD cases with 38 affected carotid segments were included. There was significant improvement in diagnostic accuracy with luminal imaging+vessel-wall MRI as compared to luminal imaging (87% vs. 32%, p<.001). The most common vessel-wall MRI findings for MMD were non-enhancing, non-remodeling lesions without T2 heterogeneity; for A-MMS eccentric, remodeling, and T2 heterogeneous lesions with mild/moderate and homogeneous/heterogeneous enhancement; and for V-MMS concentric lesions with homogeneous, moderate enhancement. Inter-reader agreement was moderate to substantial for all vessel-wall MRI characteristics (κ=0.46-0.86) and fair for collateral grading (κ=0.35). There was 11% inter-reader agreement for diagnosis on luminal imaging as compared to 82% for luminal imaging+vessel-wall MRI (p<.001). Conclusion Vessel-wall MRI can significantly improve the differentiation of moyamoya vasculopathies when combined with traditional imaging techniques.

Added Value of Vessel Wall Magnetic Resonance Imaging for Differentiation of Nonocclusive Intracranial Vasculopathies

“…The IVWI protocol included high-resolution multi-planar T1 (0.4×0.35 mm in-plane resolution; 2 mm slice thickness; TR/TE, 1000/10 ms; 36 s per slice) pre and post contrast, T2 (0.4×0.4 mm in-plane; 1 mm slice thickness; TR/TE, 3550/72 ms; 9.3 s per slice), and 3D SPACE T2-weighted (0.6×0.6 mm in-plane; 0.6 mm slice thickness; TR/TE, 2400/80 ms; 64 slices; 10:20 minutes) sequences. More detailed imaging parameters can be found in previous publications 15, 16 .…”

“…Lesions were randomized so each lesion could be reviewed based on its imaging characteristics independent of other patient lesions. The raters evaluated luminal imaging for the pattern of involvement (concentric/eccentric), diagnosis (ICAD, IVas, RCVS or unknown if diagnosis could not be narrowed down to a single disease) and confidence in their diagnosis on a 4-point Likert scale: 0=50% confidence, 1=51–75% confidence, 2=76–90% confidence, 3=>90% confidence) 15 . On luminal imaging, eccentric lesions were defined as those primarily affecting one side of the lumen on 2-dimensional review or ≤3 sides of the lumen on 3-dimensional review, while concentric was defined as lesions with circumferential narrowing of the lumen.…”

“…After a 6-week washout period, the raters reevaluated the randomized lesions using both luminal imaging+IVWI individually and independently. The raters evaluated the pattern of wall involvement (eccentric/concentric), presence of enhancement (y/n), pattern of enhancement (focal, heterogeneous, and diffuse), diagnosis and confidence in diagnosis (the 4-point scale) 15 . Concentric lesions were defined as those where the width of the thinnest wall segment was >50% that of the thickest segment, while for eccentric lesions, the thinnest segment had a width <50% that of the thickest segment 17 .…”

“…Concentric lesions were defined as those where the width of the thinnest wall segment was >50% that of the thickest segment, while for eccentric lesions, the thinnest segment had a width <50% that of the thickest segment 17 . For the enhancement pattern, focal was a punctate or short linear focus of enhancement, heterogeneous was incomplete enhancement and diffuse was complete enhancement 15, 16 .…”

“…The inclusion of IVWI can better differentiate between moyamoya disease and etiologies of moyamoya syndrome compared to luminal imaging alone 15 . Etiologies of non-occlusive intracranial vasculopathies can be differentiated using a multi-contrast IVWI protocol 16 .…”