Wido Heeman

Indocyanine green near-infrared fluorescence (ICG-NIRF) imaging is widely used to assess tissue perfusion, yet its subjective interpretation limits correlation with postoperative parathyroid function. To address this, the Workflow model for ICG-angiography integrating Standardization and Quantification (WISQ) was developed. This exploratory prospective multicenter study evaluated the reproducibility of WISQ in adults undergoing total thyroidectomy at two Dutch university centres. Patients with contraindications to ICG or prior neck surgery were excluded. Intraoperative imaging used standardized camera settings with blood volume-adjusted ICG dosing, and perfusion curves were analyzed using predefined regions of interest. Eighty patients were included. Significant inter-centre variability was observed in maximum fluorescence intensity, inflow slope, and outflow slope (n = 30). At the lead centre, outflow was the most promising predictor of postoperative hypoparathyroidism (HPT) (median −0.33 [IQR −0.49–−0.15] a.f.u./s for HPT vs. −0.68 [−0.91–−0.41], n = 17, p = 0.08), although no parameter significantly predicted HPT. Repeated ICG injections consistently produced lower maximal intensities irrespective of injection rate, and reproducible curves were achieved only when ICG was freshly dissolved at 0.5 mg/mL instead of 2.5 mg/mL. These findings indicate that ICG concentration and injection technique influence perfusion kinetics and underscore the need to update WISQ with standardized injection dilution to improve its clinical utility.

Adequate perfusion is essential to prevent anastomotic leakage in intestinal and rectal surgeries. This study compares Laser Speckle Contrast Imaging (LSCI) and Indocyanine Green Fluorescence Angiography (ICG-FA) for assessing blood flow in intestinal anastomoses during robot-assisted surgeries in pigs. Intestinal perfusion was evaluated in three pigs using LSCI and ICG-FA, before and after clamping the main arterial supply, with measurements taken across ten regions of interest (ROIs). Pearson correlation coefficients were used to compare the two techniques. ROIs were normalized for analysis to facilitate direct comparison of the perfusion patterns. The results showed a strong correlation between the maximum fluorescence intensity from ICG-FA and LSCI values after clamping (r = 0.7293), with comparable perfusion patterns observed post-unclamping. LSCI provides continuous monitoring, while ICG-FA captures contrast-enhanced snapshots, explaining weaker correlations for static values. No significant difference was found in normalized measurements between the two methods. This study supports the use of both LSCI and ICG-FA in clinical practice, highlighting their complementary roles in assessing perfusion during surgeries. Further research is needed to explore their combined utility.

Introduction: Intraoperative perfusion imaging may help the surgeon in creating the intestinal anastomoses in optimally perfused tissue. Laser speckle contrast imaging (LSCI) is such a perfusion visualisation technique that is characterized by dye-free, real-time and continuous imaging. Our aim is to validate the use of a novel, dye-free visualization tool to detect perfusion deficits using laparoscopic LSCI. Methods: In this multi-centre study, a total of 64 patients were imaged using the laparoscopic laser speckle contrast imager. Post-operatively, surgeons were questioned if the additional visual feedback would have led to a change in clinical decision-making. Results: This study suggests that the laparoscopic laser speckle contrast imager PerfusiX-Imaging is able to image colonic perfusion. All images were clear and easy to interpret for the surgeon. The device is non-disruptive of the surgical procedure with an average added surgical time of 2.5 min and no change in surgical equipment. The potential added clinical value is accentuated by the 17% of operating surgeons indicating a change in anastomosis location. Further assessment and analysis of both white light and PerfusiX perfusion images by non-involved, non-operating surgeons showed an overall agreement of 80%. Conclusion: PerfusiX-Imaging is a suitable laparoscopic perfusion imaging system for colon surgery that can visualize perfusion in real-time with no change in surgical equipment. The additional visual feedback could help guide the surgeons in placing the anastomosis at the most optimal site.

Laser speckle contrast imaging (LSCI) is so sensitive to motion that it can measure the movement of red blood cells. However, this extreme sensitivity to motion is also its pitfall as the clinical translation of LSCI is slowed down due to the inability to deal with motion artefacts. In this paper we study the effectiveness of a real-time, multi-spectral motion artefact correction and compensation by subduing an in vitro flow phantom and ex vivo porcine kidney to computer-controlled motion artefacts. On the in vitro flow phantom, the optical flow showed a good correlation with the total movement. This model results in a better signal-to-noise ratios for multiple imaging distances and the overestimation of perfusion was reduced. In the ex vivo kidney model, the perfusion overestimation was also reduced and we were still able to distinguish between ischemia and non-ischemia in the stabilized data whereas this was not possible in the non-stabilized data. This leads to a notably better perfusion estimation that could open the door to a multitude of new clinical applications for LSCI.

