Purpose: We explored normal diameter values of the cochlear (CN) and facial (FN) nerves on 3-dimensional constructive interference in steady state (3D-CISS) using a 3-tesla magnetic resonance (MR) imaging scanner.
Methods: A total of 142 patients underwent MR imaging of the inner ear at 3T. We retrospectively analyzed data from 172 ears. All ears had normal hearing and no history of ipsilateral facial palsy. Parasagittal images of 0.5-mm thickness perpendicular to the internal auditory canal were reconstructed from 0.4-mm thick axial 3D-CISS images for all ears. Two independent radiologists measured the long diameter (LD), short diameter (SD), and cross-sectional area (CSA) of each CN and FN. For each measurement, we calculated the mean value from the 2 observers and evaluated interobserver agreement. We also evaluated the correlation between nerve diameter and sex and age.
Results: Both observers could perform measurements in 157 CN from 172 ears (91%) and 165 FN from 172 ears (96%). For the CN, the mean LD was 1.35±0.16 mm, the mean SD was 0.99±0.18 mm, and the mean CSA was 1.07±0.30 mm²; for the FN, the mean values were 1.18±0.17 mm (LD), 0.87±0.16 mm (SD), and 0.83±0.27 mm² (CSA). Interobserver reliability was good for each measurement (r=0.569 to 0.691, P<0.01). The diameters of the 2 nerves tended to be larger in men, but only the CSA of the FN was significantly larger in men (P<0.05). Age did not affect nerve diameter.
Conclusion: We present normal values of CN and FN diameters on 3D-CISS at 3T. Our results warrant further study to clarify the pathophysiological state of the CN or FN using 3D-CISS.

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Purpose: We investigated the ability to detect the articular disk and joint effusion of the temporomandibular joint (TMJ) of a method of dual echo volumetric isotropic turbo spin echo acquisition (DE-VISTA) additional fusion images (AFI).
Methods: DE-VISTA was performed in the 26 TMJ of 13 volunteers and 26 TMJ of 13 patients. Two-dimensional (2D) dual echo turbo spin echo was performed in the 26 TMJ of 13 volunteers. On a workstation, we added proton density-weighted images (PDWI) and T₂ weighted images (T₂WI) of the DE-VISTA per voxel to reconstruct DE-VISTA-AFI. Two radiologists reviewed these images visually and quantitatively.
Results: Visual evaluation of the articular disk was equivalent between DE-VISTA-AFI and 2D-PDWI. The sliding thin-slab multiplanar reformation (MPR) method of DE-VISTA-AFI could detect all articular disks. The ratio of contrast (CR) of adipose tissue by the articular disk to that of the articular disk itself was significantly higher in DE-VISTA-AFI than DE-VISTA-PDWI (P<0.05) in patients and volunteers with closed or open mouth. In volunteers, the CR between adipose tissue and the disk on DE-VISTA-AFI was marginally significant to that on 2D-PDWI at opened mouth (P=0.071) and not significantly different (P=0.18) from that at closed mouth. Joint effusion could be identified in DE-VISTA-AFI in all 8 joints that had joint effusion in DE-VISTA-T₂WI but in only 3 of those joints in 2D-T₂WI. The CR of joint effusion to adipose tissue on DE-VISTA-AFI did not differ significantly from that on DE-VISTA-PDWI. However, using DE-VISTA-T₂WI in addition to DE-VISTA-PDWI, we could visually identify joint effusion on DE-VISTA-AFI that could not be identified on DE-VISTA-PDWI alone.
Conclusion: DE-VISTA-AFI can depict the articular disk and a small amount of joint effusion by the required plane of MPR using the sliding thin-slab MPR method.

