Hemodynamic evaluation of basilar and vertebral artery angioplasty

The postangioplasty evaluation of a stenotic vessel is often conducted by studying serial angiograms to determine the anatomic reduction in stenosis. In flow-limiting stenosis, the hemodynamic change that accompanies these anatomic changes is of great importance in evaluating the success of the angioplasty. The purpose of this article is to demonstrate the usefulness of phase contrast magnetic resonance angiography (PCMRA) in evaluating the hemodynamic changes that occur after angioplasty of the basilar and vertebral arteries.

Between January 1998 and February 2000, PCMRA was performed for the hemodynamic evaluation of 130 patients who presented at our institution. Twenty-six patients were evaluated for vertebrobasilar insufficiency, and flow rates of their vertebral and basilar arteries were determined. In five patients, angioplasty was done on the basilar or vertebral arteries, and PCMRA was performed to determine flow rates before and after the procedure.

Of the five patients undergoing angioplasty, the average percentage of stenosis was 81%. The average increase in basilar artery flow rate was 46 ml/min (P < 0.05) after angioplasty. Two of these patients are described. One patient demonstrated the comparison of flow rates in the vertebral and basilar arteries after angioplasty. The second patient showed follow-up flow rates measured after angioplasty and up to 4 months later to predict restenosis.

The use of flow rate data before and after angioplasty is helpful not only to evaluate the treatment immediately after the procedure but also to evaluate the effectiveness of the treatment during a long period. PCMRA provides a noninvasive method for measuring arterial flow rates with far-reaching implications in neurosurgery.