著者

Shinji Naganawa Toshiki Nakane Hisashi Kawai Toshiaki Taoka

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.mp.2017-0137, (Released:2018-01-18)

参考文献数

28

被引用文献数

16

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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.

著者

Shinji Naganawa Rintaro Ito Mariko Kawamura Toshiaki Taoka

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.bc.2023-0122, (Released:2023-11-10)

参考文献数

11

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Postsurgery intracranial air usually diminishes, presumably merging with cerebrospinal fluid (CSF) and venous circulation. Our study presents two transsphenoidal surgery cases, highlighting potential air absorption by arachnoid granulation (AG)—an underexplored phenomenon. AG has long been deemed pivotal for CSF absorption, but recent perspectives suggest a significant role in waste clearance, neuroinflammation, and neuroimmunity. These cases may stimulate renewed research on the multifaceted role of AG in neurofluid dynamics and potentially elucidate further AG functions.

著者

Naoya Kinota Hiroyuki Kameda Bai Xiawei Takaaki Fujii Daisuke Kato Bunya Takahashi Ryo Morita Daisuke Abo Ryusei Majima Hiroshi Ishii Kazuyuki Minowa Kohsuke Kudo

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.mp.2023-0023, (Released:2023-05-30)

参考文献数

42

被引用文献数

1

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Purpose: To investigate whether deep cervical lymph node (DCLN) ligation alters intracranial cerebrospinal fluid (CSF) tracer dynamics and outflow using a rat model with intrathecal dynamic contrast-enhanced (DCE) MRI.Methods: Six bilateral DCLN-ligated and six sham-operated rats were subjected to DCE MRI with Gd-BTDO3A, and dynamic T1-weighted images were acquired. ROIs were collected from the CSF at the C1 level (CSF_C1), CSF between the olfactory bulbs (CSF_OB), CSF at the pituitary recess (CSF_PitR), and CSF at the pineal recess (CSF_PinR), upper nasal turbinate (UNT), olfactory bulbs, cerebrum, and the jugular region. Time-intensity curves were evaluated, and the maximum slope, peak timing, peak signal ratio, and elimination half-life for the four CSF ROIs and UNT were calculated and compared.Results: Delayed tracer arrival in the rostral CSF space and the nasal cavity with tracer retention in the ventral CSF space were observed in the ligation group. The maximum slopes were smaller in the ligation group at UNT (sham: 0.075 ± 0.0061, ligation: 0.044 ± 0.0086/min, P = 0.011). A significant difference was not detected in peak timings. The peak signal ratio values were lower in the ligation group at UNT (sham: 2.12 ± 0.19, ligation: 1.72 ± 0.11, P = 0.011). The elimination half-life was delayed in the ligation group at CSF_C1 (sham: 30.5 ± 2.70, ligation: 44.4 ± 12.6 min, P = 0.043), CSF_OB (sham: 30.2 ± 2.67, ligation: 44.8 ± 7.47 min, P = 0.021), and CSF_PitR (sham: 30.2 ± 2.49, ligation: 41.3 ± 7.57 min, P = 0.021).Conclusion: The DCLN ligation in rats blocked CSF outflow into the nasal cavity and caused CSF retention.

著者

Shoko Hara Masaaki Hori Koji Kamagata Christina Andica Motoki Inaji Yoji Tanaka Shigeki Aoki Tadashi Nariai Taketoshi Maehara

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.mp.2022-0146, (Released:2023-04-18)

