Near-Infrared Spectroscopy (NIRS) in Wound and Flap Management

Title XVIII of the Social Security Act, §1862(a)(1)(A) allows coverage and payment for only those services that are considered to be reasonable and necessary for the diagnosis or treatment of illness or injury or to improve the functioning of a malformed body member

Title XVIII of the Social Security Act, §1862(a)(1)(D) addresses services that are determined to be investigational or experimental

CMS Internet-Only Manual, Pub. 100-02, Medicare Benefit Policy Manual, Chapter 16, §10 General Exclusions from Coverage

This is a NON-coverage policy for non-contact near-infrared spectroscopy (NIRS) use in acute or chronic wound assessment and management and for use in flap or micro-flap assessment intra- or post-operatively.

Introduction

Limb threatening diabetic wounds are a significant and common health problem within the Medicare beneficiary population.

The focus of this policy is on NIRS. NIRS relies on 2 principles: (a) that tissue is relatively transparent to near-infrared light, and (b) that compounds in tissue exist in which absorption of light is dependent on the oxygenation status of the tissue. This would allow NIRS to be able to differentiate between oxygenated and deoxygenated blood.

NIRS is a spectroscopic technique that uses light in the near-infrared region. It is most commonly implemented in clinical settings around roughly 650–950 nm wavelengths. By evaluating how tissue absorbs and scatters light, NIRS aims to estimate physiological information like changes related to oxygenated and deoxygenated hemoglobin. In many medical devices, NIRS is performed with a small number of source–detector channels placed on or near the tissue, and it typically reports a regional or bulk measurement (for example, a trend or index of tissue oxygenation) rather than forming a single detailed image. Because light in the near-infrared spectrum penetrates deeper than visible light in many tissues, NIRS is considered as a potential tool for monitoring perfusion beneath the surface, without requiring skin contact.

Similar to NIRS, reflectance imaging includes hyperspectral reflectance imaging (HSI) or multispectral reflectance imaging (MSI). This process describes approaches that illuminate tissue and measure the wavelength-dependent light, reflected back from the surface to form images, with each pixel containing spectral information. MSI acquires images at a small number of discrete wavelengths (often spanning visible and/or near-infrared, such as ~400–700 nm and ~700–1000 nm), producing a limited spectral “fingerprint” per pixel that can be used to enhance contrast and derives maps related to blood content, oxygenation surrogates, or tissue state. HSI extends this idea by sampling many more, typically contiguous and narrower wavelength bands (often tens to hundreds of bands, commonly across ~400–1000 nm and sometimes extending further into the near-infrared), yielding a data cube in which a near-continuous reflectance spectrum is available at every pixel and enabling finer discrimination of subtle spectral features and more flexible modeling.

These modalities are related because they all exploit the same underlying physics of wavelength-dependent absorption and scattering in tissue, and they often use overlapping near-infrared wavelengths to access hemoglobin-driven contrast with improved penetration compared to purely visible imaging. They differ mainly in what is being measured and reported: NIRS is primarily a spectroscopy/monitoring modality that typically provides a non-imaging regional estimate, whereas MSI and HSI are imaging modalities that provide spatial maps by measuring reflectance across a field of view, with MSI sampling a few wavelengths and HSI sampling many. In that sense, MSI and HSI can be viewed as forms of imaging spectroscopy, and when they operate in the near-infrared they can be considered “NIRS-like” in spectral content, but they remain distinct from classic NIRS because they prioritize spatial mapping and typically use different acquisition geometries and data structures.

The potential usage of NIRS for the detection or monitoring of arterial disease, vascular perfusion, and wound healing potential has been studied.¹

A literature search was conducted using the following key terms: NIRS, non-invasive wound monitoring and infrared light in wounds. Additional sources of information included publications and sources from PubMed, Google Scholar, UpToDate and Emergency Care Research Institute (ECRI). The literature search was filtered to locate articles in the English language within the last 25 years. Full-text articles, clinical trials, and systematic reviews/meta-analyses (SR/MA) were included in the review.

Evidence was analyzed to address the certainty of evidence that the change in outcome is due to the product being investigated and improves patient outcomes. Case reports, case series, review papers and animal studies were not reviewed for product coverage, but may be considered an adjunctive measure for other aspects pertinent to this subject. Editorials and unpublished reports were not included in the analysis.

