Magnetic Resonance in Medical Sciences
Online ISSN : 1880-2206
Print ISSN : 1347-3182
ISSN-L : 1347-3182
Volume 20, Issue 3
Displaying 1-12 of 12 articles from this issue
Innovative Clinical Image
Major Papers
  • Kazuhiro Kitajima, Takako Kihara, Yusuke Kawanaka, Junko Takahama, Yos ...
    2021 Volume 20 Issue 3 Pages 236-244
    Published: 2021
    Released on J-STAGE: September 01, 2021
    Advance online publication: July 22, 2020
    JOURNAL OPEN ACCESS

    Purpose: This study aimed to examine MRI features and staging of neuroendocrine carcinoma (NEC) of the endometrium and evaluate survival.

    Methods: Clinical data, pathological, and preoperative pelvic MRI findings in 22 patients with histologically surgery-proven endometrial NEC were retrospectively reviewed. Tumors were pure NEC (n = 10) or mixed histotype (n = 12), with 13 large and nine small cell type.

    Results: International Federation of Gynecology and Obstetrics (FIGO) staging was I, II, III, and IV in 6, 2, 12, and 2 patients, respectively. In 13 (76.4%) of 17 patients with pathological deep myometrial invasion, MRI showed abnormal diffusely infiltrative high T2 signal intensity throughout the myometrium with loss of normal uterine architecture. All tumors had restricted diffusion (apparent diffusion coefficient map low signal intensity, diffusion weighted imaging high signal intensity). Accuracy of T staging by MRI for all cases was 81.8%, with reference to pathology staging, while patient-based sensitivity, specificity, and accuracy for detecting metastatic pelvic lymph nodes was 60.0%, 100%, and 77.8%, respectively. Two intrapelvic peritoneal dissemination cases were detected by MRI. During follow-up (mean 30.4, range 3.3–138.4 months), 16 patients (72.7%) experienced recurrence and 12 (54.5%) died of disease. Two-year disease-free and overall survival rates for FIGO I, II, III, and IV were 66.7% and 83.3%, 50% and 100%, 10% and 33.3%, and 0% and 0%, respectively.

    Conclusion: Abnormal diffusely infiltrative high T2 signal intensity throughout the myometrium with normal uterine architecture loss and obvious restricted diffusion throughout the tumor are suggestive features of endometrial NEC. Pelvic MRI is reliable for intrapelvic staging of affected patients.

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  • Shinji Naganawa, Rintaro Ito, Rei Nakamichi, Mariko Kawamura, Hisashi ...
    2021 Volume 20 Issue 3 Pages 245-252
    Published: 2021
    Released on J-STAGE: September 01, 2021
    Advance online publication: July 14, 2020
    JOURNAL OPEN ACCESS

    Purpose: The purpose of this retrospective study was to investigate the relationship between the number and size of cystic structures around the cortical veins near the superior sagittal sinus and the leakage of gadolinium-based contrast agent (GBCA) around the cortical veins.

    Methods: Of 190 patients (91 male and 99 female), that were scanned at 4 h after an intravenous injection of GBCA as a diagnostic examination for endolymphatic hydrops, 6 patients with GBCA leakage were younger than the previously proposed threshold age of 37.3 years for leakage. Six age-matched patients without leakage were also included for reference. In addition, we included 8 cases without leakage that were older than the hypothesized threshold of 37.3 years, as well as 8 age-matched patients with GBCA leakage into the cerebrospinal fluid space. The number of cysts was counted and the sizes were measured in these 28 patients (age: 32–60 years old, 13 men and 15 women).

    Results: The mean number of cysts surrounding the cortical veins in the parasagittal region was 4.29 ± 1.77 vs. 1.79 ± 1.05 (P = 0.0001) in the subjects with and without GBCA leakage, respectively. The mean size of the largest cysts was at 8.89 ± 3.49 mm vs. 5.69 ± 2.29 (P = 0.009) in the subjects with and without GBCA leakage, respectively.

    Conclusion: The number and size of the perivenous cystic structures near the superior sagittal sinus is greater in subjects with GBCA leakage into the subarachnoid space compared with those without leakage. Future research regarding the histological and functional details of these parasagittal cystic structures is needed.

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  • Zhijun Geng, Yunfei Zhang, Shutong Wang, Hui Li, Cheng Zhang, Shaohan ...
    2021 Volume 20 Issue 3 Pages 253-263
    Published: 2021
    Released on J-STAGE: September 01, 2021
    Advance online publication: August 12, 2020
    JOURNAL OPEN ACCESS
    Supplementary material

    Purpose: No previous researches have extracted radiomics features from susceptibility weighted imaging (SWI) for biomedical applications. This research aimed to explore the correlation between histopathology of hepatocellular carcinoma (HCC) and radiomics features extracted from SWI.

