Pancreatic cancer: Lack of association between apparent diffusion coefficient values and adverse pathological features

Abstract

To identify retrospectively potential associations between apparent diffusion coefficient (ADC) values of pancreatic adenocarcinoma and tumour grade as well as other pathological features, using histopathological assessment from the Whipple procedure as the reference standard. Thirty patients with pancreatic adenocarcinoma underwent magnetic resonance imaging (MRI) including diffusion-weighted imaging with b-values of 0 and 500s/mm(2) before the Whipple procedure. Two radiologists independently recorded the ADC values of the tumour and benign pancreas for all cases. ADC values were compared with histopathological findings following the Whipple procedure. The intra-class correlation coefficient was 0.689 for benign pancreas and 0.695 for tumours, indicating good inter-reader agreement for ADC values. The mean ADC value was significantly lower in tumours than in benign pancreas for both readers (reader 1: 1.74±0.34×10(-3)mm(2)/s versus 2.08±0.48×10(-3)mm(2)/s, respectively, p=0.006; reader 2: 1.69±0.41×10(-3)mm(2)/s versus 2.11±0.54×10(-3)mm(2)/s, respectively, p<0.001). However, there was no significant difference in mean ADC between poorly and well/moderately differentiated tumours for either reader (reader 1: 1.69±0.36×10(-3)mm(2)/s versus 1.78±0.33×10(-3)mm(2)/s, respectively, p=0.491; reader 2: 1.62±0.33×10(-3)mm(2)/s versus 1.75±0.49×10(-3)mm(2)/s, respectively, p=0.405). The area under the curve (AUC) for differentiation of poorly and well/moderately differentiated tumours was 0.611 and 0.596 for readers 1 and 2, respectively, and was not significantly better than an AUC of 0.500 for either reader (p≥0.306). In addition, ADC was not significantly different for either reader between tumours with stage T3 versus stage T1/T2, between tumours with and without metastatic peri-pancreatic lymph nodes, or between tumours located in the pancreatic head versus other pancreatic regions (p≥0.413). No associations between ADC values of pancreatic adenocarcinoma and tumour grade or other adverse pathological features were observed.