A novel non-invasive, clinically scalable, and cost-effective device designed to measure cerebral blood flow and volume provides physiologic insights for stroke risk assessment, according to study findings published in Biomedical Optics Express.

Researchers trialed a portable speckle contrast optical spectroscopy laser device in conjunction with a breath-holding exercise to determine stroke risk using cerebral blood flow and blood volume measurements. Residents of Caltech, Pasadena, and Los Angeles, California aged 18 to 65 who were comfortable holding their breath were identified for study inclusion. All participants were evaluated using the Cleveland Clinic Stroke Risk Calculator and divided into a low-risk (score, 1) or higher-risk (score, ≥4) group. The higher-risk group was further stratified into smaller subgroups based on the Cleveland Clinic Stroke Risk Calculator. Between 2 and 5 datasets of breath-holding were recorded for each participant.

A total of 160 breath-holding entries were collected from 50 patients (women, 66%), of whom 25 (mean age, 31) comprised the low-risk group and 25 (mean age, 60) comprised the higher-risk group. Cleveland Stroke Risk Calculator scores of 4, 5, and 6 to 7 were obtained by 6, 10, and 9 participants, respectively.

Given its cost-effectiveness, scalability, portability, and simplicity, this laser-centric tool has significant potential for early diagnosis and treatment of stroke in the general population.

Cerebral blood flow index and cerebral blood volume index values increased during breath retention due to the brain’s increased need for blood to transport oxygen and carbon dioxide. Pulsations with similar overall shape and frequency were observed in both cerebral blood flow index and cerebral blood volume index traces. The heart rate was estimated at a frequency of 1.2 Hz (72 beats per minute).

The heart rate increase during breath-holding aligned well with the increases in cerebral blood flow index and cerebral blood volume index.

Similarities between measurements yielded in this study were similar to the arterial pressure map tracings observed in literature.

The higher- vs low-risk group experienced higher and faster increases in blood flow during breath-holding; however, the low- vs higher-risk group exhibited higher and faster increases in blood volume during breath-holding. Both groups had similar duration of breath-holding.

The median and quartiles of the flow to volume ratio are higher for the higher- vs low-risk group (P =.000001). No statistical between-group difference was observed in the duration of breath-holding, demonstrating a similar performance in the breath-holding exercise between groups. Resting heart rate (P =.467) and maximal heart rate (P =.005) were also compared between groups.

Changes in vascular peaks height ratio were found to increase during breath-holding. The peak analysis included 41 participants (higher-risk group, n=24; low-risk group, n=17). The peak ratio for the higher- vs low-risk group was higher.

Overall, results indicated that this device may be a valuable tool in the assessment of cerebrovascular health conditions.

This study was limited by a small sample size.

“Given its cost-effectiveness, scalability, portability, and simplicity, this laser-centric tool has significant potential for early diagnosis and treatment of stroke in the general population,” the study authors concluded.

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