Background

A prospective observational study included 48 patients (91 limbs) with vascular calcification or diabetes. The study evaluated the clinical correlation between the NIRS-derived plantar-palmar index (PPI) and pulse volume recordings (PVR) investigating NIRS as a replacement for ankle-brachial index (ABI). PPI, obtained using the SnapshotNIR device, was introduced in this study and is calculated as the ratio of StO₂ in the plantar foot as compared to palmar hand. The authors hypothesized the PPI may reflect lower extremity perfusion relative to a stable upper extremity reference considering this analogous to the ABI. In the cohort, each limb underwent ABI, PVR and NIRS imaging, and compared to corresponding oxygen saturation (StO₂). The authors reported that the estimated margin for NIRS derived PPI increased with disease severity and distinguished normal from peripheral arterial disease (PAD) (p<0.005). While this shows early promise, the small sample size and lack of validated comparators to understand the role of this tool was not established. The authors concluded that future research should aim to validate the identified range of PPI values in larger, multicenter trials and diverse clinical populations to confirm validity. Additionally, an understanding of how these results correlate with diagnostic ability, clinical recommendations, and outcomes are needed.²

Schmidt et al.³ conducted a small retrospective report on 23 patients with chronic venous, arterial, and mixed ulcers. The clinical state of the ulcers was documented by a clinical wound score (quantity, color, and consistency of granulation tissue). The spectroscopic readings were performed with a novel diode-array spectrometer system in the visible and near-infrared range of the spectrum (400-1600 nm) with a resolution of 5 nm. By using cross-validation the percentage of correctly predicted wound scores was about 69%. The sample size was too small to draw reliable conclusions. The authors attempted to establish standards for spectroscopic readings, but the small sample was not adequate for reliable conclusions to be drawn.

Suludere et al.⁴ evaluated normative NIRS data in 110 healthy volunteers across Fitzpatrick skin types (FSTs) in a prospective observational cross-sectional study. Individuals with FST 6 had significantly lower dorsal oxygen saturation and oxyhemoglobin compared to FST 1–5 (p<0.001), with some dorsal areas yielding no data. No differences were observed on the plantar surface. The authors concluded that skin pigmentation affects NIRS measurements and should be accounted for in clinical interpretation and future studies. This finding would limit the effectiveness of NIRS to evaluate darker wounds or heavily pigmented skin.

Niezgoda et al.² performed a prospective observational study to evaluate the clinical potential for NIRS as an alternative to ABI for evaluation of vascular disease. The authors used NIRS imaging to measure corresponding oxygen saturation (StO₂) values and created a PPI which was calculated as the ratio of plantar StO₂ to palmar StO₂. The study included 48 patients (91 limbs) with vascular calcification or diabetes. Each limb underwent ABI and PVR testing, and NIRS imaging to measure corresponding oxygen saturation (StO₂) values.

In the cohort, each limb underwent ABI, PVR and NIRS imaging and compared to corresponding oxygen saturation (StO2). The authors reported that the estimated margin for NIRS derived PPI increased with disease severity, and distinguished normal from PAD (p<0.005). While this finding shows early promise; however, due to the small sample size and lack of validated comparators to understand the role of NIRS, the utility of this tool cannot be established. The authors conclude that future research should aim to validate the identified range of PPI values in larger, multicenter trials and diverse clinical populations to confirm validity. Additionally, an understanding of how these results correlate with diagnostic ability, clinical recommendations, and outcomes are needed.²

NIRS in wound healing

As it relates to wound evaluation, studies have been done using NIRS as a noninvasive technique to estimate wound perfusion and assess tissue viability. Studies have evaluated the effectiveness of NIRS to provide an objective measure of local oxygenation and microvascular function in and around the wound bed. Studies have sought to determine if NIRS can impact or alter wound management and support decisions about interventions around wound healing or advanced therapies.

Longobardi et al.⁵ conducted a randomized controlled clinical trial evaluating whether NIRS imaging of hemoglobin oxygen saturation (StO₂), combined with wound size measurement, could predict healing of hard-to-heal venous leg ulcers (VLUs), and whether adjunctive hyperbaric oxygen therapy (HBOT) improves outcomes. Eighty-one patients were randomized into 3 groups: (A) 30 HBOT sessions delivered twice daily over 3 weeks, (B) 30 HBOT sessions delivered once daily over 6 weeks, and (C) conventional therapy alone. Seventy-three patients completed the study, with 511 NIRS images analyzed.

