(CR-066) Peripheral Arterial Disease Detection Beyond ABIs: Utilizing Near-Infrared Spectroscopy for Non-Invasive Assessment

Friday, April 10, 2026

Introduction: Diagnosing Peripheral Arterial Disease (PAD) is foundational to chronic wound management & amputation optimization, yet the often used Ankle-Brachial Index (ABI) is frequently unreliable due to medial arterial calcification in high-risk populations leading to unreliable, falsely elevated or indeterminate results. Alternative non-invasive tests, such as Toe-Brachial Index (TBI) and Transcutaneous Oxygen Monitoring (TcPO2), provide valuable functional data but are often limited by procedural complexity, cost, or time requirements. Near-Infrared Spectroscopy (NIRS) offers a non-contact, rapid method to estimate tissue oxygen saturation StO2, providing spatially-resolved functional measure of perfusion data. This study evaluated the utility of the NIRs via the MIMOSA Imager as a complementary tool for detecting compromised circulation indicative of PAD, particularly in cases where ABI results are unreliable or difficult to obtain.

Methods:
A scoping review was conducted to identify clinical studies and reviews comparing the diagnostic utility of NIRS for PAD detection and stratification. The review focused on studies evaluating high-risk populations (e.g., diabetes, renal failure) where ABI is often non-diagnostic, and utilizing St02 to evaluate circulatory reserve.
Clinical Cohort: A small, prospective cohort of limbs with indeterminate or high ABIs ( >1.3) underwent assessment using NIRS with the MIMOSA Imager (Toronto, CAN) & ABI with the MESI ABPI (Ljubljana, Slovenia). The MIMOSA Imager is a non-contact device that captured spatial StO2 heatmaps using visible and NIR LED wavelengths.

Results: The review revealed NIRS-derived metrics (particularly StO2 recovery time) demonstrated strong correlation with both TBI and StO2 values in detecting severe PAD/CLI. Studies noted NIRS advantages included non-contact application, speed (minutes vs. up to 90 minutes for TcPO2, and portability. The NIRS heatmaps clearly delineated areas of compromised perfusion that corresponded to known ulceration sites, providing spatially-registered functional evidence of ischemia where ABI failed. However, evidence supporting NIRS as a sole replacement for established methods remains insufficient, often requiring a provocative maneuver for high sensitivity requiring further definition.

Discussion: NIRS-derived St02 provides a valuable, non-invasive functional assessment of microcirculation, offering similar diagnostic insight with significant practical advantages in terms of speed and contact requirements. Its ability to identify functional compromise in limbs with non-compressible arteries makes it an essential complementary tool for PAD screening in the field. Future directions should focus on establishing standardized protocols and specific StO2 cut-off values for integration into routine clinical practice, potentially leveraging its speed and portability for broader community screening initiatives in combination with other key PAD risk factors.