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Background and Aim: Kupffer cell (KC) function and CD14 expression contributes to pathogenesis of non-alcoholic steatohepatitis (NASH). However, these relationships remain unclear. We investigated the relationship of KC function with superparamagnetic iron oxide-enhanced magnetic resonance imaging (SPIO-MRI), histopathological severity of NASH, and number of CD14-positive KCs in NASH., Methods: This retrospective study included 32 patients (24 with NASH and eight with simple steatosis) who had previously undergone SPIO-MRI with T2-weighted gradient-recalled echo sequence. All subjects were diagnosed pathologically and were evaluated for necroinflammation grade, fibrosis stage, and number of CD14-positive KCs. Patients with NASH and simple steatosis were compared by using the Mann-Whitney test to determine differences in percent reduction of liver-to-muscle signal intensity ratio (reduction-%LMR), as a surrogate parameter of KC function, and number of CD14-positive KCs. Kruskal-Wallis test and Pearson's correlation coefficient were used to analyze relation among reduction-%LMR, histopathological severity and number of CD14-positive KCs., Results: There were statistically significant differences in reduction-%LMR and number of CD14-positive KCs between NASH and simple steatosis patients (Mann-Whitney test, P < 0.001 for all comparisons). Reduction-%LMR decreased with an increase in necroinflammation grade or fibrosis stage. The number of CD14-positive KCs increased with an increase in necroinflammation grade and fibrosis stage (Kruskal-Wallis test, both, P < 0.001). A high correlation was seen between number of CD14-positive KCs and reduction-%LMR (Pearson r = 0.81; P < 0.001)., Conclusions: KC phagocytic function evaluated with SPIO-MRI correlated with histopathological severity and number of CD14-positive KCs. These results support the concept that KC phagocytic dysfunction contributes to the pathogenesis of NASH., (© 2011 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd.)

Purpose: To compare contrast material-enhanced three-dimensional (3D) magnetic resonance imaging (MRI) at 3.0T and multidetector row computed tomography (MDCT) in the same patient with regard to image quality of pancreatobiliary disease and hepatic vascular conspicuity., Materials and Methods: This study enrolled 32 patients with pancreatobiliary disease who underwent both gadolinium-enhanced 3D dynamic MRI and multiphasic CT using 16-MDCT. Data analysis of image quality was performed by two radiologists based on source images, multiplanar reconstruction (MPR), curved planar reconstruction (CPR), and maximum intensity projection (MIP) reconstruction. Determination of image quality was based on a 4-point image quality rating scale., Results: The overall image quality of the MRI axial images was superior to that of the axial MDCT images. The MRI protocol yielded an average score of 3.8 points versus 3.5 for the CT imaging. No significant difference was found between 3.0T MRI and MDCT images in MPR or CPR image quality. Image quality for visualization of the distal intrahepatic segmental arteries was significantly improved using MDCT imaging. No significant difference was found between the MDCT and 3.0T MR in portal vein branch image quality., Conclusion: High-resolution dynamic contrast-enhanced MR imaging at 3.0T is a comprehensive technique which provides high image quality in pancreatobiliary disease.

1.5T Magnetic resonance (MR) imaging has become an accepted method for assessing prostate cancer. However, the role of 1.5T MRI in local staging of prostate cancer is limited. It is hoped that 3.0T MRI will be more useful in local staging of prostate cancer. The purpose of this study was to evaluate the tissue contrast, artifact presence, and image quality of T2-weighted images (T2WI) of prostate cancer using 3T MRI with a phased-array coil at different slice thicknesses and fields of view (FOV). We examined 15 patients with prostate cancer. We obtained MR images at slice thicknesses of 2 mm and 5 mm in both small and large FOV. The image obtained at a slice thickness of 2 mm with a small FOV had inferior tissue contrast compared to the other images (P<0.05), but there was no statistically significant difference in contrast between images obtained at a slice thickness of 2 mm with a large FOV and those obtained at a slice thickness of 5 mm. Artifacts were rated equally among the parameter combinations. The overall image quality obtained at a slice thickness of 2 mm with a large FOV was significantly superior to the other three imaging parameters (p<0.05). The image obtained at a slice thickness of 2 mm with a large FOV was superior to the other three images in evaluating T2WI of prostate cancer with 3T MRI.

