gms | German Medical Science

Objective: Extracranial-to-intracranial (EC-IC) bypass surgery remains an important treatment alternative for patients with occlusive cerebrovascular disease. The aim of our study was to use CT perfusion (CTP) and CT angiography (CTA) to evaluate cerebral hemodynamics and bypass patency in such patients before and after EC-IC high-flow surgery.

Methods: Six patients underwent CTP and CTA studies before and after bypass surgery. Pre- and postoperatively we also performed digital subtraction angiography. Surgery consisted of middle cerebral artery-superficial temporal artery bypass with saphenous vein grafts. CTP was performed at the level of the basal ganglia (2 slices, 12mm slice thickness, 1 scan/s for 40s, 40ml contrast agent, flow 5.9 ml/s). Color-coded perfusion maps for rCBV, rCBF and TTP were calculated. CTA reached from the level of vertebra C6 to the roof of the lateral ventricles. Vessels were analyzed using axial source images, MIP- and VRT-reconstructions.

Results: Preoperative CTP showed significantly prolonged MTT and reduced rCBF of the affected hemisphere. No patient developed neurological deterioration after operation. Proximal and distal anastomosis as well as the course and caliber of the bypass could be evaluated by CTA. Patency of the bypass could be visualized by CTA in all patients. Postoperative CTP showed improved cerebral hemodynamics with a return of perfusion parameters to nearly normal values.

Conclusions: CTP can be used for the pre- and postoperative evaluation of patients who receive EC-IC bypass grafts. CTA is a viable alternative to DSA to assess the patency of these bypass grafts.