Magnetic Resonance in Medical Sciences
Online ISSN : 1880-2206
Print ISSN : 1347-3182
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Showing 1-35 articles out of 35 articles from Advance online publication
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  • Masami Goto, Osamu Abe, Shigeki Aoki, Koji Kamagata, Masaaki Hori, Tos ...
    Article ID: mp.2017-0127
    [Advance publication] Released: January 18, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: To evaluate the error in segmented tissue images and to show the usefulness of the brain image in voxel-based morphometry (VBM) using Statistical Parametric Mapping (SPM) 12 software and 3D T1-weighted magnetic resonance images (3D-T1WIs) processed to simulate idiopathic normal pressure hydrocephalus (iNPH).

    Materials and Methods: VBM analysis was performed on sagittal 3D-T1WIs obtained in 22 healthy volunteers using a 1.5T MR scanner. Regions of interest for the lateral ventricles of all subjects were carefully outlined on the original 3D-T1WIs, and two types of simulated 3D-T1WI were also prepared (non-dilated 3D-T1WI as normal control and dilated 3D-T1WI to simulate iNPH). All simulated 3D-T1WIs were segmented into gray matter, white matter, and cerebrospinal fluid images, and normalized to standard space. A brain image was made by adding the gray and white matter images. After smoothing with a 6-mm isotropic Gaussian kernel, group comparisons (dilated vs non-dilated) were made for gray and white matter, cerebrospinal fluid, and brain images using a paired t-test.

    Results: In evaluation of tissue volume, estimation error was larger using gray or white matter images than using the brain image, and estimation errors in gray and white matter volume change were found for the brain surface.

    Conclusion: To our knowledge, this is the first VBM study to show the possibility that VBM of gray and white matter volume on the brain surface may be more affected by individual differences in the level of dilation of the lateral ventricles than by individual differences in gray and white matter volumes. We recommend that VBM evaluation in patients with iNPH should be performed using the brain image rather than the gray and white matter images.

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  • Shinji Naganawa, Toshiki Nakane, Hisashi Kawai, Toshiaki Taoka
    Article ID: mp.2017-0137
    [Advance publication] Released: January 18, 2018
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    Purpose: To elucidate differences between the perivascular space (PVS) in the basal ganglia (BG) versus that found in white matter (WM) using heavily T2-weighted FLAIR (hT2-FL) in terms of 1) signal intensity on non-contrast enhanced images, and 2) the degree of contrast enhancement by intravenous single dose administration of gadolinium based contrast agent (IV-SD-GBCA).

    Materials and Methods: Eight healthy men and 13 patients with suspected endolymphatic hydrops were included. No subjects had renal insufficiency. All subjects received IV-SD-GBCA. MR cisternography (MRC) and hT2-FL images were obtained prior to and 4 h after IV-SD-GBCA. The signal intensity of the PVS in the BG, subinsular WM, and the cerebrospinal fluid (CSF) in Ambient cistern (CSFAC) and CSF in Sylvian fissure (CSFSyl) was measured as well as that of the thalamus. The signal intensity ratio (SIR) was calculated by dividing the intensity by that of the thalamus. We used 5% as a threshold to determine the significance of the statistical test.

    Results: In the pre-contrast scan, the SIR of the PVS in WM (Mean ± standard deviation, 1.83 ± 0.46) was significantly higher than that of the PVS in the BG (1.05 ± 0.154), CSFSyl (1.03 ± 0.15) and the CSFAC (0.97 ± 0.29). There was no significant difference between the SIR of the PVS in the BG compared to the CSFAC and CSFSyl. For the evaluation of the contrast enhancement effect, significant enhancement was observed in the PVS in the BG, the CSFAC and the CSFSyl compared to the pre-contrast scan. No significant contrast enhancement was observed in the PVS in WM.

    Conclusion: The signal intensity difference between the PVS in the BG versus WM on pre-contrast images suggests that the fluid composition might be different between these PVSs. The difference in the contrast enhancement between the PVSs in the BG versus WM suggests a difference in drainage function.

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  • Yasuo Amano, Mitsunobu Kitamura, Hitoshi Takano, Fumi Yanagisawa, Masa ...
    Article ID: rev.2017-0145
    [Advance publication] Released: January 18, 2018
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    Hypertrophic cardiomyopathy (HCM) is a relatively common myocardial genetic disease having a wide variety of symptoms and prognoses. The most serious complications of HCM are sudden cardiac death induced by ventricular arrhythmia or inappropriate changes in blood pressure, and heart failure. Cardiac MR imaging is a valuable imaging method for detecting HCM because of its accurate measurement of wall thickness and myocardial mass without limited view and the unique ability of late gadolinium enhancement (LGE) to identify myocardial fibrosis related to the prognosis of HCM. Tagging and T1 or T2 mapping MR imaging techniques have emerged as quantitative methods for the evaluation of disease severity. In this review, we introduce the MR imaging techniques applied to HCM and demonstrate the typical phenotypes and some morphological characteristics of HCM. In addition, we discuss the clinical relevance of MR imaging for risk stratification and management of HCM.