Cholesterol granuloma is a foreign-body type granuloma that forms in reaction to cholesterol crystals. We report a rare case of focal cholesterol granuloma in the anterior mediastinum of a 62-year-old asymptomatic man that presented as an indeterminate anterior mediastinal nodule on [18F]-fluoro-2-deoxy-D-glucose-positron emission tomography and computed tomography scans. T1- and T2-weighted magnetic resonance images revealed markedly hypo-intense signals reflecting pathologic hyalinized collagen fibers. Magnetic resonance signal characteristics might be helpful for distinguishing benign cholesterol granulomas from malignant neoplasms.

Objective: The purpose of this study was to compare the dynamic contrast-enhanced MRI enhancement characteristics of malignant and benign solitary pulmonary nodules., Materials and Methods: The characteristics of 202 solitary pulmonary nodules (diameter, 1-3 cm; 144 cases of primary lung cancer, 31 cases of focal organizing pneumonia, 15 tuberculomas, 12 hamartomas) were reviewed retrospectively. In all cases dynamic MR images were obtained before and 1, 2, 3, 4, 5, 6, and 8 minutes after bolus injection of gadopentetate dimeglumine. Maximum enhancement ratio, time at maximum enhancement ratio, slope of time-enhancement ratio curves, and washout ratio were assessed. Statistical analyses were performed with the Kruskal-Wallis test with Bonferroni correction, chi-square test, and receiver operating characteristic curves., Results: For 122 (85%) of 144 primary lung cancers, time at maximum enhancement ratio was 4 minutes or less. For all tuberculomas and hamartomas, time at maximum enhancement ratio was greater than 4 minutes or gradual enhancement occurred without a peak time (p < 0.0001). Lung cancers had different maximum enhancement ratios and slopes than benign lesions (all p < 0.005). With 110% or lower maximum enhancement ratio as a cutoff value, the positive predictive value for malignancy was 92%; sensitivity, 63%; and specificity, 74%. With 13.5%/min or greater slope as a cutoff value, sensitivity, specificity, positive predictive value, and negative predictive value for malignancy were 94%, 96%, 99%, and 74%, respectively., Conclusion: Dynamic contrast-enhanced MRI is helpful in differentiating benign from malignant solitary pulmonary nodules. Absence of significant enhancement is a strong predictor that a lesion is benign.

Objective: To assess the CT and magnetic resonance (MR) imaging findings of thymic epithelial tumors classified according to the current World Health Organization (WHO) histologic classification and to determine useful findings in differentiating the main subtypes., Materials and Methods: Sixty patients with thymic epithelial tumor who underwent both CT and MR imaging were reviewed retrospectively. All cases were classified according to the 2004 WHO classification. The following findings were assessed in each case on both CT and MRI: size of tumor, contour, perimeter of capsule; homogeneity, presence of septum, hemorrhage, necrotic or cystic component within tumor; presence of mediastinal lymphadenopathy, pleural effusion, and great vessel invasion. These imaging characteristics of 30 low-risk thymomas (4 type A, 12 type AB, and 14 type B1), 18 high-risk thymomas (11 type B2 and seven type B3), and 12 thymic carcinomas on CT and MR imaging were compared using the chi-square test. Comparison between CT and MR findings was performed by using McNemar test., Results: On both CT and MR imaging, thymic carcinomas were more likely to have irregular contours (P < .001), necrotic or cystic component (P < .05), heterogeneous contrast-enhancement (P < .05), lymphadenopathy (P < .0001), and great vessel invasion (P < .001) than low-risk and high-risk thymomas. On MR imaging, the findings of almost complete capsule, septum, and homogenous enhancement were more commonly seen in low-risk thymomas than high-risk thymomas and thymic carcinomas (P < .05). MR imaging was superior to CT in the depiction of capsule, septum, or hemorrhage within tumor (all comparison, P < .05)., Conclusion: The presence of irregular contour, necrotic or cystic component, heterogeneous enhancement, lymphadenopathy, and great vessel invasion on CT or MR imaging are strongly suggestive of thymic carcinomas. On MR imaging, the findings of contour, capsule, septum, and homogenous enhancement are helpful in distinguishing low-risk thymomas from high-risk thymomas and thymic carcinomas.

