Multispectral Imaging Using Fluorescent Properties of Indocyanine Green and Methylene Blue in Colorectal Surgery—Initial Experience

Introduction: Image-guided surgery is becoming a new tool in colorectal surgery. Intraoperative visualisation of different structures using fluorophores helps during various steps of operations. In our report, we used two fluorophores—indocyanine green (ICG), and methylene blue (MB)—during different steps of colorectal surgery, using one camera system for two separate near-infrared wavelengths. Material and methods: Twelve patients who underwent complex open or laparoscopic colorectal surgeries were enrolled. Intravenous injections of MB and ICG at different time points were administered. Visualisation of intraoperative ureter position and fluorescent angiography for optimal anastomosis was performed. A retrospective analysis of patients treated in our departments during 2020 was performed, and data about ureter injury and anastomotic site complications were collected. Results: Intraoperative localisation of ureters with MB under fluorescent light was possible in 11 patients. The mean signal-to-background ratio was 1.58 ± 0.71. Fluorescent angiography before performing anastomosis using ICG was successful in all 12 patients, and none required a change in position of the planned colon resection for anastomosis. The median signal-to-background ratios was 1.25 (IQR: 1.22–1.89). Across both centres, iatrogenic injury of the ureter was found in 0.4% of cases, and complications associated with anastomosis was found in 5.5% of cases. Conclusions: Our study showed a substantial opportunity for using two different fluorophores in colorectal surgery, whereby the visualisation of one will not change the possible quantification analysis of the other. Using two separate dyes during one procedure may help in optimisation of the fluorescent properties of both dyes when using them for different applications. Visualisation of different structures by different fluorophores seems to be the future of image-guided surgery, and shows progress in optical technologies used in image-guided surgery.

Image-Guided Surgery and Its Future with the Artificial Intelligence

The article's abstract is not available.

ITVT-04. Management of intraoperative technological advances [intraoperative MRI, neuronavigation system using PET, and 5-aminolevulinic acid (5-ALA)–induced fluorescence image-guided surgery] for glioblastoma

OBJECTIVE The maximum resection of Glioblastoma (GBM) is the standard therapy and is expected to improve prognosis. Image-guided surgery using a neuronavigation system is the standard technique for glioma. However, due to the brain shift during surgery, intraoperative technologies, such as 5-ALA fluorescence and intraoperative MRI (IoMRI), are employed. Radiotracers are used during positron emission tomography (PET) for metabolic imaging and assist the evaluation of glioma metabolism. We compared the effectiveness of these intraoperative technologies. METHODS Between January 2016 and May 2021, 52 patients with gliomas underwent IoMRI. 21 patients were selected for 5-ALA fluorescence-guided resection of GBM and underwent multiple PET studies (MET, FLT, and FMISO). We graded fluorescence level as strong, vague, or none. Following tumor resection, we identified the fluorescence level and evaluated the residual volume of gadolinium-enhanced T1WI (T1-Gd) on IoMRI and at each PET study. After calculating the extent of resection (EOR) for T1-Gd, we compared the residual volume on T1-Gd for IoMRI and each PET study, between EOR ≥ 93% and EOR < 93%. RESULTS We detected strong 5-ALA fluorescence during induction and before tumor resection in all 21 (100%) patients with a newly-diagnosed and histopathologically-confirmed GBM. Following tumor resection, we noted an EOR ≥ 93% for T1-Gd in 12 cases (vague, 4; none, 8) and an EOR < 93% for T1-Gd in 9 cases (vague, 5; none, 4). The compared median residual volume (mL) with no fluorescence between EOR ≥ 93% and EOR < 93% for T1-Gd were T1-Gd (0.22, 0.74), MET (0.29, 3.31), FLT (0.24, 1.77), and FMISO (0.22, 1.02). CONCLUSIONS GBM cells are difficult to distinguish in cases without 5-ALA fluorescence. For cases without 5-ALA fluorescence, we were able to maximize the resection of GBM by extracting the area of MET accumulation.