Background: Patients with lower extremity arterial disease (LEAD) frequently require revascularization procedures. Currently used diagnostic methods are insufficient in predicting successful outcomes and focus on macrovascular rather than microvascular state. Several promising modalities to increase diagnostic accuracy are emerging, including maximal systolic acceleration (ACC _max ), measured by duplex ultrasound (DUS). For the assessment of tissue perfusion, near-infrared fluorescence (NIR) imaging using indocyanine green (ICG) demonstrates promising results. This study aims to identify the usefulness of combining these two methods for macrovascular and microvascular perfusion assessment to predict successful clinical outcomes. Methods: A retrospective study was performed collecting preinterventional and postinterventional DUS and ICG NIR fluorescence imaging measurements from LEAD patients undergoing revascularization. The correlation between the preinterventional and postinterventional perfusion parameters, described as the delta (Δ) ACC _max and ΔICG NIR fluorescence parameters, were analyzed. Improvements in perfusion parameters were compared to clinical outcomes, defined as improvement in pain-free walking distance, freedom from rest pain, or tendency toward wound and ulcer healing. Results: A total of 38 patients (42 limbs) were included. ACC _max and ICG NIR fluorescence perfusion parameters improved significantly after revascularization (p<0.001). Patients with a poor clinical outcome had a significantly lower improvement of both parameters after revascularization (p<0.001–0.016). Lack of correlation was found between the delta of ACC _max and ICG NIR fluorescence imaging. Multiple non-congruent improvements of macrovascular parameters (ACC _max ) and perfusion (ICG NIR fluorescence) were seen within patients. However, for all patients with a successful clinical outcome, at least one parameter improved. Conclusion: Combining ACC _max and ICG NIR fluorescence imaging revealed improvement in at least one parameter within all patients with a successful clinical outcome. This study highlights the potential of assessing both the macrovascular state and tissue perfusion following lower extremity revascularization, as both appear to reflect different aspects of vascularization. Clinical Impact: Numerous techniques have been developed to assess tissue perfusion to predict clinical outcomes following revascularization in patients with peripheral artery disease. However, none are widely implemented in clinical practice. This study emphasized the importance of employing multiple modalities from different perspectives for more accurate prediction. By focusing on both the macrovascular state and tissue perfusion, clinicians can better guide themselves in their treatment strategies.

Near-infrared fluorescence imaging with indocyanine green (ICG) is increasingly being used in the field of image-guided surgery. Although ICG is considered non-nephrotoxic in current literature, caution is advised for the use of ICG in patients with advanced chronic kidney disease (CKD), including kidney transplant recipients. Therefore, a scoping review was performed to assess the safety of ICG in patients with advanced CKD or a renal allograft. This scoping review was guided by the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-analyses Extension for Scoping Reviews). Web of Science, PubMed, and Embase were searched for articles and abstracts in which ICG was administered in patients with CKD or a renal allograft. The extracted data included the incidence of adverse events, kidney function after injection of ICG, preservation of transplant function, and type of other possible complications. The initial search resulted in 635 records of which 19 studies were found eligible for the review. ICG was used for multiple purposes but never specifically as an objective to investigate possible nephrotoxicity. No adverse events were reported in the transplant group (n=250) or the CKD group (n=74). Despite ICG-injection, preservation of transplant function after transplantation surgery was 94% in 198 patients, and no increase in possible ICG-related other complications was reported. This scoping review found no evidence that ICG increases the risk of adverse events in patients with CKD, including kidney transplant recipients. Therefore, the administration of ICG should not be withheld from these patients.

Significance . Near-infrared fluorescence (NIRF) imaging is increasingly used for perfusion assessment in clinical care and research settings. While subjective interpretation demonstrates clinical benefits, quantitative analysis is crucial for broader adoption and classification of perfusion patterns. However, strict standardization often conflicts with fast-paced clinical workflow, obstructing broad implementation. Aim and approach . This study hypothesized that normalization of fluorescence measurements could effectively correct for measurement variability, reducing the need for strict standardization in quantitative NIRF perfusion imaging. To evaluate this, a model capable of consistently simulating fluorescence perfusion patterns was employed. Experiments were conducted in an operating room using four NIRF camera systems under varying measurement conditions. Results . Normalization to maximum signal intensity provided consistent perfusion parameter values across differences in camera type, angle, rotation and settings (Δ≤1%). In cases of severe malperfusion where peak-intensity was not reached within the measurement period, normalization did not adequately correct for measurement variability (Δ increased). Conclusion . While standardization remains valuable beyond parameter accuracy, appropriate normalization substantially reduces dependence on strict measurement protocols. These findings support broader clinical adoption of quantitative NIRF imaging, extending its utility beyond specialized tertiary centers and facilitating widespread integration into routine surgical care.

