Magnetic Resonance in Medical Sciences
Online ISSN : 1880-2206
Print ISSN : 1347-3182
Advance online publication
Showing 1-34 articles out of 34 articles from Advance online publication
  • Yasuo Amano, Ryo Takagi, Fumi Yanagisawa, Chisato Ando
    Article ID: ci.2018-0046
    Published: 2018
    [Advance publication] Released: July 20, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
    Download PDF (2566K)
  • Takayuki Tamura, Miyuki Takasu, Toru Higaki, Kazushi Yokomachi, Yuji A ...
    Article ID: mp.2018-0011
    Published: 2018
    [Advance publication] Released: July 13, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: The aim of this study was to compare the tumor conspicuity on actual measured diffusion-weighted images (aDWIs) and computed DWI (cDWI) of human breast tumors and to examine, by use of a phantom, whether cDWI improves their conspicuity.

    Materials and Methods: We acquired DWIs (b-value 0, 700, 1400, 2100, 2800, and 3500 s/mm2) of 148 women with breast tumors. cDWIs with b-values of 1400, 2100, 2800, and 3500 s/mm2 were calculated from aDWI scans where b = 0 and 700 s/mm2; the tumor signal-to-noise ratio (SNR) was compared at each b-value. We also subjected a phantom harboring a breast tumor and mammary glands to DWI. For reference we used two models. The model with b = 0, 1000, 1500, 2000, 2500, and 3000 s/mm2 was our multiple b-value model. In the single b-value model, we applied b = 0 and 1000 s/mm2 and changed the number of excitations (NEX). cDWIs were generated at b = 0 and 1000 and used to compare the SNR, the contrast ratio (CR), and the contrast-to-noise ratio (CNR).

    Results: In the phantom study, the CNR of cDWI generated from high SNR images obtained at lower b-values and a high NEX was outperformed aDWI. However, the CR and CNR on cDWI obtained using the same scanning parameters were inferior to aDWI scans. Similarly, in the clinical study, breast tumor conspicuity was worse on high b-value cDWIs than aDWIs.

    Conclusion: To improve tumor conspicuity on cDWI, the quality of the source images must be improved. It may easily cause inferior conspicuity to aDWIs if high b-value cDWIs were generated from insufficient SNR images.

    Download PDF (3580K)
  • Koung Mi Kang, Seung Hong Choi, Hyeonjin Kim, Moonjung Hwang, Roh-Eul ...
    Article ID: mp.2018-0010
    Published: 2018
    [Advance publication] Released: July 06, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: The purpose of our study was to investigate the effect of different slice thicknesses and/or interslice gaps on longitudinal and transverse relaxation times (T1 and T2) measured by a multi-dynamic, multi-echo (MDME) sequence.

    Materials and Methods: This retrospective study included nine healthy subjects who underwent MDME sequence (at 3T) with four different combinations of slice thicknesses and/or interslice gaps: slice thickness of 4 mm and interslice gap of 0 mm (TH4/G0), TH4/G1, TH5/G0, and TH5/G1. T1 and T2 were measured in various brain regions by a qualified neuroradiologist with 8 years of clinical experience: the frontal white matter (WM), occipital WM, genu, splenium, frontal cortex, thalamus, putamen, caudate head, and cerebrospinal fluid (CSF). The paired samples t-test was used to investigate the effect of different slice thicknesses and interslice gaps (TH4/G0 versus TH4/G1 and TH5/G0 versus TH5/G1). P < 0.013 was considered statistically significant.

    Results: T2 in all brain regions and T1 in the frontal WM, putamen, and CSF did not significantly change for different slice thicknesses and/or gaps (Ps > 0.013). In addition, T1 in all brain regions of interest did not significantly change between TH4/G0, TH4/G1, TH5/G0 and TH5/G1. However, T1 in some of the brain regions was higher with TH4/G0 than with TH5/G0 (occipital WM, frontal cortex, and caudate head) and with TH4/G1 than with TH5/G1 (occipital WM, genu, splenium and thalamus, all Ps < 0.013).

    Conclusion: T2 estimated using the MDME sequence was stable regardless of slice thickness or gap. Although the sequence seems to provide stable relaxation values, identical slice thicknesses need to be used for follow-up to prevent potential T1 changes.

    Download PDF (3732K)
  • Masashi Suzuki, Atsushi Senoo, Mamoru Niitsu
    Article ID: mp.2017-0175
    Published: 2018
    [Advance publication] Released: June 13, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: To improve imaging, a reliable setup method is critical for the accurate localization of lesions and surface markers. Because an anisotropic marker has not yet been validated for MRI, direct localization of surface markers is not yet feasible in fractional anisotropy (FA) maps. This study aimed to develop an anisotropic surface marker using wood for an FA map and to determine whether a wood marker is useful for various sequences.

