Yoshimasa Kurumi

Semiautomatic non-rigid 3-D image registration for MR-Guided Liver Cancer Surgery

Recently a growing interest has been seen in minimally invasive treatments with open configuration magnetic resonance (Open-MR) scanners. In this paper, we proposed a semi-automatic non-rigid 3D MR-CT image registration technique for MR-Guided Liver Cancer Surgery in which cancer tissues are coagulated by microwave ablation. Because of the lower magnetic field (0.5 T) and various different surgical conditions, sometimes tumors can not be visualized clearly on Open-MR volumes. Combining of CT volumes acquired before surgery, it is possible to identify the tumors location by application of registration techniques. Since such a registration problem belongs to a non-rigid one considering the easy deformation of livers, free-form deformation (FFD) based registration method is applied. Similarity measurement in registration is normalized mutual information (NMI). Both phantom and clinical experiments show that the registration is accurate enough (ap1.45 mm) for liver cancer surgery given some proper processing steps.

An active noise control system for MR noise: A study on an available ANC system in magnetic field

MRI (magnetic resonance imaging) is medical equipment system which in late years has been used to obtain the cross-sectional image of the human body. The MRI used in Shiga University of Medical Science generates a very large noise (about 120dBSPL). In order to reduce this noise, we attempt to implement an active noise control (ANC) system. However, MRI generates too intense magnetic field for dynamics acoustic equipment to be used. In this paper, therefore, the cancellation performance of the ANC system using optical microphone and piezo-electric loudspeaker is demonstrated through experimental results in order to realize the available ANC system in magnetic field.

An active noise control system for MR noise implementation of an ANC system by digital signal processor

Recently, magnetic resonance imaging (MRI) devices are used in many medical institutions on the grounds of safety and convenience. An open-configuration MR system is introduced at Shiga University of Medical Science in order to conduct microwave coagulation therapy by using near-real-time MR images. However, this system has a fatal defect. When MRI device works to take images, it also generates serious noises (MR noise). Hence, an operator and other medical staff (ex. nurses and anesthetists) suffer from MR noise and cannot communicate with each other during the operation. In this paper, we therefore propose a head-mounted ANC system in order to reduce the MR noise, and the some experimental results demonstrate cancellation performance of the system implemented by digital signal processor (DSP).

A new function for accurate MR guided microwave ablation using vertically opened 0.5-T MR system

The purpose of our study is to evaluate the newly developed functions in microwave thermocoagulation therapy within a vertically oriented open MR system. The newly developed functions were to record the ablation areas in 3-dimensional space and accurate targeting the planned treatment volumes of liver tumor during procedure. Before using these functions, we could know the treatment volumes in the dynamic study of post operation. The evolved function facilitated intraoperative surgical margin evaluation and prompted additional surgical margin ablation in MR-guided microwave ablation for liver tumor. Our results demonstrate the feasibility of these functions in minimally invasive MR guided microwave thermocoagulation therapy in an open MR system.