Low-grade appendiceal mucinous neoplasm with puffer ball-like appearance: A case report.

We report a case of ruptured low-grade appendiceal mucinous neoplasm with an impressive toy puffer ball-like appearance on magnetic resonance imaging. A 79-year-old woman with lower abdominal pain underwent computed tomography scanning, revealing a 6-cm mass in the right lower abdomen. T2-weighted images showed a radial low-signal structure in the central area of the mass, which was presumed to be fibrotic. Pathology confirmed ruptured low-grade appendiceal mucinous neoplasm. The rupture point was at the tip of the appendix, coinciding with the center of radial fibrosis. The unique morphology of the puffer ball-like appearance in this case may be a characteristic of low-grade appendiceal mucinous neoplasms.

Helicobacter pylori overcomes natural immunity in repeated infections.

Repeated experimental reinfection of two subjects indicates that Helicobacter pylori infection does not promote an immune response protective against future reinfection. Our results highlight the importance of preventing reinfection after eradication, through public health initiatives, and possibly treatment of family members. They indicate difficulties for vaccine development, especially therapeutic vaccines.

Detection of pancreatic carcinoma and liver metastases with gadoxetic acid-enhanced MR imaging: comparison with contrast-enhanced multi-detector row CT.

PURPOSE: To intraindividually compare gadoxetic acid-enhanced magnetic resonance (MR) imaging with contrast material-enhanced multi-detector row computed tomography (CT) in detection of pancreatic carcinoma and liver metastases. MATERIALS AND METHODS: The ethics committee approved this retrospective study with waiver of informed consent. This study included 100 patients (53 men, 47 women; mean age, 67.8 years) consisting of 54 patients with pathologically confirmed pancreatic carcinoma (mean size, 33 mm) and 46 without a pancreatic lesion. Sixty-two liver metastases (mean size, 10 mm) in 15 patients with pancreatic carcinoma were diagnosed at pathologic examination or multimodality assessment. Three readers blinded to the final diagnosis interpreted all MR (precontrast T1- and T2-weighted and gadoxetic acid-enhanced dynamic and hepatocyte phase MR images) and tetraphasic dynamic contrast-enhanced CT images and graded the presence (or absence) of pancreatic carcinoma and liver metastasis on patient-by-patient and lesion-by-lesion bases. Receiver operating characteristic analysis, McNemar test, and Fisher test were performed to compare the diagnostic performance of CT and MR imaging. RESULTS: No significant differences were observed between CT and MR images in depiction of pancreatic carcinoma. However, MR imaging had greater sensitivity in depicting liver metastasis than did CT for two of the three readers in the MR imaging-versus-CT analysis (85% vs 69%, P = .046) and for all three readers in the lesion-by-lesion analysis (92%-94% vs 74%-76%, P = .030-.044). CONCLUSION: Gadoxetic acid-enhanced MR imaging was equivalent to dynamic contrast-enhanced CT in depicting pancreatic carcinoma and had better sensitivity for depicting liver metastases, suggesting the usefulness of gadoxetic acid-enhanced MR imaging for evaluation of patients with pancreatic carcinoma.

Diagnosis of peritoneal dissemination: comparison of 18F-FDG PET/CT, diffusion-weighted MRI, and contrast-enhanced MDCT.

OBJECTIVE: The purpose of this study was to compare the diagnostic performance of (18)F-FDG PET/CT, MRI with and without diffusion-weighted imaging (DWI), and contrast-enhanced MDCT in the detection of peritoneal dissemination of malignant tumors. MATERIALS AND METHODS: We retrospectively evaluated the cases of 107 patients who underwent PET/CT and 130 patients who underwent MRI and contrast-enhanced MDCT. Twenty-six patients who underwent PET/CT and 23 who underwent MRI and contrast-enhanced MDCT were found to have peritoneal dissemination. All images were independently evaluated by two radiologists using a 5-point grading system. The results of PET/CT, T1- and T2-weighted MRI without DWI, MRI with DWI (b = 1,000 s/mm(2)), and contrast-enhanced MDCT were compared patient by patient and lesion by lesion by use of receiver operating characteristics analysis. Sensitivity, specificity, and positive predictive value were calculated and compared by use of the chi-square test. RESULTS: Patient by patient, the area under the receiver operating characteristics curve of MRI without DWI (0.88) was significantly less than that of the other modalities (contrast-enhanced MDCT, 0.91; MRI with DWI, 0.93; PET/CT, 0.97). The sensitivity of PET/CT (94%) was significantly higher than that of MRI without DWI (70%). The specificities of the modalities were not significantly different. In lesion-by-lesion analysis, MRI without DWI had significantly lower sensitivity (56%) than the other modalities (contrast-enhanced MDCT, 76%; MRI with DWI, 84%; PET/CT, 89%). The positive predictive value of PET/CT (93%) was significantly higher than that of the other three modalities (contrast-enhanced MDCT, 73%; MRI without DWI, 70%; MRI with DWI, 72%). CONCLUSION: PET/CT is the most useful technique for pathologic staging in the care of patients with malignant disease. If PET/CT is not available, DWI can be used as a screening tool.

Isolation and characterization of NMSO3-resistant mutants of respiratory syncytial virus.

We obtained two mutant strains of respiratory syncytial virus (RSV) which showed resistance against NMSO3 after 15 and 33 passages, respectively, in HEp-2 cells in the presence of 6.8 microM of NMSO3. The EC50 values of NMSO3 for the resistant virus strains were 0.48 and 0.93 microM, that is 4.8-9.3 times higher than that of the parent strain (EC50 = 0.1 microM). The most resistant strain also showed resistance against heparin but was sensitive to dextran sulfate and a polyoxotungstate, PM-523. In order to determine whether the acquisition of resistance to NMSO3 was the result of the accumulation of genetic changes of virus, we sequenced the G- and F-protein genes. In comparison with the standard type of RSV strains, we identified changes of 10 amino acids in the G protein including those at the central conserved segment. However, we did not observe any particular changes in the amino acid sequence of the F-protein of the resistant strains. From these results, we conclude that NMSO3 inhibits the G-protein interaction to the receptor. The mutations in the G-protein may result in the observed phenotypic resistance of RSV towards NMSO3.