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  • Shintaro Ichikawa, Utaroh Motosugi, Makiko Omori, Katsuhiro Sano, Yosh ...
    Article ID: tn.2017-0103
    [Advance publication] Released: January 18, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    We evaluated the value of magnetic resonance elastography (MRE) for the prediction of response to magnetic resonance-guided focused ultrasound (MRgFUS) for uterine fibroids. Eleven patients were enrolled. A fractional change of >30% in Symptoms Severity Score (SSS) was defined as a ‘substantial symptomatic improvement’ at 12 months after treatment. The fractional stiffness value reduction in the patients with a substantial improvement in SSS was significantly higher than that in those without (P = 0.0446).

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  • Masayuki Yamaguchi, Hirofumi Fujii
    Article ID: tn.2017-0115
    [Advance publication] Released: January 18, 2018
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    Techniques for testis immobilization can facilitate high-resolution MR imaging applications for testicular diseases by assuring good positioning of the testis on small radiofrequency coils and reducing motion artifacts. We tested negative pressure suction to immobilize the testis of rats during MR image acquisitions. Suction pressure between −5 and −10 kPa assured good positioning, suppressed motion artifacts, and allowed the observation of blood vessels and seminiferous tubules.

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  • Machiko Tateishi, Mika Kitajima, Toshinori Hirai, Tetsuya Yoneda, Mamo ...
    Article ID: mp.2017-0134
    [Advance publication] Released: January 15, 2018
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    Purpose: To test the feasibility of the phase difference enhanced (PADRE) imaging for differentiation between Alzheimer disease (AD) patients and control subjects on 3T MR imaging.

    Materials and Methods: Fifteen patients with AD and 10 age-matched control subjects underwent two-dimensional fast field echo imaging to obtain PADRE images on a 3T MR scanner. A double Gaussian distribution model was used to determine the threshold phase value for differentiation between the physiologic and non-physiologic iron in the cerebral cortices, and PADRE images were processed with the threshold. Using a 4-point grading system, two readers independently assessed the signal of the four cerebral cortices on PADRE images: the cuneus, precuneus, superior frontal gyrus, and superior temporal gyrus. The difference in the signals in each cortex between the AD patients and age-matched control subjects was determined by using Mann–Whitney U test. Inter-rater reliability was determined by Kappa analysis. We also evaluated the correlation between Mini-Mental State Examination (MMSE) score and the hypointense grade, and between disease duration and the hypointense grade using the Spearman rank correlation test.

    Results: The threshold phase value for differentiation between the physiologic and non-physiologic iron was −4.6% π (radian). The mean grades of the cuneus, precuneus, and superior temporal gyrus were significantly higher for the AD patients than for the control subjects (P = 0.002). Excellent inter-rater reliability was seen in the precuneus (kappa = 0.93), superior temporal gyrus (kappa = 0.94), and superior frontal gyrus (kappa = 0.93); good inter-rater reliability was observed in the cuneus (kappa = 0.75). We found a statistical correlation between MMSE score and the hypointense grade in superior temporal gyrus (STG) (P = 0.008), and no correlation between disease duration and the hypointense grade in any gyrus.

    Conclusion: Our results suggest the feasibility of PADRE imaging at 3T for differentiation between AD patients and control subjects.

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  • Lauren Wallaert, Akifumi Hagiwara, Christina Andica, Masaaki Hori, Kaz ...
    Article ID: ci.2017-0110
    [Advance publication] Released: December 12, 2017
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  • Yuki Shinohara, Ayumi Kato, Eijiro Yamashita, Jun-ichi Ueyama, Naohiro ...
    Article ID: ci.2017-0113
    [Advance publication] Released: December 12, 2017
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  • Delgerdalai Khashbat, Masafumi Harada, Takashi Abe, Mungunbagana Ganbo ...
    Article ID: mp.2017-0065
    [Advance publication] Released: December 12, 2017
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    Purpose: We evaluated the utility of arterial spin labeling (ASL) imaging of tumor blood flow (TBF) for grading non-enhancing astrocytic tumors.

    Materials and Methods: Thirteen non-enhancing astrocytomas were divided into high-grade (n = 7) and low-grade (n = 6) groups. Both ASL and conventional sequences were acquired using the same magnetic resonance machine. Intratumoral absolute maximum TBF (TBFmax), absolute mean TBF (TBFmean), and corresponding values normalized to cerebral blood flow (TBFmax and TBFmean ratios) were measured. The Mann-Whitney U test and receiver operating characteristic (ROC) curve analysis were used to assess the accuracy of TBF variables for tumor grading.

    Results: Compared with low-grade astrocytoma, high-grade astrocytoma exhibited significantly greater absolute TBFmax (90.93 ± 24.96 vs 46.94 ± 20.97 ml/100 g/min, P < 0.001), TBFmean (58.75 ± 19.89 vs 31.16 ± 17.63 ml/100 g/min, P < 0.001), TBFmax ratio (3.34 ± 1.22 vs 1.35 ± 0.5, P < 0.001), and TBFmean ratio (2.15 ± 0.94 vs 0.88 ± 0.41, P < 0.001). The TBFmax ratio yielded the highest diagnostic accuracy (sensitivity 100%, specificity 86.3%), while absolute TBFmean yielded the lowest accuracy (sensitivity 85.7%, specificity 70.1%) by ROC analysis.

    Conclusion: Parameters from ASL perfusion imaging, particularly TBFmax ratio, may be useful for distinguishing high-grade from low-grade astrocytoma in cases with equivocal conventional MRI findings.

