Head Phantom for the Acquisition of Pulsatile Optical Signals for Traumatic Brain Injury Monitoring

Abstract

(1) Background: Tissue phantoms can provide a rigorous, reproducible and convenient approach to evaluating an optical sensor’s performance. The development, characterisation and evaluation of a vascular head/brain phantom is described in this study. (2) Methods: The methodology includes the development of mould-cast and 3D-printed anatomical models of the brain and the skull and a custom-made in vitro blood circulatory system used to emulate haemodynamic changes in the brain. The optical properties of the developed phantom were compared to literature values. Artificial cerebrospinal fluid was also incorporated to induce changes in intracranial pressure. (3) Results: A novel head model was successfully developed to mimic the brain and skull anatomies and their optical properties within the near-infrared range (660–900 nm). The circulatory system developed mimicked normal arterial blood pressure values, with a mean systole of 118 ± 8.5 mmHg and diastole of 70 ± 8.5 mmHg. Similarly, the cerebrospinal fluid circulation allowed controlled intracranial pressure changes from 5 to 30 mmHg. Multiwavelength pulsatile optical signals (photoplethysmograms (PPGs)) from the phantom’s cerebral arteries were successfully acquired. Conclusions: This unique head phantom technology forms the basis of a novel research tool for investigating the relationship between cerebral pulsatile optical signals and changes in intracranial pressure and brain haemodynamics.

Keywords

• phantom
• in vitro
• optics
• photoplethysmography
• near-infrared spectroscopy