Finding of MRI ALS compared with ¹⁵O-PET in two cases of moyamoya disease with a delay of cerebral circulation and post-operative hyperperfusion

Abstract

Since MRI arterial spin labeling (ASL) is a non-invasive imaging technique for the evaluation of cerebral circulation, it is gathering attention in recent years as a screening manner. Although the previous reports suggest a good correlation between ASL and ¹⁵O-PET, the findings of ASL in the pathologic situation, such as ischemia, hyperperfusion and so on, are not established yet. In this report, we demonstrated the features of ASL compared with ¹⁵O-PET in two cases of moyamoya disease with a delay of cerebral circulation and postoperative hyperperfusion. Case 1 showed a delay of cerebral circulation that affects arterial transit time (ATT) verified by cerebral angiography. Although the finding of ASL indicates overestimation by short post-labeling delay (PLD) (1500 msec) due to prolonged ATT, there is a good correlation between ASL with long PLD (2500 msec) and cerebral blood flow (CBF) by ¹⁵O-PET. On the other hand, there is a good correlation between ASL with short PLD (1500 msec) and CBF by ¹⁵O-PET in Case 2 with postoperative hyperperfusion. Therefore, ASL is non-invasive and simple imaging technique, however, we need to judge the imaging from ASL based on the consideration of ATT.