Chronic cerebral arterial occlusion and moyamoya disease are major causes of ischemic stroke, particularly in regions where access to advanced diagnostic tools is limited. Assessing cerebral blood flow and identifying patients who may benefit from revascularization surgery remains challenging when stress-based tests are unavailable or unsafe. New research suggests that a simple imaging parameter may offer a practical alternative for guiding surgical decision-making.

In a study conducted at Rajavithi Hospital (Bangkok, Thailand), researchers evaluated a simple bypass protocol based on mean transit time, a measure of how long blood takes to pass through brain tissue, using standard perfusion imaging. The approach was designed to identify candidates for single-barrel bypass surgery without the need for stress testing.

The retrospective review included 30 patients who underwent single-barrel bypass surgery between 2010 and 2024 and had complete preoperative imaging and postoperative follow-up. Mean transit time prolongation of more than six seconds was used as the marker of hemodynamic compromise. Patients’ functional status was assessed using the Modified Rankin Scale, a standard measure of disability after stroke.

Before surgery, 23.3% of patients showed bilateral mean transit time delay, and the average Modified Rankin Scale score was 2.50. After surgery, 80% of patients experienced clinical improvement, with intraoperative graft patency exceeding 90%. Only one complication occurred, a brainstem infarction unrelated to the bypass site, and the average postoperative Modified Rankin Scale score improved to 2.0.

The findings, published in the Chinese Neurosurgical Journal, support mean transit time as a reliable, non-stress indicator for selecting patients who may benefit from revascularization, particularly in hospitals without access to advanced cerebrovascular reserve testing. By avoiding pharmacological or carbon dioxide stress challenges, the approach reduces risk while remaining cost-effective. The researchers believe this protocol could improve stroke care in resource-limited settings, although further prospective studies are needed.

“Our results show that prolonged mean transit time is a practical indicator for selecting patients who can benefit from bypass surgery, especially in regions where stress tests are not available,” said Ittipon Gunnarut, MD, lead investigator of the study.

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