Spatial-Temporal Oxygenation Mapping Using a Near-Infrared Optical Scanner: Towards Peripheral Vascular Imaging

Effect of chronic kidney disease induced calcification on peripheral vascular perfusion using near-infrared spectroscopic imaging

Low-cost techniques that can detect the presence of vascular calcification (VC) in chronic kidney disease (CKD) patients could improve clinical outcomes. In this study, we established a near-infrared spectroscopy-based imaging technique to determine changes in peripheral hemodynamics due to CKD-induced VC. Mice were fed a high-adenine diet with either normal or high levels of phosphate to induce CKD with and without VC, respectively. The mice tail was imaged to evaluate hemodynamic changes in response to occlusion. The rate of change in oxyhemoglobin in response to occlusion showed a statistically significant difference in the presence of VC in the mice.

Diabetic Foot Ulcer Imaging: An Overview and Future Directions

Diabetic foot ulcers (DFUs) affect one in every three people with diabetes. Imaging plays a vital role in objectively complementing the gold-standard visual yet subjective clinical assessments of DFUs during the wound treatment process. Herein, an overview of the various imaging techniques used to image DFUs is summarized. Conventional imaging modalities (e.g., computed tomography, magnetic resonance imaging, positron emission tomography, single-photon emitted computed tomography, and ultrasound) are used to diagnose infections, impact on the bones, foot deformities, and blood flow in patients with DFUs. Transcutaneous oximetry is a gold standard to assess perfusion in DFU cases with vascular issues. For a wound to heal, an adequate oxygen supply is needed to facilitate reparative processes. Several optical imaging modalities can assess tissue oxygenation changes in and around the wounds apart from perfusion measurements. These include hyperspectral imaging, multispectral imaging, diffuse reflectance spectroscopy, near-infrared (NIR) spectroscopy, laser Doppler flowmetry or imaging, and spatial frequency domain imaging. While perfusion measurements are dynamically monitored at point locations, tissue oxygenation measurements are static two-dimensional spatial maps. Recently, we developed a spatio-temporal NIR-based tissue oxygenation imaging approach to map for the extent of asynchrony in the oxygenation flow patterns in and around DFUs. Researchers also measure other parameters such as thermal maps, bacterial infections (from fluorescence maps), pH, collagen, and trans-epidermal water loss to assess DFUs. A future direction for DFU imaging would ideally be a low-cost, portable, multi-modal imaging platform that can provide a visual and physiological assessment of wounds for comprehensive wound care intervention and management.