Magnetic Resonance in Medical Sciences
Online ISSN : 1880-2206
Print ISSN : 1347-3182
ISSN-L : 1347-3182
Volume 8, Issue 4
Displaying 1-8 of 8 articles from this issue
Major Papers
  • Yuko NAKAMURA, Toshifumi OHMOTO, Tomoko SAITO, Toshio KAJIMA, Eiji NIS ...
    2009 Volume 8 Issue 4 Pages 143-148
    Published: 2009
    Released on J-STAGE: December 25, 2009
    JOURNAL OPEN ACCESS
    Purpose: Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) is a recently developed liver-specific contrast agent for magnetic resonance (MR) imaging that is excreted equally via the kidneys and the biliary system. To our knowledge, its effects on T2-weighted MR cholangiopancreatography (MRCP) images have not been explored. Acquisition of the hepatobiliary phase is recommended 20 min after administration of Gd-EOB-DTPA. Examination time cannot be extended if the contrast does not take effect on T2-weighted MRCP within 20 min after administration.
    We attempted to assess the change in signal of T2-weighted MRCP by excretion of Gd-EOB-DTPA.
    Methods: Between March and July 2008, 40 patients (15 women, 25 men; mean age 70.8 years) were examined with abdominal MR imaging. T2-weighted MRCP was performed before and 10 and 20 min after administration of Gd-EOB-DTPA. We analyzed signal intensity of the bile duct, gallbladder, cystic duct, and pancreatic duct on MRCP for changes in intensity.
    Results: T2-weighted MRCP 20 min after contrast administration showed loss of signal of the bile duct (intrahepatic bile duct in all cases, upper extrahepatic duct in 36 [90%], middle extrahepatic duct in 33 [85%], and lower extrahepatic duct in 26 [67%]), the gallbladder in 23 cases (72%), and the cystic duct in 25 (64%). This signal change increased with time. We observed no change in signal of the pancreatic duct.
    Conclusion: T2-weighted MRCP sequences should not be obtained after administration of Gd-EOB-DTPA because this contrast agent decreases signal intensity of the biliary structure on these images.
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  • Masahiro TAKIZAWA, Taeko ITO, Hiroyuki ITAGAKI, Tetsuhiko TAKAHASHI, K ...
    2009 Volume 8 Issue 4 Pages 149-158
    Published: 2009
    Released on J-STAGE: December 25, 2009
    JOURNAL OPEN ACCESS
    Purpose: Because radial sampling imposes many limitations on magnetic resonance (MR) imaging hardware, such as on the accuracy of the gradient magnetic field or the homogeneity of B0, some correction of the echo signal is usually needed before image reconstruction. In our previous study, we developed an echo-peak-shift correction (EPSC) algorithm not easily affected by hardware performance. However, some artifacts remained in lung imaging, where tissue is almost absent, or in cardiac imaging, which is affected by blood flow. In this study, we modified the EPSC algorithm to improve the image quality of the radial aquisition regime (RADAR) and expand its application sequences.
    Methods: We assumed the artifacts were mainly caused by errors in the phase map for EPSC and used a phantom on a 1.5-tesla (T) MR scanner to investigate whether to modify the EPSC algorithm. To evaluate the effectiveness of EPSC, we compared results from T1- and T2-weighted images of a volunteer's lung region using the current and modified EPSC. We then applied the modified EPSC to RADAR spin echo (SE) and RADAR balanced steady-state acquisition with rewound gradient echo (BASG) sequence.
    Results: The modified EPSC reduced phase discontinuity in the reference data used for EPSC and improved visualization of blood vessels in the lungs. Motion and blood flow caused no visible artifacts in the resulting images in either RADAR SE or RADAR BASG sequence.
    Conclusion: Use of the modified EPSC eliminated artifacts caused by signal loss in the reference data for EPSC. In addition, the modified EPSC was applied to RADAR SE and RADAR BASG sequences.
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  • Hideki HYODOH, Ryuji SHIRASE, Nobuyoshi KAWAHARADA, Kazusa HYODOH, Tai ...
