A comparison of hyperspectral imaging with routine vascular noninvasive techniques to assess the healing prognosis in patients with diabetic foot ulcers.

OBJECTIVE

To compare the potential healing prognosis of the different routine noninvasive techniques implemented in the International Working Group Diabetic Foot Guidelines with the novel use of hyperspectral imaging (HSI) in patients with diabetic foot ulcers (DFUs).

METHODS

Twenty-one patients with active DFUs participated in this 1-year prospective study in a specialized diabetic foot unit between December 2018 and January 2020. HSI was performed at baseline to quantify tissue oxygenation and should be presented on an anatomical map by analyzing the following parameters: (1) oxygen saturation of the hemoglobin, (2) tissue hemoglobin index, (3) the near-infrared perfusion index, and (4) tissue water index. In addition, transcutaneous oxygen pressure (TcpO2), systolic toe and ankle pressures, ankle-brachial index, and toe-brachial index values were calculated for the ulcerated limb. The primary outcome measure was wound healing, defined as complete epithelization without any drainage confirmed for at least 10 days after closure was first documented at 24 weeks.

RESULTS

During the follow-up period 14 patients (66.66 %) healed and 7 patients did not heal (33.3%) by 24 weeks. The TcpO2 optimal cut-off point as determined by a balance of sensitivity and specificity of 28.5 mm Hg that yielded a sensitivity of 91% and a specificity of 100%, and area under the curve of 0.989 (P = .005; 95% confidence interval [CI], 0.945-1.000). Followed by the oxygen saturation of the hemoglobin optimal cut-off point as determined by a balance of sensitivity and specificity of 48.5 mm Hg that yielded a sensitivity of 93% and a specificity of 0.71%, and area under the curve of 0.932 (P = .013; 95% CI, 0.787-1.000). The logistic regression analyses showed that TcpO2 was the only variable associated with wound healing at 24 weeks (P < .001; 95% CI, 0.046-0.642).

CONCLUSIONS

The HSI was shown to be effective in the prognosis of DFU healing compared with other noninvasive test; only TcpO2 values resulted in better diagnosis potential in wound healing.