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  • Makiko Kawai, Masako Kataoka, Shotaro Kanao, Mami Iima, Natsuko Onishi ...
    Article ID: mp.2017-0024
    [Advance publication] Released: December 07, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: This study aimed to evaluate the MRI findings of breast solitary masses in diagnostic procedures to decide the appropriate category based on American College of Radiology (ACR) BI-RADS-MRI 2013, with the focus on lesion size.

    Methods: A retrospective review of 2,603 consecutive breast MRI reports identified 250 pathologically-proven solitary breast masses. Dynamic-contrast enhanced images and diffusion-weighted images were performed on a 3.0/1.5 Tesla Scanner with a 16/4 channel dedicated breast coil. MRI findings were re-evaluated according to ACR BI-RADS-MRI 2013. BI-RADS-MRI descriptors, lesion size and minimum apparent diffusion coefficient (ADC) value were statistically analyzed using univariate/multivariate logistic regression analysis and receiver operator characteristic (ROC) analysis. Based on the results, a diagnostic decision tree was constructed.

    Results: Of the 250 lesions, 152 (61%) were malignant and 98 (39%) were benign. In univariate logistic regression analysis, most of the BI-RADS descriptors, lesion size, and ADC value were significant. Lesion size and ADC value were binarized with optimal cut-off values of 12 mm and 1.1 × 10−3 mm2/s, respectively. Multivariate logistic regression analysis showed that lesion size (≥12 mm or not), margin (circumscribed or not), kinetics (washout or not) and internal enhancement characteristics (IEC) (rim enhancement present or absent) significantly contributed to the diagnosis (P < 0.05). Using these four significant parameters, a decision tree was constructed to categorize lesions into detailed assessment categories/subcategories (Category 4A, 4B, 4C and 5).

    Conclusion: Lesion size is an independent contributor in diagnosing solitary breast masses. Adding the information of lesion size to BI-RADS-MRI 2013 descriptors will allow more detailed categorizations.

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  • Ryusuke Irie, Koji Kamagata, Aurelien Kerever, Ryo Ueda, Suguru Yokosa ...
    Article ID: mp.2017-0031
    [Advance publication] Released: December 07, 2017
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    Purpose: Diffusional kurtosis imaging (DKI) enables sensitive measurement of tissue microstructure by quantifying the non-Gaussian diffusion of water. Although DKI is widely applied in many situations, histological correlation with DKI analysis is lacking. The purpose of this study was to determine the relationship between DKI metrics and neurite density measured using confocal microscopy of a cleared mouse brain.

    Methods: One thy-1 yellow fluorescent protein 16 mouse was deeply anesthetized and perfusion fixation was performed. The brain was carefully dissected out and whole-brain MRI was performed using a 7T animal MRI system. DKI and diffusion tensor imaging (DTI) data were obtained. After the MRI scan, brain sections were prepared and then cleared using aminoalcohols (CUBIC). Confocal microscopy was performed using a two-photon confocal microscope with a laser. Forty-eight ROIs were set on the caudate putamen, seven ROIs on the anterior commissure, and seven ROIs on the ventral hippocampal commissure on the confocal microscopic image and a corresponding MR image. In each ROI, histological neurite density and the metrics of DKI and DTI were calculated. The correlations between diffusion metrics and neurite density were analyzed using Pearson correlation coefficient analysis.

    Results: Mean kurtosis (MK) (P = 5.2 × 10−9, r = 0.73) and radial kurtosis (P = 2.3 × 10−9, r = 0.74) strongly correlated with neurite density in the caudate putamen. The correlation between fractional anisotropy (FA) and neurite density was moderate (P = 0.0030, r = 0.42). In the anterior commissure and the ventral hippocampal commissure, neurite density and FA are very strongly correlated (P = 1.3 × 10−5, r = 0.90). MK in these areas were very high value and showed no significant correlation (P = 0.48).

    Conclusion: DKI accurately reflected neurite density in the area with crossing fibers, potentially allowing evaluation of complex microstructures.

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  • Atsushi Tachibana, Yasuhiko Tachibana, Jeff Kershaw, Hiromi Sano, Masa ...
    Article ID: mp.2017-0079
    [Advance publication] Released: December 05, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: The purpose of this study was to evaluate the suitability of two phantoms, one made of capillary plates and the other polyethylene fibers, for assessing the quality of diffusion tensor imaging (DTI).

    Methods: The first phantom was a stack of glass capillary plates with many parallel micropores (CP). The second phantom was a bundle of polyethylene fiber Dyneema held together with a thermal shrinkage tube (Dy). High resolution multi-shot echo planar imaging (EPI) DTI acquisitions were performed at b-values of 0 and 1000 s/mm2 and diffusion-times (Tdiff) of 37.7 and 97.7 ms on a preclinical 7T MRI scanner. Thirty diffusion-encoding directions were used. The data were used to calculate the fractional anisotropy (FA), mean diffusivity (MD), and angular dispersion (AD). Further acquisitions were performed at b-values from 0 to 8000 s/mm2 in 14 steps with the diffusion gradient applied parallel (axial) and perpendicular (radial) to the Z direction. On the other hand, the data acquired with a 3T MRI scanner were used to confirm that measurements on a clinical machine are consistent with the 7T MRI results.