    Methods: Wood infiltrated with water was used to develop an anisotropic surface marker. The wood marker was compared with phantoms composed of clinically available markers, including MR-SPOTS Packets (Beekley Medical, Bristol, CT, USA), Breath Care Oral Refreshing Capsules (Kobayashi Pharmaceutical Co., Ltd., Osaka, Japan), and baby oil (Johnson & Johnson, New Brunswick, NJ, USA). Magnetic resonance images were acquired using the Achieva 3T TX MRI System (Philips HealthCare, Best, Netherlands) equipped with a QD head coil including T1- and T2-weighted imaging, proton-density-weighted imaging, T2*-weighted imaging, T1-weighted imaging spectral pre-saturation with inversion recovery, T2-weighted imaging spectral attenuated inversion recovery, proton-density-weighted imaging spectral attenuated inversion recovery, diffusion weighted imaging, and diffusion tensor imaging. Apparent diffusion coefficient, FA values, and signal-to-noise ratio (SNR) were measured and recorded, and the coefficient of variation was calculated for two consecutive imaging scans. The wood was observed using a microscope.

    Results: Breath Care Oral Refreshing Capsules and baby oil were not observed in the FA map. The FA value of the MR-SPOTS Packets was 0.18. The FA value of the wood marker was 0.80. The coefficient of variation of the MR-SPOTS Packets and the wood marker were 0.0263 and 0.0013, respectively, in the FA map. Microscopic observation revealed a wood anisotropic structure.

    Conclusion: The wood maker enabled direct localization in the FA map. Hence, wood markers may be useful to radiologists and contribute to obtaining useful findings.

    Download PDF (3283K)
  • Shixing Bao, Yoshiyuki Watanabe, Hiroto Takahashi, Hisashi Tanaka, Ats ...
    Article ID: mp.2017-0135
    Published: 2018
    [Advance publication] Released: May 31, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: This study aimed to determine whether whole-tumor histogram analysis of normalized cerebral blood volume (nCBV) and apparent diffusion coefficient (ADC) for contrast-enhancing lesions can be used to differentiate between glioblastoma (GBM) and primary central nervous system lymphoma (PCNSL).

    Methods: From 20 patients, 9 with PCNSL and 11 with GBM without any hemorrhagic lesions, underwent MRI, including diffusion-weighted imaging and dynamic susceptibility contrast perfusion-weighted imaging before surgery. Histogram analysis of nCBV and ADC from whole-tumor voxels in contrast-enhancing lesions was performed. An unpaired t-test was used to compare the mean values for each type of tumor. A multivariate logistic regression model (LRM) was performed to classify GBM and PCNSL using the best parameters of ADC and nCBV.

    Results: All nCBV histogram parameters of GBMs were larger than those of PCNSLs, but only average nCBV was statistically significant after Bonferroni correction. Meanwhile, ADC histogram parameters were also larger in GBM compared to those in PCNSL, but these differences were not statistically significant. According to receiver operating characteristic curve analysis, the nCBV average and ADC 25th percentile demonstrated the largest area under the curve with values of 0.869 and 0.838, respectively. The LRM combining these two parameters differentiated between GBM and PCNSL with a higher area under the curve value (Logit (P) = −21.12 + 10.00 × ADC 25th percentile (10−3 mm2/s) + 5.420 × nCBV mean, P < 0.001).

    Conclusion: Our results suggest that whole-tumor histogram analysis of nCBV and ADC combined can be a valuable objective diagnostic method for differentiating between GBM and PCNSL.

    Download PDF (3382K)
  • Huai Wu Yuan, Ren Jie Ji, An Li Wang, Ya Jie Lin, Han Feng Chen, Zi Qi ...
    Article ID: mp.2018-0001
    Published: 2018
    [Advance publication] Released: May 31, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: To verify whether a new grading based on time-of-flight magnetic resonance angiography source images (TOF-MRAsi) can reflect the abundance of pial collaterals, in patients with total occlusion of M1 segment of middle cerebral artery in the chronic stage.

    Methods: In this single-center retrospective study, consecutive patients with total occlusion of M1 segment of middle cerebral artery, with both magnetic resonances angiography and digital subtraction angiography image were included. Time-of-flight magnetic resonance angiography source images were evaluated in a blinded fashion for pial collaterals (PCs) that were graded on a four-point scale. Good and poor PCs were defined as TOF-MRAsis grade <2 and ≥2, respectively. Receiver operating characteristic curve analysis was done to calculate the area under curve, sensitivity, and specificity.