参考文献数

57

被引用文献数

3

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Purpose: Moyamoya disease (MMD) is a cerebrovascular disease associated with steno-occlusive changes in the arteries of the circle of Willis and with hemodynamic impairment. Previous studies have reported that parenchymal extracellular free water levels may be increased and the number of neurites may be decreased in patients with MMD. The aim of the present study was to investigate the postoperative changes in parenchymal free water and neurites and their relationship with cognitive improvement.Methods: Multi-shell diffusion MRI (neurite orientation dispersion and density imaging and free water imaging using a bi-tensor model) was performed in 15 hemispheres of 13 adult patients with MMD (11 female, mean age 37.9 years) who had undergone revascularization surgery as well as age- and sex-matched normal controls. Parameter maps of free water and free-water-eliminated neurites were created, and the regional parameter values were compared among controls, patients before surgery, and patients after surgery.Results: The anterior and middle cerebral artery territories of patients showed higher preoperative free water levels (P ≤ 0.007) and lower postoperative free water levels (P ≤ 0.001) than those of normal controls. The change in the dispersion of the white matter in the anterior cerebral artery territory correlated with cognitive improvement (r = –0.75; P = 0.004).Conclusion: Our study suggests that increased parenchymal free water levels decreased after surgery and that postoperative changes in neurite parameters are related to postoperative cognitive improvement in adult patients with MMD. Diffusion analytical methods separately calculating free water and neurites may be useful for unraveling the pathophysiology of chronic ischemia and the postoperative changes that occur after revascularization surgery in this disease population.

著者

Makoto Obara Jihun Kwon Masami Yoneyama Yu Ueda Marc Van Cauteren

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.rev.2022-0107, (Released:2023-03-15)

参考文献数

195

被引用文献数

1

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Since its first observation in the 18th century, the diffusion phenomenon has been actively studied by many researchers. Diffusion-weighted imaging (DWI) is a technique to probe the diffusion of water molecules and create a MR image with contrast based on the local diffusion properties. The DWI pixel intensity is modulated by the hindrance the diffusing water molecules experience. This hindrance is caused by structures in the tissue and reflects the state of the tissue. This characteristic makes DWI a unique and effective tool to gain more insight into the tissue’s pathophysiological condition. In the past decades, DWI has made dramatic technical progress, leading to greater acceptance in clinical practice. In the abdominal region, however, acquiring DWI with good quality is challenging because of several reasons, such as large imaging volume, respiratory and other types of motion, and difficulty in achieving homogeneous fat suppression. In this review, we discuss technical advancements from the past decades that help mitigate these problems common in abdominal imaging. We describe the use of scan acceleration techniques such as parallel imaging and compressed sensing to reduce image distortion in echo planar imaging. Then we compare techniques developed to mitigate issues due to respiratory motion, such as free-breathing, respiratory-triggering, and navigator-based approaches. Commonly used fat suppression techniques are also introduced, and their effectiveness is discussed. Additionally, the influence of the abovementioned techniques on image quality is demonstrated. Finally, we discuss the current and future clinical applications of abdominal DWI, such as whole-body DWI, simultaneous multiple-slice excitation, intravoxel incoherent motion, and the use of artificial intelligence. Abdominal DWI has the potential to develop further in the future, thanks to scan acceleration and image quality improvement driven by technological advancements. The accumulation of clinical proof will further drive clinical acceptance.

著者

Shoto Ikegami Dai Ishiyama Yoshiki Oda Kinuko Niihara Masafumi Yoshida Keiichi Honda Takashi A. Inoue Kagayaki Kuroda

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.bc.2022-0070, (Released:2023-02-08)

参考文献数

12

被引用文献数

2

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Metamorphosis in the pupae of the Trypoxylus dichotomus was continuously observed at 9.4T until their emergence. A large liquid-like mass occupied most of the volume in the trunk, while the surrounding tissue already existed at the beginning of the observation period. As the mass shrunk, tissues such as flight muscle formed, whereas the reservoir became prolonged to form the intestinal tract. This implies that the liquid-like mass worked as the raw material for creating adult tissues.

著者

Hiroyuki Kabasawa Shigeru Kiryu

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.rev.2022-0114, (Released:2023-02-07)

参考文献数

54

被引用文献数

3

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The liver moves with respiratory motion. Respiratory motion causes image artifacts as MRI is a motion-sensitive imaging modality; thus, MRI scan speed improvement has been an important technical development target for liver MRI for years. Recent pulse sequence and image reconstruction technology advancement has realized a fast liver MRI acquisition method. Such new technologies allow us to obtain liver MRI in a shorter time, particularly, within breath-holding time. Other benefits of new the technology and the higher spatial resolution liver MRI within a given scan time are improved slice coverage and smaller pixel size. In this review, MRI pulse sequence and reconstruction technologies to accelerate scan speed for T1- and T2-weighted liver MRI will be discussed. Technologies that reduce scan time while keeping image contrast, SNR and image spatial resolution are needed for fast MRI acquisition. We will discuss the progress of MRI acquisition methods, the enabling technology, established applications, current trends, and the future outlook.