    Methods: A total of 53 patients were ultimately enrolled into this retrospective study with MR examinations undertaken at a 3T scanner. About 107 radiomics features were extracted from SWI images of each patient. Then, the Spearman correlation test was performed to evaluate the correlation between the SWI-derived radiomics features and histopathologic indexes including histopathologic grade, microvascular invasion (MVI) as well as the expression status of cytokeratin 7 (CK-7), cytokeratin 19 (CK-19) and Glypican-3 (GPC-3). With SWI-derived radiomics features utilized as independent variables, four logistic regression-based diagnostic models were established for diagnosing patients with positive CK-7, CK-19, GPC-3 and high histopathologic grade, respectively. Then, receiver operating characteristic analysis was performed to evaluate the diagnostic performance.

    Results: A total of 11, 32, 18 and one SWI-derived radiomics features were significantly correlated with histopathologic grade, the expression of CK-7, the expression of CK-19 and the expression of GPC-3 (P < 0.05), respectively. None of the SWI-derived radiomics features was correlated with MVI status. The areas under the curve were 0.905, 0.837, 0.800 and 0.760 for diagnosing patients with positive CK-19, positive CK-7, high histopathologic grade and positive GPC-3.

    Conclusion: Extracting the radiomics features from SWI images was feasible to evaluate multiple histopathologic indexes of HCC.

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  • Atsuko Yamamoto, Kai Takaki, Shigehiro Morikawa, Kiyoshi Murata, Ryuta ...
    2021 Volume 20 Issue 3 Pages 264-271
    Published: 2021
    Released on J-STAGE: September 01, 2021
    Advance online publication: August 21, 2020
    JOURNAL OPEN ACCESS

    Purpose: (1) To evaluate the enhancement patterns of an ultrasmall superparamagnetic iron oxide contrast agent (USPIO-CA) compared with those of a gadolinium-based contrast agent (Gd-BCA). (2) To compare the histologic distribution of USPIO-related iron particles (USPIO-IPs) with the USPIO-enhancement area in the early vascular and in the cellular imaging phase (E- and L-phase, respectively) after intravenous CA administration.

    Methods: We performed USPIO-enhanced MRI of N-ethyl-N-nitrosourea (ENU)-induced endogenous rat glioma, including spin-echo (SE) T1-weighted images (T1WIs) and gradient-recalled-echo (GRE) T2-weighted images (T2WIs), before and at 3–6 h after USPIO-CA administration for E-phase images. For L-phase images, MRI was performed at 16–19 and 62–69 h after administration. Two observers determined the USPIO-enhancement area on E-phase images and Gd-enhancement areas. We compared the USPIO-enhancement size (USPIO-ES) and Gd-ES on SE T1WIs, and the hypo-intense USPIO-ES on GRE T2WIs and Gd-ES using the Wilcoxon signed-rank test. In addition, two raters visually evaluated the correspondence between the histologic distribution of USPIO-IPs and the USPIO-enhancement area on corresponding GRE T2WIs at each phase using a 3-rating scale.

    Results: Significantly smaller hyper-intense, hypo-intense and combined hyper-/hypo-intense areas were observed on USPIO-enhanced SE T1WIs compared with Gd-enhanced images (all P < 0.001). The hypo-intense USPIO-ES on GRE T2WIs was significantly smaller than the Gd-ES (P = 0.001). The distribution of USPIO-IPs on histopathological specimen and USPIO-enhancement on GRE T2WIs exhibited poor agreement in 5 of 9 tumors with enhancement from rats sacrificed early. The distribution of microglia containing USPIO-IPs corresponded with the pattern of USPIO-enhancement in the 2 tumors with late enhancement.

    Conclusion: The enhancement pattern and size of USPIO-CA in a rat glioma model were statistically different from those of Gd-BCA. Our histological data suggests that USPIO-enhanced MRI offers vascular bed imaging in E-phase and might depict the intra-tumoral distribution of immune effector cells in L-phase.

