Purpose: We used a whole-brain, isotropic-voxel acquisition technique to improve the geometric distortion in diffusion-weighted (DWI) and diffusion tensor imaging (DTI) in coronal directions, which is remarkable at high magnetic fields.
Materials and Methods: We performed magnetic resonance imaging of 17 healthy volunteers using a 3T scanner and obtained coronal DWI/DTI as well as coronal images that were reformatted from isotropic volume data acquired by 1.6-mm-thick axial DWI/DTI. We visually evaluated the degree of image distortion and quantitated the findings by co-registration analysis.
Results: In-plane geometric distortions in coronal DWI/DTI, particularly at the frontal base and medial temporal lobe, were dramatically diminished when the isotropic-voxel acquisition technique was used. Quantitative measurement revealed a reduction in areas of misregistration, but not their absence, in reformatted coronal images, mainly because of distortion in the anteroposterior direction in the source images.
Conclusion: The isotropic-voxel DWI/DTI technique enabled acquisition of coronal images that represented anatomical details accurately with permissible spatial distortion while maintaining spatial resolution, even at 3T.

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Purpose: To establish a practical method that uses concurrent b0 images to standardize the display conditions for diffusion-weighted images (DWI) that vary among institutions and interpreters.
Method: Using identical parameters, we obtained DWI for 12 healthy volunteers at 4 institutions using 4 MRI scanners from 3 vendors. Three operators manually set the window width for the images equal to the signal intensity of the normal-appearing thalamus on b0 images and set the window level at half and then exported the images to 8-bit gray-scale images. We calculated the mean pixel values of the brain objects in the images and examined the variation among scanners, operators, and subjects.
Result: Following our method, the DWI of the 12 subjects obtained using the 4 different scanners had nearly identical contrast and brightness. The mean pixel values of the brain on the exported images among the operators and subjects were not significantly different, but we found a slight, significant difference among the scanners.
Conclusion: Determining DWI display conditions by using b0 images is a simple and practical method to standardize window width and level for evaluating diffusion abnormalities and decreasing variation among institutions and operators.

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Using 4 and 8-channel super-parallel magnetic resonance (MR) microscopes with a horizontal bore 2.34T superconducting magnet developed for 3-dimensional MR microscopy of the large Kyoto Collection of Human Embryos, we acquired T₁-weighted 3D images of 1204 embryos at a spatial resolution of (40 μm)³ to (150 μm)³ in about 2 years. Similarity of image contrast between the T₁-weighted images and stained anatomical sections indicated that T₁-weighted 3D images could be used for an anatomical 3D image database for human embryology.

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Purpose: We assessed the diagnostic value of whole body magnetic resonance (MR) imaging (WB-MRI) using diffusion-weighted images (DWI) for detecting bone metastasis and compared it with that of skeletal scintigraphy (SS).
Materials and Methods: Thirty patients with malignancies (breast cancer, 17 patients; prostate cancer, 9; and one patient each, thyroid cancer, liposarcoma, leiomyosarcoma, and extraskeletal Ewing sarcoma) underwent both WB-MRI and SS to detect bone metastasis. All patients were followed more than 6 months by MR imaging, SS, or computed tomographic (CT) examination. For WB-MRI, patients were placed in feet-first supine position with table-top extender and quadrature body coil.
We acquired DWI (axial plane from lower neck to proximal femur) (single shot short TI inversion-recovery [STIR]: repetition time [TR] 6243/echo time [TE] 59/inversion time [TI] 180 ms; b value: 600 s/mm²; 5-mm slice thickness; 112×112 matrix), T₁-weighted fast spin echo (T₁WI), and STIR (sagittal plane of total spine images and coronal plane of whole body images) images.
Four blinded readers independently and separately interpreted images of combined MR sequences of T₁WI+STIR (session 1) and T₁WI+STIR+DWI (session 2).
Results: In 10 of 30 patients, we detected a total of 52 metastatic bone lesions; in the other 20, follow-up examinations confirmed no metastatic bone lesions.
For these 52 lesions, for session 2, the mean sensitivity was 96% and the positive predictive value (PPV) was 98%. Those values were superior to those of session 1 (sensitivity: 88%; PPV: 95%) and those of SS (sensitivity: 96%; PPV: 94%).
Conclusion: WB-MRI that included DWI was useful for detecting bone metastasis.

