Reliability assessment of hyperspectral imaging with the HyperView™ system for lower extremity superficial tissue oxygenation in young healthy volunteers

Abstract

Purpose: Hyperspectral imaging (HSI) is a noninvasive spectroscopy technique for determining superficial tissue oxygenation. The HyperView™ system is a hand-held camera that enables perfusion image acquisition. The evaluation of superficial tissue oxygenation is warranted in the evaluation of patients with peripheral arterial disease. The aim was to determine the reliability of repeated HSI measurements.

Methods: In this prospective cohort study, HSI was performed on 50 healthy volunteers with a mean age of 26.4 ± 2.5 years, at the lower extremity. Two independent observers performed HSI during two subsequent measurement sessions. Short term test-retest reliability and intra- and inter-observer reliability were determined, and generalizability and decision studies were performed. Transcutaneous oxygen pressure (TcPO₂) measurements were also performed.

Results: The short term test-retest reliability was good for the HSI values determined at the lower extremity, ranging from 0.72 to 0.90. Intra- and inter-observer reliability determined at different days were poor to moderate for both HSI (0.24 to 0.71 and 0.30 to 0.58, respectively) and TcPO₂ (0.54 and 0.56, and 0.51 and 0.31, respectively). Reliability can be increased to >0.75 by averaging two measurements on different days.

Conclusion: This study showed good short term test-retest reliability for HSI measurements, however low intra- and inter-observer reliability was observed for tissue oxygenation measurements with both HSI and TcPO₂ performed at separate days in young healthy volunteers. Reliability of HSI can be improved when determined as a mean of two measurements taken on different days.

Keywords: Hyperspectral imaging; Lower extremity; Reproducibility of Results; Tissue oxygenation; Tissue perfusion; Transcutaneous oxygen pressure.

Fig. 1

A flowchart of study procedures demonstrating the measurements used for the test–retest reliability and intra- and inter-observer reliability, respectively. During the measurement session, two consecutive images at each location were taken according to the standardized measurement protocol. The two consecutive images from one measurement session were used to determine test–retest reliability. The first image from measurement session 1 and 2 were used to determine intra-observer reliability. The first image from measurement session 1and 3 were used to determine inter-observer reliability. The same measurement sessions were used to determine the intra- and inter-observer reliability of TcPo₂ measurements. * 2 images per measurement location; plantar side right foot, right calf, plantar side left foot, left calf. ** TcPo₂ of the left and right calf