Purpose: The aim of the present study was to determine whether preoperative cerebrovascular reactivity (CVR) to acetazolamide measured by quantitative brain perfusion single-photon emission computed tomography (SPECT) predicts development of cerebral ischemic lesions on postoperative diffusion-weighted magnetic resonance imaging (DWI) that are caused by microemboli during carotid endarterectomy (CEA).
Materials and methods: One hundred and fifty patients with ipsilateral internal carotid artery stenosis (>70%) underwent CEA under transcranial Doppler monitoring of microembolic signals (MES) in the ipsilateral middle cerebral artery (MCA). Preoperative CVR to acetazolamide was measured using [(123)I]N-isopropyl-p-iodoamphetamine SPECT, and region of interest (ROI) analysis in the ipsilateral MCA territory was performed using a three-dimensional stereotaxic ROI template. DWI was performed within 3 days before and 24 h after surgery.
Results: Twenty-six patients (17.3%) developed new postoperative ischemic lesions on DWI. Logistic regression analysis demonstrated that, among the variables tested, a high number of MES during carotid dissection (95% CIs, 1.179 to 1.486; P < 0.0001) and preoperative reduced CVR to acetazolamide (95% CIs, 0.902 to 0.974; P = 0.0008), which were significantly associated with the development of new postoperative ischemic lesions on DWI. In 47 patients with MES during carotid dissection, the combination of number of MES during carotid dissection and CVR to acetazolamide identified development of new postoperative ischemic lesions on DWI with a positive predictive value of 100% or zero.
Conclusions: Preoperative CVR to acetazolamide measured by quantitative brain perfusion SPECT predicts development of cerebral ischemic lesions on postoperative DWI that are caused by microemboli during CEA.