Indocyanine-green fluorescence imaging to detect anastomotic insufficiency after esophagectomy

Sammanfattning: This research project is concerned with the development of simulation models and image analysis algorithms, as well as instrumentation for characterizing anastomotic leakages after a patient has undergone surgery for esophageal cancer. Anastomotic leakage is a high-incidence complication after esophagectomy, a surgical procedure for esophageal cancer. In an esophagectomy, the cancerous part of the esophagus is resected, and an artificial counterpart is created by stretching the ventricle. After sewing these two tissues together, there is a high chance of the stitches rupturing due to poor healing, something which in turn arises from poor and complicated blood perfusion in the area. This thesis work aims to utilize indocyanine green, a fluorescent molecule which binds to plasma proteins in blood. By imaging the anastomotic area after an ICG injection and illuminating it with a fitting excitation light source, one may be able to determine areas of poor perfusion by studying the time evolution of the fluorescence signal. The algorithms developed in this thesis achieve this in two different ways: purely by calculating the time to the fluorescence maximum for each pixel, and also by numerically approximating the time-intensity derivative. These are tested on the aforementioned Monte-Carlo simulation model, as well as on tissue phantoms, and finally in-vivo in a porcine model. The results indicate that the algorithms perform well and reveal relevant features in the fluorescence signal, in all cases. The porcine measurements prove highly useful to show the benefits and disadvantages of each algorithm, and the conclusion is that they should likely be used together to provide physicians with a full picture of the perfusion. Finally, an outlook on how this could be incorporated into a gastroscopy setup is provided, something which was discussed during this thesis work but never fully realized.