A prospective study presented by researchers from Heritage Wound Care in Montclair, NJ, investigated the use of near-infrared spectroscopy (NIRS) as a diagnostic tool for the early detection of deep tissue injuries (DTIs) and pressure injuries (PIs), with a particular focus on improving diagnostic equity across skin tones. Conducted across 15 long-term care facilities, the study enrolled 17 patients with a total of 20 confirmed DTIs/PIs. Participants represented the full spectrum of Fitzpatrick skin types I through V, and the wounds evaluated included injuries to the heel, sacrum, hip, medial foot, and thigh.

The research team used the FDA 501(k)-cleared handheld MIMOSA Pro device to capture 3 types of images for each participant: standard visual light images, thermal images, and oximetry images that measure tissue oxygenation. A region of interest (ROI), typically the area of discoloration or injury, was identified on each participant, and oxygenation and temperature values were compared with those of surrounding healthy tissue to determine the degree of compromise.¹

The study findings emphasize the potential of NIRS to fill a critical gap in wound care assessment, particularly for patients with darker skin tones. Traditional visual skin assessment methods rely on color changes that may be difficult or impossible to detect in Fitzpatrick types IV and V, putting these patients at increased risk for delayed diagnosis and worse outcomes. As the authors point out, “DTIs are often marked by reduced tissue oxygenation,” a physiological change that NIRS can detect regardless of skin pigmentation.¹

The results were compelling; the NIRS readings showed tissue oxygenation deficits ranging from –27% to –79%, with an average deficit of –56.8%.¹ Importantly, no statistically significant correlation was observed between Fitzpatrick skin type and the degree of oxygenation loss, suggesting that NIRS is equally effective across skin tones.¹ This stands in contrast to thermal imaging, which showed inconsistent patterns. In over half of the cases, no significant temperature difference was detected between injured and healthy tissue at the time of assessment.¹ Although thermography has long been studied as a noninvasive tool for early pressure injury detection, the results of this study indicate that it may not reliably capture early-stage DTIs, particularly those that have not yet resulted in discernible surface temperature changes.

Despite thermography’s limitations, the researchers do not position NIRS as a replacement but rather as a complementary tool. Thermography continues to provide value through its established clinical use and interpretation frameworks, while NIRS adds a deeper, more physiologically grounded dimension by directly measuring tissue oxygenation. “Compared to thermography, NIRS showed greater consistency in identifying early-stage DTIs,” the authors explained.¹ They noted that thermal “cold spots” associated with ischemia were often absent in early injury stages or developed only days later.¹

This study offers an important step forward in advancing diagnostic accuracy and equity in pressure injury care. By demonstrating that NIRS performs consistently regardless of skin tone and may be capable of detecting tissue compromise earlier than thermal or visual methods alone, the findings support its integration into wound assessment protocols. In particular, clinicians in long-term care settings may benefit from a multimodal assessment strategy that combines visual inspection, thermography, and NIRS to capture both surface and sub-surface indicators of tissue damage.¹

As pressure injuries continue to pose clinical and financial challenges to health care systems, affecting an estimated 0.4% of hospitalized patients and costing billions of dollars annually, technologies that improve early detection and equitable care offer meaningful potential benefits to patients and health care providers alike.¹ NIRS may represent a significant advancement in that direction, offering a noninvasive, real-time measure of tissue health that could help clinicians intervene sooner, more accurately, and more equitably.

Reference

1. Caprara H, Marcaida MR, Tulsyan N. Enhancing Deep Tissue Injury Detection: The Role of Near-Infrared Spectroscopy in Early Diagnosis Across Skin Tones. Presented at the Symposium on Advanced Wound Care Fall 2025, Las Vegas, NV.