Modified Beer-Lambert algorithm to measure pulsatile blood flow, critical closing pressure, and intracranial hypertension

Wesley B Baker; Rodrigo M Forti; Pascal Heye; Kristina Heye; Jennifer M Lynch; Arjun G Yodh; Daniel J Licht; Brian R White; Misun Hwang; Tiffany S Ko; Todd J Kilbaugh

doi:10.1364/BOE.529150

Modified Beer-Lambert algorithm to measure pulsatile blood flow, critical closing pressure, and intracranial hypertension

Biomed Opt Express. 2024 Aug 27;15(9):5511-5532. doi: 10.1364/BOE.529150. eCollection 2024 Sep 1.

Authors

Affiliations

¹ Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
² Division of General, Thoracic and Fetal Surgery, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
³ Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
⁴ Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
⁵ Department of Prenatal Pediatrics, Children's National, Washington DC, USA.
⁶ Division of Pediatric Cardiology, Department of Pediatrics, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
⁷ Department of Radiology, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.

Abstract

We introduce a frequency-domain modified Beer-Lambert algorithm for diffuse correlation spectroscopy to non-invasively measure flow pulsatility and thus critical closing pressure (CrCP). Using the same optical measurements, CrCP was obtained with the new algorithm and with traditional nonlinear diffusion fitting. Results were compared to invasive determination of intracranial pressure (ICP) in piglets (n = 18). The new algorithm better predicted ICP elevations; the area under curve (AUC) from logistic regression analysis was 0.85 for ICP ≥ 20 mmHg. The corresponding AUC for traditional analysis was 0.60. Improved diagnostic performance likely results from better filtering of extra-cerebral tissue contamination and measurement noise.