Cancer affects the mechanical properties of tissue. Therefore, elastography techniques can be used to differentiate cancerous from healthy tissue. Due to probe size and restricted handling, most elastography techniques are not applicable in minimally invasive surgery (MIS). Established techniques such as endoscopic ultrasound elastography measure under undefined boundary conditions, making the determination of quantitative mechanical properties challenging. Water flow elastography (WaFE) has recently been introduced for application in MIS. Here, we present an improved WaFE measurement method in which the probe attaches itself to the sample with a small suction pressure. This leads to defined boundary conditions, allowing for a quantitative determination of the Young's modulus of tissue. To facilitate fast measurements, we developed a correction model for the hydrodynamic resistance and the fluid inertia of the tubing. We used WaFE for ex vivo measurements on human bladders and found a significantly larger Young's modulus for cancerous vs. healthy tissue. We determined the optimal classification threshold for the Young's modulus to be 8 kPa and found that WaFE can differentiate between cancerous and healthy tissue with a sensitivity of 0.96 and a specificity of 1. Our results underline that WaFE can be a helpful differentiating tool in MIS.
Journal of the mechanical behavior of biomedical materials. 2023 Dec 18 [Epub ahead of print]
Paul L Kalwa, Simon Walz, Massimo Granai, Falko Fend, Arnulf Stenzl, Tilman E Schäffer
Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany., Department of Urology, University of Tübingen Medical Center, Hoppe-Seyler-Str. 3, 72076 Tübingen, Germany., Institute of Pathology and Neuropathology, University Hospital of Tübingen, Liebermeisterstr. 8, 72076 Tübingen, Germany., Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany. Electronic address: .