Angioleiomyomas are smooth muscle tumors that occur most often in the extremities and are usually less than 2 cm in diameter. We present 2 case reports of giant angioleiomyoma. Case 1 was a 51-year-old woman with a 5-year history of a slowly growing mass 12x10 cm in diameter in the right posterior thigh. The tumor was larger than any previously reported. Case 2 was a 72-year-old man with an 8-year history of a slowly growing mass 6x6 cm in diameter in the left palm. The tumor was unique in that it grew to a giant size in the hand of the elderly patient. Magnetic resonance imaging of both cases confirmed the tumors' presence in the subcutis. T1-weighted images showed homogenous signal isointense to muscle. On T2-weighted images, areas of hyperintensity and hypointensity intermingled. Three-dimensional gadolinium-enhanced magnetic resonance angiography showed rapid initial enhancement followed by a gradual increase in enhancement, suggesting that the tumors were rich in vessels. Microscopic examination revealed numerous vascular channels embedded within a huge smooth muscle component.

We report a case of giant cell-rich osteosarcoma in the right distal femur of a 32-year-old man. Giant cell-rich osteosarcomas are sometimes difficult to distinguish from giant cell tumors by age, location, magnetic resonance imaging findings, and pathology. Radiography may be useful in the diagnosis of giant cell-rich osteosarcoma.

Magnetization transfer contrast (MTC) was evaluated by changing the off-set frequency and pulse intensity of MTC with the spoiled gradient echo (SPGR) sequence (T2*-weighted image) using an experimental phantom that included olive oil, protein, fiber, collagen, and pure water. The intensity of pure water reached a constant level just above the off-set frequency (1200 Hz) regardless of MT pulse power. The contrast-to-noise ratio (CNR) in each of the phantom materials was maximal at the MT pulse power of 2500 degrees (equivalent flip angle). The CNR and image noise obtained by body coil were inferior to those obtained with an extremity coil. In clinical application, the MTC effect on chondrosarcoma was higher (MT ratio, ROI-1:0.448, ROI-2:0.382) than those of other cases in this study. Since the image contrast was improved between the malignant fibrous histiocytoma (MFH, MT ratio, ROI-1:0.282, ROI-2:0.289) and peripheral tissues, extraskeletal extension could be observed more easily than without MTC imaging. In conclusion, the effects of MTC might be in providing useful information, in presuming composed tissues, differential diagnoses, and extent to the surrounding structures because of changing the image contrast to surrounding tissues corresponding to the rate of included bound water.

Purpose: To correlate the findings at contrast material-enhanced dynamic magnetic resonance (MR) imaging of small peripheral pulmonary carcinomas with tumor vascularity and prognosis., Materials and Methods: Ninety-four patients with small peripheral pulmonary carcinomas who underwent surgical resection were examined retrospectively. Pathologic specimens were stained with hematoxylin-eosin and elastin-van Gieson. CD34 and vascular endothelial growth factor (VEGF) were assessed immunohistochemically. Delineated CD34-positive cells were counted as microvessels. Dynamic MR imaging was performed prior to and at 1, 2, 3, 4, 5, 6, and 8 minutes after injection of a bolus of gadopentetate dimeglumine. The two observers reviewed all images, and two pathologists performed all histologic analyses; a decision was determined with consensus. The maximum enhancement ratio (MER), the time lapse between the completion of the injection and the point of maximum signal intensity (Tmax), the washout ratio, and the slope value of the time-signal intensity curve were correlated with the microvessel density. VEGF-positive and VEGF-negative tumors were compared. All statistical analyses were performed by using nonparametric methods., Results: The MER and the slope value were positively correlated, and the Tmax was negatively correlated (Spearman rank test, P <.0001, all comparisons) with the microvessel counts. The distribution of elastic and collagen fibers correlated with the washout ratio (Kruskal-Wallis test, P <.001). There was a statistically significant difference between the slope value of VEGF-positive tumors and that of VEGF-negative tumors (Mann-Whitney U test, P <.0001). Patients with VEGF-positive tumors had a significantly shorter overall survival than did those with VEGF-negative tumors (log-rank test, P <.0001)., Conclusion: Dynamic MR imaging findings correlate with tumor vascularity and may be helpful in the prediction of prognosis.

