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PURPOSE To assess the feasibility of extracellular volume (ECV) fraction determined with equilibrium contrast-enhanced MRI for prediction of treatment response to chemotherapy in pancreatic ductal adenocarcinoma (PDAC) in comparison with dynamic contrast-enhanced MRI (DCE-MRI), and to clarify the association between ECV fraction and DCE-MRI-derived pharmacokinetic parameters. METHODS This retrospective study included 58 consecutive patients with histologically confirmed PDAC who underwent DCE-MRI before systemic chemotherapy. Tumor pharmacokinetic parameters, including the volume transfer coefficient (Ktrans), rate constant (kep), and extracellular extravascular volume fraction (ve) of DCE-MRI, and ECV fraction determined with equilibrium contrast-enhanced MRI were compared between the response and non-response groups. The correlation of tumor ECV fraction with each DCE-MRI-derived pharmacokinetic parameter was examined using Spearman's rank correlation coefficient. RESULTS Tumor Ktrans, ve, and ECV fraction were significantly higher in the response group than in the non-response group (all, P 37.6%). The ECV fraction showed a significant positive correlation with Ktrans (Spearman's coefficient = 0.66, P

Objective To assess the feasibility of computed diffusion-weighted imaging (cDWI) in comparison with directly acquired DWI for visualizing pancreatic adenocarcinomas. Materials and methods Patients with pancreatic adenocarcinoma underwent DWI at b-values of 0, 1000 (DWI1000), 1500 (DWI1500) and 2000 (DWI2000) s/mm2. From DWIs at b-values of 0 and 1000 s/mm2, we generated cDWIs at b-values of 1500 (cDWI1500) and 2000 (cDWI2000) s/mm2. DWI findings of pancreatic adenocarcinomas (clear hyperintensity; hyperintensity with an unclear distal border; and isointensity), the image quality and the tumor to pancreas contrast ratio (CR) were compared between directly acquired DWI and cDWI. Results Among the 63 included patients, clear hyperintense tumors were seen in 35 on DWI1000, 50 on DWI1500, 50 on cDWI1500, 53 on DWI2000 and 44 on cDWI2000. Incidence of clear hyperintense tumors was significantly higher on cDWI1500 than on DWI1000 (P = 0.013). There was no significant difference in the incidence of clear hyperintense tumors between DWI1500 and cDWI1500 (P > 0.999), but a lower incidence was seen on cDWI2000 than on DWI2000 (P = 0.028). Image quality was lower on cDWI than on DWI at b-values of 1500 (P = 0.002) and 2000 s/mm2 (P Conclusions cDWI1500 generated from b-values of 0 and 1000 s/mm2 should be considered more effective than DWI1000 and at least as effective as DWI1500.

Purpose To evaluate whether diffusion tensor imaging (DTI) can be used to differentiate malignant parotid gland tumors from the benign ones. Materials and methods The study population comprised 59 parotid gland tumors (24 Warthin’s tumors, 19 pleomorphic adenomas, seven other benign tumors, and nine malignant tumors). Single-shot echo-planar DTI was performed with motion-probing gradients along 30 noncollinear directions (b = 1000 s/mm2) at 3.0 T. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values for benign and malignant tumors were compared using the Mann–Whitney U test. Receiver-operating characteristic (ROC) curve analysis was performed to assess the ability of the ADC and FA values to differentiate malignant tumors from the benign ones. Results ADC values showed no significant difference between malignant (0.93 ± 0.21 × 10−3 mm2/s) and benign tumors (1.19 ± 0.50 × 10−3 mm2/s) (p = 0.225). FA values of malignant tumors were significantly higher than those of benign tumors (0.26 ± 0.06 vs. 0.17 ± 0.05, p Conclusions DTI, particularly FA, can help differentiate malignant parotid gland tumors from the benign ones.

Objective To compare the quality of contrast enhancement and hepatic CT images acquired using bolus tracking technique at two different time points and those acquired with fixed scan delay technique using a previous bolus tracking data. Materials and methods Fifty patients who underwent 3 different hepatic CT exams (25-s fixed injection of 600 mg iodine (I)/kg or 100 mL of 370 mg I/mL nonionic contrast medium) were enrolled. The first and second exams were performed with a bolus tracking technique. The third exam was performed with a fixed scan delay technique using the first exam data. Differences in attenuation values in the abdominal organs were examined and evaluated visually on hepatic arterial phase images. Results There was no significant difference in the mean 50-HU threshold times between the first and second bolus tracking exams with intra-patient differences between them (1.3 ± 0.9 s). No significant intra-patient differences were noted in organ attenuation and visual evaluation on hepatic arterial phase images between the 3 exams. Conclusion The fixed scan delay technique using a previous bolus tracking data is feasible for hepatic CT exams to follow up hepatocellular carcinoma.