著者

Kenichiro Ihara Hideko Onoda Masahiro Tanabe Etsushi Iida Takaaki Ueda Taiga Kobayashi Mayumi Higashi Marcel Dominik Nickel Hiroshi Imai Katsuyoshi Ito

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.mp.2022-0137, (Released:2023-02-04)

参考文献数

20

被引用文献数

1

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Purpose: To evaluate the feasibility of breath-hold (BH) high-resolution (HR) T1-weighted gradient echo hepatobiliary phase (HBP) imaging using compressed sensing (CS) in gadoxetic acid-enhanced liver MRI in comparison with standard HBP imaging using parallel imaging (PI).Methods: The study included 122 patients with liver tumors with hypointensity in the HBP who underwent both HR HBP imaging with CS and standard HBP imaging with PI. Two radiologists evaluated the liver edge sharpness, hepatic vessel conspicuity, bile duct conspicuity, image noise, and overall image quality, as well as the lesion conspicuity on HR and standard HBP imaging and the contrast-enhanced (CE) MR cholangiography (MRC) image quality reconstructed from HBP images. As a quantitative analysis, the SNR of the liver and the liver to lesion signal intensity ratio (LLSIR) were also determined.Results: The liver edge sharpness, hepatic vessel conspicuity, bile duct conspicuity, and overall image quality as well as the lesion conspicuity and the LLSIR on HR HBP imaging with CS were significantly higher than those on standard HBP imaging (all of P < 0.001). The image quality of CE-MRC reconstructed from HR HBP imaging with CS was also significantly higher than that from standard HBP imaging (P < 0.001). Conversely, the SNR of liver in standard HBP was significantly higher than that in HR HBP with CS (P < 0.001).Conclusion: BH HR HBP imaging with CS provided an improved overall image quality, lesion conspicuity, and CE-MRC visualization when compared with standard HBP imaging without extending the acquisition time.

著者

Tsuyoshi Matsuda Yuji Iwadate Futoshi Mori Kota Takeda Makoto Sasaki

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.tn.2022-0053, (Released:2022-11-30)

参考文献数

24

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Flip angle (FA) measurements using the actual flip angle imaging (AFI) method may induce significant errors in ultrahigh fields. We aimed to develop a method for detecting errors in FA measurements using phase information at 7 tesla. We performed computer simulations to elucidate the relationship between the FA calculation errors and the phase difference between the two AFI source images. We then examined whether a method based on the phase difference could detect FA calculation errors and determine the prescribed nominal FA of the scanner for accurate measurements in phantoms and healthy volunteers. The simulations confirmed that the calculated FA values erroneously decreased when the longitudinal magnetization and phase in one of the source images were inverted. Tests on phantoms and human subjects demonstrated that the phase difference information between the source images with a cut-off of 90° could readily detect FA calculation errors in the AFI method.

著者

Toru Shirai Ryota Sato Yasuo Kawata Yoshitaka Bito Hisaaki Ochi

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.mp.2021-0043, (Released:2022-11-12)

参考文献数

26

被引用文献数

2

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Purpose: Quantitative susceptibility mapping (QSM) is useful for obtaining biological information. To calculate susceptibility distribution, it is necessary to calculate the local field caused by the differences of susceptibility between the tissues. The local field can be obtained by removing a background field from a total field acquired by MR phase image. Conventional approaches based on spherical mean value (SMV) filtering, which are widely used for background field calculations, fail to calculate the background field of the brain surface region corresponding to the radius of the SMV kernel, and consequently cannot calculate the QSM of the brain surface region. Accordingly, a new method calculating the local field by expansively removing the background field is proposed for whole brain QSM.Methods: The proposed method consists of two steps. First, the background field of the brain surface is calculated from the total field using a locally polynomial approximation of spherical harmonics. Second, the whole brain local field is calculated by SMV filtering with a constraint term of the background field of the brain surface. The parameters of the approximation were optimized to reduce calculation errors through simulations using both a numerical phantom and a measured human brain. Performance of the proposed method with the optimized parameters was quantitatively and visually compared with conventional methods in an experiment of five healthy volunteers.Results: The proposed method showed the accurate local field over the expanded brain region in the simulation studies. It also showed consistent QSM with conventional methods inside of the brain surface and showed clear vein structures on the brain surface.Conclusion: The proposed method enables accurate calculation of whole brain QSM without eroding the brain surface region while maintaining same values inside of the brain surface as the conventional methods.

