Vol 50, No 8 (2019)

To investigate the effect of the number of spin-lock (SL) and T2 preparation pulse using T1rho and T2 values obtained from the combined T1rho and T2 sequence. We included 30 patients who underwent magnetic resonance imaging of the lumbar spine because of low back pain and leg numbness, tingling, and pain. We used 3D turbo-field echo and the adiabatic pulse as SL pulse for T1rho mapping and the block pulse as T2 preparation pulse for T2 mapping of the combined T1rho and T2 sequence. The preparation time of T1rho and T2 was set at 0, 20, 40, 60, and 80 ms. We defined the T1rho and T2 values calculated from all SL and T2 preparation pulses as Dfull and decreased several number of SL and T2 preparation pulses from Dfull as other groups (D1, D2, and D3). We used the Bland–Altman analyses to estimate the systematic and proportional bias between Dfull and other groups. The 95% CI of the mean difference included zero in all groups. Therefore, systematic bias was not detected. The regression coefficients with D3 of the T1rho and T2 value were − 0.34 and − 0.23, respectively (p < 0.01). We detected the proportional bias in the T1rho and T2 values in only D3 (0 and 80 ms). An investigation of the T1rho and T2 values of IVDs using the combined T1rho and T2 sequence suggested that the accuracy of these values decreased with suitably adjusted three preparation pulses, facilitating the assessment of both T1rho and T2 values at approximately 10 min.

Golden-angle radial sparse parallel (GRASP) magnetic resonance imaging (MRI) is a recent MR image reconstruction technique which integrates parallel imaging, compressed sensing and golden-angle radial scheme to reconstruct the dynamic contrast-enhanced MRI (DCE-MRI) data. Conventionally, GRASP exploits non-uniform fast Fourier transform to grid and de-grid the golden-angle radial data and employs nonlinear conjugate gradient method to recover the unaliased images. GRASP performs gridding and de-gridding operations of golden-angle radial data in every iteration which increases the computational complexity of the conventional GRASP and takes a long image reconstruction time. In this paper, self-calibrated GRAPPA operator gridding (SC-GROG) followed by iterative soft thresholding (IST) is proposed for faster GRASP reconstruction of the golden-angle radial DCE-MRI data. In the proposed method, firstly SC-GROG maps the undersampled golden-angle radial data to a Cartesian grid and then reconstructs the solution image using the IST technique. The proposed method does not require gridding and de-gridding in each iteration; therefore, it is computationally less expensive as compared to the conventional GRASP reconstruction approach. The proposed method is tested for undersampled DCE golden-angle radial liver perfusion data (at acceleration factors 11.8, 19.1 and 30.9). The reconstruction results are assessed visually as well as using mean square error, line profiles and reconstruction time. The reconstruction results are compared with the conventional GRASP reconstruction. The results show that the proposed method provides better quality reconstruction results in terms of reconstruction time and spatio-temporal resolution than the conventional GRASP approach.

If intra-cerebral hemorrhage (ICH) rehabilitation animal model studies had included processes related to imaging diagnosis, not only interim evaluation of treatment effects but also the objectification of treatment effects would have been possible. The purpose of this study was to examine the rehabilitation treatment effect on biomarkers identified on magnetic resonance imaging/spectroscopy in an animal intra-cerebral hemorrhage model. Two groups of rats were used in this study: (1) the rehabilitation treatment group, 12 6-week-old Sprague–Dawley rats with experimental hemorrhage that received rehabilitation; and (2) the control group of 12 rats with experimental hemorrhage that received no intervention. Training rehabilitation was implemented 15 min daily for 2 weeks with 55–85% of the VO₂ max. We conducted MRI/MRS scans before and after ICH rat modeling to evaluate brain metabolite concentration changes. The signal intensity of T2WI was measured at the site of ICH and in a similarly sized area on the opposite side. Integration of the areas under the peaks was conducted to measure cerebral metabolite concentrations. Differences in the mean T2WI-SI ratios measured 2 weeks after ICH induction were not statistically significant (p = 0.514) between the control group and the experimental group. However, the brain tCho/tCr metabolite ratio in the control group was significantly lower than in the experimental group 2 weeks after ICH induction (0.243 ± 0.044 vs. 0.326 ± 0.061, p = 0.007). The tCho/tCr ratio might be used as a biomarker to evaluate the effect of rehabilitation treatment for ICH.