The value of signal intensity of diffusion weighted 3.0T magnetic resonance imaging in the diagnosis of pancreatic cancer

Abstract

Objective To investigate the value of signal intensity (SI) of diffusion weighted imaging(DWI) at 3.0 T magnetic resonance in the diagnosis of pancreatic adenocarcinoma. Methods Seventy patients with histologically confirmed pancreatic ductal adenocarcinoma and 18 healthy volunteers underwent DWI at 3.0 T (b=0, 600 s/mm2). The SIb0, SIb600 and apparent diffusion coefficient (ADC) values of normal pancreas as well as the pancreatic adenocarcinomas were measured by two independent observers. The inter-observer variability for SIb0, SIb600 and ADC values was analyzed by using interclass correlation coefficient (ICC). The SIb0, SIb600 and ADC values between the tumors and normal pancreatic tissues were analyzed and compared by using Mann-Whitney U test, and receiver-operating characteristic (ROC) analyses were used to determine the diagnostic performances of the three parameters to distinguish pancreatic adenocarcinoma from normal pancreas. Results All the SIb0, SIb600 and ADC indicated excellent inter-observer variability. ICC values for ADC, SIb0, SIb600 of pancreatic adenocarcinoma were 0.977, 0.983, 0.961, and ICC values of normal pancreas were 0.969, 0.979, 0.973. The mean SIb0, SIb600 and ADC values were 1165.7±273.4, 503.6±119.8, (1.40±0.20)×10-3 mm2/s in pancreatic adenocarcinoma, and650.9±104.5, 263.7±49.1, (1.53±0.21)×10-3 mm2/s in normal pancreas, and the difference between the two groups was statistically significant (P<0.01). With the SIb0、SIb600 and ADC values of normal pancreas as a reference, the area under ROC curve (AUC) were 0.987, 0.980 and 0.697, respectively. SI was significantly better than ADC for diagnosis of pancreatic adenocarcinoma (P<0.01). With the SIb600 of normal pancreas as a reference, SIb600≤324.4 as the cutoff value for diagnosis of pancreatic adenocarcinoma, the sensitivity and specificity were 95.7% and 94.4%. Conclusions SI of DWI at 3.0 T has a better diagnostic accuracy in the diagnosis of pancreatic ductal adenocarcinoma than ADC. As a quantitative imaging bio-marker in clinical practice, SI should be valued. Key words: Pancreatic neoplasms; Diffusion weighted imaging; Signal intensity; Apparent diffusion coefficient