Perfusion images can enhance the accuracy to evaluate intracranial artery stenosis

초록

BACKGROUND AND PURPOSE: Although digital subtraction angiography (DSA) provides excellent and accurate visualization of the intracranial artery stenosis(ICAS), it has several limitations. Purfusion images are known to show the hypoperfused and critical brain areas in the hyperacute ischemic stroke patients. However, it remains unclear whether perfusion images can give additional information for ICAS in subacute or chronic stroke patients. Our purpose was to evaluate the ability of MR perfusion images to help detect and quantify intracranial stenosis and occlusion compared with DSA and MR angiography (MRA). METHODS: From 2008, 83 patients underwent 3D time-of-flight (TOF) MRA, MR perfusion images and DSA for suspected cerebrovascular lesions like ICAS and intracranial aneurysm. All three studies were performed within a 14-day period. Four readers blinded to prior estimated or calculated stenoses, patient history and clinical information, examined 1079 vessel segments including basilar artery, PCA, M1,M2, A1,A2 and distal ICA. Lesions were categorized as normal (0&#8211;49%), moderate (50&#8211;69%), and severe (70&#8211;100%). DSA was the reference standard. Unblinded consensus readings were obtained for all discrepancies. First, we compared the only MRA with MRA combined with perfusion images(MRA/P). RESULTS:A total of 73 diseased vessel segments were identified on DSA. After consensus interpretation, MRA/P revealed higher sensitivity and specificity than that of only MRA for intracranial stenosis (sensitivity, 68% versus 55%, P = 0.02;specificity, 85% versus 35%, P <0.01). MRA/P had a higher positive predictive value than only MRA(88% versus 51%, P < 0.01) and a high interoperator reliability. All of five patients with false positive lesions on MRA/P had the large territorial infarction. Three false negative lesions on MRA/P were caused by the well developed collateral flows from ECA. CONCLUSION: Perfusion MR images enhanced the accuracy of diagnosis for ICAS,