The aim of this study is to clarify serial vessel wall enhancement change on High-Resolution MRI Vessel Wall Image (HR-VWI) in primary angiitis of the central nervous system (PACNS).

We extracted PACNS patients from Cleveland Clinic prospective CNS vasculopathy registry (n=200) from 2012-2019. Vessel wall imaging protocol included black-blood contrast-enhanced T1-weighted sequences with fat suppression and a saturation band, and time-of-flight MRA of the circle of Willis, as previously reported. Vessel wall characteristics including enhancement, wall thickening, and lumen narrowing were collected on initial and follow-up image.

Of the 36 PACNS patients (21 males, median age 49 years), we identified 23 cases who underwent HR-VWI. Among them, follow-up HR-VWI was performed in 10 patients. The median interval between initial and follow-up HR-VWI was 10.5 months. On the initial HR-VWI, 7 patients showed smooth, concentric wall enhancement and thickening; 2 patient had smooth, eccentric wall enhancement and thickening; and 1 patient was without wall enhancement and thickening. Serial vessel wall enhancement change on follow-up HR-VWI were classified as followed; 1) complete resolution: 3 cases, 2) improvement with residual enhancement: 2 cases, 3) no-change with persistent enhancement; 2 cases, and 4) worsening: 3 cases. Clinical flare-up was observed in 4 cases. Of these, 3 cases revealed worsening enhancement change and 1 case showed no-change with persistent concentric enhancement.

Serial vessel wall enhancement change on HR-VWI can be categorized into 4 patterns. Moreover, worsening vessel wall enhancement on follow-up image may suggest clinical flare-up.