著者

Ryota Hyodo Yasuo Takehara Ayumi Nishida Masaya Matsushima Shinji Naganawa

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.mp.2021-0069, (Released:2021-10-07)

参考文献数

44

被引用文献数

1

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Purpose: To elucidate MRI features of primary hepatic mucosa-associated lymphoid tissue (MALT) lymphoma, particularly, the “speckled enhancement” on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI.Methods: The institutional review board approved this retrospective observational study and waived informed consent. Using our picture archiving and communication systems and electronic medical records, five patients histopathologically diagnosed as hepatic MALT lymphoma and clinically confirmed as primary lesions who had undergone dynamic contrast-enhanced (DCE)-CT and DCE-MRI with Gd-EOB-DTPA were identified from September 2009 to December 2020. Two radiologists assessed their CT and MRI data in consensus with a pathologist’s advice.Results: Overall, five lesions in five patients were included in this study. Precontrast CT showed hypoattenuation in all lesions. In the arterial phase of DCE-CT, four lesions (80%) showed hyperattenuation, whereas all lesions showed iso- to hypoattenuation in the delayed phase. A vessel penetration sign was also observed in all lesions. On MRI, all lesions showed hypointensity on T1-weighted images, hyperintensity on T2-weighted images, and restricted diffusion on diffusion-weighted images. Both DCE-CT and DCE-MRI with Gd-EOB-DTPA showed similar enhancement patterns, except for the hepatocyte phase. Notably, however, four out of five lesions showed characteristic “speckled enhancement” that refers to punctate positive enhancements within the low signal lesions on the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI pathologically confirmed to be hepatocyte clusters that remained in the tumor.Conclusion: Primary hepatic MALT lymphomas were characterized by arterial phase enhancement, restricted diffusion, vessel penetration sign, and more specifically “speckled enhancement” in the hepatobiliary phase of DCE-MRI with Gd-EOB-DTPA.

著者

Hiroyuki Akai Koichiro Yasaka Haruto Sugawara Taku Tajima Masaaki Akahane Naoki Yoshioka Kuni Ohtomo Osamu Abe Shigeru Kiryu

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.mp.2022-0020, (Released:2022-07-09)

参考文献数

27

被引用文献数

5

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Purpose: This study aimed to evaluate whether the image quality of 1.5T magnetic resonance imaging (MRI) of the knee is equal to or higher than that of 3T MRI by applying deep learning reconstruction (DLR).Methods: Proton density-weighted images of the right knee of 27 healthy volunteers were obtained by 3T and 1.5T MRI scanners using similar imaging parameters (21 for high resolution image and 6 for normal resolution image). Commercially available DLR was applied to the 1.5T images to obtain 1.5T/DLR images. The 3T and 1.5T/DLR images were compared subjectively for visibility of structures, image noise, artifacts, and overall diagnostic acceptability and objectively. One-way ANOVA and Friedman tests were used for the statistical analyses.Results: For the high resolution images, all of the anatomical structures, except for bone, were depicted significantly better on the 1.5T/DLR compared with 3T images. Image noise scored statistically lower and overall diagnostic acceptability scored higher on the 1.5T/DLR images. The contrast between lateral meniscus and articular cartilage of the 1.5T/DLR images was significantly higher (5.89 ± 1.30 vs. 4.34 ± 0.87, P < 0.001), and also the contrast between medial meniscus and articular cartilage of the 1.5T/DLR images was significantly higher (5.12 ± 0.93 vs. 3.87 ± 0.56, P < 0.001). Similar image quality improvement by DLR was observed for the normal resolution images.Conclusion: The 1.5T/DLR images can achieve less noise, more precise visualization of the meniscus and ligaments, and higher overall image quality compared with the 3T images acquired using a similar protocol.