All groups demonstrated wound area reduction over time; however, at 6 weeks, group B (once-daily HBOT) showed significantly greater wound area reduction compared to group A (twice daily HBOT) and conventional therapy alone (P<0.01). Complete healing occurred most frequently in group B (20%) as well. Wounds that ultimately healed (defined as >40% area reduction) demonstrated a progressive decline in StO₂ values at both the wound center and edge, whereas non-healing wounds showed no significant StO₂ change. Transcutaneous oxygen (TCO₂) did not correlate with healing outcomes. The authors conclude that NIRS-derived StO₂ trends, combined with wound size measurements, can serve as predictive markers of VLU healing, and that adjunctive HBOT improves healing when delivered in a less intensive, longer-duration schedule.

While NIRS-derived StO₂ trends showed a correlation with wound healing, there is no indication whether NIRS would change wound management, as the primary intervention of this study was HBOT.

Weingarten et al.⁶ conducted a pilot study evaluating diffuse NIRS as a predictor of healing in diabetic foot ulcers. Sixteen patients with chronic diabetic ulcers were followed weekly with NIRS measurements of subsurface oxyhemoglobin concentration. Of the 16 wounds, 7 healed, 6 resulted in amputation, and 3 remained open after 20 visits. Healing wounds demonstrated a consistent decline in oxyhemoglobin concentration weeks before clinical closure, approaching values of healthy control tissue. Nonhealing wounds maintained elevated hemoglobin levels despite apparent clinical improvement in some cases. A negative slope in hemoglobin concentration over time was significantly associated with healing. The authors conclude that NIRS may predict wound healing earlier than traditional visual assessment and could serve as an objective tool to guide treatment decisions. Limitations of this study include a very small sample size and its observational nature.

Bowen et al.⁷ conducted a prospective study to evaluate the correlation between NIRS and transcutaneous oxygen measurement (TCO₂) in assessing tissue oxygenation in patients with chronic lower extremity wounds. Twenty patients with FSTs I–III and various wound etiologies (venous, arterial, diabetic, and radiation-related) underwent simultaneous periwound TCO₂ measurements and NIRS imaging. Using linear regression analysis, the authors found a strong correlation between the 2 modalities, with a correlation coefficient of 0.92 and r² of 0.84. There was demonstrated close agreement between calculated oxygen saturation from TCO₂ and NIRS-measured saturation. The authors concluded that NIRS correlates well with TCO₂ and may serve as a more cost-effective method for evaluating tissue oxygenation in chronic wounds. The authors also noted that skin pigmentation, as evidenced by FST, may affect absolute values, and different skin tones would have different measurements. Considering that limitation, serial trend monitoring may be more clinically useful than single measurements. Other limitations include lack of control group, and small sample size.

Serena et al.⁸ performed a pilot comparison study of NIRS and transcutaneous oxygen measurement (TCOM) in 10 patients with hard-to-heal wounds, generating 24 paired measurements. After converting StO₂ values to partial pressure of oxygen (pO₂), the authors found a strong correlation between modalities (r = 0.74). Bland–Altman analysis demonstrated a positive mean difference of 18.75 mmHg, indicating that TCOM tended to overestimate oxygenation compared to NIRS. The extremely small sample size was too small for definitive conclusions, although the study supported NIRS as a practical alternative to TCOM for assessing tissue oxygenation in wound care settings.

Musatto et al.⁹ performed a cross-sectional study comparing TCOM with NIRS for assessing tissue oxygenation in 76 patients with 85 hard-to-heal lower extremity wounds. TCOM, the traditional method, measures transcutaneous partial pressure of oxygen but is time-consuming, contact-based, and limited to intact skin. NIRS, by contrast, is a handheld, non-contact imaging modality that measures StO₂. The authors stratified results by wound severity (Wagner classification), skin pigmentation (Fitzpatrick type), and use of melanin correction. Among 402 TCOM and 347 NIRS measurements, only 1 statistically significant correlation was found—specifically in less severe wounds (Wagner 0–2) without melanin correction. No significant correlations were seen in more severe wounds or when adjusting for pigmentation. The authors conclude NIRS did not consistently correlate with TCOM in this cohort. Differences may reflect the distinct physiological parameters each method measures (surface pO₂ diffusion versus composite hemoglobin oxygenation), and concluded that further research is needed to clarify NIRS’s clinical role.

