CT Perfusion with Angiography as a Substitute for both Conventional Digital Subtraction Angiography and Acetazolamide-Challenged SPECT in the Follow-Up of Postbypass Patients

Abstract

Background: We evaluated the clinical usefulness of CT perfusion (CTP) with angiography (CTA) as an alternative to digital subtraction angiography (DSA) and acetazolamide (ACZ)-challenged single-photon emission computed tomography (SPECT) in the follow-up evaluation of hemodynamic changes and bypass patency after bypass surgery in chronic cerebral ischemic diseases. Methods: Thirty-five patients who underwent superficial temporal artery/middle cerebral artery bypass surgery for chronic cerebral ischemic diseases were retrospectively enrolled. We assessed the relationship between CTP parameters [cerebral blood volume, cerebral blood flow (CBF), mean transit time (MTT), affected-to-unaffected hemisphere (ATU) ratio of perfusion parameters and MTT differences between hemispheres] and SPECT parameters (regional CBF and cerebrovascular reserve) and compared the preoperative CTP parameters with the postoperative ones. For the bypass patency, we compared CTA with DSA. Results: MTT showed the best correlation with CVR of SPECT (r = –0.343; p < 0.001). ATU ratio (r = –0.547; p < 0.001) and ATU differences (r = –0.592; p < 0.001) of MTT correlated well with the ATU ratio of rCBF on ACZ-challenged SPECT. Significant improvement of perfusion parameters could be demonstrated in the affected vascular territory with postoperative CTP. The CTA findings were consistent with those of DSA in 96% of the cases. The examination-related complication rate was 0, 2.8 and 8.6% for CT studies, DSA and SPECT, respectively. Conclusions: CTP performed simultaneously with CTA seems to be a safe and efficient substitute for DSA and ACZ-challenged SPECT in the follow-up evaluation after bypass surgery in patients with chronic cerebral ischemic diseases.