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Since its introduction, magnetic resonance (MR) imaging has undergone continued technical and methodological development and found numerous practical clinical applications. Cardiac MR imaging is one of the more sophisticated applications of MR, owing to the inherent presence of flow and motion and specific anatomy. Among the different categories of cardiac MR imaging, coronary MR angiography (MRA) places particularly high demands on planning, spatial resolution, high signal-to-noise ratio (SNR), and precise cardiac and respiratory motion correction.
However, recent advances in hardware, MR sequences, and motion detection techniques have made it possible to perform coronary MRA that includes volumetric acquisition of the entire heart as well as imaging of the vessel walls on a submillimeter scale within a clinically acceptable scan time. We discuss from a technical perspective some of the milestones leading to the current state of coronary MR imaging and outline recent developments that will further advance coronary MR imaging. We discuss planning procedure, contrast preparation mechanisms and MR sequences, motion correction, high-resolution coronary artery and vessel wall imaging, and fast volumetric scanning techniques. Although MR imaging has certain limitations in providing simultaneous speed, resolution, and high SNR, it nonetheless offers a dedicated scanning procedure that addresses most clinically relevant questions in the diagnosis of ischemic heart disease.

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We attempted to measure the area and volume of visceral fat using magnetic resonance (MR) imaging to avoid radiation exposure. We used water suppression-spectral attenuation with inversion recovery (WS-SPAIR) as prepulses and conducted T₁ high-resolution isotropic volume examination (THRIVE).¹ Image processing software can be used to estimate the area and volume of fat and separate the fat and water signals at a visually optimal threshold in the MR image, which requires contrast enhancement between intestinal contents and visceral fat. In 14 volunteers, we evaluated WS-SPAIR and water suppression-spectral presaturation with inversion recovery (WS-SPIR) with respect to the relationship between the flip angle of THRIVE and signal contrast. We used flip angles of 5°, 10°, and 20°. The minimum threshold that allowed exclusion of intestinal contents from the masked region was determined for each technique. The volume and area of the masked region, which included subcutaneous fat, were measured at the umbilicus level. Both volume and area increased with a smaller flip angle. The masked region was larger with WS-SPIR-THRIVE (flip angle 5°). The size of the masked region was determined according to the minimum threshold that allowed exclusion of the intestinal contents from the masked region, expressing the contrast between the intestinal contents and fat in a relative manner. It was speculated that by separating the signals at the threshold, WS-SPIR-THRIVE (flip angle 5°) was a more suitable technique for measuring the area and volume of visceral fat.

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Purpose: To evaluate the performance advantages of an 8-element phased array head coil (8 ch coil) over a conventional quadrature-type birdcage head coil (QD coil) with regard to the signal-to-noise ratio (SNR) and image uniformity in 3 Tesla magnetic resonance (MR) imaging.
Materials and Methods: We scanned a phantom filled with silicon oil using an 8 ch coil and a QD coil in a 3T MR imaging system and compared the SNR and image uniformity obtained from T₁-weighted spin echo (SE) images and T₂-weighted fast SE images between the 2 coils. We also visually evaluated images from 4 healthy volunteers.
Results: The SNR with the 8 ch coil was approximately twice that with the QD coil in the region of interest (ROI), which was set as 75% of the area in the center of the phantom images. With regard to the spatial variation of sensitivity, the SNR with the 8 ch coil was lower at the center of the images than at the periphery, whereas the SNR with the QD coil exhibited an inverse pattern. At the center of the images with the 8 ch coil, the SNR was somewhat lower, and that distribution was relatively flat compared to that in the periphery. Image uniformity varied less with the 8 ch coil than with the QD coil on both imaging sequences.
Conclusion: The 8 ch phased array coil was useful for obtaining high quality 3T images because of its higher SNR and improved image uniformity than those obtained with conventional quadrature-type birdcage head coil.

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