Andersen et al.¹⁰ conducted a single-center feasibility study to determine whether non-contact near-infrared (NIRS) imaging (SnapshotNIR) could provide an objective measure of complete wound healing beyond visual inspection. Fifteen adult patients with 16 lower extremity wounds of various etiologies (including diabetic foot ulcers, postsurgical wounds, pressure injuries, trauma, and VLUs) were followed weekly with standard wound care and serial NIR imaging. The investigators compared the date of 100% re-epithelialization on visual physical examination to the date when tissue oxygen measurement returned to levels similar to the surrounding intact skin. They found an average difference of 13.5 ± 10 days (median 12 days; range 0–35 days), meaning that physiologic normalization detected by NIR imaging lagged visible closure by approximately 2 weeks, and in some cases up to 5 weeks. The authors concluded that NIR imaging may provide an objective assessment of deeper dermal healing and may help guide decisions about when to discontinue protective dressings and return patients to activity, potentially reducing recurrence risk. However, the small sample size and variability amongst the wounds and treatments restricts further conclusions. In addition, this study showed that NIR imaging might not be helpful to predict wound healing, as the measurements returned to normal well-after physical evidence of healing.

Geskin et al.¹¹ conducted a retrospective cohort study evaluating the effects of lower limb endovascular revascularization on microcirculation in patients with chronic limb-threatening ischemia (CLTI), and whether macrovascular and microvascular assessments correlate. Thirty patients (38 interventions) underwent pre- and post-intervention evaluation using Arterial Doppler acceleration time (AcT) and, in a subset, ABI for macrovascular assessment, along with multispectral NIRS imaging (SnapshotNIR) to assess StO₂, oxyhemoglobin (HbO), deoxyhemoglobin (Hb), and total hemoglobin (TotHb) in dorsal and plantar foot regions. NIRS metrics demonstrated significant increases in microvascular oxygenation and perfusion, particularly in the dorsal circulation where StO₂ and HbO increased significantly (p=0.005 and p=0.007, respectively). However, macrovascular measures (ABI and AcT) did not significantly correlate with NIRS-derived microcirculatory parameters (r² < 0.15, p > 0.06), suggesting that macro- and microvascular assessments provide distinct and non-interchangeable information. The authors concluded that both macrovascular and microvascular evaluations are necessary for comprehensive assessment of revascularization efficacy. Their lack of correlation, however, suggests that independent use may cause diagnostic information to be missed.

Landsman¹² conducted a retrospective study of 25 patients with diabetic foot ulcers and VLUs to determine whether NIRS could identify tissue oxygenation patterns predictive of wound healing. The author identified 4 distinct oxygenation patterns within the wound bed and peri-wound tissues and proposed a conceptual framework termed HINT (Hyperperfusion, Imbibition, Neovascularization, Trailing) to describe the progression toward healing. Wounds with average StO₂ below 40% across the wound bed rarely healed. Persistent uniform hyperoxygenation without gradient changes often corresponded to stalled wounds. The study suggests that qualitative pattern recognition, in addition to quantitative StO₂ values, may help predict wound trajectory, and that NIRS could be used to examine large areas and deeper tissue using reflected light to calculate perfusion by detecting color change related to oxygenated vs. deoxygenated hemoglobin. Limitations included insufficient sample size, lack of controls, and retrospective design resulting in very low certainty evidence.

A large retrospective report analyzed the electronic records from a large mobile wound care practice (Wound Care Plus, LLC) for 6147 patients, and 19,192 wounds. A portable NIRS device was used in 2165 patients, and 4060 wounds. The reasons for NIRS use included microcirculation assessment and vascular referral (8.89%), debridement necessity and effectiveness (29.16%), tissue oxygenation trending (66.65%), and care plan evaluation (92.98%). The authors reported that NIRS impacted medical decision making and plan of care including palliative (5.22%), maintenance (20.76%), healable (17.39%), hospice (0.64%), additional studies (11.6%), vascular consultation or surgical referral (5.44%), and/or vascular studies (10%). They also reported a higher healing rate compared to healing rates in a separate cohort represented in a different publication. There was no propensity match or randomization to ensure these populations were equivalent, so the validity of this comparison is questionable and therefore of lower certainty evidence.¹³

Kelso et al.¹³ looked at the selective use of NIRS in improving healing rates. Data analysis was performed by Kent Imaging and Would Care Plus, with Kent being the maker of the NIRS devices used in the study. Strength of the study includes large sample sizes. Significant limitations include lack of standardized protocol of when to use NIRS creating a high risk of selection bias. There is high risk of confounding as well including high heterogeneity among wounds, patient factors, and treatments. Additionally, the data analysis was not conducted independent of the device manufacturer, increasing potential risk of bias.

