Comparison of Optical Imaging Techniques to Quantitatively Assess the Perfusion of the Gastric Conduit during Oesophagectomy

Imaging Photoplethysmography for Noninvasive Anastomotic Perfusion Assessment in Intestinal Surgery

INTRODUCTION

Anastomotic leakage after gastrointestinal surgery has a high impact on patient's quality of life and its origin is associated with inadequate perfusion. Imaging photoplethysmography (iPPG) is a noninvasive imaging technique that measures blood-volume changes in the microvascular tissue bed and detects changes in tissue perfusion.

MATERIALS AND METHODS

Intraoperative iPPG imaging was performed in 29 patients undergoing an open segment resection of the small intestine or colon. During each surgery, imaging was performed on fully perfused (true positives) and ischemic intestines (true negatives) and the anastomosis (unknowns). Imaging consisted of a 30-s video from which perfusion maps were extracted, providing detailed information about blood flow within the intestine microvasculature. To detect the predictive capabilities of iPPG, true positive and true negative perfusion conditions were used to develop two different perfusion classification methods.

RESULTS

iPPG-derived perfusion parameters were highly correlated with perfusion-perfused or ischemic-in intestinal tissues. A perfusion confidence map distinguished perfused and ischemic intestinal tissues with 96% sensitivity and 86% specificity. Anastomosis images were scored as adequately perfused in 86% of cases and 14% inconclusive. The cubic-Support Vector Machine achieved 90.9% accuracy and an area under the curve of 96%. No anastomosis-related postoperative complications were encountered in this study.

CONCLUSIONS

This study shows that noninvasive intraoperative iPPG is suitable for the objective assessment of small intestine and colon anastomotic perfusion. In addition, two perfusion classification methods were developed, providing the first step in an intestinal perfusion prediction model.

Intraoperative visualization and quantitative assessment of tissue perfusion by imaging photoplethysmography: comparison with ICG fluorescence angiography

Intraoperative monitoring of tissue perfusion is of great importance for optimizing surgery and reducing postoperative complications. To date, there is no standard procedure for assessing blood circulation in routine clinical practice. Over the past decade, indocyanine green (ICG) fluorescence angiography is most commonly used for intraoperative perfusion evaluation. Imaging photoplethysmography (iPPG) potentially enables contactless assessment of the blood supply to organs. However, no strong evidence of this potential has been provided so far. Here we report results of a comparative assessment of tissue perfusion obtained using custom-made iPPG and commercial ICG-fluorescence systems during eight different gastrointestinal surgeries. Both systems allow mapping the blood-supply distribution over organs. It was demonstrated for the first time that the quantitative assessment of blood perfusion by iPPG is in good agreement with that obtained by ICG-fluorescence imaging in all surgical cases under study. iPPG can become an objective quantitative monitoring system for tissue perfusion in the operating room due to its simplicity, low cost and no need for any agent injections.

Advances in Hyperspectral and Multispectral Optical Spectroscopy and Imaging of Tissue

Optical imaging and characterization of tissue has become a huge applied field due to the advantages of the optical analysis methods, which include non-invasiveness, portability, high sensitivity, and high spectral specificity [...]

Imaging PPG for In Vivo Human Tissue Perfusion Assessment during Surgery

Surgical excision is the golden standard for treatment of intestinal tumors. In this surgical procedure, inadequate perfusion of the anastomosis can lead to postoperative complications, such as anastomotic leakages. Imaging photoplethysmography (iPPG) can potentially provide objective and real-time feedback of the perfusion status of tissues. This feasibility study aims to evaluate an iPPG acquisition system during intestinal surgeries to detect the perfusion levels of the microvasculature tissue bed in different perfusion conditions. This feasibility study assesses three patients that underwent resection of a portion of the small intestine. Data was acquired from fully perfused, non-perfused and anastomosis parts of the intestine during different phases of the surgical procedure. Strategies for limiting motion and noise during acquisition were implemented. iPPG perfusion maps were successfully extracted from the intestine microvasculature, demonstrating that iPPG can be successfully used for detecting perturbations and perfusion changes in intestinal tissues during surgery. This study provides proof of concept for iPPG to detect changes in organ perfusion levels.

Near-Infrared Fluorescence with Indocyanine Green to Assess Bone Perfusion: A Systematic Review

Background: Adequate perfusion of a bone flap is essential for successful reconstruction of osseous defects. Unfortunately, complications related to inadequate bone perfusion are common. Near-infrared fluorescence (NIRF) imaging enables intraoperative visualization of perfusion. NIRF has been investigated in reconstructive surgery to aid the surgeon in clinical perioperative assessment of soft tissue perfusion. However, little is known on the beneficial use of NIRF to assess bone perfusion. Therefore, the aim of this review was to search for studies evaluating NIRF to assess bone perfusion. Methods: A systematic review, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline, was performed. Studies up to October 2021 were included. We extracted data regarding the study population, size and design, reported objective fluorescence parameters and the methodology used for fluorescence imaging and processing. Results: Ten articles were included. Studies reported unevenly on the protocol used for NIRF imaging. Five studies reported objective parameters. Absolute and relative perfusion parameters and parameters derived from maximum fluorescence were reported. The clinical significance of these parameters has not been evaluated in humans. Conclusion: The evidence on bone perfusion as measured with NIRF is limited. More clinical studies are required.