    2009 Volume 8 Issue 4 Pages 159-164
    Published: 2009
    Released on J-STAGE: December 25, 2009
    JOURNAL OPEN ACCESS
    Purpose: We evaluated the efficacy of magnetic resonance angiography (MRA) for detecting the artery of Adamkiewicz (AKA) and the vertebral level of its feeding arteries branching from the aorta.
    Materials and Methods: Eighty-two patients (67 men, 15 women; aged 34 to 86 years, mean age 68.6 years) with thoracic descending and thoracoabdominal aortic lesions (aneurysm in 55, dissection in 25, coarctation in 2) underwent MRA to detect AKA. MRA was performed using 6-phase, dynamic-enhanced, 3-dimensional, fast spoiled gradient recalled acquisition in steady state (GRASS) on a 1.5-tesla (T) system, with double-dose bolus contrast injection. The vertebral levels of AKA branching and the AKA feeder artery branching from the aorta were determined.
    Results: The AKA was detected in 67 patients (81.7%). Branching of AKA occurred at levels T7 to T12 on the left side (n=52) and on the right (n=15). Vascular continuity from the aorta to the anterior spinal artery was demonstrated in 55 patients (67.1%). Comparing the vertebral level of arterial branching from the aorta to that of the AKA at the intervertebral foramen, the AKA branched at the same vertebral level in 44 patients (80.0%), one vertebral level above/below in 10 (18.2%), and 2 vertebral levels above in one (1.8%).
    Conclusion: MRA can be useful in the preoperative work-up of patients with thoracoabdominal aortic lesions to localize AKA and the segmental trajectories of vessels supplying blood to the AKA.
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Review
  • Kei YAMADA, Koji SAKAI, Kentaro AKAZAWA, Sachiko YUEN, Tsunehiko NISHI ...
    2009 Volume 8 Issue 4 Pages 165-174
    Published: 2009
    Released on J-STAGE: December 25, 2009
    JOURNAL OPEN ACCESS
    Magnetic resonance tractography based on diffusion-tensor imaging was first introduced to the medical imaging community a decade ago. It has been successfully applied to a number of neurological conditions and most commonly used for preoperative planning for brain tumors and vascular malformations. Areas of active research include stroke, and dementia, where it provides valuable information not available through other imaging techniques. This technique was first introduced using the deterministic streamline algorithm and has evolved to use more sophisticated probabilistic approaches. We will review the past, present, and future of tractography, focusing primarily on its clinical applications.
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Technical Notes
Case Reports
  • Shinji NAGANAWA, Shunichi ISHIHARA, Shingo IWANO, Michihiko SONE, Tsut ...
    2009 Volume 8 Issue 4 Pages 187-191
    Published: 2009
    Released on J-STAGE: December 25, 2009
    JOURNAL OPEN ACCESS
    We examined a 61-year-old woman with sudden left-side hearing loss accompanied by severe vertigo. High signal in the ampullar endolymph of the left semicircular canal on magnetic resonance (MR) fluid attenuated inversion recovery (3D-FLAIR) images suggested labyrinthine hemorrhage. The patient had been treated for chronic heart failure and prescribed 100 mg/day of acetylsalicylic acid (aspirin) for its antiplatelet effect. The 3D-FLAIR images demonstrated a small amount of focal hemorrhage in the labyrinthine fluid that may have been overlooked on T1-weighted images.
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  • Keiko SAKAMOTO, Ritsuko FUJIMITSU, Mikiko IDA, Shinji HORIUCHI, Yoshih ...
    2009 Volume 8 Issue 4 Pages 193-195
    Published: 2009
    Released on J-STAGE: December 25, 2009
    JOURNAL OPEN ACCESS
    A 53-year-old asymptomatic woman was found to have a pelvic mass at medical examination. Magnetic resonance (MR) imaging revealed a 4-cm solid mass at the right adnexal region, which showed marked hyperintensity on T2-weighted imaging and marked enhancement on post-contrast T1-weighted imaging. Chemical-shift imaging showed slight but significant signal loss on out-of-phase images, which suggested the presence of intratumoral lipid. The resected specimen exhibited typical features of steroid cell tumor, and Oil Red O stain was positive for cytoplasmic lipid.
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