Abstract 134: Relative MTT Predicts Subsequent Stroke in Symptomatic Carotid Occlusion
Relative mean transit time (MTT) is readily obtainable from dynamic susceptibility contrast MRI of the brain. While it has received much attention in acute ischemic stroke as a possible means to identify patients for reperfusion therapies, little has been done to determine if it has clinical significance outside the acute setting. To determine if relative MTT could be used to identify patients who are at high risk for subsequent stroke, we analyzed data from the St. Louis Carotid Occlusion Study. This prospective study was carried out from 1992-1997 to determine if PET measurement of oxygen extraction fraction could identify medically treated patients with recently symptomatic carotid artery occlusion at high risk for subsequent stroke. Sixty-eight of the participants in the study had quantitative PET measurements of cerebral blood flow (CBF) and cerebral blood volume (CBV). From these we calculated the MTT (CBV/CBF) in each middle cerebral artery territory and determined the MTT ratio of the ipsilateral to the contralateral hemisphere (I/C MTT ratio). Nine of the 68 participants had a subsequent ipsilateral ischemic stroke during mean follow-up of 2.6 years (range .5 - 5 years). The I/C MTT ratio was significantly associated with subsequent stroke as a continuous variable by Cox regression analysis (HR 65, 95%CI 7-613, p < .001). The maximum combination of sensitivity (.778) and specificity (.763) was obtained with a cutpoint of ≥ 1.387 which identified 7/9 subsequent strokes (PPV .333, NPV .957). Relative MTT shows great promise as a means to identify patients with large artery disease who are at high risk for subsequent stoke. These results need to be confirmed using MRI in a cohort receiving contemporary medical management.
Author Disclosures: W.J. Powers: None. T.O. Videen: None. C.P. Derdeyn: Ownership Interest; Modest; Pulse Therapeutics. Consultant/Advisory Board; Modest; Microvention, Penumbra, Silk Road, Pulse Therapeutics. D.A. Carpenter: None. R.L. Grubb: None.
- © 2015 by American Heart Association, Inc.