Defining the Zone of Acute Peripheral Nerve Injury Using Fluorescence Lifetime Imaging in a Crush Injury Sheep Model

Area of Science:

• Biomedical Optics
• Surgical Technology
• Neuroscience

Background:

• Intraoperative identification of acute peripheral nerve injuries is challenging due to limitations in current technologies.
• Existing methods rely on subjective surgical experience, time-consuming procedures, and complex electrodiagnostic equipment.

Purpose of the Study:

• To evaluate a real-time, label-free optical technique, fluorescence lifetime imaging (FLIm), for intraoperative imaging of peripheral nerve injuries.
• To determine if FLIm can detect differences in fluorescence signatures between acute crush injuries and uninjured nerve segments in a preclinical model.

Main Methods:

• Label-free FLIm utilized ultraviolet laser pulses to excite endogenous fluorophores and measure their decay over time.
• A hand-held FLIm instrument captured time-resolved fluorescence signatures from crushed and uninjured sheep peripheral nerves across three spectral channels.
• Linear discriminant analysis was employed to differentiate between injured and uninjured nerve segments based on FLIm parameters.

Main Results:

• A total of 23,692 measurements were collected from eight crushed peripheral nerves in two sheep.
• Significant differences in average fluorescence lifetime were observed at 470 nm and 540 nm between crushed and uninjured nerve segments.
• The analysis achieved 92% sensitivity, 85% specificity, and 88% accuracy in differentiating injured from uninjured nerve areas.

Conclusions:

• FLIm successfully detected distinct average lifetime values for crushed versus uninjured sheep peripheral nerves.
• The technique demonstrated high sensitivity, specificity, and accuracy in identifying nerve injury zones.
• Further research may establish FLIm as a valuable tool for surgeons to precisely locate nerve injuries for reconstruction.