Study on middle cerebral artery stenosis or occlusion by CT perfusion and CT angiography with 64-detector row CT

Objective To evaluate the application value of combining cerebral CT perfusion (CTP) with CT angiography (CTA) of 64-detector row CT (MDCT) in cerebral ischemia caused by stenosis or occlusion of middle cerebral artery (MCA). Methods Thirty-seven patients with unilateral or bilateral stenosis or occlusion of MCA diagnosed by DSA and 10 normal adult volunteers were scanned by CT, and the unenhanced axial CT, CTP and CTA were performed. To discriminate the ischemic focus, the parameter maps of cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and time to peak (TP) were obtained. Results According to MTT and TP maps of CTP, the cerebral perfusion delay was divided into three types: type Ⅰ, the lesion only involved the MCA territory; type Ⅱ, the lesion only involved the boundary zone; and type Ⅲ, the lesion involved the both MCA territory and boundary zone. In 25 patients with unilateral stenosis or occlusion of MCA, 4 patients of CTP were normal, the type Ⅰ cerebral perfusion delay was depicted on CTP maps in 17 cases, and the type Ⅲ cerebral perfusion delay was seen in 4 cases. Comparing with normal control group, there were MTT and TP delay, CBF decrease and CBV increase in bilateral MCA territory in 12 cases with severe stenosis of bilateral MCA. These changes indicated the bilateral ischemia of brain. The collateral circulation could decrease the damage of symptomatic side of cerebral perfusion in the cases with unilateral stenosis of MCA, but no matter with or without collateral circulation, bilateral brain damage were also severe for the patents with significant stenosis and occlusion of bilateral MCA. Conclusion MTT and TP were sensitive to depict the perfusion damage of brain caused by MCA severe stenosis or occlusion, and play an important role in diagnosis, treatment of cerebral ischemia, and prevention of cerebral infarct.