Background
Mean transit time (MTT) measurements to assess cerebral hemodynamics are easily obtained
by computed tomography and magnetic resonance imaging. We reviewed hemodynamic and
clinical outcome data from the St. Louis Carotid Occlusion Study to determine if increased
MTT was associated with an increased risk of stroke in patients with symptomatic complete
carotid artery occlusion.
Methods
Positron emission tomography (PET) studies of cerebral blood volume-to-cerebral blood
flow ratios were used to calculate MTTs. Mean ipsilateral (side of the occluded internal
carotid artery)-to-contralateral ratios of MTTs in the middle cerebral artery territories
were determined. MTT was tested as a predictor of stroke risk using Cox regression
analysis. Receiver operating characteristic curves for stroke risk prediction were
generated by varying the mean ispilateral-to-contralateral MTT ratio to identify an
optimal cutpoint.
Results
Increased MTT ratio was associated with an increased risk of ipsilateral stroke (P < .001). The maximum combination of sensitivity (.778) and specificity (.763) was
obtained at a cutpoint ratio of 1.387 or higher. Subjects with a MTT ratio of 1.387
or higher had a 29.3% 2-year risk of ipsilateral stroke compared to 4.6% for those
without (P < .001).
Conclusions
PET relative MTT ratio identified patients with symptomatic complete internal artery
occlusion who were at high risk for subsequent ipsilateral stroke. Confirmation using
measurements of relative MTT from other imaging modalities in a patient cohort receiving
contemporary medical management is needed.
Key Words
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Article info
Publication history
Published online: March 22, 2016
Accepted:
December 30,
2015
Received in revised form:
October 26,
2015
Received:
September 10,
2015
Footnotes
Sources of funding: This work was supported by National Institutes of Health grants NS28947, AG05681, AG03991, and RR000036; and the Charles A. Dana Foundation, New York.
Presentation at a meeting: This work was presented at the 2015 International Stroke Conference, February 11-13, 2015, Nashville, TN.
Identification
DOI: https://doi.org/10.1016/j.jstrokecerebrovasdis.2015.12.041
Copyright
© 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.
