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  • 1
    Keywords: CANCER ; carcinoma ; PERFUSION ; DIAGNOSIS ; DIFFERENTIATION ; MRI ; LESIONS ; COEFFICIENT ; PRELIMINARY EXPERIENCE ; ABDOMINAL ORGANS
    Abstract: Diffusion-based intravoxel incoherent motion imaging has recently gained interest as a method to detect and characterize pancreatic lesions, especially as it could provide a radiation- and contrast agent-free alternative to existing diagnostic methods. However, tumor delineation on intravoxel incoherent motion-derived parameter maps is impeded by poor lesion-to-pancreatic duct contrast in the f-maps and poor lesion-tovessel contrast in the D-maps. The distribution of the diffusion and perfusion parameters within vessels, ducts, and tumors were extracted from a group of 42 patients with pancreatic adenocarcinoma. Clearly separable combinations of f and D were observed, and receiver operating characteristic analysis was used to determine the optimal cutoff values for an automated segmentation of vessels and ducts to improve lesion detection and delineation on the individual intravoxel incoherent motion-derived maps. Receiver operating characteristic analysis identified f 5 0.28 as the cutoff for vessels (Area under the curve (AUC) 5 0.901) versus tumor/duct and D 5 1.85 mu m(2)/ms for separating duct from tumor tissue (AUC = 0.988). These values were incorporated in an automatic segmentation algorithm and then applied to 42 patients. This yielded clearly improved tumor delineation compared to individual intravoxel incoherent motion-derived maps. Furthermore, previous findings that indicated that the f value in pancreatic cancer is strongly reduced compared to healthy pancreatic tissue were reconfirmed.
    Type of Publication: Journal article published
    PubMed ID: 21437979
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  • 2
    Keywords: CANCER ; PERFUSION ; DIFFERENTIATION ; adenocarcinoma ; QUANTITATIVE-ANALYSIS ; DIFFUSION ; CIRRHOSIS ; pancreas ; PHASE HELICAL CT ; APPARENT-DIFFUSION-COEFFICIENT ; DUAL-PHASE ; DWI ; IVIM
    Abstract: Purpose: To determine which of the quantitative parameters obtained from intravoxel incoherent motion diffusion weighted imaging (DWI) is the most significant for the differentiation between pancreatic carcinoma and mass-forming chronic pancreatitis. Materials and Methods: Twenty-nine patients with pancreatic masses were included, 9 proved to have a mass-forming pancreatitis and 20 had a pancreatic carcinoma. The patients were studied using intravoxel incoherent motion DWI with 11 b-values and the apparent diffusion coefficient (ADC), the true diffusion constant (D) and the perfusion fraction (f) were calculated. The diagnostic strength of the parameters was evaluated using receiver operating characteristic analysis. Results: The ADC in chronic pancreatitis was higher than in pancreatic carcinoma with significant differences at b = 50, 75, 100, 150, 200, 300 s/mm(2) (ADC(50) = 3.17 +/- 0.67 vs. 2.55 +/- 1.09, ADC(75) = 2.46 +/- 0.4 vs. 1.93 +/- 0.52, ADC(100) = 2.28 +/- 0.48 vs. 1.73 +/- 0.45, ADC(150) = 1.97 +/- 0.26 vs. 1.63 +/- 0.40, ADC(200) = 1.98 +/- 0.24 vs. 1.53 +/- 0.28, and ADC(300) = 1.76 +/- 0.19 vs. 1.46 +/- 0.31 x 10(-3) mm(2)/s). No significant differences were found at b = 25, 400, 600, and 800 s/mm(2) (ADC(25) = 4.69 +/- 0.65 vs. 4.04 +/- 1.35, ADC(400) = 1.57 +/- 0.21 vs. 1.37 +/- 0.30, ADC(600) = 1.38 +/- 0.18 vs. 1.24 +/- 0.25, and ADC(800) = 1.27 +/- 0.10 vs. 1.18 +/- 0.19 x 10(-3) mm(2)/s) nor using ADC(tot) (1.42 +/- 0.23 vs. 1.28 +/- 0.12 x 10(-3) mm(2)/s). The perfusion fraction f was significantly higher in pancreatitis compared with pancreatic carcinoma (16.3% +/- 5.30% vs. 8.2% +/- 4.00%, P = 0.0001). There was no significant difference between groups for D (1.07 +/- 0.224 x 10(-3) mm(2)/s for chronic pancreatitis and 1.09 +/- 0.3 x 10(-3) mm(2)/s for pancreatic carcinoma, P = 0.66). For f, the highest area under the curve (0.894) and combined sensitivity (80%) and specificity (89.9%) were found. Conclusions: There were significant differences in ADC(50-300) between chronic pancreatitis and pancreatic carcinoma. Because D is not significantly different between groups, differences in ADC can be attributed mainly to differences in perfusion. The perfusion fraction f proved to be the superior DWI-derived parameter for differentiation of mass-forming pancreatitis and pancreatic carcinoma
    Type of Publication: Journal article published
    PubMed ID: 21139505
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