Alveolar adenoma of the lung is a rare benign neoplasm with distinctive gross and microscopic findings. Radiographically, alveolar adenoma usually presents as a well-circumscribed, peripheral, solitary nodule. The authors describe the contrast-enhanced computed tomography and magnetic resonance imaging features of alveolar adenoma of lung. Magnetic resonance imaging demonstrated the presence of a cystic space with central fluid and thin-rim enhancement. These findings are suggestive of a benign nodule, and alveolar adenoma of lung should be added to the differential diagnosis of nodules that demonstrate this pattern of enhancement and are probably benign.

Magnetic resonance (MR) imaging has an increasing role in evaluating soft-tissue masses of the extraperitoneal spaces. Since the MR imaging features of most soft-tissue masses are nonspecific, prediction of a specific histologic diagnosis remains a challenge for the radiologist. However, there are certain specific MR imaging appearances that are helpful for more accurate diagnosis. Some histologic components, such as myxoid stroma, collagen fibers, calcification, and fat, have characteristic MR imaging features. Recognition of these features can assist the radiologist in limiting the differential diagnosis. Dynamic enhancement patterns can reflect the vascularity of masses and may be useful in diagnosis, especially in differentiating benign from malignant soft-tissue masses. Familiarity with specific signs and knowledge of diagnostic pitfalls are also important for shortening the list of differential diagnoses. Specific signs are the target sign, the bowl of fruit sign, a whorled appearance, a flow void, speckled enhancement, associated lymphadenopathy, and extension into the intervertebral foramen. Diagnostic pitfalls are as follows: a myxoid stroma simulating cystic degeneration and necrosis, collagen fibers simulating hemorrhage, a fat component simulating extraperitoneal fat, extensive intratumoral hemorrhage simulating hematoma, benign masses mimicking malignant ones, malignant masses mimicking benign ones, and peritoneal lesions mimicking extraperitoneal masses.

We describe a new sequence, flow artifact-insensitive fluid-attenuated inversion recovery (FAIS-FLAIR), that capitalizes on the advantages of fluid-attenuated inversion recovery (FLAIR) while minimizing FLAIR-related artifacts such as those often encountered in the posterior fossa. Twenty-eight patients with posterior fossa disease underwent FAIS-FLAIR, conventional FLAIR, and spin-echo MR studies, and the findings yielded by the three techniques were compared. In this patient population, postcontrast FAIS-FLAIR imaging was obtained in 20 patients and compared with postcontrast T1-weighted images. The images were assessed for lesion conspicuity by three radiologists. FAIS-FLAIR markedly reduces the inflow artifacts from noninverted CSF on FLAIR images. It does so with and without contrast agent administration, and produces higher lesion conspicuity compared with T1- and T2-weighted spin-echo sequences and conventional FLAIR images of the posterior fossa.

Purpose: The purpose of this work was to compare dynamic MRI (D-MRI) with dynamic CT (D-CT) for the diagnosis of peripheral cholangiocarcinoma (PCC) of the liver., Method: Twenty patients with PCC underwent both D-CT and D-MRI during the early, middle, and delayed phase after contrast medium administration. The findings from D-MRI were compared with those from D-CT., Results: D-CT and D-MRI exhibited a similar tumoral enhancement pattern, and this enhancement was more conspicuous on D-MRI. A wedge-like enhancement area peripheral to the tumor was observed in 9 (45%) patients on D-CT and 11 (55%) patients on D-MRI. Ductal dilatation was found in 13 (65%) patients on both techniques. Vascular involvement and extrahepatic invasion were seen in nine (45%) and two (10%) patients, respectively. The relationship of the tumor to the vessels and surrounding organs was more easily evaluated on D-CT., Conclusion: Both D-CT and D-MRI can provide important information for the diagnosis of PCC. D-CT is better than D-MRI for demonstrating vascular involvement and extrahepatic invasion. D-MRI gives more conspicuous enhancement.