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Purpose: Many inner ear disorders, including Ménière's disease, are believed to be based on endolymphatic hydrops. We evaluated a newly proposed method for semi-quantification of endolymphatic size in patients with suspected endolymphatic hydrops that uses 2 kinds of processed magnetic resonance (MR) images.
Methods: Twenty-four consecutive patients underwent heavily T₂-weighted (hT₂W) MR cisternography (MRC), hT₂W 3-dimensional (3D) fluid-attenuated inversion recovery (FLAIR) with inversion time of 2250 ms (positive perilymph image, PPI), and hT₂W-3D-IR with inversion time of 2050 ms (positive endolymph image, PEI) 4 hours after intravenous administration of single-dose gadolinium-based contrast material (IV-SD-GBCM). Two images were generated using 2 new methods to process PPI, PEI, and MRC. Three radiologists contoured the cochlea and vestibule on MRC, copied regions of interest (ROIs) onto the 2 kinds of generated images, and semi-quantitatively measured the size of the endolymph for the cochlea and vestibule by setting a threshold pixel value.
Results: Each observer noted a strong linear correlation between endolymphatic size of both the cochlea and vestibule of the 2 kinds of generated images. The Pearson correlation coefficients (r) were 0.783, 0.734, and 0.800 in the cochlea and 0.924, 0.930, and 0.933 in the vestibule (P<0.001, for all). In both the cochlea and vestibule, repeated-measures analysis of variance showed no statistically significant difference between observers.
Conclusion: Use of the 2 kinds of generated images generated from MR images obtained 4 hours after IV-SD-GBCM might enable semi-quantification of endolymphatic size with little observer dependency.

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Purpose: We aimed to determine which of the following magnetic resonance (MR) imaging sequences is most effective for detecting prostate cancer: T₂-weighted (T₂W), dynamic contrast-enhanced (DCE) T₁-weighted (T₁W), or diffusion-weighted (DWI) imaging or apparent diffusion coefficient (ADC) mapping.
Materials and Methods: We included 37 male patients with prostate cancer who underwent MR imaging before radical prostatectomy in this retrospective study. Sixty-four foci (>5 mm in size; 35 in the peripheral zone [PZ], 29 in the transitional zone [TZ]) were histopathologically determined to be prostate cancer. We determined the capacity of T₂W, DCE-T₁W, DWI, ADC mapping alone, and the combination of ADC mapping with DWI, and conventional MR sequences to detect prostate cancer, including their sensitivity and positive predictive value (PPV), with reference to the results obtained in histopathological examinations of whole-mount sections.
Results: In the PZ, sensitivities were 31.4% (T₂W), 37.1% (DCE-T₁W), 51.4% (DWI), and 71.4% (ADC mapping); PPVs were 78.6% (T₂W), 92.9% (DCE-T₁W), 94.7% (DWI), and 96.0% (ADC mapping). Sensitivity was significantly higher of ADC mapping than other sequences. In the TZ, sensitivities were 55.1% (T₂W), 44.8% (DCE-T₁W), 82.8% (DWI), and 89.7% (ADC mapping); PPVs were 64.0% (T₂W), 46.4% (DCE-T₁W), 70.6% (DWI), and 72.2% (ADC mapping). Sensitivity was significantly higher of ADC mapping and DWI than conventional MR imaging, but there was no significant correlation between DWI/ADC mapping and T₂W/DCE-T₁W with respect to PPVs. Combining sequences did not improve sensitivity; only the PPV in the TZ improved when ADC mapping was combined with DCE-T₁W.
Conclusion: ADC mapping is the most effective standard MR imaging tool for detecting prostate cancer. The addition of DCE-T₁W may improve the PPV of ADC mapping for diagnosing cancer in the TZ.

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Purpose: Hypovascular nodules that exhibit hypointensity in hepatocyte-phase images of gadoxetic acid-enhanced magnetic resonance (MR) imaging are frequently encountered in clinical practice. We investigated risk factors for the development of these nodules into hypervascular hepatocellular carcinoma (HCC).
Methods: We retrospectively reviewed our institutional database and identified 302 patients who underwent gadoxetic acid-enhanced MR imaging for suspected or confirmed HCC from February 1, 2008 to January 30, 2011. We excluded patients who were examined for metastasis of other malignancies or for other hepatic tumors, such as focal nodular hyperplasia. We identified hypovascular nodules that were hypointense in hepatocyte-phase images, recorded their characteristics, and calculated the cumulative hypervascularization rate for nodules that were followed up.
Results: Of the 302 patients, 82 had hypovascular nodules (178 nodules; mean size, 9.3 mm). Sixty nodules were followed up for over 6 months, and eight progressed to hypervascular HCC. Hypervascularization occurred more frequently in nodules with fat than those without (P<0.01). The cumulative hypervascularization rate was 5.1% over a year.
Conclusion: The presence of intralesional fat was found to be a risk factor for hypervascularization of hypovascular nodules that exhibited hypointensity in the hepatocyte-phase images of gadoxetic acid-enhanced MR imaging.

