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.

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.

Clinical application of single-shot echo-planar diffusion-weighted imaging with compressed SENSE in prostate MRI at 3T: preliminary experience.

OBJECTIVES: Image quality (IQ) of diffusion-weighted imaging (DWI) with single-shot echo-planar imaging (ssEPI) suffers from low signal-to-noise ratio (SNR) in high b-value acquisitions. Compressed SENSE (C-SENSE), which combines SENSE with compressed sensing, enables SNR to be improved by reducing noise. The aim of this study was to compare IQ and prostate cancer (PC) detectability between DWI with ssEPI using SENSE (EPIS) and using C-SENSE (EPICS). MATERIALS AND METHODS: Twenty-five patients with pathologically proven PC underwent multi-parametric magnetic resonance imaging at 3T. DW images acquired with EPIS and EPICS were assessed for the following: lesion conspicuity (LC), SNR, contrast-to-noise ratio (CNR), mean and standard deviation (SD) of apparent diffusion coefficient (ADC) of lesion (lADCm and lADCsd), coefficient of variation of lesion ADC (lADCcv), and mean ADC of benign prostate (bADCm). RESULTS: LC were comparable between EPIS and EPICS (p > 0.050), and SNR and CNR were significantly higher in EPICS than EPIS (p = 0.001 and p < 0.001). In both EPIS and EPICS, lADCm was significantly lower than bADCm (p < 0.001). In addition, lADCcv was significantly lower in EPICS than in EPIS (p < 0.001). CONCLUSION: Compared with EPIS, EPICS has improved IQ and comparable diagnostic performance in PC.

[Evaluation of potentially influential factors for positron emission tomography image quality in liver signal-to-noise ratio utilizing a delivery ¹8F-fluoro-2-deoxy-D-glucose study on Bi4Ge3O12-positron emission tomography/computed tomography].

UNLABELLED: The purpose of this study was to evaluate the relationship of body habitus, blood glucose level and injected dose, respectively, with BGO (Bi4Ge3O12) positron emission tomography (PET) image quality using commercially available 2-deoxy-2-[¹8F] fluoro-D-glucose (FDG). We also evaluated the relationship between PET image quality and acquisition time for each weight group. METHOD: One hundred twenty-five patients (66 male, 59 female) were enrolled in the study. We adopted liver signal-to-noise ratio (liver SNR) as an image quality index, derived from the region of interest (ROI) placed on the axial image of the liver. RESULTS: The correlation coefficient between liver SNR and dose per weight was 0.502. The liver SNR indicated a negative relationship with body weight, body mass index (BMI) and cross sectional area of the patient's body, with the correlation coefficients of -0.594, -0.479 and -0.522, respectively. For all weight groups, an extended acquisition time of at least 60 s/bed was necessary to improve liver SNR. CONCLUSION: The findings of this study are potentially of use for designing imaging protocols for the BGO-PET/CT system when using commercially available FDG. It is easy to obtain good image quality for patients of low to average body size with the standard injection dose. However, large patients should be injected, wherever possible, with an FDG dose of up to 5 MBq/kg. The acquisition time in overweight and obese patients should be as longer as possible than in standard weight patients.

[Impact of the standardized uptake value on the body trunk with truncation error of µ-map in the positron emission tomography/computed tomography: phantom studies].

PURPOSE: The aim of this study was evaluate to impact of standardized uptake value (SUV) on the body trunk with truncation error of µ-map for CT attenuation correction (CTAC) in whole-body 2-deoxy-2-[(18)F] fluoro-D-glucose ((18)F-FDG)-positron emission tomography (PET)/CT with use of anthropomorphic phantom. METHODS: We used body phantom (2.5 MBq/l) including simulated tumor targets (11.25 MBq/l) and arm phantom. The CT scan was used with a field of view (FOV) of 50 cm. The µ-maps were created by assuming a state of the arm protruding from the FOV (Pmap). A 3D-PET scan with an emission time of 20 min was performed. The PET images were then reconstructed with CTAC, and with and without scatter correction. We evaluated the relationship to Pmap size and the count of simulated tumors and background (B.G.) in PET images which reconstructed the use of each Pmap, respectively. RESULTS: The count of simulated tumor (large) with scatter correction was decreased to 1.3% (Pmap: 15 mm) and 8.8% (Pmap: 35 mm). Then, the count severe reduction was 86.9% in Pmap of 65 mm. The same trend was shown by simulated tumor (middle, small) and B.G. The count of the simulated tumor (large) without scatter correction decreased to 1.3% (Pmap: 15 mm), 6.4% (Pmap: 35 mm) and 13.1% (Pmap: 65 mm). CONCLUSION: Truncation error by µ-map for CTAC in whole-body (18)F-PET/CT caused a decrease of the SUV on the body trunk used for attenuation and scatter correction in the PET images.

[Assessment of the exposure dose value displayed on operator console in a computed tomography system deciding exposure dose from positioning image].

The aim of this study was to assess the exposure dose value (DLP) displayed on the operator console in a computed tomography system with automatic exposure control (CT-AEC) which decides the exposure dose from a positioning image. We measured exposure dose with two kinds of CT systems and evaluated the error of the displayed DLP value on the operator console against the measured DLP value. The assessment was performed in three sites: head and neck, upper chest, and lower abdomen. As a result, the errors of displayed value with CT-AEC against the error without CT-AEC in system A (4.09%) were significantly different on two assessment sites (head and neck: -4.02%, upper chest: 6.60%). There is no significant difference on the third assessment site (lower abdomen: 0.06%). On the other hand, those values in system B (8.38%) were almost similar with no significant differences (head and neck: -1.12%, upper chest: -1.85%, lower abdomen: -0.64%). The results show that there were significant differences noted between the errors of displayed value with CT-AEC and without CT-AEC in system A for the head and neck and the upper chest. In conclusion, displayed value with CT-AEC and without CT-AEC were about the same error. However, the possibility that the error depended on a model and the examination site of CT was shown.