[Imaging Parameter Optimization of 3D Radial Stack-of-stars MRA with FID Sampling after Treatment of Cerebral Aneurysms with Metallic Devices].

Magnetic resonance angiography (MRA) using ultra-short TE (uTE) is known to be used for the evaluation of cerebral aneurysm after treatment such as clipping and coiling. However, conventional uTE sequences are not appropriate as an additional imaging sequence for 3D time-of-flight (TOF)-MRA because it is not possible to shorten scan time and acquire selective-volume imaging. To solve the problem, we focused on the combination of uTE sampling and 3D radial scan sequences. In this study, we examined the optimal imaging parameters of the proposed uTE-MRA. A simulated blood flow phantom with stents (Enterprise) and titanium clips (YASARGIL) was used for optimizing the TR, flip angle (FA), and radial percentage. The signal intensity in the simulated vessel was measured in each imaging condition, and the ratio of the presence or absence of a stent was evaluated as a relative in-stent signal (RIS). In addition, the diameter of the signal loss of the simulated artery was measured for each imaging condition, and signal loss length (SLL) of a clip was calculated from the average value. The RIS improved with increasing the FA and shortening the TR, but it did not change by changing the radial percentage. The SLL became smaller at the coil as the FA increased, but there was no significant difference between the intersection and the blade. There was also no significant difference between TR and radial percentage. The effective imaging conditions for uTE-MRA to improve the vascular description of the evaluation after treatment of cerebral aneurysms with metallic devices were those with large FA and short TR.

[A Questionnaire Survey on the Levels of Perception and Implementation on Diagnostic Reference Levels in Japan (Japan DRLs 2015)].

In June 2015, Japanese diagnostic reference levels (Japan DRLs 2015) was released by Japan Network for Research and Information on Medical Exposures (J-RIME). After six months the release of Japan DRLs 2015, we have conducted a questionnaire and received 222 responses from hospital staff regarding their perception level, and implementation on Japan DRLs 2015 at their facilities. 131 people (59.0%) were familiar with Japan DRLs 2015, of which 56 people (29.2%) were not currently implementation of them. A total of 66 people (30.1%) understood how to implement Japan DRLs 2015. There were 35 people (18.2%) who heard of diagnostic reference levels (DRLs) for the first time through this survey. Those are the levels of perception and implementation on Japan DRLs 2015 became clear. It is necessary to compare the dose levels used at each facility with Japan DRLs 2015 to optimize patient protection during medical exposure. It is essential to continue to grow the medical community's understanding of DRLs with the expanded perception and implementation of this survey as an opinion poll across Japan.

[Examination of Lower-extremity MRA Using Single-shot Balanced SSFP with Saturation Recovery].

Currently, non-contrast angiography using the balanced steady-state free precession (b-SSFP) method, which uses a short scan time imaging method, has been reported as an alternative to lower-extremity MRA's conventional method. We investigated a new imaging method using balanced SSFP. This method uses a sequence of spectral attenuated inversion recovery (SPAIR) pulse for fat suppression, selective saturation pre-pulse for imaging range of background signal suppression, and rest slab on the downstream side of the imaging range for vein signal suppression. In the examination, we changed dummy pulse (0, 5, 10), saturation delay time (150 ms, 225 ms, 300 ms), and acquisition time (200 ms, 250 ms, 300 ms). For physical evaluation, we used the ROI method and for visual evaluation, we used the Scheffe's method. CR was the best and the visual evaluation was also good 10 for dummy pulse, a saturation delay time of 150 ms, and an acquisition time of 200 ms. Balanced SSFP with saturation recovery has the potential to shorten scanning times. Balanced SSFP with saturation recovery is useful for lower-extremity MRA.