    Results: The dependence of FA, MD and AD on Tdiff was smaller for the Dy than for the CPs. The b-value-dependent signal attenuations in the axial direction at Tdiff = 37.7 and 97.7 ms were similar for both phantoms. In the radial direction, Dy demonstrated similar b-value attenuation to that of in vivo tissue for both Tdiffs, but the attenuation for the CPs was affected by the change in Tdiff. Parameter estimates were similar for 3T and 7T MRI.

    Conclusion: The characteristics of the CP indicate that it can be used as a restricted-diffusion dominant phantom, while the characteristics of the Dy suggest that it can be used as a hindered-diffusion dominant phantom. Dy may be more suitable than CP for DTI quality control.

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  • Hiroyuki Uetani, Toshinori Hirai, Mika Kitajima, Minako Azuma, Shigeto ...
    Article ID: mp.2016-0098
    [Advance publication] Released: November 29, 2017
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    Introduction: We investigated the additive value of the 3T three-dimensional (3D) constructive interference in steady state (CISS) sequence to conventional magnetic resonance imaging (MRI) for the evaluation of spinal dural arteriovenous fistulae (SDAVF).

    Materials and Methods: We included 16 consecutive patients (15 men, 1 woman; age range 42–81 years; mean 64 years) with SDAVF who underwent 3T MRI and digital subtraction angiography (DSA) before treatment. Two neuroradiologists independently evaluated the presence of abnormal vessels on 3D CISS-, T2- and T1-weighted images (T1WI, T2WI), and contrast-enhanced T1WI using a 3-point grading system. Interobserver agreement was assessed by calculating the κ coefficient.

    Results: The SDAVF site was the cervical region in one patient, the thoracic region in 12 patients, the lumbar region in two, and the sacral region in one. For the visualization of abnormal vessels, the mean score was significantly higher for 3D CISS than the other sequences (P < 0.05). In 12 of 16 cases (75%) both readers made definite positive findings on additional 3D-CISS images. Interobserver agreement was excellent for 3D CISS images (κ = 1.0), good for T1WI (κ = 0.78; 95% confidence interval [CI] 0.54–1.00) and T2WI (κ = 0.74; 95% CI 0.48–1.00) and moderate for contrast-enhanced T1WI (CET1WI) (κ = 0.50; 95% CI 0.21–0.80).

    Conclusion: For the assessment of abnormal vessels of SDAVF, the 3T 3D CISS sequence adds value to conventional MRI.

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  • Satoshi Yatsushiro, Saeko Sunohara, Naokazu Hayashi, Akihiro Hirayama, ...
    Article ID: mp.2017-0014
    [Advance publication] Released: November 29, 2017
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    Purpose: A correlation mapping technique delineating delay time and maximum correlation for characterizing pulsatile cerebrospinal fluid (CSF) propagation was proposed. After proofing its technical concept, this technique was applied to healthy volunteers and idiopathic normal pressure hydrocephalus (iNPH) patients.

    Methods: A time-resolved three dimensional-phase contrast (3D-PC) sampled the cardiac-driven CSF velocity at 32 temporal points per cardiac period at each spatial location using retrospective cardiac gating. The proposed technique visualized distributions of propagation delay and correlation coefficient of the PC-based CSF velocity waveform with reference to a waveform at a particular point in the CSF space. The delay time was obtained as the amount of time-shift, giving the maximum correlation for the velocity waveform at an arbitrary location with that at the reference location. The validity and accuracy of the technique were confirmed in a flow phantom equipped with a cardiovascular pump. The technique was then applied to evaluate the intracranial CSF motions in young, healthy (N = 13), and elderly, healthy (N = 13) volunteers and iNPH patients (N = 13).

    Results: The phantom study demonstrated that root mean square error of the delay time was 2.27%, which was less than the temporal resolution of PC measurement used in this study (3.13% of a cardiac cycle). The human studies showed a significant difference (P < 0.01) in the mean correlation coefficient between the young, healthy group and the other two groups. A significant difference (P < 0.05) was also recognized in standard deviation of the correlation coefficients in intracranial CSF space among all groups. The result suggests that the CSF space compliance of iNPH patients was lower than that of healthy volunteers.

    Conclusion: The correlation mapping technique allowed us to visualize pulsatile CSF velocity wave propagations as still images. The technique may help to classify diseases related to CSF dynamics, such as iNPH.

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  • Kohsuke Kudo, Taisuke Harada, Hiroyuki Kameda, Ikuko Uwano, Fumio Yama ...
    Article ID: mp.2017-0094
    [Advance publication] Released: November 16, 2017
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    Purpose: The feasibility of steady-state sequences for 17O imaging was evaluated based on a kinetic analysis of the brain parenchyma and cerebrospinal fluid (CSF).

    Materials and Methods: The institutional review board approved this prospective study with written informed consent. Dynamic 2D or 3D steady-state sequences were performed in five and nine participants, respectively, with different parameters using a 3T scanner. During two consecutive dynamic scans, saline was intravenously administered for control purposes in the first scan, and 20% 17O-labeled water (1 mL/Kg) was administered in the second scan. Signal changes relative to the baseline were calculated, and kinetic analyses of the curves were conducted for all voxels. Region of interest analysis was performed in the brain parenchyma, choroid plexus, and CSF spaces.

