Assessment of blood flow velocity and diameter of the middle cerebral artery during the acetazolamide provocation test by use of transcranial Dopplersonography and MR imaging

BACKGROUND AND PURPOSE: Our purpose was to show changes in the diameter of the M1 segment of the middle cerebral artery (MCA) by using high-resolution MR imaging in patients with chronic internal carotid artery occlusion afte r TV administered acetazolamide challenge. Changes in blood flow velocity o f the basal cerebral arteries are thought to correlate with changes of cere bral blood how, Changes in the diameter of the basal cerebral arteries, how ever, might influence the validity of transcranial Doppler measurements. METHODS: Eight patients with internal carotid artery occlusion who were und ergoing acetazolamide testing for assessment of cerebrovascular vasomotor r eactivity were included in the study. Blood how velocities of both MCAs wer e measured with transcranial Doppler sonography before and 25 minutes after the administration of acetazolamide. Before and 15 minutes after the admin istration of medication, MR imaging was performed contralateral to the occl usion side. A T2-weighted turbo-gradient spin-echo sequence was chosen to s how a cross section of the M1 segment in high resolution (pixels, 0.27 x 0. 29 mm), Based on interpolated data, the smallest and greatest MCA diameters were determined. RESULTS: We did not find changes in the diameter of the MCA after acetazola mide provocation testing with high-resolution MR imaging in patients with o cclusive extracranial carotid artery disease. CONCLUSION: The results of our study support the hypothesis that changes in MCA flow velocity measured by transcranial Doppler sonography reflect rela tive changes in cerebral blood how after acetazolamide provocation testing.