Technique Devised to Monitor Blood Flow in Brain

(NIH.gov)

30 April 2018. A bioengineering lab developed a technique using common photography chips to measure blood flow in the brain, which could help detect traumatic brain injury, stroke, and related disorders. A team from University of California in Davis describes its process in the 26 April issue of the journal Optica.

Researchers from the university’s Neurophotonics Lab led by engineering professor Vivek Srinivasan are seeking a more reliable and economical technology for measuring blood flow in the brain, an indicator of oxygen delivery to nerve cells and brain health. Today’s advanced techniques use a process known as diffuse correlation spectroscopy that sends near infrared light rays into the skull to detect blood flow, but the moving blood and tissue inside the skull scatter and weaken the light waves. As a result, say the authors, the technique requires as many as 20 specialized and higher-power detectors that count individual photons as well as a system to integrate the readings from those sensors.

Srinivasan and colleagues offer a process that uses a standard complementary metal-oxide-semiconductor or CMOS photo chip like those found in everyday digital cameras. The technique, designed by postdoctoral researcher and first author Wenjun Zhou, sends a laser beam into the brain to sample blood flow, with a second reference beam sent to join with the sample beam before it reaches the target detector.

This reference beam acts as a booster for the sample beam that strengthens the signal so a standard CMOS photo chip can record the measurements, instead of 20 separate sensors. “The strong reference light,” says Zhou in a university statement, “enhances the weaker signal from the sample.”

The UC-Davis team tested its multimode interferometric multispeckle detection system, or iDWS, first in lab simulations, then with three healthy human subjects. The researchers found the iDWS could record blood flow that correlated with readings on a commercial pulse oximeter, a device worn on the finger measuring blood oxygen levels.

The researchers are working with neurosurgeons in the university’s medical school to validate and advance the technology into the clinic. UC-Davis also filed for a provisional patent on the technology.

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