[Setting Method of the Optimal Slab of Brain MRA for Detective Unruptured Cerebral Aneurysm].

Generally, the imaging range of the brain magnetic resonance angiography (MRA) is determined in the subjectivity by the operator used by the plan image that a blood vessel is not depicted. However, a necessary blood vessel may not be often depicted by an error of the setting of the imaging area. Therefore, optimal slab angle, thickness, distance, and image contrast for depiction of the unruptured cerebral aneurysm were examined. The brain MRA of 14 subjects was imaged in a wide area parallel to an orbitomeatal line (OM) line. The line which linked the arteria vertebral (the first cervical vertebrae curved section) to anterior cerebral artery (A3) was determined with an optimal slab base line, and the angle with the OM line was evaluated. Moreover, slavic range including the unruptured aneurysm was calculated. In addition, the distance from the inferior margin of pons to the slavic bottom end was measured. Furthermore, the cerebrovascular contrast by the slave angle was compared. As a result, the slave setting of the range was recommended in brain-MRA as an angle was 34.3 degrees, and the thickness was 56.4 mm, and, as the distance from the inferior margin of pons was 27.6 mm. The cerebrovascular contrast of the optimal slab base line angle did not have a significant difference for an OM line.

[Verification of "IEC 62464-12007": The Evaluation Method of Spatial Resolution in MRI].

Recently, many methods are suggested to evaluate spatial resolution in MRI. However, those techniques are not simple and easy. The International Electrotechnical Commission (IEC) recommends a method to evaluate spatial resolution using a periodic pattern image as IEC 62464-1. IEC 62464-1 prescribes specifications and placement of phantom, and a method of analysis, but these details grounds are not clear. A purpose of this study is to examine the effect in each factor of IEC 62464-1 method and define the characteristics of this method. Nine phantoms with different plate thickness were made including prescribed specifications of IEC 62464-1. Imaging was conducted with changing the placement angle of these phantoms. Also, analysis was carried out in region of interest (ROI) of three different size. As a result, the placement angle of the phantom, measurement error was <1% on a condition prescribed by a method of IEC 62464-1. There was not the effect if the transverse diameter for the longitudinal diameter exceeded 100% fort the size of ROI. In specifications of the phantom, there was not the dependence for the thickness of the plate of the phantom in IEC 62464-1 prescribes.

[Improvement of Fat Suppressing Effect for Finger and Neck MRI by Using Small Glass Beads].

The defectiveness of the fat suppression becomes the factor of the decrease of the quality of the diagnosis of magnetic resonance imaging. It is reported that the use of magnetic field uniformity adjuvant pad is effective for reduce poor fat suppression. The ball bullets, polystyrene balls, and polished rice are used for pad packing material, in recently, it was reported that fat suppression effect was good by the use of the small glass beads. Therefore, we tested the utility of small glass beads pad in the neck and fingers in this study. Neck and the fingers of subjects were imaged with T1-weighted image with fat suppression and T1-high resolution isotropic volume excitation image. The fat suppression effect of each image was compared with the polished rice and glass beads as material of pad used by physical, observation, and contact evaluation. In the result, satisfactory results were obtained by using glass beads, and it is suggested that fat suppression effect is improved by using glass beads as a filling material of pad in clinical study as a conclusion.