Preliminary clinical experiences of a motorized manipulator for magnetic resonance image-guided microwave coagulation therapy of liver tumors.

Background: In magnetic resonance (MR) image-guided microwave thermocoagulation of liver tumors, the choice of the optimal puncture route is an important and time-consuming process. To assist this process, we have developed a motorized MR-compatible manipulator.

Methods: The manipulator consists of a passive end effecter with 2 degrees-of-freedom (DOF) rotation and active base stages with 3 ultrasonic motors.

Adaptive 4D MR imaging using navigator-based respiratory signal for MRI-guided therapy.

For real-time 3D visualization of respiratory organ motion for MRI-guided therapy, a new adaptive 4D MR imaging method based on navigator echo and multiple gating windows was developed. This method was designed to acquire a time series of volumetric 3D images of a cyclically moving organ, enabling therapy to be guided by synchronizing the 4D image with the actual organ motion in real time. The proposed method was implemented in an open-configuration 0.

New 4-D imaging for real-time intraoperative MRI: adaptive 4-D scan.

Aiming at real-time 3-D visualization of organ motion to navigate surgical procedures in MRI-guided surgery, a new 4-D MR imaging technique called "Adaptive 4-D Scan" has been proposed. The technique is designed to acquire a time series of volumetric 3-D images (4-D image) of cyclically moving organ, even in a low-field open-configuration MR scanner. A pre-operative 4-D image is acquired with respiratory phase parameter, which is monitored by using navigator-echo-based real-time tracking of the liver and diaphragm.

Alternate biplanar MR navigation for microwave ablation of liver tumors.

Real-time MR (magnetic resonance) images in two perpendicular planes, both of which included the path of the needle, were utilized for MR-guided microwave ablation of liver tumors. The two image planes were automatically and alternately switched by new MR scanner control software installed on an external PC. This technique is possible only with MRI (magnetic resonance imaging) units with multiplanar and multisection capabilities.

Feasibility of respiratory triggering for MR-guided microwave ablation of liver tumors under general anesthesia.

We obtained clear and reproducible MR fluoroscopic images and temperature maps for MR image-guided microwave ablation of liver tumors under general anesthesia without suspending the artificial ventilation. Respiratory information was directly obtained from air-way pressure without a sensor on the chest wall. The trigger signal started scanning of one whole image with a spoiled gradient echo sequence.

Advanced computer assistance for magnetic resonance-guided microwave thermocoagulation of liver tumors.

Rationale And Objectives: The purpose of this study was to utilize computer assistance effectively for both easy and accurate magnetic resonance (MR) image-guided microwave thermocoagulation therapy of liver tumors.

Materials And Methods: An open configuration MR scanner and a microwave coagulator at 2.45 GHz were used.

New assistive devices for MR-guided microwave thermocoagulation of liver tumors.

Rationale And Objectives: The purpose of this study was to develop and test new assistive devices to aid in the performance of safe, easy, and accurate microwave thermocoagulation therapy guided by magnetic resonance (MR) imaging.

Materials And Methods: An open-configuration MR imager with an optical tracking system for image plane control and a microwave coagulator operating at 2.45 GHz were used.

Template-based method for multiple volumes of interest of human brain PET images.

Specific region-based analysis for the quantification of brain imaging is very time-consuming work and subject to errors in both accuracy and reproducibility. In this study, we assessed a two-step template-based method for defining volumes of interest (VOIs). The first step was the spatial transformation of the VOI template from a model MRI to an individual MRI with SPM99.