LAUSR

OBJECTIVE Recent three-dimensional constructive interference in steady state (3D-CISS) studies have shown that the involved arteries decrease not only their own luminal caliber but also outer diameter in moyamoya disease (MMD). This study was aimed to clarify how the outer diameter of the involved arteries serially change during disease progression in MMD using qunatitaive 3D-CISS imaging. METHODS This study included 8 hemispheres of 7 patients with MMD whose Suzuki angiographic stage spontaneously progressed during follow-up. Using 3D-CISS, the outer diameter was quantified serially in supraclinoid portion of internal carotid artery (C1), the horizontal portion of middle and anterior cerebral arteries (M1 and A1, respectively) before and after the spontaneous disease progression, and also 3-12 months later. RESULTS In 7 hemispheres with early disease stage (stage 1-3) at initial presentation, the involved arteries decreased in their outer dimater in parallel with luminal stenosis during spontaneous disease progression in the C1 (P = 0.005), M1 (P < 0.0001), and A1 portions (P = 0.0048). In the remaining 1 hemisphere with stage 4 at initial presentation, 3D-CISS imaging showed no significant change in the outer diameter of C1, M1, and A1 segments during disease progression. CONCLUSIONS Using quantitative 3D-CISS imaging, this study clearly shows that the involved arteries serially decrease in their own outer diameter in parallel with luminal stenosis during spontaneous disease progression in early stages of MMD (stage 1-3). This phenomenon has not been reported previously and may result from the pathognomic mechanisms underlying the development of MMD.