We proposed a method for segmentation of brain tissues—gray matter, white matter, and cerebrospinal fluid—using multi-contrast images, including a T1 map and a uniform T1-weighted image, from a magnetization-prepared 2 rapid acquisition gradient echoes (MP2RAGE) sequence at 7 Tesla. The proposed method was evaluated with respect to the processing time and the similarity of the segmented masks of brain tissues with those obtained using FSL, FreeSurfer, and SPM12. The processing time of the proposed method (28 ± 0 s) was significantly shorter than those of FSL and SPM12 (444 ± 4 s and 159 ± 2 s for FSL and SPM12, respectively). In the similarity assessment, the tissue mask of the brain obtained by the proposed method showed higher consistency with those obtained using FSL than with those obtained using SPM12. The proposed method misclassified the subcortical structures and large vessels since it is based on the intensities of multi-contrast images obtained using MP2RAGE, which uses a similar segmentation approach as FSL but is not based on a template image or a parcellated brain atlas, which are used for FreeSurfer and SPM12, respectively. However, the proposed method showed good segmentation in the cerebellum and white matter in the medial part of the brain in comparison with the other methods. Thus, because the proposed method using different contrast images of MP2RAGE sequence showed the shortest processing time and similar segmentation ability as the other methods, it may be useful for both neuroimaging research and clinical diagnosis.

Purpose: This study aimed to evaluate comprehensively; accuracy, repeatability and reproducibility of T 1 and T 2 relaxation times measured by magnetic resonance fingerprinting using B + 1 -corrected fast imaging with steady-state precession (FISP-MRF). Methods:The International Society of Magnetic Resonance in Medicine/National Institute of Standards and Technology (ISMRM/NIST) phantom was scanned for 100 days, and six healthy volunteers for 5 days using a FISP-MRF prototype sequence. Accuracy was evaluated on the phantom by comparing relaxation times measured by FISP-MRF with the reference values provided by the phantom manufacturer. Daily repeatability was characterized as the coefficient of variation (CV) of the measurements over 100 days for the phantom and over 5 days for volunteers. In addition, the cross-scanner reproducibility was evaluated in volunteers. Results:In the phantom study, T 1 and T 2 values from FISP-MRF showed a strong linear correlation with the reference values of the phantom (R 2 = 0.9963 for T 1 ; R 2 = 0.9966 for T 2 ). CVs were <1.0% for T 1 values larger than 300 ms, and <3.0% for T 2 values across a wide range. In the volunteer study, CVs for both T 1 and T 2 values were <5.0%, except for one subject. In addition, all T 2 values estimated by FISP-MRF in vivo were lower than those measured with conventional mapping sequences reported in previous studies. The crossscanner variation of T 1 and T 2 showed good agreement between two different scanners in the volunteers. Conclusion: B +1 -corrected FISP-MRF showed an acceptable accuracy, repeatability and reproducibility in the phantom and volunteer studies.

Purpose: It has been reported that leakage of intravenously administered gadolinium-based contrast agents (IV-GBCAs) into the cerebrospinal fluid (CSF) from the cortical veins even in healthy subjects can be detected using a highly sensitive pulse sequence such as heavily T 2 -weighted 3D fluid-attenuated inversion recovery and 3D-real inversion recovery (IR). The purpose of this study was to evaluate the feasibility of MR fingerprinting to detect GBCA leakage from the cortical veins after IV-GBCA. Materials:Fourteen patients with suspected endolymphatic hydrops (EH) who received a single dose of IV-GBCA (39-79 years old) were included. The real IR images as well as MR fingerprinting images were obtained at 4 h after IV-GBCA. T 1 and T 2 values were obtained using MR fingerprinting and analyzed in ROIs covering intense GBCA leakage, and non-leakage areas of the CSF as determined on real IR images. The scan time for real IR imaging was 10 min and that for MR fingerprinting was 41 s. Results:The mean T 1 value of the ROI in the area of GBCA leakage was 2422 ± 261 ms and that in the nonleakage area was 3851 ± 235 ms (P < 0.01). There was no overlap between the T 1 values in the area of GBCA leakage and those in the non-leakage area.The mean T 2 value in the area of GBCA leakage was 319 ± 90 ms and that in the non-leakage area was 670 ± 166 ms (P < 0.01). There was some overlap between the T 2 values in the area of GBCA leakage and those in the non-leakage area. Conclusion:Leaked GBCA from the cortical veins into the surrounding CSF can be detected using MR fingerprinting obtained in <1 min.

The proposed method does not require carbon ( C)- labeled glucose injections and C hardware; as such, it has a potential to provide valuable information on intrinsic glucose concentration in the human brain in vivo. Magn Reson Med 76:1653-1660, 2016. © 2016 International Society for Magnetic Resonance in Medicine.

Eye blinks are among the dominant artifacts in electroencephalogram (EEG) recordings.Although several removal methods for e y e-blink artifacts have been reported, most of them concurrentl y removed a part of the original EEGs as well.In this stud y , we focused on the number of pure EEGs that were retained, and proposed a locall y -restricted removal method based on independent component anal y sis (ICA), empirical mode decomposition (EMD), and the Kalman filter. Simulated and measured results confirmed that the proposed method is more suitable for the local removal of e y e-blink artifacts without the loss of EEG information when compared to previous methods.Index Terms -E y e-blink artifact, EEG, ICA, EMD, Kalman filter.