In vivo, noncontact, real-time, PV[O]H imaging of the immediate local physiological response to spinal cord injury in a rat model

Abstract

We report a small exploratory study of a methodology for real-time imaging of chemical and physical changes in spinal cords in the immediate aftermath of a localized contusive injury. One hundred separate experiments involving scanning NIR images, one-dimensional, two-dimensional (2-D), and point measurements, obtained in vivo, within a 3 × 7 mm field, on spinal cords surgically exposed between T9 and T10 revealed differences between injured and healthy cords. The collected raw data, i.e., elastic and inelastic emission from the laser probed tissues, combined via the PV[O]H algorithm, allow construction of five images over the first 5 h post injury. Within the larger study, a total of 13 rats were studied using 2-D images, i.e., injured and control. A single 830-nm laser (100-μm diameter round spot) was spatially line-scanned across the cord to reveal photobleaching effects and surface profiles possibly locating a near surface longitudinal artery/vein. In separate experiments, the laser was scanned in two dimensions across the exposed cord surface relative to the injury in a specific pattern to avoid uneven photobleaching of the imaged tissue. The 2-D scanning produced elastic and inelastic emission that allowed construction of PV[O]H images that had good fidelity with the visually observed surfaces and separate line scans and suggested differences between the volume fractions of fluid and turbidity of injured and healthy cord tissue.

Noninvasive Blood and Tissue Analysis: Raman Spectroscopy, One Perspective for Monitoring of Glucose and Beyond

“…Table 1 includes the vital signs/variables for which there is preliminary published data [38][39][40][41][42][43] that could result from a new PVOH configuration along with technical comments of feasibility and differences from currently used technologies. Elastic scattering and fluorescence/Raman activity of a tissue, turbid medium, object, or material can be used for imaging fingertips 10 or spinal cords 42 and other applications with a PVOH. In validating the basic PV[O]H in various venues from quartz spheres to bacteria we have shown that bacteria, and possibly viruses and perhaps even microclots can be sensed before they become a problem.…”

“…Recently PVOH with Raman was able to image and measure the pH of cerebrospinal fluid in vivo and perimortem in rat and pig models. 42,43 In summary, the journey that began with a search for an approach to noninvasive blood glucose monitoring technologies has now come full circle to providing the raw data to stimulate an era of noninvasive analytics that may benefit not only those with diabetes but many others as well.…”

“…Recently PVOH with Raman was able to image and measure the pH of cerebrospinal fluid in vivo and perimortem in rat and pig models. 42,43…”

“…Vital Signs/Variables for Which There Is Preliminary Published Data[38][39][40][41][42][43] That Could Result From a New PVOH Configuration Along With Technical Comments of Feasibility and Differences From Currently Used Technologies.…”

PVOH and spontaneous Raman-based images of spinal cord in the immediate aftermath of localized contusive injury obtained noninvasively and in vivo in a rat model using remitted light from a single spatially scanned laser

“…The PVOH and Raman CSF results have been previously published 7,8,9 and patents have been obtained 10,11 in addition to the in vivo PVOH and FRD patents. Since the algorithms have been described in detail in various publications, in this paper we present a very brief introduction to PVOH/FRD before describing the addition of Raman based pH mapping and then implications for diagnosing and possibly treating spinal cord injury.…”