    Results: Average signal drops were significantly larger in the 17O group than in the controls for most of the imaging parameters. Different kinetic parameters were observed between the brain parenchyma and CSF spaces. Average and maximum signal drops were significantly larger in the CSF spaces and choroid plexus than in the brain parenchyma. Bolus arrival, time to peak, and the first moment of dynamic curves of 17O in the CSF space were delayed compared to that in the brain parenchyma. Significant differences between the ventricle and subarachnoid space were also noted.

    Conclusion: Steady-state sequences are feasible for indirect 17O imaging with reasonable temporal resolution; this result is potentially important for the analysis of water kinetics and aquaporin function for several disorders.

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  • Haruomi Yamaguchi, Akira Uchino, Naoko Saito, Ichiro Deguchi, Masaki T ...
    Article ID: ci.2017-0089
    [Advance publication] Released: November 13, 2017
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  • Christina Andica, Masaaki Hori, Kouhei Kamiya, Saori Koshino, Akifumi ...
    Article ID: cr.2017-0111
    [Advance publication] Released: November 13, 2017
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    We report two cases of pathologically proven intracranial epidermoid cysts. Both cases were scanned with diffusion-weighted imaging using pulsed gradient spin-echo (PGSE) and oscillating gradient spin-echo (OGSE; 50 Hz) prototype sequences with diffusion times of 47.3 ms and 8.5 ms, respectively. The apparent diffusion coefficient measured by OGSE was higher than that measured by PGSE, indicating the spatial restriction of water diffusion in the laminated keratin layers within the cyst as demonstrated by histopathology.

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  • Hidehiro Watanabe, Nobuhiro Takaya
    Article ID: mp.2017-0062
    [Advance publication] Released: November 08, 2017
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    Purpose: The quantitation accuracy in proton magnetic resonance spectroscopy (1H MRS) improves at higher B0 field. However, a larger chemical shift displacement (CSD) and stronger B1 inhomogeneity exist. In this work, we evaluate the quantitation accuracy for the spectra of metabolite mixtures in phantom experiments at 4.7T. We demonstrate a position-dependent error in quantitation and propose a correction method by measuring water signals.

    Materials and Methods: All experiments were conducted on a whole-body 4.7T magnetic resonance (MR) system with a quadrature volume coil for transmission and reception. We arranged three bottles filled with metabolite solutions of N-acetyl aspartate (NAA) and creatine (Cr) in a vertical row inside a cylindrical phantom filled with water. Peak areas of three singlets of NAA and Cr were measured on three 1H spectra at three volume of interests (VOIs) inside three bottles. We also measured a series of water spectra with a shifted carrier frequency and measured a reception sensitivity map.

    Results: The ratios of NAA and Cr at 3.92 ppm to Cr at 3.01 ppm differed amongst the three VOIs in peak area, which leads to a position-dependent error. The nature of slope depicting the relationship between peak areas and the shifted values of frequency was like that between the reception sensitivities and displacement at every VOI.

    Conclusion: CSD and inhomogeneity of reception sensitivity cause amplitude modulation along the direction of chemical shift on the spectra, resulting in a quantitation error. This error may be more significant at higher B0 field where CSD and B1 inhomogeneity are more severe. This error may also occur in reception using a surface coil having inhomogeneous B1. Since this type of error is around a few percent, the data should be analyzed with greater attention while discussing small differences in the studies of 1H MRS.

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  • Mohamed Jarraya, Luis E. Diaz, Frank W. Roemer, William F. Arndt, Ajay ...
    Article ID: rev.2017-0063
    [Advance publication] Released: October 10, 2017
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    Peripatellar fat pads are intracapsular extrasynovial adipose cushions that accommodate the changing shape and volume of articular spaces during movement. Variations in bone geometry, passive and active stabilization mechanisms and/or functional demands may lead to peripatellar fat pad abnormalities. While peripatellar fat pads may be affected a variety of conditions such as synovial inflammation, tumor and fibrosis, a mechanical origin should also be considered. Commonly, the clinical term “impingement” is used synonymously in the radiological literature to refer to three distinct entities of structural peripatellar fat pad abnormalities: superolateral the infrapatellar fat pad (Hoffa fat pad) edema, suprapatellar fat pad edema, and prepatellar fat pad edema, implying a mechanical origin of these conditions. The aim of this pictorial review is to describe the normal anatomy of the extensor mechanism of the knee, and discuss the relation of patellofemoral maltracking to the above-mentioned peripatellar fat pad conditions based on current evidence.

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  • Yasuhisa Kurata, Aki Kido, Yusaku Moribata, Kyoko Kameyama, Sachiko Mi ...
    Article ID: mp.2017-0055
    [Advance publication] Released: October 06, 2017
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    Purpose: Seromucinous borderline tumor (SMBT) is a newly categorized ovarian tumor in the 2014 revised World Health Organization (WHO) classification. SMBT is similar to serous borderline tumor (SBT) on magnetic resonance imaging (MRI) reflecting their pathological findings. This study was conducted to demonstrate the usefulness of MRI findings and quantitative values for differentiating SMBT from SBT.