    Results: A total of 26 patients were included. The inter-reader agreement for time TOF-MRAsi and digital subtraction angiography images were 0.930 and 0.843, respectively. Compared with digital subtraction angiography grading, the area under curve of pial collateral grading based on TOF-MRAsi was 0.830 (0.636–1.000; P = 0.006). The sensitivity and specificity were 0.700 and 0.933, respectively. The modified Rankin Scale at follow-up was lower in patients with good PCs than in those with poor PCs (0[0, 1] vs. 1[1, 3], P = 0.055), although statistical significance was not reached.

    Conclusion: The grading scale based on TOF-MRAsi could be a new empirical approach for pial collateral evaluation. The clinical use of the proposed approach for identifying patients with total occlusion of middle cerebral artery with a high risk of poor outcome requires evaluation in further studies.

    Download PDF (3492K)
  • Mayumi Takeuchi, Kenji Matsuzaki, Yoshimi Bando, Masato Nishimura, Aki ...
    Article ID: ci.2017-0177
    Published: 2018
    [Advance publication] Released: May 24, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
    Download PDF (2455K)
  • Masahiro Yamada, Toshiaki Taoka, Ai Kawaguchi, Kenji Yasuda, Yasushi N ...
    Article ID: mp.2017-0172
    Published: 2018
    [Advance publication] Released: May 24, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: Gadobutrol is a gadolinium-based contrast material (GBCM) with a high concentration of gadolinium and high relaxivity. Our purpose was to evaluate the signal intensity profiles in brain tissue for the bolus width and degree of signal change after bolus injection using an echo planar dynamic susceptibility contrast (DSC) sequence. We compared gadobutrol to gadoteridol using various injection speeds and saline flush volumes.

    Methods: We studied 97 patients who underwent brain MRI. Datasets for perfusion studies were acquired using a 3T scanner with an echo planar imaging (EPI) sequence. The injection protocols were set up with combinations of injection speed and saline flush volume for both gadobutrol and gadoteridol. The full width at half maximum (FWHM) and the maximum signal change ratio (SCRmax) of the time intensity curves were measured.

    Results: The FWHM did not show a statistically significant difference according to injection speed, flush volume, or type of GBCM. The SCRmax showed a greater change with a faster injection speed, larger saline flush, and gadobutrol administration. The difference between gadobutrol and gadoteridol became smaller with a faster injection speed and a larger saline flush.

    Conclusion: The maximum signal drop was larger with gadobutrol when the injection speed was slow and the saline flush was small. Thus, gadobutrol may be useful to obtain a better profile for DSC perfusion MRI in conditions requiring a slower injection speed and/or a smaller volume of saline flush.

    Download PDF (2705K)
  • Yuta Kobayashi, Yasuhiko Terada
    Article ID: tn.2018-0027
    Published: 2018
    [Advance publication] Released: May 24, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Magnetic resonance fingerprinting (MRF) is a promising framework that allows the quantification of multiple magnetic resonance parameters with a single scan. MRF using fast imaging with steady-state precession (MRF-FISP) has robustness to off-resonance artifacts and has many applications in inhomogeneous fields. However, the spoiler gradient used in MRF-FISP is sensitive to diffusion motion, and may lead to quantification errors when the spoiler moment increases. In this study, we examined the effect of the diffusion weighting in MRF-FISP caused by spoiler gradients. The T2 relaxation times were greatly underestimated when large spoiler moments were used. The T2 underestimation was prominent for tissues with large values of T2 and diffusion coefficients. The T2 bias was almost independent of the apparent diffusion coefficient (ADC) and T2 values when the ADC map was measured and incorporated into the matching process. These results reveal that the T2 underestimation resulted from the diffusion weighting caused by the spoiler gradients.

    Download PDF (6622K)
  • Akira Kunimatsu, Natsuko Kunimatsu, Koichiro Yasaka, Hiroyuki Akai, Ko ...
    Article ID: mp.2017-0178
    Published: 2018
    [Advance publication] Released: May 16, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: Although advanced MRI techniques are increasingly available, imaging differentiation between glioblastoma and primary central nervous system lymphoma (PCNSL) is sometimes confusing. We aimed to evaluate the performance of image classification by support vector machine, a method of traditional machine learning, using texture features computed from contrast-enhanced T1-weighted images.

