# Application of multispectral optoacoustic tomography for lower limb musculoskeletal sports injuries in adults

## TL;DR

This paper explores using multispectral optoacoustic tomography to non-invasively assess hemoglobin in musculoskeletal sports injuries of the lower limb.

## Contribution

The study demonstrates the feasibility of using MSOT for label-free imaging of hemoglobin in musculoskeletal injuries.

## Key findings

- MSOT showed high reproducibility and systematic changes in hemoglobin levels in response to exercise.
- Hemoglobin content was equal in injured and contralateral limbs.
- Collagen and lipid measures were inconsistent and did not show expected patterns.

## Abstract

Compositional changes in relation to musculoskeletal injuries are difficult to measure non-invasively. This study aims to use non-invasive label-free imaging with Multispectral Optoacoustic Tomography (MSOT) to evaluate compositional changes with injury. Five different patient groups were examined, covering diagnoses of Achilles or patellar tendinopathy, Achilles tendon rupture and gastrocnemius muscle strain injury. Injured and contralateral limbs were imaged using a commercial MSOT device. Hemoglobin, collagen, and lipid contents were estimated. Some patients were examined before and after exercise. Hemoglobin measures had high reproducibility and displayed systematic changes in response to exercise. The content and exercise response of hemoglobin was equal on both limbs. In contrast, collagen and lipid measures were inconsistent and did not display the expected distribution. In conclusion, MSOT is applicable to imaging of hemoglobin in musculoskeletal injuries, providing complimentary information to conventional ultrasound, but applicability to other components like collagen and lipids could not be shown.