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  • Shinji Naganawa, Rei Nakamichi, Kazushige Ichikawa, Mariko Kawamura, H ...
    2021 Volume 20 Issue 3 Pages 272-279
    Published: 2021
    Released on J-STAGE: September 01, 2021
    Advance online publication: August 21, 2020
    JOURNAL OPEN ACCESS

    Purpose: MRI of endolymphatic hydrops (EH) 4 h after intravenous administration of a single dose of gadolinium-based contrast agent is used for clinical examination in some institutions; however, further improvement in image quality would be valuable for wider clinical utility. Denoising using deep learning reconstruction (Advanced Intelligent Clear-IQ Engine [AiCE]) has been reported for CT and MR. The purpose of this study was to compare the contrast-to-noise ratio of endolymph to perilymph (CNREP) between the improved hybrid of reversed image of the positive endolymph signal and the native image of the perilymph signal multiplied with the heavily T2-weighted MR cisternography (iHYDROPS-Mi2) images, which used AiCE for the three source images (i.e. positive endolymph image [PEI], positive perilymph image [PPI], MR cisternography [MRC]) to those that did not use AiCE. We also examined if there was a difference between iHYDROPS-Mi2 images with and without AiCE for degree of visual grading of EH and in endolymphatic area [EL] ratios.

    Methods: Nine patients with suspicion of EH were imaged on a 3T MR scanner. iHYDROPS images were generated by subtraction of PEI images from PPI images. iHYDROPS-Mi2 images were then generated by multiplying MRC with iHYDROPS images. The CNREP and EL ratio were measured on the iHYDROPS-Mi2 images. Degree of radiologist visual grading for EH was evaluated.

    Results: Mean CNREP ± standard deviation was 1681.8 ± 845.2 without AiCE and 7738.6 ± 5149.2 with AiCE (P = 0.00002). There was no significant difference in EL ratio for images with and without AiCE. Radiologist grading for EH agreed completely between the 2 image types in both the cochlea and vestibule.

    Conclusion: The CNREP of iHYDROPS-Mi2 images with AiCE had more than a fourfold increase compared with that without AiCE. Use of AiCE did not adversely affect radiologist grading of EH.

    Editor's pick

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  • Shintaro Ichikawa, Utaroh Motosugi, Kazuyuki Sato, Tatsuya Shimizu, Te ...
    2021 Volume 20 Issue 3 Pages 280-289
    Published: 2021
    Released on J-STAGE: September 01, 2021
    Advance online publication: August 28, 2020
    JOURNAL OPEN ACCESS

    Purpose: To investigate whether shortened acquisition or multiple arterial phase acquisition improves image quality of the arterial phase compared with conventional protocol.

    Methods: This retrospective study was approved by the relevant Institutional Review Board. A total of 615 consecutive patients who underwent gadoxetate disodium-enhanced MRI including one of the following three sequences in three different periods were included: (i) conventional liver acquisition with volume acceleration (LAVA) (between October 2014 and January 2015, n = 149), (ii) Turbo-LAVA (between March and August 2016, n = 216), and (iii) differential sub-sampling with Cartesian ordering (DISCO) (between January and September 2015, n = 250). We monitored the respiratory bellows waveform during breath holding for each patient and recorded breath-hold fidelity of the patients. Two radiologists independently evaluated the degree of respiratory artifact and scan timing on the arterial phase and compared them between the three protocols (i.e., conventional LAVA, Turbo-LAVA, and DISCO), with conventional LAVA as control.

    Results: The ratio of patients with breath-hold failure was not significantly different among the three protocols (P = 0.6340 and 0.1085). Respiratory artifact was significantly lower in DISCO than in conventional LAVA (P = 0.0424), while there was no significant difference between Turbo-LAVA and conventional LAVA (P = 0.2593). The ratio of adequate scan timing and diagnosable image defined as no or mild artifact and adequate scan timing were higher in DISCO than in conventional LAVA (P = 0.0025 and 0.0019), while there was no significant difference between Turbo-LAVA and conventional LAVA (P = 0.0780 and 0.0657).

    Conclusion: Compared with conventional protocol, multiple arterial phase acquisition (DISCO) obtained a higher number of diagnosable images by reducing respiratory motion artifact and optimizing the scan timing of arterial phase.

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  • Osamu Yanagisawa, Tomoki Oshikawa, Naoto Matsunaga, Gen Adachi, Koji K ...
    2021 Volume 20 Issue 3 Pages 290-294
    Published: 2021
    Released on J-STAGE: September 01, 2021
    Advance online publication: September 01, 2020
    JOURNAL OPEN ACCESS

    Purpose: We aimed to evaluate the acute physiological effects of high-load deadlift exercise on the lumbar intervertebral discs using MR diffusion-weighted imaging (DWI).