    Methods: This retrospective study on preoperative brain tumor MRI included 76 consecutives, initially treated patients with glioblastoma (n = 55) or PCNSL (n = 21) from one institution, consisting of independent training group (n = 60: 44 glioblastomas and 16 PCNSLs) and test group (n = 16: 11 glioblastomas and 5 PCNSLs) sequentially separated by time periods. A total set of 67 texture features was computed on routine contrast-enhanced T1-weighted images of the training group, and the top four most discriminating features were selected as input variables to train support vector machine classifiers. These features were then evaluated on the test group with subsequent image classification.

    Results: The area under the receiver operating characteristic curves on the training data was calculated at 0.99 (95% confidence interval [CI]: 0.96–1.00) for the classifier with a Gaussian kernel and 0.87 (95% CI: 0.77–0.95) for the classifier with a linear kernel. On the test data, both of the classifiers showed prediction accuracy of 75% (12/16) of the test images.

    Conclusions: Although further improvement is needed, our preliminary results suggest that machine learning-based image classification may provide complementary diagnostic information on routine brain MRI.

    Download PDF (2878K)
  • Ayana Setoi, Katsumi Kose
    Article ID: tn.2017-0170
    Published: 2018
    [Advance publication] Released: May 16, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    We developed ultrashort echo-time (UTE) imaging sequences with 3D Cones trajectories for a home-built compact MRI system using a 1.5T superconducting magnet and an unshielded gradient coil set. We achieved less than 7 min imaging time and obtained clear in vivo images of a human forearm with a TE of 0.4 ms. We concluded that UTE imaging using 3D Cones acquisition was successfully implemented in our 1.5T MRI system.

    Download PDF (5049K)
  • Takumi Yokohama, Motoyuki Iwasaki, Daisuke Oura, Sho Furuya, Tomoyuki ...
    Article ID: mp.2017-0078
    Published: 2018
    [Advance publication] Released: March 23, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: To compare the accuracy of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values between reduced FOV or so-called zonally oblique multislice (ZOOM) and conventional diffusion tensor imaging (DTI) in the cervical spinal cord.

    Methods: Both ZOOM and conventional DTI were performed on 10 healthy volunteers. Intraclass correlation coefficient (ICC) was used to evaluate the reliability of the measurements obtained. Four radiologists evaluated the FA and ADC values at each cervical cord level and classified the visibility by 4 ranks. The geometric distortion ratios of the long axis and short axis were compared between ZOOM and conventional DTI. The imaging parameters were as follows: b-value = 600 s/mm2; TR = 4500 ms; TE = 81 ms; FOV = 70 × 47 mm2 / 200 × 200 mm2; matrix = 80 × 51 / 128 × 126 (ZOOM and conventional DTI, respectively). The region of interest was carefully drawn inside the spinal cord margin to exclude the spinal cord component, without excluding the white matter fiber tracts.

    Results: The average FA value decreased in both ZOOM and conventional DTI in lower spinal cord levels; in contrast, the ADC value increased in lower spinal cord levels. Zonally oblique multislice DTI was superior to conventional DTI with regard to inter-rater and intra-rater reliability; further, visibility was better and the standard deviation was smaller in ZOOM DTI. On both the long and short axis, the geometric distortion ratio was lower in ZOOM DTI at all cervical spinal cord levels compared with the conventional DTI. There was a significant difference in the distortion ratios of the long and short axis between ZOOM and conventional DTI.

    Conclusion: Conventional DTI is unreliable owing to its susceptibility to the surrounding magnetic field. ZOOM DTI is reliable for performing highly accurate evaluations.

    Download PDF (4051K)
  • Tomonori Kanda
    Article ID: e.2017-0176
    Published: 2018
    [Advance publication] Released: March 16, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
    Download PDF (2286K)
  • Manisha Bohara, Kiyohisa Kamimura, Masanori Nakajo, Tomohide Yoneyama, ...
    Article ID: ci.2017-0160
    Published: 2018
    [Advance publication] Released: March 13, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
    Download PDF (2660K)
  • Hidenori Takeshima, Kanako Saitoh, Shuhei Nitta, Taichiro Shiodera, To ...
    Article ID: mp.2017-0132
    Published: 2018
    [Advance publication] Released: March 13, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: Dynamic MR techniques, such as cardiac cine imaging, benefit from shorter acquisition times. The goal of the present study was to develop a method that achieves short acquisition times, while maintaining a cost-effective reconstruction, for dynamic MRI. kt sensitivity encoding (SENSE) was identified as the base method to be enhanced meeting these two requirements.