著者

Yuta Endo Kuninori Kobayashi Haruna Shibo Makoto Amanuma Shigehide Kuhara

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.tn.2022-0013, (Released:2022-06-23)

参考文献数

24

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We analyzed modified Look-Locker inversion recovery (MOLLI) T1 measurements by applying a dictionary matching strategy and aimed to acquire T1 measurements more accurately than those acquired by the conventional three-parameter matching analysis. We particularly clarified the robustness of this method for measuring heart rate (HR) variability. A phantom experiment using a 3T MRI system was performed for various HRs. The ideal MOLLI signal corresponding to the scan parameter in the MRI experiment was simulated over a wide range of T1 values according to the dictionary. The unknown T1 values were determined by finding the simulated signals in the dictionary corresponding to the measured signals using pattern matching. The measured T1 values showed that the proposed analysis improved the accuracy of T1 measurements compared to those acquired by traditional analysis by up to 10%. In addition, the variability of measurements at several HRs was reduced by up to 100 ms.

著者

Shintaro Ichikawa Utaroh Motosugi Kazuyuki Sato Tatsuya Shimizu Tetsuya Wakayama Hiroshi Onishi

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.mp.2020-0064, (Released:2020-08-28)

参考文献数

30

被引用文献数

11

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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.

著者

Keiko SAKAMOTO Yoshinobu SHINAGAWA Kimiyo INOUE Ayako MORITA Hiroshi URAKAWA Ritsuko FUJIMITSU Kouichi TAKANO Kengo YOSHIMITSU

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

vol.15, no.1, pp.137-143, 2016-01-01 (Released:2016-01-12)

参考文献数

14

被引用文献数

3 4

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Purpose: We retrospectively evaluated the incidence and related factors of obliteration of the lower bile duct after oral administration of contrast medium (OCM) probably resulting from its regurgitation into the biliary system (OCMRB) as observed on images of MR cholangiopancreatography (MRCP).Methods: We retrospectively analyzed 305 MRCP images in 278 patients obtained between February 2010 and March 2011 using negative OCM with 1.0- and 1.5-tesla clinical units. OCMRB was defined as positive when visualization of the common bile duct was clear on precontrast 2-dimensional (2D) MRCP but obliterated on postcontrast 3-dimensional (3D) MRCP. Two abdominal radiologists reviewed all images in consensus. The incidence of OCMRB was correlated to various clinicoradiological factors.Results: We observed OCMRB on 11 MRCP images in 10 patients (3.6%). Among various clinicoradiological factors, the presence of juxtapapillary diverticula, pneumobilia, and history of intervention to the papilla were suggested as significant factors related to positive OCMRB with multivariate analysis (P < 0.05).Conclusion: OCMRB occurs in about 4% of the patients who undergo MRCP, typically in those with juxtapapillary diverticula, pneumobilia, and history of papillary intervention. Acquisition of MRCP images before OCM may secure visualization of the common bile duct in these patients.

著者

Shigeyoshi Soga Taro Koyama Ayako Mikoshi Tatsuhiko Arafune Makoto Kawashima Kazuhiro Kobayashi Hiroshi Shinmoto

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.mp.2020-0026, (Released:2020-05-01)

参考文献数

14

被引用文献数

1 2

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Purpose: Although androgenetic alopecia (AGA) is a common cause of hair loss, little is known regarding the magnetic resonance imaging (MRI) of the AGA or scalp. This study aimed to analyze whether MRI for hair and scalp (MRH) can evaluate anatomical changes in the scalp caused by AGA.Methods: Twenty-seven volunteers were graded for the severity of AGA using the Hamilton–Norwood Scale (HNS), commonly used classification system. All subjects underwent MRH; two radiologists independently analyzed the images. As a quantitative measurement, the number of hair follicles was analyzed and compared with the HNS. As a qualitative analysis, each MRH scan was visually graded in terms of the severity of alopecia, using a 4-point MR severity score. The scores were compared with the HNS.Results: The volunteers were divided into two groups of 12 and 15 males without and with AGA at their vertex, respectively. Inter-observer agreements for the hair count and the MR severity score were excellent. The mean hair count on MRI in the normal group was significantly higher than that in the AGA group (P < 10−4). The MR severity score in the AGA group was significantly more severe than that in the control group (P < 10−4). In terms of the presence or absence of thinning hair, the MR severity score was consistent with the HNS determined by a plastic surgeon in 96% of cases. MR severity scores of clinically moderate AGA cases were significantly lower than those of severe cases (P = 0.022).Conclusion: MRH could depict scalp anatomy showing a clear difference between AGA and normal scalps, in both hair count and subjective visual assessment. The MR severity score was in good agreement with the clinical stages by HNS. The results support the potential of MRH as a promising imaging technique for analyzing healthy and pathological scalps.

