Utarou Motosugi

High-b Value Diffusion-Weighted MRI for Detecting Pancreatic Adenocarcinoma: Preliminary Results

OBJECTIVE The objective of our study was to evaluate the usefulness of high-b value diffusion-weighted MRI (DWI) in the detection of pancreatic adenocarcinoma. SUBJECTS AND METHODS Twenty-six patients with pancreatic adenocarcinoma were included in the study. Twenty-three other patients who were being followed up due to pancreatic diseases other than adenocarcinoma were included as control subjects. All patients and subjects underwent DWI, and the images were evaluated by three blinded radiologists. RESULTS Receiver operating characteristic (ROC) curve analysis yielded A(z) values (i.e., area under the ROC curve) of 0.998, 0.998, and 0.995 for the three radiologists. The mean sensitivity and specificity for the detection of pancreatic adenocarcinoma were 96.2% and 98.6%, respectively. The kappa values indicating interobserver agreement between different pairs of radiologists were in the category of excellent. CONCLUSION High-b value DWI allows the detection of pancreatic adenocarcinoma with a high sensitivity and specificity.

High-B-value diffusion-weighted MRI in colorectal cancer.

OBJECTIVE The purpose of this article is to evaluate the usefulness of high-b-value diffusion-weighted MRI (DW-MRI) in the detection of colorectal adenocarcinoma. CONCLUSION High-b-value DW-MRI allows detection of colorectal adenocarcinoma with a high sensitivity and specificity.

Diffusion-Weighted MR Imaging in the Evaluation of Pancreatic Exocrine Function Before and After Secretin Stimulation

OBJECTIVES: To evaluate diffusion weighted MR imaging before and after secretin stimulation in the assessment of pancreatic exocrine function in the setting of chronic pancreatitis.METHODS: Nine patients with severe chronic pancreatitis and sixteen patients without chronic pancreatitis but with a history of chronic alcohol consumption were enrolled in the chronic pancreatitis and risk groups, respectively. Thirty-eight patients without any pancreatic disease or history of alcohol consumption were included in the control group. Diffusion weighted images were obtained before and after secretin administration in all patients. The peak ADC values and times were determined and intergroup differences were compared. A receiver operating characteristic curve (ROC) was used to identify the cutoff values of the peak ADC times for discrimination of control group from risk and chronic pancreatitis groups.RESULTS: In the control group, a peak increase in ADC value of 57–120% (median: 75%) was observed between 90 s and 4 min (median: 2 min) after administration of secretin (Pattern 1). In the risk group, in 13 patients, a peak increase of 52–150% was observed between 4 and 8 min (median: 7 min; Pattern 2). Peak times were significantly longer in risk group (p < 0.01). In three patients in the risk group, and in all patients in the chronic pancretitis group, no ADC peak was observed within 10 min following secretin administration (Pattern 3). Using a peak time of 4 min as the cut-off value, a sensitivity of 100% and specificity of 94.7% were achieved in discriminating the control group from the combined risk and chronic pancreatitis groups.CONCLUSION: Diffusion-weighted MR imaging before and after secretin administration could yield clinically useful information for detecting pathophysiologic alterations in the setting of chronic pancreatitis.

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.

MDCT of Pancreatic Adenocarcinoma: Optimal Imaging Phases and Multiplanar Reformatted Imaging

OBJECTIVE The objective of our study was to evaluate the individual contributions of arterial, pancreatic parenchymal, and portal venous phase (PVP) images and the utility of coronal and sagittal multiplanar reformatted (MPR) images in the assessment of pancreatic adenocarcinoma using triple-phase MDCT. MATERIALS AND METHODS Thirty-one patients with and 35 patients without pancreatic adenocarcinoma underwent triple-phase MDCT. Three radiologists independently attempted to detect pancreatic adenocarcinoma and assess local extension using the MDCT images in five sessions. The first three sessions involved sets of images obtained in arterial phase, pancreatic parenchymal phase, and PVP separately and respectively. In the fourth session, a combination of axial images from all phases was evaluated. During the fifth session, radiologists had access to coronal and sagittal MPR images together with the axial images obtained in all phases. Results were compared with surgical findings using receiver operating characteristic (ROC) analysis and kappa statistics. RESULTS Regarding tumor detection, the image set composed of coronal and sagittal MPR images and of axial images obtained in all phases had a significantly higher value for the area under the ROC curve (A(Z), 0.98 +/- 0.01) than the other image sets and yielded the highest sensitivity (93.5%). The sensitivity of the arterial phase image set (80.6%) was significantly lower than that of all other image sets. Whereas the image set composed of coronal and sagittal MPR images and axial images obtained in all phases yielded the highest kappa values for all local extension factors evaluated, the image set composed of only arterial phase images yielded the lowest kappa values for almost all of the factors. CONCLUSION A combination of pancreatic parenchymal phase and PVP imaging is necessary and efficient for the assessment of pancreatic adenocarcinoma. The addition of coronal and sagittal MPR images increased the performance of MDCT, especially in the evaluation of local extension.

Pancreatic adenocarcinoma: MDCT versus MRI in the detection and assessment of locoregional extension.