    Methods: The proposed method achieves a reduction in acquisition time by estimating the spatiotemporal (xf) sensitivity without requiring the acquisition of the alias-free signals, typical of the kt SENSE technique. The cost-effective reconstruction, in turn, is achieved by a computationally efficient estimation of the xf sensitivity from the band-limited signals of the aliased inputs. Such band-limited signals are suitable for sensitivity estimation because the strongly aliased signals have been removed.

    Results: For the same reduction factor 4, the net reduction factor 4 for the proposed method was significantly higher than the factor 2.29 achieved by kt SENSE. The processing time is reduced from 4.1 s for kt SENSE to 1.7 s for the proposed method. The image quality obtained using the proposed method proved to be superior (mean squared error [MSE] ± standard deviation [SD] = 6.85 ± 2.73) compared to the kt SENSE case (MSE ± SD = 12.73 ± 3.60) for the vertical long-axis (VLA) view, as well as other views.

    Conclusion: In the present study, kt SENSE was identified as a suitable base method to be improved achieving both short acquisition times and a cost-effective reconstruction. To enhance these characteristics of base method, a novel implementation is proposed, estimating the xf sensitivity without the need for an explicit scan of the reference signals. Experimental results showed that the acquisition, computational times and image quality for the proposed method were improved compared to the standard kt SENSE method.

    Download PDF (3540K)
  • Shota Hodono, Akihiro Shimokawa, Neil J. Stewart, Yukiko Yamauchi, Ren ...
    Article ID: mp.2017-0163
    Published: 2018
    [Advance publication] Released: March 09, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: High Mobility Group Box1 (HMGB1), which is one of the damage-associated molecular pattern molecules relating to various inflammatory diseases, has gained interest as a therapeutic target because of its involvement in wound healing processes. In the present study, we investigated HMGB1 as a potential therapeutic target in a model of lung fibrosis using a preclinical hyperpolarized 129Xe (HPXe) MRI system.

    Methods: Lung injury was induced by intra-peritoneal injection of bleomycin (BLM) in 19 mice. Three weeks post-injection (when fibrosis was confirmed histologically), administration of ethyl pyruvate (EP) and alogliptin (ALG), which are down- and up-regulators of HMGB1, respectively, was commenced in six and seven of the 19 mice, respectively, and continued for a further 3 weeks. A separate sham-instilled group was formed of five mice, which were administered with saline for 6 weeks. Over the second 3-week period, the effects of disease progression and pharmacological therapy in the four groups of mice were monitored by HPXe MRI metrics of fractional ventilation and gas-exchange function.

    Results: Gas-exchange function in BLM mice was significantly reduced after 3 weeks of BLM challenge compared to sham-instilled mice (P < 0.05). Ethyl pyruvate was found to improve HPXe MRI metrics of both ventilation and gas exchange, and repair tissue damage (assessed histologically), to a similar level as sham-instilled mice (P < 0.05), whilst ALG treatment caused no significant improvement of pulmonary function.

    Conclusion: This study demonstrates the down-regulator of HMGB1, EP, as a potential therapeutic agent for pulmonary fibrosis, as assessed by a non-invasive HPXe MRI protocol.

    Download PDF (3665K)
  • Kimihiro Kajita, Satoshi Goshima, Yoshifumi Noda, Hiroshi Kawada, Nobu ...
    Article ID: mp.2017-0173
    Published: 2018
    [Advance publication] Released: March 09, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: To compare four free-breathing scan techniques for gadoxetic acid-enhanced hepatobiliary phase imaging with conventional breath-hold scans.

    Materials and Methods: Gadoxetic acid-enhanced hepatobiliary phase imaging with six image acquisition sets performed in 50 patients. Image acquisition sets included fat-suppressed 3D T1-weighted turbo field echo with free-breathing pseudo-golden-angle radial stack-of-stars (FBRS) acquisition, FBRS with track (FBRST), FBRS with gate and track (FBRSG&T), thin-slice FBRS with gate and track (thin-slice FBRSG&T), free-breathing Cartesian acquisition (CartesianFB), and breath-hold Cartesian acquisition (CartesianBH). Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and image quality compared to the six-image acquisition sets.

    Results: Signal-to-noise ratio and CNR were significantly higher in FBRS, FBRST, FBRSG&T, and thin-slice FBRSG&T than in CartesianFB and CartesianBH (P < 0.001). Based on sharpness, motion artifacts, visibility of intrahepatic vessels, and overall image quality, thin-slice FBRSG&T had the highest image quality followed by CartesianBH and FBRSG&T (P < 0.001). Severe motion artifacts were observed in 25 patients in CartesianFB and three patients in CartesianBH, whereas image quality remained above the acceptable range in FBRSG&T, FBRST, FBRS, and thin-slice FBRSG&T in all cases.