著者

Tomoki Miyasaka Michiru Kajiwara Akito Kawasaki Yoshikazu Okamoto Yasuhiko Terada

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.tn.2021-0158, (Released:2022-04-26)

参考文献数

12

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Portable MRI scanners, in which a permanent magnet with a low magnetic field is mounted on a small car, have enabled the performance of MRI examinations in various remote environments. Here, we have modified the portable MRI system to enable the early diagnosis of wrist sports injuries among tennis players. A RF probe specifically designed for the human wrist was developed, and a power supply scheme using a small generator was introduced. The portable MRI system was located at a tennis school and imaging of the wrists of junior tennis players was performed. To demonstrate clinical feasibility, image quality was assessed by a radiologist and clinical evaluations were performed. In most cases, the image quality was sufficient for diagnosis, and triangular fibrocartilage complex damage could be detected. The results indicated that the modified portable MRI system could be applied for an early diagnosis of wrist injuries.

著者

Tomoko Maekawa Kouhei Kamiya Katsutoshi Murata Thorsten Feiweier Masaaki Hori Shigeki Aoki

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

vol.20, no.2, pp.227-230, 2021 (Released:2021-06-01)

参考文献数

12

被引用文献数

2 5

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The microstructural underpinnings of reduced diffusivity in transient splenial lesion remain unclear. Here, we report findings from oscillating gradient spin-echo (OGSE) diffusion imaging in a case of transient splenial lesion. Compared with normal-appearing white matter, the splenial lesion exhibited greater differences between diffusion time t = 6.5 and 35.2 ms, indicating microstructural changes occurring within the corresponding length scale. We also conducted 2D Monte-Carlo simulation. The results suggested that emergence of small and non-exchanging compartment, as often imagined in intramyelinic edema, does not fit well with the in vivo observation. Simulations with axonal swelling and microglial infiltration yielded results closer to the in vivo observations. The present report exemplifies the importance of controlling t for more specific radiological image interpretations.

著者

Ryusuke Irie Shiori Amemiya Tsuyoshi Ueyama Yuichi Suzuki Hidemasa Takao Osamu Abe

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.tn.2022-0002, (Released:2022-04-05)

参考文献数

14

被引用文献数

1

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Liver acquisition with volume acceleration-flex (LAVA-Flex) acquires out-of-phase and in-phase echo images and automatically generates water-only and fat-only images from one single acquisition. The scan time of carotid MR angiography (MRA) using LAVA-Flex (LAVA MRA) is about one-fifth that of conventional time-of-flight MRA (cTOF MRA). We aimed to investigate whether LAVA MRA could provide useful information for the diagnosis of carotid plaque by utilizing the ability to acquire multiple sequences simultaneously. Comparing LAVA MRA and cTOF MRA images for carotid plaque, low-intensity plaques were more clearly identified in the in-phase images, and high-intensity plaques were more clearly identified in the water-only or out-of-phase images. None of the plaques exhibited superior visualization with the cTOF sequence. We concluded that LAVA MRA can provide more useful information on plaque evaluation using multiple sequences than cTOF MRA.

著者

Shinji Naganawa Rintaro Ito Toshiaki Taoka Tadao Yoshida Michihiko Sone

出版者

Japanese Society for Magnetic Resonance in Medicine

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.bc.2021-0141, (Released:2021-12-25)

参考文献数

16

被引用文献数

1

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It has been reported that perivenous cystic structures near the parasagittal dura are associated with the leakage of gadolinium-based contrast agents at 4 hours after intravenous administration. The origin of such cystic structures remains unknown. While reading many cases of MR cisternography, we noticed that some of the cystic structures appeared to connect to the perivenous subpial space. This new imaging finding might facilitate future research of the waste clearance system for the central nervous system.