Multiecho echo‐planar imaging (EPI) was implemented for blood‐oxygenation‐level‐dependent functional MRI at 1.5 T and compared to single‐echo EPI with and without parallel imaging acceleration. A time‐normalized breath‐hold task using a block design functional MRI protocol was carried out in combination with up to four echo trains per excitation and parallel imaging acceleration factors R = 1–3. Experiments were conducted in five human subjects, each scanned in three sessions. Across all reduction factors, both signal‐to‐fluctuation‐noise ratio and the total number of activated voxels were significantly lower using a single‐echo EPI pulse sequence compared with the multiecho approach. Signal‐to‐fluctuation‐noise ratio and total number of activated voxels were also considerably reduced for nonaccelerated conventional single‐echo EPI when compared to three‐echo measurements with R = 2. Parallel imaging accelerated multiecho EPI reduced geometric distortions and signal dropout, while it increased blood‐oxygenation‐level‐dependent signal sensitivity all over the brain, particularly in regions with short underlying T *₂. Thus, the presented method showed multiple advantages over conventional single‐echo EPI for standard blood‐oxygenation‐level‐dependent functional MRI experiments. Magn Reson Med 63:959–969, 2010.

Purpose: To enable motion‐robust diffusion weighted imaging of the brain using well‐established imaging techniques.Methods: An optical markerless tracking system was used to estimate and correct for rigid body motion of the head in real time during scanning. The imaging coordinate system was updated before each excitation pulse in a single‐shot EPI sequence accelerated by GRAPPA with motion‐robust calibration. Full Fourier imaging was used to reduce effects of motion during diffusion encoding. Subjects were imaged while performing prescribed motion patterns, each repeated with prospective motion correction on and off.Results: Prospective motion correction with dynamic ghost correction enabled high quality DWI in the presence of fast and continuous motion within a 10° range. Images acquired without motion were not degraded by the prospective correction. Calculated diffusion tensors tolerated the motion well, but ADC values were slightly increased.Conclusions: Prospective correction by markerless optical tracking minimizes patient interaction and appears to be well suited for EPI‐based DWI of patient groups unable to remain still including those who are not compliant with markers.

BACKGROUND AND PURPOSE: The long scan time of MR imaging is a major drawback limiting its clinical use in neuroimaging; therefore, we aimed to investigate the clinical feasibility of a 1-minute full-brain MR imaging using a multicontrast EPI sequence on a different MR imaging scanner than the ones previously reported. MATERIALS AND METHODS: We retrospectively reviewed the records of 146 patients who underwent a multicontrast EPI sequence, including T1-FLAIR, T2-FLAIR, T2WI, DWI, and T2*WI sequences. Two attending neuroradiologists assessed the image quality of each sequence to compare the multicontrast EPI sequence with routine MR imaging protocols. We used the Wilcoxon signed rank test and McNemar test to compare the 2 MR imaging protocols. RESULTS: The multicontrast EPI sequence generally showed sufficient image quality of >2 points using a 4-point assessment scale. Regarding image quality and susceptibility artifacts, there was no significant difference between the multicontrast EPI sequence DWI and routine DWI (P > .05), attesting to noninferiority of the multicontrast EPI, whereas there were significant differences in the other 4 sequences between the 2 MR imaging protocols. CONCLUSIONS: The multicontrast EPI sequence showed sufficient image quality for clinical use with a shorter scan time; however, it was limited by inferior image quality and frequent susceptibility artifacts compared with routine brain MR imaging. Therefore, the multicontrast EPI sequence cannot completely replace the routine MR imaging protocol at present; however, it may be a feasible option in specific clinical situations such as screening, time-critical diseases or for use with patients prone to motion.

Purpose: To investigate the use of 3D EPI for rapid T₁‐weighted brain imaging, focusing on the RF pulse’s influence on the contrast between gray and white matter.Methods: An interleaved 3D EPI sequence use partial Fourier and CAIPIRINHA sampling was used to acquire T₁‐weighted brain volumes with isotropic resolution, low echo times, and low geometric distortions. Five different RF pulses were evaluated in terms of fat suppression performance and gray–white matter contrast. Two binomial RF pulses were compared to a single rectangular (WE‐rect) RF pulse exciting only water, and two new RF pulses developed in this work, where one was an extension of the WE‐rect, and the other was an SLR pulse. The technique was demonstrated in three clinical cases, where brain tumor patients were imaged before and after gadolinium administration.Results: A fat‐suppressed 3D EPI sequence with a phase encoding bandwidth of around 100 Hz was found to exhibit a good trade‐off between geometrical distortions and scan duration. Whole‐brain T₁‐weighted 3D EPI images with 1.2 mm isotropic voxel size could be acquired in 24 seconds. The WE‐rect, its extension, and the SLR RF pulses resulted in reduced magnetization transfer effects and provided a 20% mean increase in gray–white matter contrast.Conclusion: Using a high phase encoding bandwidth and RF pulses that reduce magnetization transfer effects, a fat‐suppressed multi‐shot 3D EPI sequence can be used to rapidly acquire isotropic T₁‐weighted volumes.

Purpose: Implement a fast, motion‐robust pulse sequence that acquires T₁‐weighted, T₂‐weighted, T₂^*‐weighted, T₂ fluid‐attenuated inversion recovery, and DWI data in one run with only one prescription and one prescan.Methods: A software framework was developed that configures and runs several sequences in one main sequence. Based on that framework, the NeuroMix sequence was implemented, containing motion robust single‐shot sequences using EPI and fast spin echo (FSE) readouts (without EPI distortions). Optional multi‐shot sequences that provide better contrast, higher resolution, or isotropic resolution could also be run within the NeuroMix sequence. An optimized acquisition order was implemented that minimizes times where no data is acquired.Results: NeuroMix is customizable and takes between 1:20 and 4 min for a full brain scan. A comparison with the predecessor EPIMix revealed significant improvements for T₂‐weighted and T₂ fluid‐attenuated inversion recovery, while taking only 8 s longer for a similar configuration. The optional contrasts were less motion robust but offered a significant increase in quality, detail, and contrast. Initial clinical scans on 1 pediatric and 1 adult patient showed encouraging image quality.Conclusion: The single‐shot FSE readouts for T₂‐weighted and T₂ fluid‐attenuated inversion recovery and the optional multishot FSE and 3D‐EPI contrasts significantly increased diagnostic value compared with EPIMix, allowing NeuroMix to be considered as a standalone brain MRI application.