    Methods: Fifteen volunteers (11 men and 4 women; 23.2 ± 3.3 years) without lumbar intervertebral disc degeneration performed deadlift exercise (70% of 1 repetition maximum, 6 repetitions, 5 sets, 90 s rest between sets) using a Smith machine. Sagittal MR diffusion-weighted images of the lumbar intervertebral discs were obtained using a 1.5-Tesla MR system with a spine coil before and immediately after the exercise. We calculated apparent diffusion coefficient (ADC; an index of water movement) of the nucleus pulposus from diffusion weighted images at all lumbar intervertebral discs (L1/2 through L5/S1).

    Results: All lumbar intervertebral discs showed significantly decreased ADC values immediately after deadlift exercise (L1/2, −2.8%; L2/3, −2.1%; L3/4, −2.8%; L4/5, −4.9%; L5/S1, −6.2%; P < 0.01). In addition, the rate of ADC decrease of the L5/S1 disc was significantly greater than those of the L1/2 (P = 0.017), L2/3 (P < 0.01), and L3/4 (P = 0.02) discs.

    Conclusion: The movement of water molecules within the lumbar intervertebral discs is suppressed by high-load deadlift exercise, which would be attributed to mechanical stress on the lumbar intervertebral discs during deadlift exercise. In particular, the L5/S1 disc is subjected to greater mechanical stress than the other lumbar intervertebral discs.

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  • Yumi Shiina, Kei Inai, Ryoko Ohashi, Michinobu Nagao
    2021 Volume 20 Issue 3 Pages 295-302
    Published: 2021
    Released on J-STAGE: September 01, 2021
    Advance online publication: September 07, 2020
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    Purpose: The native T1 value at 3T MRI is a sensitive marker for diffuse fibrosis or damage in various organs including the heart, liver, and pancreas. Despite the fact that Fontan-associated liver disease (FALD) is a crucial issue in adults with Fontan circulation, there are only a few studies with liver T1 mapping in children and adolescents. We investigated the potential of the liver native T1 mapping in detecting FALD in adult patients.

    Methods: We prospectively enrolled 16 consecutive adults with Fontan circulation (age 31.3 ± 8.5 years), who were in New York Heart Association Functional class II–IV. Twenty with tetralogy of Fallot (TOF), and 20 age-matched controls also underwent cardiac magnetic resonance (CMR) imaging at 3T. Myocardial T1 mapping with a Modified Look-Locker Inversion recovery sequence was applied to liver T1 mapping. Patients in the Fontan group underwent the right heart catheter and liver function tests, including those for fibrotic markers.

    Results: Liver native T1 values in the Fontan group were significantly higher than that in TOF and controls (P < 0.001). In the Fontan group, the liver native T1 value was significantly correlated with age, γ-glutamyltransferase, model for end-stage liver disease XI score, and albumin-bilirubin score (P = 0.01, 0.01, 0.044, 0.001). However, it demonstrated no correlation with central venous pressure, pulmonary vessel resistance, or fibrotic markers.

    Conclusion: Liver native T1 value derived from CMR may be a non-invasive adjunctive and/or screening marker to detect FALD.

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  • Hiroshi Kato, Norio Ootani, Kentaro Abiru, Mika Okahara
    2021 Volume 20 Issue 3 Pages 303-311
    Published: 2021
    Released on J-STAGE: September 01, 2021
    Advance online publication: September 18, 2020
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    Purpose: In this study, we investigated the factors of signal loss out because of the presence of a stent and optimized imaging parameters for improvement in depiction ability.

    Methods: We investigated the relationship between the stent type and magnetic susceptibility effect by measuring the signal value between the inside and outside of the stent with different Bw and TE for two different kinds of stents respectively. Similarly, flip angles were changed for two different kinds of stents respectively to the signal intensity between the inside and the outside of the stent was measured, in which examine the relationship between the stent type and the Ernst angles in RF-shielding effect. The conventional imaging parameters and the optimum imaging parameters for each stent obtained from the result of the phantom experiment were examined. Optimized 3D time-of-flight MR angiography (3D-TOF-MRA) was performed and compared with conventional 3D-TOF-MRA and computed tomography angiography (CTA).

    Results: The influence of the magnetic susceptibility effect is small in the central part of Carotid Wallstent and in PRECISE, and large in the Carotid Wallstent at the both ends. The influence of RF-shielding effect was large at PRECISE, where the Ernst angle was greatly shifted while the effect is no longer influenced at Carotid Wallstent. Both Carotid Wallstent and PRECISE made imaging capability improved by optimizing the imaging parameters.

    Conclusion: During clinical imaging of patients post-carotid artery stenting (CAS) using our protocol, the ability to visualize blood vessels was improved. Thus, we demonstrated that the ability of 3D-TOF-MRA post-CAS was improved via optimizing imaging parameters.

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