    Methods: This retrospective study examined 23 lesions (20 patients) from SMBT and 26 lesions (22 patients) from SBT. The following quantitative values were evaluated using receiver-operating characteristics analysis: overall and solid portion sizes, intracystic fluid signal intensity (SI) ratio compared with skeletal muscle on T1weighted image (T1WI) and T2weighted image (T2WI), contrast enhancement (CE) ratio, and mean and minimum apparent diffusion coefficient values of the solid portion. Two radiologists evaluated the prevalence of MRI finding characteristics of SMBT and SBT. The SI of the intracystic fluid on T1WI and T2WI and the association with endometriosis were evaluated visually.

    Results: The CE ratio was significantly higher in SBT (P = 0.007). It achieved the highest area under the curve (AUC) (0.739). The fluid SI ratio on T1WI was higher in SMBT (P = 0.036, AUC = 0.676). Exophytic growth of the solid portion was observed only in SBT (P = 0.011). Intracystic fluid SI of SMBT was higher on T1WI and lower on T2WI in visual evaluation (P = 0.008 and 0.007, respectively). Findings suggesting endometriosis were observed more frequently in SMBT patients (P = 0.019).

    Conclusion: Higher CE ratio of the solid portion and exophytic growth were findings suggesting SBT. Higher intracystic fluid SI on T1WI and lower SI on T2WI suggested SMBT. MRI findings suggesting endometriosis favored the diagnosis of SMBT.

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  • Toshitada Hiraka, Masafumi Kanoto, Yuki Toyoguchi, Ryousuke Igari, Tak ...
    Article ID: ci.2017-0043
    [Advance publication] Released: October 03, 2017
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  • Minako Maruyama, Takeshi Yoshizako, Rika Yoshida, Noriyoshi Ishikawa, ...
    Article ID: ci.2017-0067
    [Advance publication] Released: September 29, 2017
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  • Shinji Naganawa, Toshiaki Taoka, Hisashi Kawai, Masahiro Yamazaki, Koj ...
    Article ID: mp.2017-0088
    [Advance publication] Released: September 29, 2017
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    Purpose: Circumventricular organs (CVOs) lack a blood brain barrier and are also called “brain windows”. Among CVOs, the organum vasculosum of the lamina terminalis (OVLT) is an osmotic regulator involved in the release of vasopressin. In a previous study of healthy subjects, it was reported that contrast enhancement in the OVLT can be recognized in only 34% of 3 Tesla thin slice contrast-enhanced T1-weighted images. The purpose of this study was to evaluate the leakage of gadolinium contrast from the OVLT in healthy subjects using heavily T2-weighted three dimensional-fluid attenuated inversion recovery (3D-FLAIR) (HF) imaging.

    Methods: Eight healthy male subjects were included in this study. A standard dose (0.1 mmol/kg) of gadoteridol was intravenously administered. magnetic resonance cisternography (MRC) and HF were obtained before and 0.5, 1.5, 3, 4.5 and 6 h after the injection. Enhancement of the OVLT including the surrounding cerebral spinal fluid (CSF) was measured by manually drawing a rectangular region of interest (ROI) centered on the OVLT. The ROI was copied to the HF image and the signal intensity was measured. The signal intensity ratio (SIR) was obtained by dividing the signal intensity value of the OVLT ROI by that of the midbrain.

    Results: The differences between the mean SIR at pre-contrast and those at 0.5, 1.5, 3, 4.5, and 6 h were significant (P < 0.05). The mean SIR at 0.5 h was higher than those at all other time points (P < 0.05).

    Conclusion: Using HF imaging, enhancement around the OVLT was observed in all subjects at 0.5 h after intravenous administration of single dose gadoteridol.

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  • Shuhei Shibukawa, Tosiaki Miyati, Tetsu Niwa, Mitsunori Matsumae, Tets ...
    Article ID: tn.2017-0032
    [Advance publication] Released: August 24, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    We assessed labeling region selectivity on time-spatial labeling inversion pulse (Time-SLIP) with pencil beam pulse (PB Time-SLIP) for the use of visualizing cerebrospinal fluid (CSF) flow dynamics. We compared the selectivity of labeling to the third and fourth ventricles between PB Time-SLIP and conventional Time-SLIP (cTime-SLIP) in eight volunteers and one patient using a 1.5T magnetic resonance imaging (MRI). PB Time-SLIP provided more selective labeling in CSF than cTime-SLIP, particularly in complex anatomical regions.

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  • Yasuhito Tanase, Ryuji Kawaguchi, Junko Takahama, Hiroshi Kobayashi
    Article ID: mp.2016-0149
    [Advance publication] Released: August 21, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: Mural nodules and papillary projections can be seen in benign ovarian endometriosis (OE) and malignant transformation of OE (endometriosis-associated ovarian cancer [EAOC]), which can pose a challenging diagnostic dilemma to clinicians. We identify the preoperative imaging characteristics helpful to the differential diagnosis between benign OE with mural nodules and EAOC.

    Materials and Methods: This was a retrospective study of 82 patients who were diagnosed pathologically to have OE with mural nodules (n = 42) and malignant transformations of these tumors (n = 40) at the Nara Medical University Hospital from January 2008 to January 2015. All patients were assessed with contrast-enhanced magnetic resonance imaging (MRI) before surgery. Patient demographics, and clinical and pathologic features were analyzed to detect the significant differences between the two groups.