NIRS in monitoring of free flaps or tissue transfer

A 2018 systematic review without meta-analysis included a total of 15 clinical studies and 8 animal studies. The overall flap success rate was 99.5%, and the flap salvage rate was 91.1%, when measuring tissue oxygenation saturation (StO2) at intervals of every 2 hours or sooner. Single StO2 monitoring was able to detect vascular compromise with 99.1% sensitivity and 99.9% specificity, and earlier than other monitoring methods, but additional hemoglobin concentration monitoring was useful for avoiding false negatives and differentiating arterial and venous occlusion. In the end they concluded NIRS can be used for flap monitoring, and displayed high accuracy in various situations. NIRS appeared to be reliable as a non-invasive monitoring of perfusion, however it remained unclear if there was any significant change to plan of care or benefit compared to other methods of monitoring. Significant limitations included lack of any definite consensus regarding its use or utility for NIRS.¹⁴

Newton et al.¹⁵ conducted a systematic review evaluating the effectiveness of NIRS for postoperative monitoring of free flap reconstructions and its impact on flap salvage outcomes. Ten studies (8 prospective and 2 retrospective cohorts) met inclusion criteria, encompassing 1639 flaps in 1248 patients. Of these, 1181 flaps were monitored with NIRS in addition to conventional clinical monitoring (CM), and 458 were monitored with CM alone. The overall rate of vascular compromise was similar between groups; however, flaps monitored with NIRS had a significantly higher salvage rate (89%) compared to those monitored by CM alone (50%) (p<0.05). Additionally, partial flap loss following salvage was markedly lower in the NIRS group (16%) vs CM alone (80%) (p<0.05). Detection of vascular compromise by NIRS preceded clinical signs on average by 82 ± 49 minutes. NIRS was accurate in detecting compromised flaps with a low false-positive and false-negative rate. The authors concluded, however, that there was a lack of robust data although the potential for postoperative NIRS monitoring of free flap monitoring was present. Limitations include heterogeneity among studies and the absence of randomized controlled trials.

Chen et al.¹⁶ performed a systematic review assessing the clinical value of NIRS in postoperative free flap monitoring. Eight studies were included, comprising 710 free flaps monitored with NIRS and 433 controls monitored with conventional methods alone. While rates of vascular crisis and re-exploration were similar between groups, salvage rates were significantly higher in the NIRS group (P<0.001), and flap failure rates were significantly lower (P=0.003). In cases monitored with NIRS, vascular compromise was detected at least 30 minutes before clinical findings, and no false-positive or false-negative results were reported in these studies, yielding 100% sensitivity and specificity under the reviewed conditions. The authors conclude that NIRS is highly suitable for flap monitoring, but stress the need for larger randomized trials and standardized alarm thresholds. The data collected also did not result in changes in clinical management.

Berthelot et al.¹⁷ conducted a systematic review and meta-analysis evaluating the use of NIRS and implantable Doppler (ID) devices compared to conventional clinical assessment (CCA) for postoperative monitoring of free tissue transfer (FTT) in breast reconstruction. Nineteen studies published between 2008 and 2018 met inclusion criteria. The pooled data demonstrated that both NIRS and ID showed very high diagnostic performance, with mean sensitivities of 99.36% for NIRS and 100% for ID, and specificities of 99.36% and 97.63%, respectively. Meta-analysis showed that NIRS (OR 0.09, P<0.001) and ID (OR 0.39, P=0.04) were both associated with significantly reduced odds of flap failure compared to conventional CM alone. Weighted averages across studies indicated overall survival rates exceeding 97% for both technologies. The authors conclude that NIRS and ID are both superior to CCA for detecting vascular compromise after free flap breast reconstruction, largely due to their ability to provide continuous, objective perfusion data. They note, however, that each modality has technical limitations, including probe positioning for ID and hardware, algorithm, and patient-related factors (such as skin tone and ambient conditions) for NIRS. Overall, the review supports both technologies as effective adjuncts to improve flap salvage and potentially reduce staff workload and hospital costs. Limitations include lack of predictive value, and the inability to determine if the imaging modalities impacted or influenced management of wounds.

