Purpose : The objective of this study was to show an alteration in diffusion tensor indices caused by image averaging. Materials and Methods : We recruited four healthy volunteers. The diffusion tensor images (DTI) were obtained with non-collinear motion-proving gradients along 12 axes and were repeated 10 times using a 3.0T MR scanner. The images were averaged in the order of the sessions. The fractional anisotropy (FA), apparent diffusion coefficient (ADC) and eigenvalues (λ1, λ2, λ3) were calculated based on the regions of interest (ROIs) drawn on the commissural, association and projection fibers. To determine the alterations to the FA caused by image averaging, we performed a multiple regression analysis using statistical parametric mapping. Results : The FA, ADC, λ1 and λ2 values tended to decrease, and the λ3 value tended to increase in proportion to the number of averaging times in the ROI study. In the voxel-based analysis, the FA values significantly decreased proportionally with the increasing number of averaging times. Conclusions : DTI analysis after image averaging is not desirable because the sharpness of the tensor can be lost.
Purpose : We aimed to identify brain activation on functional magnetic resonance imaging after a sound localization task in artificial unilateral hearing loss using an earplug. Materials and Methods : Subjects were 16 healthy volunteers who were divided equally into the right hearing loss group (R group) and the left hearing loss group (L group). Sound stimuli were stereo and pure tone of 2000 Hz with varying right and left amplitude ratios. Using a block design, sound stimuli were randomly presented to the subjects every 2 sec into the task. We investigated the activation areas under conditions of normal hearing (NH) and artificial unilateral hearing loss (UHL). The analysis region was focused on the combined Heschl's and superior temporal gyri. In addition, the % signal change was calculated to examine hemispheric laterality of the hemisphere. Results : In artificial unilateral hearing loss, significant activation in response to the sound localization task was observed in the hemisphere ipsilateral to the ear with hearing loss. The % signal change of the right hemisphere was significantly higher in the R group under UHL conditions and that of the left hemisphere was significantly higher in the L group under NH conditions. In the analysis of laterality index (LI) and LI of each individual after wearing the earplug, the shift of laterality was right predominance. Conclusion : In an artificial acute-phase UHL, the ipsilateral combined Heschl's and superior temporal gyri showed significant activation in a sound localization task. The right hemisphere was suggested to be the dominant brain region associated with sound localization.
Severe atherosclerosis and vascular calcification, causing coronary artery stenosis or peripheral artery diseases (PAD), are frequently detected in hemodialysis (HD) patients. Ankle brachial index (ABI) is a useful marker for detecting PAD, as well as being predictive of the development of cardiovascular diseases (CVD). However, obvious atherosclerotic vascular changes in HD patients might elevate the optimal cut-off value of ABI for screening CVD over the conventional ABI cut-off value, 0.9. Moreover, the ABI cut-off value may be altered by the presence of diabetes mellitus (DM) in HD patients. This retrospective cohort study involved 110 patients on maintenance HD. The ABI cut-off value predicting CVD in HD patients was determined by receiver operating curve (ROC) analysis. ABI cut-off values were also compared in groups of subjects with and without DM. The ABI cut-off value predictive of CVD in all 110 HD patients was 0.960 (area under the curve ［AUC］ 0.761, sensitivity 0.641, specificity 0.803). The cut-off value of ABI was 1.045 in the DM group (AUC 0.735, sensitivity 0.813, specificity 0.606) and 0.960 in the non-DM group (AUC 0.773, sensitivity 0.714, specificity 0.868). Kaplan-Meier analysis showed that patients with ABI below the cut-off values in each group were significantly more likely to develop CVD. The optimal ABI cut-off values for screening high-risk HD patients with CVD should be set at higher levels than the conventional cut-off value (0.9), and that the optimal cut-off values might differ in HD patients with and without DM, at 1.045 and 0.960, respectively.
In ABO-mismatched renal transplantation, acute hemolytic anemia is sometimes caused by donor-originated lymphocytes in the renal graft. We report a retrospective examination of renal graft irradiation for the prevention of acute hemolytic anemia in ABO-mismatched renal transplantation. From January 2011 to September 2012, three patients who were recipients of the ABO-mismatched renal transplantation underwent renal graft irradiation at our facility. Irradiation was started on the day after renal transplantation and lasted for three consecutive days. Conventional fractionated irradiation was performed in order to deliver a total dose of 4.5 Gy in 3 fractions. The follow-up periods were 25 months, 30 months, and 45 months, respectively. No patients developed acute hemolytic anemia. Renal function remained good in all patients, and no malignancy was detected in any patient. In conclusion, acute hemolytic anemia might be prevented by renal graft irradiation in ABO-mismatched renal transplantation. Long-term observation focused on renal function or secondary malignancy is required.
When surgery is performed in the brainstem region, the parasympathetic cardiac reflex via the vagus nerve may occur, possibly resulting in bradycardia/asystole and hypotension. We report a case in which temporary cardiac pacing was useful to prevent recurrent atropine-resistant bradycardia during surgery in the brainstem region. A 42-year-old woman underwent resection of a large ependymoma that extended from the midbrain to the medulla oblongata. She had no episodes of syncope, preoperative bradycardia, or arrhythmia. Because the anticipated long duration of surgical manipulation in the brainstem region came with a high risk of bradycardia/asystole occurrence due to tumor removal, a transvenous pacing (TVP) wire was temporarily implanted before surgery. Just after the beginning of tumor removal, severe bradycardia (28 bpm) and hypotension occurred. Tumor removal was paused, and 0.5mg of atropine was administered intravenously. The heart rate immediately increased to 57 bpm and hemodynamics were stable for 2 min ; however, severe bradycardia (13 bpm) and hypotension recurred 1 min after the resumption of tumor removal. TVP (back-up VVI pacing at 40 bpm) was initiated, and bradycardia and hypotension did not occur again. The subsequent course was uneventful and there were no neurological abnormalities. These findings suggested that atropine was only initially effective in this patient after surgical manipulation was started, and that placement of a TVP wire is useful even when atropine-resistant bradycardia occurs during brainstem surgery.