Laminar microvascular transit time distribution in the mouse somatosensory cortex revealed by Dynamic Contrast Optical Coherence Tomography

Conrad W. Merkle, Vivek Srinivasan

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The transit time distribution of blood through the cerebral microvasculature both constrains oxygen delivery and governs the kinetics of neuroimaging signals such as blood-oxygen-level-dependent functional Magnetic Resonance Imaging (BOLD fMRI). However, in spite of its importance, capillary transit time distribution has been challenging to quantify comprehensively and efficiently at the microscopic level. Here, we introduce a method, called Dynamic Contrast Optical Coherence Tomography (DyC-OCT), based on dynamic cross-sectional OCT imaging of an intravascular tracer as it passes through the field-of-view. Quantitative transit time metrics are derived from temporal analysis of the dynamic scattering signal, closely related to tracer concentration. Since DyC-OCT does not require calibration of the optical focus, quantitative accuracy is achieved even deep in highly scattering brain tissue where the focal spot degrades. After direct validation of DyC-OCT against dilution curves measured using a fluorescent plasma label in surface pial vessels, we used DyC-OCT to investigate the transit time distribution in microvasculature across the entire depth of the mouse somatosensory cortex. Laminar trends were identified, with earlier transit times and less heterogeneity in the middle cortical layers. The early transit times in the middle cortical layers may explain, at least in part, the early BOLD fMRI onset times observed in these layers. The layer-dependencies in heterogeneity may help explain how a single vascular supply manages to deliver oxygen to individual cortical layers with diverse metabolic needs.

Original languageEnglish (US)
Pages (from-to)350-362
Number of pages13
JournalNeuroImage
Volume125
DOIs
StatePublished - Jan 15 2016

Fingerprint

Somatosensory Cortex
Optical Coherence Tomography
Oxygen
Microvessels
Magnetic Resonance Imaging
Neuroimaging
Calibration
Blood Vessels
Brain

Keywords

  • Blood flow
  • Dynamic contrast
  • Functional magnetic resonance imaging
  • Hemodynamics
  • Optical coherence tomography
  • Transit time

ASJC Scopus subject areas

  • Neurology
  • Cognitive Neuroscience

Cite this

Laminar microvascular transit time distribution in the mouse somatosensory cortex revealed by Dynamic Contrast Optical Coherence Tomography. / Merkle, Conrad W.; Srinivasan, Vivek.

In: NeuroImage, Vol. 125, 15.01.2016, p. 350-362.

Research output: Contribution to journalArticle

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