University of Twente Student Theses


Intraoperative Quantification of Intestinal Microcirculation : A Modern Interpretation of Fluorescence Angiography

Vaassen, H.G.M. (2021) Intraoperative Quantification of Intestinal Microcirculation : A Modern Interpretation of Fluorescence Angiography.

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Abstract:Background – Intraoperative assessment of local intestinal perfusion is critical for evaluating bowel vitality and preventing anastomotic complications. In current practice, surgeons employ subjective and inaccurate methods, relying on clinical signs. Fluorescence angiography (FA) allows immediate tracing of blood flow, but the subjective interpretation of images has been inadequate in reducing perfusion related complications. The work in this thesis is dedicated to developing an FA-based technique that enables reliable quantification of intestinal perfusion levels and aids surgeons with intraoperative decision-making. Methods – Algorithms were designed to quantify the inflow of contrast agent indocyanine green in tissue, and accompanying software was developed to perform this intraoperatively. The behaviour and comparability of two near-infrared (NIR) acquisition systems were investigated in-vitro. A clinical pilot study was initiated to evaluate the (potential) clinical value of two quantified FA parameters. In order to provide a healthy reference frame, FA data was obtained in 32 patients without bowel perfusion impairment. Measurements were subsequently performed in nine patients with a diagnosed form of impaired bowel perfusion. Seven of these patients underwent revascularization, after which FA was performed once more. Results and Discussion – In-vitro experiments revealed unpredictable behaviour in one of the NIR acquisition systems. However, inflow-based FA quantification in a dynamic perfusion phantom was reasonably comparable. Algorithm validation using more sophisticated phantoms and the use of unprocessed NIR signals are advised before threshold values for clinical decision-making are pursued. In the clinical pilot study, median values of inflow parameters differed significantly from those of the healthy group (P < 0.01). Moreover, six of the seven patients who underwent revascularization showed a clear recovery of the parameters into the healthy range after intervention. Using our developed technique, bowel perfusion impairment that was not observed on clinical inspection could be detected. These findings illustrate a great potential value. Further studies should define threshold values for various perfusion requirements.
Item Type:Essay (Master)
Medisch Spectrum Twente, Enschede, The Netherlands
Faculty:TNW: Science and Technology
Subject:44 medicine, 50 technical science in general
Programme:Technical Medicine MSc (60033)
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