    Conclusion: Thin-slice FBRSG&T demonstrated excellent image quality compared with conventional CartesianBH in gadoxetic acid-enhanced hepatobiliary phase imaging. It can be apply to supplemental sequences of patients with unstable breath holding.

    Download PDF (3863K)
  • Jianmin Yuan, Andrew J. Patterson, Pascal P. R. Ruetten, Scott A. Reid ...
    Article ID: mp.2017-0141
    Published: 2018
    [Advance publication] Released: March 08, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: This study is to compare the accuracy of four different black-blood T2 mapping sequences in carotid vessel wall.

    Methods: Four different black-blood T2 mapping sequences were developed and tested through phantom experiments and 17 healthy volunteers. The four sequences were: 1) double inversion-recovery (DIR) prepared 2D multi-echo spin-echo (MESE); 2) DIR-prepared 2D multi-echo fast spin-echo (MEFSE); 3) improved motion-sensitized driven-equilibrium (iMSDE) prepared 3D FSE and 4) iMSDE prepared 3D fast spoiled gradient echo (FSPGR). The concordance correlation coefficient and Bland–Altman statistics were used to compare the sequences with a gold-standard 2D MESE, without blood suppression in phantom studies. The volunteers were scanned twice to test the repeatability. Mean and standard deviation of vessel wall T2, signal-to-noise (SNR), the coefficient of variance and interclass coefficient (ICC) of the two scans were compared.

    Results: The phantom study demonstrated that T2 measurements had high concordance with respect to the gold-standard (all r values >0.9). In the volunteer study, the DIR 2D MEFSE had significantly higher T2 values than the other three sequences (P < 0.01). There was no difference in T2 measurements obtained using the other three sequences (P > 0.05). iMSDE 3D FSE had the highest SNR (P < 0.05) compared with the other three sequences. The 2D DIR MESE has the highest repeatability (ICC: 0.96, [95% CI: 0.88–0.99]).

    Conclusion: Although accurate T2 measurements can be achieved in phantom by the four sequences, in vivo vessel wall T2 quantification shows significant differences. The in vivo images can be influenced by multiple factors including black-blood preparation and acquisition method. Therefore, a careful choice of acquisition methods and analysis of the confounding factors are required for accurate in vivo carotid vessel wall T2 measurements. From the settings in this study, the iMSDE prepared 3D FSE is preferred for the future volunteer/patient scans.

    Download PDF (3483K)
  • Shinji Naganawa, Hisashi Kawai, Toshiaki Taoka, Michihiko Sone
    Article ID: bc.2017-0158
    Published: 2018
    [Advance publication] Released: March 07, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
    Download PDF (2524K)
  • Yumiko Oishi Tanaka, Yutaka Takazawa, Motoki Matsuura, Kohei Omatsu, N ...
    Article ID: ci.2017-0146
    Published: 2018
    [Advance publication] Released: March 07, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
    Download PDF (2915K)
  • Fumi Yanagisawa, Yasuo Amano, Masaki Tachi, Keisuke Inui, Kuniya Asai, ...
    Article ID: mp.2017-0136
    Published: 2018
    [Advance publication] Released: March 07, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: We sought to use non-contrast-enhanced T1 mapping to determine the native T1 values required to identify myocardial fibrosis in patients with dilated cardiomyopathy (DCM).

    Methods: A total of 25 patients with DCM and 15 healthy controls were enrolled. All subjects underwent T1 mapping using modified look–locker inversion recovery, and the patients underwent late gadolinium-enhancement (LGE) imaging. Basal and mid-ventricular levels were divided into eight segments and the T1 value was measured in each segment. The T1 values of septal segments with LGE were compared with those of the septal segments without LGE, the minimum T1 value of each patient, and the T1 values of the normal septal myocardium.

    Results: Late gadolinium-enhancement was present in 12 septal segments (24.0%) from 10 patients (40.0%). T1 values were significantly higher in septal segments with LGE than in those without (1373.7 vs. 1288.0 ms; P = 0.035) or in normal septal myocardium (1209.1 ms; P < 0.01). A receiver operating characteristic analysis revealed the appropriate cutoff value of 1349.4 ms for identifying LGE with a sensitivity of 75% and specificity of 92.1%. When the minimum T1 value + 1.2 standard deviation (SD) was used as the threshold, the sensitivity was 75% and specificity was 89.5%.

