Abstract 167: Noninvasive MRI Measurement of Cerebrovascular Reactivity Enables Evaluation of Surgical Revascularization Response in Moyamoya
Introduction: Frequent dissociation between clinical severity and angiographic grading of moyamoya supports a role for alternative tissue-level hemodynamic measures. Here, angiography is complemented with noninvasive MRI measurements of parenchymal impairment to assess changes in cerebrovascular reactivity (CVR) after extracranial-intracranial bypass in moyamoya.
Hypothesis: CVR is regionally impaired pre-operatively, yet increases after surgery. This can be visualized noninvasively by assessing blood oxygenation level-dependent (BOLD) MRI changes with safe, mildly hypercarbic gas.
Methods: Using a block MRI paradigm, carbogen (5% CO2; 95% O2 3 min) was interleaved with atmospheric air (<1% CO2; 3 min) administration during BOLD MRI in intracranial stenosis patients (n=70), a subset of which (n=9; age=35.7+/-10.8; 7F/2M) underwent indirect (n=8) or direct (n=1) revascularization for moyamoya. Five patients had both pre-operative and post-operative hemodynamic imaging, with post-operative scans performed after 7.3+/-4.1 months. CVR, calculated as a z-statistic in response to hypercarbia vs. atmospheric air, was compared (two-tailed t-test) for each patient between the two time points to correlate CVR changes with surgery.
Results: Fig. 1 shows BOLD MRI on a patient scanned before and 2 years after right-sided indirect bypass, with significant (t=79.29, p<0.01) right-sided hemodynamic improvement. Cohort analyses of patients with pre/post-operative scans revealed significant interhemispheric CVR differences prior to surgery (t=3.48, p<0.01), which resolved after bypass (t=0.88, p=0.20). Additionally, CVR increased significantly in the operative hemisphere (t=4.50, p<0.01).
Conclusions: CVR-weighted hemodynamic MRI can be implemented into routine clinical protocols, corresponds well with revascularization response, and has potential as a noninvasive complement to angiography for serial monitoring of moyamoya patients.
Author Disclosures: T.R. Ladner: None. C. Faraco: None. M.J. Donahue: None. D. Arteaga: None. L.C. Jordan: None. P. Clemmons: None. L. Thompson: None. J. Mocco: Ownership Interest; Modest; Blockade Medical. Consultant/Advisory Board; Modest; Lazarus Effect, Pulsar, Reverse Medical, Edge Therapeutics. R.J. Singer: None. M.K. Strother: None.
- © 2014 by American Heart Association, Inc.