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Purpose: We performed single-voxel magnetic resonance spectroscopy (MRS) of the human prostate at 3 tesla using a surface coil to measure prostate water, choline (Cho), creatine (Cr), and citrate (Cit) relaxation times T₁, T₂, and to estimate concentrations of Cho, Cr, and Cit in healthy volunteers.
Methods: In nine of 17 healthy volunteers, we performed experiments to estimate relaxation time, and we used the spectra of the other eight to compute metabolite concentrations. Spectra were processed by LCModel and AMARES (advanced method for accurate, robust, and efficient spectral fitting) algorithms. T₁ and T₂ values were obtained by monoexponential fitting of the spectral intensities. Metabolite concentrations were estimated using prostate tissue water as an internal concentration reference.
Results: Relaxation times are reported for prostate water (T₁, 2163±166 ms; T₂, 110±18 ms), Cho (T₁, 987±71 ms; T₂, 239±24 ms), Cr (T₁, 1128±149 ms; T₂, 188±20 ms), and Cit (T₁, 476±70 ms; T₂, 228±42 ms). Mean concentrations in healthy prostate were Cho, 2.6±0.3 mM, Cr, 5.8±1.3 mM, and Cit, 26.9±5.5 mM.
Conclusion: We observed metabolite relaxation times and concentrations consistent with published values of healthy volunteers at 1.5 and 3T. T₁ values increased and T₂ slightly decreased with magnetic field strength. Our preliminary patient results indicate that water-referenced quantitative MRS of the human prostate is a promising tool for monitoring therapeutic effects and detecting tumor relapse, i.e., in situations when Cit intensity is small or undetectable.

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Purpose: We evaluated the safety of gadopentetate dimeglumine (Gd-DTPA), the first contrast agent for magnetic resonance imaging, using pharmacovigilance data for spontaneously reported adverse events (AEs) after 120 million cumulative administrations worldwide.
Methods: We analyzed spontaneously reported AEs for Gd-DTPA for pre-specified time periods between 1988 and 2011.
Results: Since the market introduction of Gd-DTPA in 1988, its global utilization reached 120 million cumulative administrations in 2011, more than 80% of which was by the USA, countries in the European Union (EU), and Japan. The global AE reporting rate was 21.2 in 100,000 administrations in 1988 and 14.4 in 100,000 administrations by 2011. Regional differences included higher reporting rates in the USA and Japan, and reporting rates lower than global rates in the EU. The reported rate of global serious AEs changed from 1.4 in 100,000 administrations in 1988 to 4.0 in 100,000 administrations in 2011. The highest number of reports of nephrogenic systemic fibrosis (NSF) was received from 2006 to 2008. Since 2009, no report of a current onset of NSF has been received. The reduced report rate of NSF may be due to increased awareness about the use of gadolinium-based contrast agents (GBCAs).
Conclusion: After more than 120 million cumulative administrations, Gd-DTPA is a widely used GBCA that shows a consistently low and stable incidence of AEs.

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Clear cell adenofibroma (CCAF) is a rare surface epithelial-stromal tumor of the ovary and recently considered another precursor of clear cell adenocarcinoma (CCA) other than endometrioma. We report magnetic resonance (MR) findings of a borderline CCAF that contained a small CCA focus. The tumor manifested a characteristic “black sponge” appearance. The CCA focus showed high signal intensity on diffusion-weighted imaging (DWI) and early enhancement on dynamic contrast-enhanced (DCE) MR imaging (DCE-MRI), and the CCAF components showed low signal intensity on DWI and gradually increasing contrast enhancement on DCE-MRI.

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Breast leukemia is extremely rare. Only 7 other reports describe its magnetic resonance (MR) imaging findings. This report describes a case of breast leukemia presenting as isolated intramammary leukemic relapse in the breasts after complete remission of acute myeloid leukemia. Dynamic contrast-enhanced MR imaging showed diffuse heterogeneous non-mass-like enhancement in one breast and a diffuse irregular heterogeneously enhancing mass in the other. Previous reports of MR imaging findings in breast leukemia have included only mass-like lesions; hence, the finding reported here is uncommon.

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Bifid tail of the pancreas is an extremely rare developmental anomaly, and its clinical importance is not well known. We report the case of a 28-year-old man with acute pancreatitis limited to one side of a bifid tail with no otherwise detectable parenchymal edema on magnetic resonance (MR) imaging. Neither was there evidence of other anatomical ductal abnormalities that could have contributed to the patient's pancreatitis. To the best of our knowledge, this is the first report to suggest that bifid tail of the pancreas might cause acute pancreatitis.

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