Background: Ischemia at the site of an intestinal anastomosis is one of the most important risk factors for anastomotic leakage (AL). Consequently, adequate intestinal microperfusion is essential for optimal tissue oxygenation and anastomotic healing. As visual inspection of tissue viability does not guarantee an adequate objective evaluation of intestinal microperfusion, surgeons are in dire need of supportive tools to decrease anastomotic leakage after colorectal surgery. Methods: In this feasibility study, laparoscopic laser speckle contrast imaging (LSCI) was used to evaluate intestinal microperfusion in an experimental ischemic bowel loop model. Both large and small ischemic loops were created from the small intestine of a pig; each loop was divided into 5 regions of interest (ROI) with varying levels of ischemia. Speckle contrast and local capillary lactate (LCL) was measured in all ROIs. Results: Both real-time visualization of intestinal microperfusion and induced perfusion deficits was achieved in all bowel loops. As a result, the emergence of regions of intestinal ischemia could be predicted directly after iatrogenic perfusion limitation, whereas without LSCI signs of decreased intestinal viability could only be seen after 30 minutes. Additionally, a significant relation was found between LCL and LSCI. Conclusion: In conclusion, LSCI can achieve real-time intraoperative visualization of intestinal microperfusion deficits, allowing for accurate prediction of long-term postoperative ischemic complications. With this revealing capacity, LSCI could potentially facilitate surgical decision-making when constructing intestinal anastomoses in order to mitigate ischemia-related complications such as AL.

Background: Intestinal resection causes inevitable vascular damage, which cannot always be seen during an intraoperative clinical assessment of local intestinal perfusion. If left unaltered, impaired perfusion can lead to complications, such as anastomotic leakage (AL). Therefore, we demonstrate the use of a novel laparoscopic laser speckle contrast imaging (LSCI)-based approach in order to assess local intestinal perfusion during the construction of intestinal anastomoses. Methods: Three segments were isolated from the small intestine of a pig, while the perfusion of each was compromised by coagulating 7–8 mesenteric arteries. Both clinical assessments and LSCI were used to detect the induced perfusion deficits and to subsequently guide a transection in either a well perfused, marginally perfused, or poorly perfused tissue area within the segment. Bowel ends were then utilized for the creation of three differently perfused anastomoses: well perfused/well perfused (anastomosis segment 1), well perfused/poorly perfused (anastomosis segment 2), and poorly perfused/poorly perfused (anastomosis segment 3). After construction of the anastomoses, a final perfusion assessment using both clinical assessment and LSCI was executed in order to evaluate the vascular viability of the anastomosis. Results: Laparoscopic LSCI enabled continuous assessment of local intestinal perfusion and allowed for detection of perfusion deficits in real time. The imaging feedback precisely guided the surgical procedure, and, when evaluating the final anastomotic perfusion, LSCI was able to visualize the varying degrees of perfusion, whereas standard clinical assessment yielded only minor differences in visual appearance of the tissue. Conclusions: In this technical note, we demonstrate a novel LSCI-based approach for intraoperative perfusion assessment. With its ability to continuously visualize perfusion in real time, laparoscopic LSCI has significant potential for the optimization of anastomotic surgery in the near future.

Background: Postoperative hypoparathyroidism is the most common complication after total thyroidectomy. Over the past years, optical imaging techniques, such as parathyroid autofluorescence, indocyanine green (ICG) angiography, and laser speckle contrast imaging (LSCI) have been employed to save parathyroid glands during thyroid surgery. This study provides an overview of the utilized methods of the optical imaging techniques during total thyroidectomy for parathyroid gland identification and preservation. Methods: PUBMED, EMBASE and Web of Science were searched for studies written in the English language utilizing parathyroid autofluorescence, ICG-angiography, or LSCI during total thyroidectomy to support parathyroid gland identification or preservation. Case reports, reviews, meta-analyses, animal studies, and post-mortem studies were excluded after the title and abstract screening. The data of the studies were analyzed qualitatively, with a focus on the methodologies employed. Results: In total, 59 articles were included with a total of 6190 patients. Overall, 38 studies reported using parathyroid autofluorescence, 24 using ICG-angiography, and 2 using LSCI. The heterogeneity between the utilized methodology in the studies was large, and in particular, regarding study protocols, imaging techniques, and the standardization of the imaging protocol. Conclusion: The diverse application of optical imaging techniques and a lack of standardization and quantification leads to heterogeneous conclusions regarding their clinical value. Worldwide consensus on imaging protocols is needed to establish the clinical utility of these techniques for parathyroid gland identification and preservation.

Intraoperative-hampered renal cortical microperfusion (RCM) during, for example, anastomosis has been associated with ischemia/reperfusion-injury related postoperative complications. Others have shown the potential of near-surface perfusion imaging for the prediction of postoperative complications, including reduced creatinine clearance, delayed graft function, and even graft rejection.^{1 – 4} As such, it is conceivable that intraoperative monitoring of RCM using optical imaging methods may support surgical decision making, which may lead to improved perfusion during organ reperfusion and potentially contribute to a reduction in unfavorable postoperative outcomes.