High-resolution MR imaging of gastrointestinal tissue by intracavitary RF coil with remote tuning and matching technique for integrated MR-endoscope system

Abstract

The goal of this study is to establish novel medical technologies by combining magnetic resonance imaging (MRI) with endoscopy to improve diagnostic precision and the safety of endoscopic surgeries. One of the key components of the integrated magnetic resonance (MR) endoscope system is a radio-frequency (RF) coil; this detects the MR signal from tissue and should be placed inside the body. Resonance characteristics such as the resonant frequency and the impedance of the RF coil, which affect the quality of MR images, change depending on the electric properties of the surrounding tissue and the coil deformation. Therefore, the technique of remote tuning and matching of the RF coil was developed, and its feasibility was investigated using a developed intracavitary RF coil, 1.5 tesla MR scanner, and models of phantom and resected porcine stomach. As a result, the frequency tuning and impedance matching was remotely adjusted in both models. In addition, the signal-to-noise ratio (SNR) of MR images was improved up to 134%. The developed remote tuning and matching technique was able to adjust the resonant characteristics of RF coil and can contribute the improvement of MR image quality, which would facilitate safe and precise endoscopy and endoscopic surgeries.

Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery

“…Consequently, it is advantageous to develop small coils that can be placed adjacent to the target tissue of interest and increase the signal-to-noise ratio (SNR) in the target organs. Specifically, coils that have been developed to provide high-resolution MR imaging include intravascular MR imaging coils for vascular angiography, 15 intracavitary endoscope-mounted MR imaging coils for gastrointestinal imaging, 21 and endorectal coils for MR imaging of the prostate. 30 The increases in SNR can, for example, be used to increase resolution (when holding the imaging time constant) or image more rapidly (at the same resolution).…”