The state of mind of a person is supported by the brain activity, and hence features of the state of mind appear in the scalp potentials, as seen on an electroencephalogram (EEG). The EEG features have been extracted into a set of 135 state variables of cross-correlation coefficients of EEGs collected with ten scalp electrodes in the 0, c~, and [3 frequency bands corresponding to anger, sadness, joy, and relaxation. An emotion matrix is defined which transforms the set of 135 state variables into a fourelement emotion vector of which the components are indexes corresponding to the four elementary emotional states. The maximum time resolution of the emotion analysis is 0.64s and it is done in real time. This new technique has a wide variety of applications in both medical and nonmedical areas, and the technology suggests the possibility of direct control of systems by the human emotional state.
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 0.5T clinical MR scanner. To evaluate the feasibility and determine optimal imaging conditions, studies were conducted with a phantom, volunteers, and a patient. In the phantom study the root mean square (RMS) position error in the 4D image of the cyclically moving phantom was 1.9 mm and the imaging time was Ϸ10 min when the 4D image had six frames. In the patient study, 4D images were successfully acquired under clinical conditions and a liver tumor was discriminated in the series of frames. The image quality was affected by the relations among the encoding direction, the slice orientation, and the direction of motion of the target organ. In conclusion, this study has shown that the proposed method is feasible and capable of providing a real-time dynamic 3D atlas for surgical navigation with sufficient accuracy and image quality.
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. The delay time before the start of scanning was adjusted to acquire the data corresponding to the k-space center at the maximal expiratory phase. The triggered images were apparently clearer than the nontriggered ones and the location of the liver was consistent, which made targeting of the tumor easy. MR temperature images, which were highly susceptible to the movement of the liver, during microwave ablation using a proton resonance frequency method, could be obtained without suspending the artificial ventilation. Respiratory triggering technique was found to be useful for MR fluoroscopic images and MR temperature monitoring in MR-guided microwave ablation of liver tumors under general anesthesia.
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. Reformatted images in the corresponding two planes were also constructed from preoperative three-dimensional volume data. These four images (two real-time and two reformatted) were continuously visible to the surgeons. These images enabled the needle position in the three-dimensional space to be accurately and clearly recognized, in contrast to the di‹culty encountered with two-dimensional MR images in a single image plane. This technique was also applied to MR temperature mapping during microwave ablation, as it allowed monitoring of the spread of the heat in a three-dimensional space. This type of computer-integrated image navigation was demonstrated to be feasible for MR-guided microwave ablation of liver tumors.
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