Purpose: To compare dynamic-contrast enhanced multirow detector computed tomography (MDCT) including multiplanar reformatted images (MPR) and magnetic resonance imaging (MRI) including magnetic resonance cholangiopancreatography images for the detection and assessment of locoregional extension of pancreatic adenocarcinoma. Materials and Methods: Twenty-four patients with and 21 patients without pancreatic adenocarcinoma underwent triple-phase MDCT and MRI. Three radiologists independently attempted to detect pancreatic adenocarcinoma and assess locoregional extension in 3 sessions. First session involved MDCT images. In the second session, radiologists had access to coronal and sagittal MPR images together with the axial images (MDCT + MPR). Third session involved MR images. Results were compared with surgical findings using receiver operating characteristic analysis and kappa statistics. Results: Regarding tumor detection, MDCT + MPR had a significantly higher value for areas under the curve (0.96 ± 0.02) at receiver operating characteristic analysis compared with those of MRI (0.90 ± 0.03) and MDCT (0.85 ± 0.04). MDCT + MPR had the highest mean sensitivity (96%), and MRI had the highest mean specificity (98%). For locoregional extension, MDCT + MPR showed the highest kappa values of the study for all factors evaluated (range, 0.63-0.86). Conclusions: In conclusion, multiphasic MDCT imaging with MPR images was superior to multiphasic MDCT imaging without MPR images and to comprehensive MRI employing 2-D sequences and magnetic resonance cholangiopancreatography for both the detection and assessment of locoregional extension of pancreatic adenocarcinomas. MRI might be used for further lesion characterization regarding its high specificity.

Effect of duration of contrast material injection on peak enhancement times and values of the aorta, main portal vein, and liver at dynamic MDCT with the dose of contrast medium tailored to patient weight

AIM To investigate the effects of contrast material injection duration on peak enhancement times and attenuation values of the aorta, main portal vein, and liver at MDCT when the dose of contrast material is adjusted to patient weight. MATERIAL AND METHODS Seventy-five patients were randomly assigned to one of five groups, with durations of injection of 25, 30, 35, 40, or 45 s. All patients were injected with 2 ml/kg iodine (300 mg/ml). Attenuation values and peak enhancement times for the aorta, main portal vein, and liver were determined. The relationship between patient weight and enhancement times and values, the differences regarding peak enhancement times, and the relationship between injection duration and enhancement values were investigated using Pearson correlation, analysis of variance (ANOVA), and Spearman rank correlation, respectively. RESULTS No significant correlations were seen between patient weight and peak enhancement times or values. Mean peak enhancement times for the aorta, main portal vein, and liver were 9-11 s, 18-22 s, and 30-34 s, respectively (p>0.05). The correlations between injection duration and peak enhancement values were significant and negative. CONCLUSIONS Regardless of patient weight and injection duration, peak enhancement times of aorta, main portal vein and liver were approximately 10, 20, and 30 s, respectively. The enhancement values tended to be higher for shorter injection durations.

Magnetic resonance diffusion-weighted imaging in the characterization of pancreatic mucinous cystic lesions

AIM The aim of the study was to evaluate the utility of diffusion-weighted imaging (DWI), including apparent diffusion coefficient (ADC) measurement, in order to differentiate mucinous cystic neoplasms (MCNs) from intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. MATERIALS AND METHODS Fifty cases of IPMN with a total of 62 lesions, and eight cases of MCN, were retrospectively selected for the study. The cases of IPMN were selected using multimodality clinical or histopathological criteria, while all MCN lesions were histopathologically proven. DWI was carried out using b values of 500 and 1000s/mm(2). Visual assessment was performed by two radiologists who used two categories (low-iso or high signal intensity). ADC values of the lesions were also calculated. Fishers exact test and the Mann-Whitney U test were used for statistical analysis. RESULTS All IPMN lesions demonstrated low-iso signal intensities compared with the pancreatic parenchyma on DWI. Two of the MCN lesions demonstrated low-iso signal intensities, and six lesions demonstrated high signal intensities. The ADC values for IPMNs (mean 2.9 ± 0.024 × 10(-3)mm(2)/s) were significantly higher than those for MCNs (mean 2.1 ± 0.30 × 10(-3)mm(2)/s). ROC analysis showed an optimal cut-off value of 2.4 × 10(-3)mm(2)/s for differentiating between the two types of lesions, providing a sensitivity of 98% and a specificity of 88%. CONCLUSION The results of the present study suggest that ADC values in mucinous cystic lesions of the pancreas can be advantageous for their characterization into IPMN and MCN.

Diffusion-weighted magnetic resonance imaging for characterization of focal liver masses: impact of parallel imaging (SENSE) and b value.

Purpose: To evaluate the impact of parallel imaging (sensitivity encoding [SENSE] technique) on diffusion-weighted (DW) magnetic resonance imaging, compare DW imaging techniques with 2 different b values for characterization of focal hepatic lesions, and determine apparent diffusion coefficient cutoff values. Materials and Methods: Seventy-eight patients with 86 lesions were examined with 4 different DW techniques with 2 different b values (400 and 1000 s/mm2) and with/without the use of SENSE. The differences in signal-noise ratio values and image quality between DW images obtained with different techniques were compared using repeated-measures analysis of variance and Friedman test, respectively. A receiver operating characteristic analysis was applied to evaluate the apparent diffusion coefficient values as a discriminating variable to differentiate malignant lesions from benign ones; sensitivity and specificity were calculated. Results: There was no significant difference in the signal-noise ratio value and image quality between DW images obtained with b = 400 s/mm2 without SENSE (DW400) and b = 1000 s/mm2 with SENSE (DW1000SENSE). DW1000SENSE had the highest Az values for discriminating malignant from benign hepatic lesions (0.97) and hemangioma from metastasis (0.89). Using 1.63 × 10−3 mm2/s as the cutoff value, DW1000SENSE had a sensitivity of 95.2% (40/42) and a specificity of 91.0% (40/44) for differentiating benign from malignant hepatic lesions. Using a cutoff value of 1.45 × 10−3 mm2/s, DW1000SENSE had a sensitivity of 90.5% (19/21) and a specificity of 93.7% (15/16) for differentiating metastases from hemangiomas. Conclusions: Diffusion-weighted imaging with a b value of 1000 s/mm2 and SENSE has the potential to differentiate hepatic focal lesions with improved sensitivity and specificity.