Research

Noninvasive optical methods, built for use

The lab develops in vivo optical imaging and spectroscopy techniques and takes them through to instruments that work outside the optical bench. 3 funded projects carry the main effort, with 2 further lines of work running alongside them.

Main projects

NIH R01, BRAIN Initiative

Time gated diffuse correlation spectroscopy for brain function

Diffuse correlation spectroscopy measures blood flow by reading the way speckle intensity fluctuates as near infrared light passes through moving red blood cells. The difficulty in the brain is that most detected photons never reached the cortex, so the signal is dominated by scalp and skull.

This project addresses that by gating on photon arrival time. Late arriving photons have travelled further and carry more cortical weighting, so separating them from early arrivals recovers a depth resolved measurement. Working at 1064 nm with superconducting nanowire single photon detectors improves tissue penetration, photon throughput and the safety margin under exposure limits at the same time. The applications are neurointensive care and functional neuroimaging.

NIH R03

Characterizing traumatic brain injury

Electroencephalography and optical spectroscopy see different halves of the same event. EEG reports electrical field potentials, optical measurement reports cerebral blood flow and oxygenation. Recorded together and noninvasively, they give a fuller view of the neurovascular unit than either does alone.

The project uses that combination to characterize brain injury and to test whether low frequency oscillations in perfusion carry information that neither modality shows on its own. Work so far indicates that oscillation measures shift after injury more clearly than blood flow alone does, which makes them a candidate early biomarker of neurovascular disruption.

NIH R01

Ovarian cancer detection and therapy

Peritoneal micrometastases are hard to see and often resist systemic therapy. This project develops quantitative fluorescence imaging through a laparoscope to detect them, and pairs the imaging with chemophototherapy, where near infrared light triggers release of a chemotherapeutic from porphyrin phospholipid liposomes at the target site.

Because tissue absorption and scattering distort any raw fluorescence measurement, the imaging is built on spatial frequency domain imaging, which recovers optical properties first and then corrects the fluorescence to an absolute concentration. That correction is what turns a picture into a dose, and it is what makes intraoperative monitoring of treatment plausible during minimally invasive surgery.

Alongside

Fluorescence imaging and tomography

Time domain and continuous wave fluorescence molecular tomography, used to quantify tumor characteristics and to follow photochemical reactions such as photosensitizer photobleaching during treatment.

Photoacoustic imaging

Light in, sound out. Absorbed optical energy generates an acoustic wave, which gives access to blood vessels and oxygenation at high spatial resolution and without a contrast agent, at depths where purely optical imaging has lost its resolution.

Where the results are

Every claim on this page is set out in full in the peer reviewed literature. The publications page lists selected papers with links, and the complete record is on Google Scholar.