    Results: Histological examinations of resected OE tissue specimens revealed that a majority (78.6%) of the mural nodular lesions were retracted blood clots. We found that the patients with malignant mural nodules, when compared to those with benign nodules, were older, had larger cyst diameters and larger mural nodule sizes, and were more likely to exhibit a taller than wider lesion. They were also more likely to present with various signal intensities on T1-weighted images (T1WI), high-signal intensity on T2-weighted images (T2WI), a lower proportion of shading on T2WI, and were more likely to show an anterior location of the cyst. In the multivariate logistic regression analysis, “Height” (>1.5 cm) and “Height-Width ratio (HWR)” (>0.9) of mural nodules, maximum diameter of the cyst (>7.9 cm), and age at diagnosis (>43 years) were independent predictors to distinguish EAOC from OE with mural nodules.

    Conclusion: The “Height” and “HWR” of the mural nodules in the cyst may yield a novel potential diagnostic factor for differentiating EAOC from benign OE with mural nodules.

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  • Hisao Nakamura, Masatomo Doi, Takuya Suzuki, Yasuyuki Yoshida, Masahir ...
    Article ID: mp.2017-0042
    [Advance publication] Released: August 16, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: 1H-MRS is a non-invasive technique used to assess the metabolic activity of brain tumors. The technique is useful for the preoperative prediction of tumor grade, which is important for treatment planning and accurate prognosis. We used 1H-MRS to study the lactate peak, which appears in various conditions, including hyperglycemia, ischemia, and hypoxia and lipid peak, which is associated with necrotic cells. The purpose of this study was to retrospectively examine the frequency and significance of lactate and lipid peaks in relation to brain tumor grade.

    Materials and Methods: Fifty-five patients diagnosed with neuroepithelial tumors of Grades I (3 cases), II (11 cases), III (15 cases), and IV (26 cases) were enrolled. Biopsies were excluded. Single voxel (echo time [TE] = 144 ms) point resolved 1H-MRS spectroscopy sequences were retrospectively analyzed. An inverted doublet peak at 1.3 ppm was defined as lactate, a negative and positive peak was defined as combined lactate and lipid, and a clear upward peak was defined as lipid.

    Results: Lactate peaks were detected in all grades of brain tumors and were least common in Grade II tumors (9.1%). The frequency of combined lactate-lipid peaks was 0% (Grades I and II), 8.3% (Grade III), and 44% (Grade IV). Grade IV tumors were significantly different to the other grades. There were three cases with a lipid peak. All were glioblastoma.

    Conclusions: The presence of a lac peak may be useful to largely rule out the Grade II tumors, and allow the subsequent differentiation of Grade I tumors from Grade III or IV tumors by conventional imaging. The presence of a lipid peak may be associated with Grade IV tumors.

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  • Shintaro Ichikawa, Utaroh Motosugi, Diego Hernando, Hiroyuki Morisaka, ...
    Article ID: mp.2017-0047
    [Advance publication] Released: August 16, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: To compare the abilities of three intravoxel incoherent motion (IVIM) imaging approximation methods to discriminate the histological grade of hepatocellular carcinomas (HCCs).

    Methods: Fifty-eight patients (60 HCCs) underwent IVIM imaging with 11 b-values (0–1000 s/mm2). Slow (D) and fast diffusion coefficients (D*) and the perfusion fraction (f) were calculated for the HCCs using the mean signal intensities in regions of interest drawn by two radiologists. Three approximation methods were used. First, all three parameters were obtained simultaneously using non-linear fitting (method A). Second, D was obtained using linear fitting (b = 500 and 1000), followed by non-linear fitting for D* and f (method B). Third, D was obtained by linear fitting, f was obtained using the regression line intersection and signals at b = 0, and non-linear fitting was used for D* (method C). A receiver operating characteristic analysis was performed to reveal the abilities of these methods to distinguish poorly-differentiated from well-to-moderately-differentiated HCCs. Inter-reader agreements were assessed using intraclass correlation coefficients (ICCs).

    Results: The measurements of D, D*, and f in methods B and C (Az-value, 0.658–0.881) had better discrimination abilities than did those in method A (Az-value, 0.527–0.607). The ICCs of D and f were good to excellent (0.639–0.835) with all methods. The ICCs of D* were moderate with methods B (0.580) and C (0.463) and good with method A (0.705).

    Conclusion: The IVIM parameters may vary depending on the fitting methods, and therefore, further technical refinement may be needed.

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  • Shintaro Ichikawa, Utaroh Motosugi, Akihiro Okumura, Tatsuya Shimizu, ...
    Article ID: tn.2017-0056
    [Advance publication] Released: August 16, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    We measured the changes in the cerebrospinal fluid (CSF) flow dynamics after compression of the bilateral jugular veins using phase contrast-magnetic resonance imaging (PC-MRI). PC-MRI was performed in 10 healthy male volunteers using a 3T clinical scanner with a two-dimensional gradient echo sequence. We successfully measured the changes in CSF flow velocity using PC-MRI with and without compression of the bilateral jugular veins. The relative velocity range decreased by about 30% when the bilateral jugular veins were compressed.

