Value of 3-T MR imaging in intraductal papillary mucinous neoplasm with a concomitant invasive carcinoma.

OBJECTIVES: To examine the value of 3-T MRI for evaluating the difference between the pancreatic parenchyma of intraductal papillary mucinous neoplasm with a concomitant invasive carcinoma (IPMN-IC) and the pancreatic parenchyma of patients without an IPMN-IC. METHODS: A total of 132 patients underwent abdominal 3-T MRI. Of the normal pancreatic parenchymal measurements, the pancreas-to-muscle signal intensity ratio in in-phase imaging (SIR-I), SIR in opposed-phase imaging (SIR-O), SIR in T2-weighted imaging (SIR-T2), ADC (×10-3 mm2/s) in DWI, and proton density fat fraction (PDFF [%]) in multi-echo 3D DIXON were calculated. The patients were divided into three groups (normal pancreas group: n = 60, intraductal papillary mucinous neoplasm (IPMN) group: n = 60, IPMN-IC group: n = 12). RESULTS: No significant differences were observed among the three groups in age, sex, body mass index, prevalence of diabetes mellitus, and hemoglobin A1c (p = 0.141 to p = 0.657). In comparisons among the three groups, the PDFF showed a significant difference (p < 0.001), and there were no significant differences among the three groups in SIR-I, SIR-O, SIR-T2, and ADC (p = 0.153 to p = 0.684). The PDFF of the pancreas was significantly higher in the IPMN-IC group than in the normal pancreas group or the IPMN group (p < 0.001 and p < 0.001, respectively), with no significant difference between the normal pancreas group and the IPMN group (p = 0.916). CONCLUSIONS: These observations suggest that the PDFF of the pancreas is associated with the presence of IPMN-IC. KEY POINTS: • The cause and risk factors of IPMN with a concomitant invasive carcinoma have not yet been clarified. • The PDFF of the pancreas was significantly higher in the IPMN-IC group than in the normal pancreas group or the IPMN group. • Pancreatic PDFF may be a potential biomarker for the development of IPMN with a concomitant invasive carcinoma.

Short repetition time diffusion-weighted imaging improves visualization of prostate cancer.

PURPOSE: This study aimed to assess whether short repetition time (TR) diffusion-weighted imaging (DWI) could improve diffusion contrast in patients with prostate cancer (PCa) compared with long TR (conventional) reference standard DWI. MATERIALS AND METHODS: Our Institutional Review Board approved this retrospective study and waived the need for informed consent. Twenty-five patients with suspected PCa underwent multiparametric magnetic resonance imaging (mp-MRI) using a 3.0-T system. DWI was performed with TR of 1850 ms (short) and 6000 ms (long) with b-values of 0, 1000, and 2000s/mm2. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), visual score, apparent diffusion coefficient (ADC), and diagnostic performance were compared between short and long TR DWI for both b-values. The statistical tests included paired t-test for SNR and CNR; Wilcoxon signed-rank test for VA; Pearson's correlation and Bland-Altman plot analysis for ADC; and McNemar test and receiver operating characteristic analysis and Delong test for diagnostic performance. RESULTS: Regarding b1000, CNR and visual score were significantly higher in short TR compared with long TR (P = .003 and P = .002, respectively), without significant difference in SNR (P = .21). Considering b2000, there was no significant difference in visual score between short and long TR (P = .07). However, SNR and CNR in long TR were higher (P = .01 and P = .04, respectively). ADC showed significant correlations, without apparent bias for ADC between short and long TR for both b-values. For diagnostic performance of DWI between short and long TR for both b-values, one out of five readers noted a significant difference, with the short TR for both b-values demonstrating superior performance. CONCLUSIONS: Our data showed that the short TR DWI1000 may provide better image quality than did the long TR DWI1000 and may improve visualization and diagnostic performance of PCa for readers.

Liver cirrhosis: relationship between fibrosis-associated hepatic morphological changes and portal hemodynamics using four-dimensional flow magnetic resonance imaging.

PURPOSE: The mechanisms underlying the morphological changes in liver cirrhosis remain unknown. This study aimed to clarify the relationship between fibrotic hepatic morphology and portal hemodynamic changes using four-dimensional flow magnetic resonance imaging (MRI). MATERIALS AND METHODS: Overall, 100 patients with suspected liver disease who underwent 3-T MRI were evaluated in this retrospective study. Liver fibrosis was assessed using a combination of visual assessment of the hepatic morphology and quantitative measures, including the fibrosis-4 index and aspartate transaminase-to-platelet ratio. It was classified into three groups according to the severity of fibrosis as follows: A (normal), B (mild-to-moderate), and C (severe). Quantitative indices, including area (mm2), net flow (mL/s), and average velocity (cm/s), were measured in the right portal vein (RPV) and left portal vein (LPV), and were compared across the groups using the Kruskal-Wallis and Mann-Whitney U tests. RESULTS: Among the 100 patients (69.1 ± 12.1 years; 59 men), 45, 35, and 20 were categorized into groups A, B, and C, respectively. The RPV area significantly differed among the groups (from p < 0.001 to p = 0.001), showing a gradual decrease with fibrosis progression. Moreover, the net flow significantly differed between groups A and B and between groups A and C (p < 0.001 and p < 0.001, respectively), showing a decrease during the early stage of fibrosis. In the LPV, the net flow significantly differed among the groups (from p = 0.001 to p = 0.030), revealing a gradual increase with fibrosis progression. CONCLUSION: The atrophy-hypertrophy complex, which is a characteristic imaging finding in advanced cirrhosis, was closely associated with decreased RPV flow in the early stage of fibrosis and a gradual increase in LPV flow across all stages of fibrosis progression.

Improvement of growth stability of photosynthetic bacterium Rhodobacter capsulatus.

Using a semicontinuous culture method, in which operational parameters such as cell concentration and light intensity distribution were maintained almost constant, instability of the specific growth rate of Rhodobacter capsulatus B-100, a purple bacterium, was observed to be similar to that of R. capsulatus ST-410 when cultivated under high ratios of light intensity on the illuminated side to that of the transmitted light. Such instability was not observed in the cultivation of Chlorella vulgaris, a eukaryotic green alga, even at higher cell concentrations. Under the same conditions, the increase in only the ferrous concentration from 43 microM, the concentration in the original RCV medium, to 172 microM sustained a stable growth, whereas Fe(2+) was slightly consumed during the cultivation. Supplemental illumination with a fluorescent lamp on the transmitted side of a flat plate photobioreactor sustained a moderate level of stable growth, while a halogen lamp slightly affected the growth stability. Our results showed that an increase in Fe(2+) concentration or supplemental illumination improves the growth stability of R. capsulatus.