The objective of this study was to evaluate the predictive value of near-infrared (NIR) fluorescence imaging with indocyanine on wound healing complications within 6 weeks after lower extremity amputation. In this dual-center cohort study, patients undergoing minor (below ankle) or major (above ankle) amputations due to peripheral arterial disease (PAD) or diabetes mellitus, with perfusion assessment performed using indocyanine green (ICG) NIR fluorescence imaging, were included. Fluorescence videos were recorded using standardized protocols following intravenous administration of 0.1 mg/kg ICG. The fluorescence pattern and clinical perfusion were assessed intraoperatively as normal, questionable, or poor. A total of 63 patients undergoing 85 amputations were included, with a near-equal distribution of minor (51%) and major (49%) procedures. Within the entire cohort, the sensitivity of a poor fluorescence pattern on wound healing complications was 46% and specificity was 90%, with a positive predictive value (PPV) of 85% and a negative predictive value (NPV) of 55%. In the major amputation group, a significant correlation was observed between the fluorescence pattern and the occurrence of necrosis (P = 0.008) as well as minor and major complications (P = 0.049; P = 0.013). Poor fluorescence patterns were significantly correlated with the occurrence of major complications following minor amputations (P = 0.027). In 57% (n = 12) of patients with a poor fluorescence pattern, the vascular surgeon assessed the clinical perfusion as good. Poor perfusion observed with ICG NIR fluorescence imaging can predict wound healing complications following lower extremity amputation. A difference was observed between the predictive values of minor and major amputations, with the PPV being considerably higher for minor amputations than major amputations. Clinical assessment of perfusion was inferior to ICG NIR fluorescence in detecting patients at risk.

Background: Fracture non-union cause chronic pain, dysfunction, and high healthcare costs. Treatment consists of revitalizing the nonhealed fracture site through debridement, bone resection, grafting, or stabilization if indicated. Adequate bone perfusion is essential for healing, but current intraoperative assessments are subjective. This study explores the feasibility of using quantitative near-infrared fluorescence (NIRF) imaging with indocyanine green (ICG) to assess bone perfusion in non-union surgery. This technique allows real-time visualization of tissue perfusion through tracing intravascular injected ICG. Methods: This prospective, multicenter feasibility study was conducted in 2 Dutch academic hospitals. Intraoperative ICG NIRF imaging was performed in non-union patients after debridement and before osteosynthesis. Time-intensity curves were derived from intraoperative data, and 3 time-related perfusion parameters were extracted to quantify the perfusion in various osseous structures. Demographic data included patient's age, sex, race, and body mass index. Results: ICG NIRF measurement was successfully performed in 20 patients (median age 50.5 years, 65% female, and 90% White) at 7 fracture locations. Three distinct perfusion patterns were observed. (1) rapid ingress and egress, (2) rapid ingress with a plateau phase, and (3) prolonged ingress with no egress within the measurement. The median Tmax was 214 s (inter-quartile range [IQR]): 69-246 s. The normalized maximum ingress slope was 4.4%/s (IQR: 2.4-6.5), and the median Egress-60 was 84.7% (IQR: 77.4-94.8). Conclusion: ICG NIRF imaging is a feasible and reproducible method for intraoperative bone perfusion assessment in fracture non-union, potentially offering an objective measure of bone vitality. Perfusion parameters and time-intensity curves were successfully quantified across various bone structures, revealing patterns similar to those linked with clinical outcomes in other studies. Future research should evaluate how these perfusion patterns relate to bone healing. Level of Evidence: Level II . See Instructions for Authors for a complete description of levels of evidence.