Bian et al.¹⁸ conducted a systematic review of 24 studies evaluating the use of NIRS for postoperative monitoring of free flap reconstruction. The review included 3529 free flaps in 2529 patients and compared outcomes between conventional CM alone and CM combined with NIRS. The authors found that NIRS frequently detected vascular compromise earlier than clinical assessment, with reported time advantages ranging from 0.5 to 32 hours. Flap salvage rates were significantly higher in the CM plus NIRS group (87.2%) compared to CM alone (50.0%), and overall flap survival rates were also minimally higher (98.1% vs 96.3%). Diagnostic accuracy was high, with most studies reporting sensitivity above 96% and specificity above 95%, and very low false-positive and false-negative rates. Cost analyses suggested that NIRS may reduce intensive care unit (ICU) monitoring time and overall hospital costs, potentially offsetting device expenses. The review also examined variables affecting NIRS accuracy, noting that systemic oxygen saturation (SpO₂) significantly influenced StO₂ readings, while most surgical factors did not consistently affect measurements. The review showed that NIRS could be a reliable, objective adjunct to CM to assess flap survival. However, there was no comparison to other modalities, and that accuracy could be subject to other variables as well (SpO2). The authors concluded that larger studies are needed to standardize threshold criteria and validate use across different flap types.

Hill et al.¹⁹ conducted a prospective, blinded cohort study to evaluate whether intraoperative NIRS could detect clinically meaningful differences in skin flap perfusion predictive of postoperative skin flap necrosis (SFN). Forty-two patients undergoing oncologic resection with flap reconstruction (regional, pedicled, free, or mastectomy flaps) were included, and surgeons were blinded to intraoperative StO₂ measurements obtained with the handheld SnapshotNIR device. Nine patients (20.9%) developed SFN involving 11 surgical sites. Mean intraoperative StO₂ values were 74.9% in control areas, 71.1% in areas at risk, and 58.3% in areas that ultimately developed necrosis. Compared to control regions, areas that became necrotic had significantly lower StO₂ values (−17.5%, P=0.01) and were also significantly lower than areas at risk that survived (−8.3%, P=0.04). These findings demonstrate that intraoperative NIRS may objectively differentiate between viable tissue and tissue that later becomes necrotic. The authors conclude that NIRS shows promise as a noninvasive, portable, and cost-effective adjunct to clinical examination for predicting SFN, though larger studies are needed to establish definitive perfusion thresholds and sensitivity/specificity parameters. The small sample size for each wound type precludes further conclusions that NIRS would be accurate versus other measures of wound perfusion or monitoring.

Hill et al.²⁰ conducted a prospective cohort study of 102 patients undergoing oncologic resection with flap reconstruction to evaluate whether intraoperative NIRS could predict postoperative SFN. Surgeons were blinded to intraoperative StO₂ measurements obtained with the handheld SnapshotNIR device, and clinical decisions were made using standard subjective assessment alone. Patients were followed for at least 30 days postoperatively, and 18 patients (17.6%) developed SFN. Mean intraoperative StO₂ values differed significantly between zones: control areas averaged 74.8%, areas at risk averaged 70.9%, and areas that ultimately necrosed averaged 54.3%. StO₂ values ≤60% were highly specific (96%) and strongly predictive of necrosis (positive predictive value 95%), whereas values ≥85% were highly sensitive (96%) for ruling out necrosis. A midpoint threshold of 72.5% provided 86% sensitivity and specificity. The authors conclude that intraoperative NIRS provides objective perfusion data that correlates with postoperative necrosis risk and may assist surgeons in identifying hypoperfused tissue requiring debridement or modification of reconstructive strategy. Limitations of this study include a small sample size. Larger studies are needed to establish definitive correlation of NIRS data with postoperative necrosis risk.