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  • Yuji Iyama, Takeshi Nakaura, Yasunori Nagayama, Seitaro Oda, Daisuke U ...
    Article ID: mp.2017-0037
    [Advance publication] Released: June 26, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: We investigated the feasibility of single breath hold unenhanced coronary magnetic resonance angiography (MRA) using multi-shot gradient echo planar imaging (MSG-EPI) on a 3T-scanner.

    Methods: Fourteen volunteers underwent single breath hold coronary MRA with a MSG-EPI and free-breathing turbo field echo (TFE) coronary MRA at 3T. The acquisition time, signal to noise ratio (SNR), and the contrast of the sequences were compared with the paired t-test. Readers evaluated the image contrast, noise, sharpness, artifacts, and the overall image quality.

    Results: The acquisition time was 88.1% shorter for MSG-EPI than TFE (24.7 ± 2.5 vs 206.4 ± 23.1 sec, P < 0.01). The SNR was significantly higher on MSG-EPI than TFE scans (P < 0.01). There was no significant difference in the contrast on MSG-EPI and TFE scans (1.8 ± 0.3 vs 1.9 ± 0.3, P = 0.24). There was no significant difference in image contrast, image sharpness, and overall image quality between two scan techniques. The score of image noise and artifact were significantly higher on MSG-EPI than TFE scans (P < 0.05).

    Conclusion: The single breath hold MSG-EPI sequence is a promising technique for shortening the scan time and for preserving the image quality of unenhanced whole heart coronary MRA on a 3T scanner.

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  • Fang Yuan, Bin Song, Zixing Huang, Xijiao Liu, Chunchao Xia
    Article ID: mp.2016-0139
    [Advance publication] Released: June 16, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: To assess the feasibility of using oxygen and glucose as stimulating agents in blood-oxygen-level-dependent (BOLD) Functional Magnetic Resonance Imaging (fMRI) of rabbit liver and analyze the impacts by blood flow.

    Methods: Pure oxygen inhalation, intravenous injection and oral administration of glucose were given to 11 New Zealand white rabbits to compare the differences of liver T2*, aortic flow (AF), portal vein flow (PVF), aortic area (AA) and portal vein area (PVA) before and at 5 min, 10 min, 20 min, 30 min after administrations. AF and PVF were acquired by two dimensional (2D) Phase Contrast MR (2D-PCMR). The impacts of AF and PVF upon BOLD fMRI were analyzed.

    Results: AF and PVF declined at 5 min after oxygen inhalation and were significantly different from baseline, then reverted to baseline. No significant difference was observed in liver T2*, AA and PVA before and after oxygen inhalation. AF, PVF, AA and PVA showed no significant difference before and after glucose intravenous injection, while liver T2* increased gradually with significant difference. AF and liver T2* were significantly different before and after glucose oral administration and increased gradually, AA was significantly different before and after glucose administration at 10 min and 20 min. PVF and PVA started to be different from baseline at 10 min. Greatest variation of T2* (19.6%) was induced by glucose oral administration after 30 min.

    Conclusion: Rabbit liver T2* increasing by glucose intravenous injection is possibly associated with glycogen synthesis, provides the possibility to evaluate liver function. Glucose oral administration demonstrated an optimal comparative effect of raising T2*, however, resulted from the superposition of increased glycogen synthesis and blood flow. Inhalation of pure oxygen didn’t alter the rabbit liver T2*, which may possibly result from an offset between the increased concentration of oxyhemoglobin and decreased blood flow.

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  • Yuki Arita, Hirokazu Fujiwara, Jun Kurasawa, Suketaka Momoshima, Tsuba ...
    Article ID: ci.2017-0057
    [Advance publication] Released: June 08, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
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  • Yutaka Shigenaga, Masato Sasaki, Takeshi Ishimoto, Keiko Ama
    Article ID: cr.2017-0002
    [Advance publication] Released: May 24, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    The sequence for concurrently depicting engulfed vessels and a well-enhanced tumor in once-off scanning has never been reported for preoperative magnetic resonance imaging for brain tumor resection. Multimodal fusion techniques have been recently developed, but the risks of misregistration still remain. Here a case is reported where contrast-enhanced three-dimensional phase contrast sequence concurrently depicted an engulfed vessel and metastatic brain tumor in once-off scanning and related technical aspects are discussed.

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  • Keita Kuya, Yuki Shinohara, Hiroki Yoshioka, Satoshi Kuwamoto, Masamic ...
    Article ID: ci.2017-0025
    [Advance publication] Released: May 22, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
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  • Koichi Ito, Yumiko Oishi Tanaka, Ryosuke Watanabe, Hiroko Tanaka, Yuta ...
    Article ID: ci.2016-0135
    [Advance publication] Released: May 18, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
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  • Nao Kodama, Ayana Setoi, Katsumi Kose
    Article ID: tn.2016-0049
    [Advance publication] Released: March 27, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Spiral magnetic resonance imaging (MRI) sequences were developed for a 9.4T vertical standard bore (54 mm) superconducting magnet using unshielded and self-shielded gradient coils. Clear spiral images with 64-shot scan were obtained with the self-shielded gradient coil, but severe shading artifacts were observed for the spiral-scan images acquired with the unshielded gradient coil. This shading artifact was successfully corrected with a phase-correction technique using reference scans that we developed based on eddy current field measurements. We therefore concluded that spiral imaging sequences can be installed even for unshielded gradient coils if phase corrections are performed using the reference scans.

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