Proton magnetic resonance spectroscopy (MRS) is widely used to detect alterations in cerebral metabolite levels in various neurological disorders. Data acquisitions with a short echo-time (TE) are recommended. Subsequently, provided that time permits, it is also recommended to apply long TE with shimming/adjustment of radiofrequency pulses and careful setting of voxels of interest. In those cases where contrast agents are administered, it is preferable to perform short-TE acquisitions using non-ionic media. Advanced systems with higher static magnetic field enable the detection of low-concentration metabolites, particularly when using short TE. MRS data acquisition and processing can be performed semi-automatically; however, sufficient knowledge and skills are needed to obtain high quality spectra.

 In this study, we surveyed policies on allocating MRI scan duties to pregnant employees, and investigated the respondents' level of awareness of non-ionizing radiation. We sent 5763 questionnaires to facilities equipped with MRI devices in Japan (the corresponding respondent was a member of the personnel responsible for MRI scan duties). The questionnaire comprised: 1) Basic information; 2) General questions about the employees' pregnancies (e.g., whether the hospital has a particular policy); 3) The policy on MRI scan duties while pregnant and alternative duties ; and 4) Level of awareness of non-ionizing radiation in general. The results revealed inconsistent handling within Japan. Answers stating that ``increase the opportunity of allocation to MRI scan duties compared with the current situation'' accounted for 7.6％, ``maintaining the current frequency of allocation to MRI scan duties'' for 32.3％, and ``reduce the opportunity of allocation to MRI scan duties compared with current situation'' for 52.6％. Around half of facilities prepared work options (e.g. access restriction into MRI scan room or assign extra staff to MRI scan duties) in MRI scan duties during pregnancy. In an attitude survey for non-ionizing radiation emitted by medical devices, respondents showed higher attention compared with that for the radiation emitted by home electronic devices. This report describes a summary of the survey. Further analysis is in progress and will be reported soon.

 BACKGROUND AND PURPOSE : Myelin and axon volume fractions can now be estimated via MR imaging in vivo, as can the g-ratio, which equals the ratio of the inner to the outer diameter of a nerve fiber. The purpose of this study was to evaluate WM damage in patients with MS via this novel MR imaging technique.

 MATERIALS AND METHODS : Twenty patients with relapsing-remitting MS with a combined total of 149 chronic plaques were analyzed. Myelin volume fraction was calculated based on simultaneous tissue relaxometry. Intracellular and CSF compartment volume fractions were quantified via neurite orientation dispersion and density imaging. Axon volume fraction and g-ratio were calculated by combining these measurements. Myelin and axon volume fractions and g-ratio were measured in plaques, periplaque WM, and normal-appearing WM.

 RESULTS : All metrics differed significantly across the 3 groups (P＜.001, except P＝.027 for g-ratio between periplaque WM and normal-appearing WM). Those in plaques differed most from those in normal-appearing WM. The percentage changes in plaque and periplaque WM metrics relative to normal-appearing WM were significantly larger in absolute value for myelin volume fraction than for axon volume fraction and g-ratio (P＜.001, except P＝.033 in periplaque WM relative to normal-appearing WM for comparison between myelin and axon volume fraction).

 CONCLUSIONS : In this in vivo MR imaging study, the myelin of WM was more damaged than axons in plaques and periplaque WM of patients with MS. Myelin and axon volume fractions and g-ratio may potentially be useful for evaluating WM damage in patients with MS.