Moritz et al.²¹ prospectively evaluated SnapshotNIR point-of-care imaging in 70 breasts undergoing alloplastic or autologous reconstruction. No patients developed skin necrosis. In alloplastic reconstruction, tissue oxygen saturation (StO₂) increased after mastectomy and closure, while in autologous reconstruction, StO₂ declined at follow-up. The device detected expected physiologic oxygenation changes across time, suggesting it can characterize normal healing patterns, and potentially identify abnormal perfusion trends. Larger trials are needed to determine sensitivity and specificity for necrosis prediction.

Reflectance Imaging (MSI/HSI)

Lindelauf et al.²² conducted a systematic review comparing NIRS and HSI for detecting flap failure in reconstructive surgery. Sixteen NIRS studies (3662 flaps) and 5 HSI studies (90 flaps) were analyzed. NIRS demonstrated higher flap survival (99.2%) compared to HSI (92.5%), with statistically significant differences in flap survival, return to operating room, salvage rate, and partial flap loss. Both modalities were reliable and user-friendly, but no definitive superiority could be established due to study heterogeneity, observational design, and lack of control groups.

George et al.²³ conducted a prospective cohort study evaluating indocyanine green (ICG) angiography versus MSI during prepectoral direct-to-implant breast reconstruction. Fifty-three cases were assessed intraoperatively with both modalities, but surgical decisions were guided by MSI. ICG predicted necrosis in 13 patients; however, only 2 of those actually developed necrosis, meaning ICG might have led to unnecessary tissue resection in 11 cases (84.6% false prediction rate for necrosis in that subset). MSI predicted viability in 96.2% of cases and demonstrated high positive predictive value. Demographic factors did not explain ICG’s overprediction, suggesting intrinsic modality differences. The authors argue that ICG measures perfusion alone, whereas MSI evaluates tissue oxygenation, which may better reflect viability. This study is limited by small sample size, and high risk of bias. While the investigators compared the 2 modalities, the lack of controls were significant as the surgeon’s determination of how aggressively to debride and confounding was not controlled; therefore, superiority cannot be established. The authors acknowledge this limitation and suggest future research in which the surgeons decision to resect are randomized to either ICG angiography, or MSI to more adequately address this limitation.

Lee et al.²⁴ conducted a pilot observational study evaluating HSI to quantify microvascular perfusion in 73 subjects (36 non-diabetic and 37 diabetic). The study measured oxygenated (HT-Oxy) and deoxygenated hemoglobin (HT-Deoxy) across multiple regions of the foot to establish baseline perfusion values. Results showed wide variability in perfusion metrics across individuals, with some statistically significant regional differences between diabetic and non-diabetic groups depending on the device used. They found that both HSI devices could quantify microvascular oxygenation, but they produced differing absolute values and variability across measurement sites, highlighting that device-specific wavelength differences and algorithms can affect perfusion readings, and limit direct comparability between platforms. The study highlights that HSI can noninvasively quantify microcirculatory oxygenation, but also emphasizes variability due to factors such as skin pigmentation, device wavelength differences, and patient characteristics. The authors concluded that HSI shows promise for assessing perfusion and potentially identifying vascular compromise, but further standardized studies are needed before clinical thresholds can be established.

The evidence for NIRS is highly heterogenous with applications across multiple different conditions. Further investigation is needed with studies designed to access non-inferiority to current standard of care (SOC) modalities to understand the role NIRS may play in these various applications. Current literature is not consistent in the value of NIRS with several studies reflecting a positive trend, but with notable limitations and conflicts of interest (COI). The only study without COI did not reflect the positive trends, but utilized older version of the device, so may not reflect the currently available technology.²⁵

At this time there are 2 systematic reviews without meta-analysis that incorporated only low certainty evidence, and therefore are inconclusive. There are no randomized controlled trials, or comparative studies to access this technology and its role in any of the proposed applications. The remaining literature consisted of small prospective or retrospective designs, and were not eligible for upgrading per GRADE methodology, therefore represents low and very low certainty literature. Future investigation is needed to determine the clinical validity (how accurate is the device) and utility (does it accurate predict healing, guide therapy and improve patient outcomes) of this technology before widespread clinical use. Therefore, based upon the available evidence, the use of NIRS for wound management does not meet the criteria for reasonable and necessary, and is non-covered at this time.

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• Creation of Uniform LCDs With Other MAC Jurisdiction