MR perfusion imaging in moyamoya syndrome - Potential implications for clinical evaluation of occlusive cerebrovascular disease

Background and Purpose-Ischemic symptoms in patients with moyamoya syndrome (MMS) are usually due to hemodynamical ly mediated perfusion failure. and identification of abnormal tissue perfusion in these patients is therefore clinically important. Although dynamic susceptibility contrast (DSC) MRI ca n be used to study tissue perfusion. there are potential technical problems in MMS. This study investigates the scope and limitations of perfusion MRI in the clinical evaluation of such patients. Methods-Thirteen patients with bilateral MMS were studied with the use of s tructural. diffusion, and perfusion MRI. The DSC MRI data were analyzed bot h visually and by a quantitative regional analysis, and the relationship be tween perfusion Status and clinical symptoms was investigated. Results-Extensive bilateral DSC MRI abnormalities were observed in all the patients. There was a very heterogeneous distribution of bolus arrival time . The areas of abnormality included the major arterial border zones in all cases, although these usually appeared normal on structural and diffusion M RI. Only the most clinically unstable patients had peak width (defined as t ime to peak minus bolus arrival time) > 5 seconds on the quantitative regio nal analysis. Several technical limitations of perfusion quantification in MMS are described. as well Lis the implications of these limitations in pat ients with other forms of occlusive large-vessel disease. Conclusions-The technical limitations of DSC MRI described in this study ar e important for the accurate interpretation of perfusion MRI in MMS. Despit e these limitations, these preliminary findings suggest that the use of qua ntitative regional analysis of summary parameters may provide clinically us eful information in patients with MMS.