    Conclusion: Non-contrast-enhanced T1 mapping can be used for assessment of myocardial fibrosis associated with DCM by using the appropriate threshold.

    Download PDF (2775K)
  • Fabian Kording, Bjoern P. Schoennagel, Manuela Tavares de Sousa, Kai F ...
    Article ID: mp.2017-0100
    Published: 2018
    [Advance publication] Released: February 21, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: Fetal cardiac MRI has the potential to play an important role in the assessment of fetal cardiac pathologies, but it is up to now not feasible due to a missing gating method. The purpose of this work was the evaluation of Doppler ultrasound (DUS) for external fetal cardiac gating with regard to compatibility, functionality, and reliability. Preliminary results were assessed performing fetal cardiac MRI.

    Methods: An MRI conditional DUS device was developed to obtain a gating signal from the fetal heart. The MRI compatibility was evaluated at 1.5T and 3T using B1 field maps and gradient echo images. The quality and sensitivity of the DUS device to detect the fetal heart motion for cardiac gating were evaluated outside the MRI room in 15 fetuses. A dynamic fetal cardiac phantom was employed to evaluate distortions of the DUS device and gating signal due to electromagnetic interferences at 1.5T and 3T. In the first in vivo experience, dynamic fetal cardiac images were acquired in four-chamber view at 1.5T and 3T in two fetuses.

    Results: The maximum change in the B1 field and signal intensity with and without the DUS device was <6.5% for 1.5T and 3T. The sensitivity of the DUS device to detect the fetal heartbeat was 99.1%. Validation of the DUS device using the fetal cardiac phantom revealed no electromagnetic interferences at 1.5T or 3T and a high correlation to the simulated heart frequencies. Fetal cardiac cine images were successfully applied and showed good image quality.

    Conclusion: An MR conditional DUS gating device was developed and evaluated revealing safety, compatibility, and reliability for different field strengths. In a preliminary experience, the DUS device was successfully applied for in vivo fetal cardiac imaging at 1.5T and 3T.

    Download PDF (3908K)
  • Takuya Urushihata, Hiroyuki Takuwa, Chie Seki, Yasuhiko Tachibana, Man ...
    Article ID: mp.2017-0149
    Published: 2018
    [Advance publication] Released: February 13, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: Chronic cerebral hypoperfusion model mice were created by unilateral common carotid artery occlusion (UCCAO) surgery, which does not cause cerebral infarction, but which does cause long-term reduction in cerebral blood flow (CBF) to the occluded side. Cognitive dysfunction in this mouse model has been demonstrated in behavioral experiments, but neuron density change was not found in a previous positron emission tomography (PET) study. As a next step, in this study we investigated the injury of neuronal fibers in chronic cerebral hypoperfusion model mice using diffusion tensor imaging (DTI).

    Methods: In diffusion-weighted imaging (DWI), not only the diffusion of water but also the capillary flow in the voxel, i.e., intravoxel incoherent motion (IVIM), contributes to the signal. Thus, we used DTI to evaluate DWI signal changes in the brains of chronic hypoperfusion model mice at 4 weeks after UCCAO while monitoring the possible influence of CBF change using arterial spin-labeling (ASL) MRI.

    Results: Simple t-tests indicated that there were significant differences in CBF between the control and occluded sides of the brain, but there was no significant difference for the mean diffusivity (MD) or fractional anisotropy (FA). However, as Pearson correlation analysis showed that MD was strongly correlated with CBF, analysis-of-covariance (ANCOVA) was then performed using CBF as a covariate and a significant difference in MD between the contra- and ipsilateral sides was found. Performing a similar procedure for the FA found no significant differences.

    Conclusion: The results suggest the injury of neuronal fibers due to chronic hypoperfusion. It is also suggested that CBF-related signal changes should be considered when DWI-based information is used for pathological diagnosis.

    Download PDF (4154K)
  • Sota Oguro, Shigeo Okuda, Hiroaki Sugiura, Shunsuke Matsumoto, Aya Sas ...
    Article ID: mp.2017-0072
    Published: 2018
    [Advance publication] Released: February 01, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    Purpose: To assess the clinical importance in the feature change in giant cell tumors of the bone (GCTB) after denosumab treatment, detected by MRI.

    Methods: In 12 patients, MRI and CT of GCTB obtained before and after the treatment retrospectively compared. The tumor size, the signal intensity (SI) ratio between the solid part of the GCTB and muscle, cystic part size, gadolinium enhancement and apparent diffusion coefficient (ADC) value were measured on MRI. The bone formation in the tumor was observed on CT and X-ray.

