Dual-Modality Detection of Liver Coagulation via Optical Diffuse Reflectance and a Microwave Antenna

Abstract

Coagulation and unusual blood clotting levels are considered to be major warning signs of a variety of liver problems, including liver damage, toxicity, and cirrhosis. This paper provides a dual-modality technique for detecting liver tissue coagulation that employs both optical diffuse reflectance and a custom-designed implantable microwave antenna. The antenna was designed to test its ability to discriminate between native and coagulated chicken liver tissue. To evaluate optical diffuse reflectance, a 632 nm laser was used. In parallel, different aspects of the suggested antenna, such as its gain, efficiency, radiation patterns, voltage standing wave ratio (VSWR), specific absorption rate (SAR), and reflection coefficient (S11), were examined through simulations and experiments. The simulation results show that the proposed antenna resonates at 450 MHz (MICS band). S₁₁ parameter for the native liver was determined by simulations to be −24 dB. In contrast, the measured S₁₁ values were −18 and −10 dB for the native and coagulated samples, respectively. Additionally, the diffuse reflectance of coagulated liver varied noticeably when compared to the original tissue. Both modalities (microwave and optical) demonstrated noticeable changes in signal response as a result of tissue coagulation, with the antenna revealing variations in S11 and the optical system demonstrating variations in reflectance intensities. The detection performance of both modalities was evaluated using receiver operating characteristic (ROC) curve analysis, which revealed that the proposed microwave antenna has the potential to be a useful tool for noninvasive tissue coagulation monitoring when combined with optical reflectance sensing.