Novel algorithmic frameworks for functional neuroimaging using hybrid high density speckle contrast optical tomography and high density diffuse optical tomography

Functional neuroimaging is important for understanding brain health, assessing pathologies and guiding therapeutic interventions.

Fundamental to neuroimaging is the neurovascular unit (NVU) which relates delivery and consumption of oxygen to neuronal activity. Dysfunction of NVU is associated with pathologies like stroke as well as dyspraxia.

Estimating the cerebral metabolic rate of oxygen (CMRO2) that describes NVU activity, requires estimates of oxygen saturation in cerebral blood as well as cerebral blood flow (CBF).

Functional magnetic resonance imaging (fMRI), the current gold standard for functional neuroimaging, is expensive, lacks portability and provides only surrogate estimates of CBF.

Recent advancements in diffuse optics and functional near-infrared imaging paved the way for non-invasive neuroimaging using diffuse optical techniques.

Development of high-density diffuse optical tomography (HDDOT) for imaging oxygen saturation and high-density speckle contrast optical tomography (HDSCOT) for measuring CBF have enabled imaging at spatial resolutions comparable to fMRI.

However, combining independently obtained CBF and oxygenation values to compute CMRO2 leads to artifacts and systematic errors.

A hybrid imaging modality providing more accurate CMRO2 quantification via co-dependent estimates of oxygen saturation and CBF is needed to tap into potential of optical neuroimaging to paradigms like continuous cerebral monitoring in clinical and naturalistic settings.

In this project, we propose development of algorithmic frameworks for such a modality i.e., hybrid HDSCOT/DOT for concurrent estimation of blood flow and oxygenation through (i) development of an inversion algorithm for hybrid imaging, (ii) development of frameworks for selection of optimal acquisition configuration and (iii) numerical and experimental validation of the developed frameworks.

This research will closely follow ongoing hardware and system development in the Medical Optics group at ICFO.