    Results: The mean number of denosumab injections was 19 ± 10. The follow-up period was up to 2 years. One case showed partial remission, while the other 11 cases were stable. A mean SI ratio on T2-weighted image statistically significantly decreased from 3.9 to 1.9 after the treatment. A cystic component in the tumor was observed in five cases before the treatment, and the diameter of the cystic part decreased after the treatment in 80% of cases (4/5). All the tumors showed contrast enhancement on T1-weighted image pre- and post-treatment (11/11). The averaged ADC values were 1.52 × 10−3 mm2/s before and 1.44 × 10−3 mm2/s after the treatment (P = 0.63). Bone formation in the tumor was observed in 58% of cases (7/12).

    Conclusion: The decrease of SI ratio on T2-weighted image, shrinkage of cystic part and bone formation should be regarded as the effectiveness of denosumab treatment despite of no substantial change in the tumor size.

    Download PDF (3533K)
  • Seung Hyun Lee, Young Han Lee, Ho-Taek Song, Jin-Suck Suh
    Article ID: tn.2017-0121
    Published: 2018
    [Advance publication] Released: February 01, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    The purpose was to evaluate the feasibility of quantitative MRI T2 mapping based on the quantitative MRI (QRAPMASTER) sequence for the quantitative assessment of knee cartilage. The T2 values from the phantom study showed excellent correlation between the two techniques (r2 = 0.998). The cartilage T2 values exhibited strong correlations (r2 = 0.867–0.982). Quantitative MRI (qMRI) T2 mapping can be used as an alternative to multi-echo T2 mapping, with relatively short scan time.

    Download PDF (4302K)
  • Yasuo Takatsu, Katsusuke Kyotani, Tsuyoshi Ueyama, Tosiaki Miyati, Ken ...
    Article ID: tn.2017-0144
    Published: 2018
    [Advance publication] Released: January 30, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    To obtain objective and concrete data by physically assessing the quality of breast magnetic resonance images based on the fat-suppression effect by the modified Dixon method (mDixon) and frequency-selective fat suppression (e-Thrive) using an original lipid-content breast phantom that could easily reveal the influence of non-uniform fat suppression in breast magnetic resonance imaging. The fat-suppression uniformity was approximately seven times superior when using mDixon compared with when using e-Thrive. mDixon appears to have a significant advantage.

    Download PDF (3030K)
  • Masami Goto, Osamu Abe, Shigeki Aoki, Koji Kamagata, Masaaki Hori, Tos ...
    Article ID: mp.2017-0127
    Published: 2018
    [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.

    Download PDF (4556K)
  • Shinji Naganawa, Toshiki Nakane, Hisashi Kawai, Toshiaki Taoka
    Article ID: mp.2017-0137
    Published: 2018
    [Advance publication] Released: January 18, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    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.

    Download PDF (3095K)
  • Shintaro Ichikawa, Utaroh Motosugi, Makiko Omori, Katsuhiro Sano, Yosh ...
    Article ID: tn.2017-0103
    Published: 2018
    [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).

    Download PDF (3444K)
  • Masayuki Yamaguchi, Hirofumi Fujii
    Article ID: tn.2017-0115
    Published: 2018
    [Advance publication] Released: January 18, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    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.

    Download PDF (3832K)
  • Machiko Tateishi, Mika Kitajima, Toshinori Hirai, Tetsuya Yoneda, Mamo ...
    Article ID: mp.2017-0134
    Published: 2017
    [Advance publication] Released: January 15, 2018
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    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.

    Download PDF (3280K)
  • Lauren Wallaert, Akifumi Hagiwara, Christina Andica, Masaaki Hori, Kaz ...
    Article ID: ci.2017-0110
    Published: 2017
    [Advance publication] Released: December 12, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
    Download PDF (2815K)
  • Yuki Shinohara, Ayumi Kato, Eijiro Yamashita, Jun-ichi Ueyama, Naohiro ...
    Article ID: ci.2017-0113
    Published: 2017
    [Advance publication] Released: December 12, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION
    Download PDF (2865K)
  • Delgerdalai Khashbat, Masafumi Harada, Takashi Abe, Mungunbagana Ganbo ...
    Article ID: mp.2017-0065
    Published: 2017
    [Advance publication] Released: December 12, 2017
    JOURNALS OPEN ACCESS ADVANCE PUBLICATION

    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.

    Download PDF (3418K)
feedback
Top