Japanese encephalitis (JE) is an acute encephalomyelitis which is a primary viral encephalitis accompanying a viral infection. Clinically, the patient who either resides in an endemic region or who has been exposed to the viral vector (mosquito) may have symptoms including high fever, headache, and impaired consciousness. JE involves many portions of the supratentorial and infratentorial compartments including the brain stem, hippocampus, thalamus, basal ganglia, and white matter. Classically MR imaging demonstrates the lesions of JE as hyperintense on T2-weighted images and hypointense on T1-weighted images. Hemorrhagic transformations have also been described in JE lesions, with corresponding expected T1 and T2 changes. Differential considerations based on the MRI appearance are somewhat broad, including but not limited to primary viral encephalitis, acute encephalopathy, limbic encephalitis, and acute disseminated encephalomyelitis. The therapy for JE is primarily conservative and supportive since there is no specific treatment for JE, and the disease has a high fatality rate. The prognosis depends on the extent of involvement at primary presentation, and on the autoimmune mechanisms of this disease.

Unlabelled: Abnormal parathyroid tissue can be identified by radionuclide imaging with either 99mTc-MIBI or 99mTc-tetrofosmin. This study compared the relative sensitivity of these two agents to localize parathyroid hyperplasia and adenoma., Methods: Twenty patients with primary (n = 9) or secondary (n = 11) hyperparathyroidism were studied with 99mTc-MIBI and 99mTc-tetrofosmin parathyroid imaging, ultrasonography and MRI. Radionuclide images of the neck were acquired 10 min and 2-3 hr after radiopharmaceutical injection. The images were visually evaluated for abnormal focal areas of increased tracer localization in the neck and mediastinum. A parathyroid gland/normal thyroid tissue activity ratio (referred to as the P/T uptake ratio) was calculated for each positive scan., Results: Of the 46 parathyroid glands surgically explored, the overall sensitivity and specificity of MIBI imaging were 83% and 83% (38/46); tetrofosmin imaging 87% and 83% (40/46); ultrasonography 78% and 40% (36/46); and MRI 80% and 60% (37/46), respectively. Both radiopharmaceuticals performed well in the nine patients found to have adenoma. The sensitivity and specificity of MIBI imaging were 100% and 100% (9/9); tetrofosmin imaging 100% and 100% (9/9); ultrasonography 78% and 67% (7/9); and MRI 100% and 100% (9/9), respectively. In the 37 glands with hyperplasia, MIBI imaging had a sensitivity of 78% and specificity of 75%; tetrofosmin imaging 84% and 75%; ultrasonography 78% and 43%; and MRI 73% and 60%, respectively., Conclusion: All imaging techniques localized abnormal parathyroid glands. The radiotracers have equal sensitivity for the localization of abnormal parathyroid glands. The sensitivity of these tracers was high as compared to ultrasonography or MRI.

We report a case of synovial sarcoma of the chest wall in a 41-year-old man. Chest CT revealed a huge tumor of the left chest wall with heterogeneous enhancement. On MR imaging, the tumor showed the "bowl-of-fruit" mixed-signal appearance with fluid-fluid levels similar to those of synovial sarcoma of the extremities. Synovial sarcoma arising from the chest wall is extremely rare; only four cases have been reported in the English literature. As synovial sarcoma is considered a carcinosarcoma-like tumor with true epithelial differentiation, it is able to originate from various regions. Even if the tumor is found in a region distant from the synovial membrane, the differential diagnosis of a tumor which demonstrates such findings on MR imaging should include synovial sarcoma.

We report a case of dysplastic arterial vascular abnormality in a 32-year-old man with overlying neuronal cell migration disorder. MR images showed a thickened left insular cortex adjacent to the abnormal vascular network. These findings suggest the possibility of leptomeningeal damage during neuronal cell migration as the cause of the overlying vasculopathy. The true pathogenesis of these seemingly associated abnormalities is unknown.