MR perfusion in patients with stenoocclusive cerebrovascular disease confirms indication for EC-IC bypass surgery: an alternative to Xenon CT?

Ziele: The purpose of this study was to investigate whether MR-perfusion (MRP) yields adequate information about cerebrovascular reserve capacity (CVRC) in patients with stenoocclusive cerebrocvascular disease to verify the decision if extracranial-intracranial (EC-IC) bypass surgery is needed to improve cerebral perfusion. We analysed the relation between CVRC as determined by XeCT as the given gold standard and time to peak (TTP) as

determined by MRP. Methode: 10 patients with Moya-Moya-disease or symptomatically stenosis of the distal internal carotid artery, diagnosed by DSA, were prospectively examined using XeCT and MRP. XeCT was performed before and after application of acetacolamid. CVRC was analysed by software of Diversified Diagnostic Products (Houston, TX, USA). Pathologically reduced CVRC was defined <30%. Contrast-enhanced T2*w sequences were evaluated for TTP using DPTools. Regions of interests (ROI) were located in relation to vascular territories of the anterior, middle and posterior cerebral artery. Region matching between MRI and CT was performed using anatomical landmarks. Ergebnis: CVRC and TTP were evaluated in 504 ROIs. Pearson correlation coefficient for CVRC vs. TTP was r=-0.4, p<0.001. Roc-analysis on the basis of logistic regression established the optimum threshold for TTP at 4 s with 90.8% specificity and 44.4% sensitivity to differentiate normal from pathological perfusion (McNemar test, p<0.0001). The given specificity, sensitivity and an estimated prevalence of 40% in the selected patient group delivered a positive predictive value of 0.77 and a negative predictive value of 0.71. At the optimum threshold for TTP at 4 s, t-test analysis of TTP demonstrated a significant difference in ROIs with normal and pathologically reduced CVRC (CVRC >30%, TTP mean=2.45, p<0.001; CVRC <30%, TTP mean=4.41, p<0.001). Schlussfolgerung: TTP as determined by MRP yields information about CVRC in patients with stenoocclusive cerebrovascular disease. The optimum threshold for TTP of 4 s. affecting an entire vascular territory is a valuable parameter to confirm the indication for EC-IC bypass surgery with a specifity of >90% in a preselected patient group if XeCT is not applicable.

Korrespondierender Autor: Weinmann C

Universitätsklinikum Mannheim, Institut für Klinische Radiologie, Theodor-Kutzer-Ufer 1–3, 68167 Mannheim

E-Mail: [e-mail]

cerebrovascular reserve capacity - Xenon CT - MR perfusion imaging