Abstract
BackgroundTo investigate the associations between the diffusion parameters obtained from multiple-b-values diffusion weighted imaging (DWI) of pancreatic ductal adenocarcinoma (PDAC) and the aggressiveness and local stage prediction, and assess the values of the quantitative parameters for the discrimination of tumors from healthy pancreas.MethodsFifty-one patients with surgical pathology-proven PDAC (size, 35 ± 12 mm) and fifty-seven healthy volunteers were enrolled. Diffusion parameters including monoexponential apparent diffusion coefficient (ADCb and ADCtotal) and biexponential intravoxel incoherent motion (IVIM) parameters (ADCslow, ADCfast and f) based on 9 b-values (0 to 1000s/mm2) DWI were calculated for the lesions and the healthy pancreas. These parameters were compared by grades of differentiation, lymph node status, tumor stage and location. The diagnostic performances were calculated and compared by using the receiver operating characteristic curves (ROC) analyses.ResultsThere was no statistically significant difference in ADCb, ADCtotal, ADCslow, ADCfast or f between PDAC stage T1/T2 and stage T3/T4 or moderately differentiated versus poorly differentiated PDAC (p = 0.060-0.941). In addition, no significant differences were observed for the quantitative parameters between tumors located in the pancreatic head versus other pancreatic regions (p = 0.203-0.954) or between tumors with and without metastatic peri-pancreatic lymph nodes (p = 0.313-0.917). ADC25-600, ADC1000, ADCtotal and ADCfast were significantly lower for PDAC compared the healthy pancreas (all p < 0.05). ROC analyses showed the area under curve for ADC20 was the largest (0.911) to distinguish PDAC from normal pancreas (cut-off value, 5.58 × 10−3mm2/s) and had the highest combined sensitivity (89.5%) and specificity (82.4%).ConclusionsMultiple-b-values DWI derived monoexponential and biexponential parameters of PDAC do not exhibit significance dependence on tumor grade or tumor characteristics. ADC20 provided the best accuracy for differentiating PDAC from healthy pancreas in the study.
Highlights
To investigate the associations between the diffusion parameters obtained from multiple-b-values diffusion weighted imaging (DWI) of pancreatic ductal adenocarcinoma (PDAC) and the aggressiveness and local stage prediction, and assess the values of the quantitative parameters for the discrimination of tumors from healthy pancreas
Tumors Based on the World Health Organization (WHO) classification criteria, 14 patients with poorly differentiated adenocarcinoma and 37 patients with moderately differentiated tumors were identified
Our study showed that multiple-b-values DWI derived parameters including ADC20-600, ADC1000, ADCtotal, ADCfast might be useful markers to distinguish PDAC from healthy pancreas, and the ADC20 provided the highest accuracy
Summary
To investigate the associations between the diffusion parameters obtained from multiple-b-values diffusion weighted imaging (DWI) of pancreatic ductal adenocarcinoma (PDAC) and the aggressiveness and local stage prediction, and assess the values of the quantitative parameters for the discrimination of tumors from healthy pancreas. The role of ADC values in predicting adverse pathological features of pancreatic cancer were reported [12, 24, 25]. Conflicting results have been described: significant association [24] and lack of association [12, 25] between the ADC and pathological grade of pancreatic cancer were reported. These reports, used only two b values (0, 500 or 800 s/mm2) to measure ADC, which is influenced by the structures of the tissue, and by the microcirculation of blood in the capillary network. Multiple-b-values DWI with intravoxel incoherent motion (IVIM) model should be set up for the separate estimation of tissue perfusion and diffusivity [26]
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