Manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis(phosphate) (DPDP) was tested as a contrast agent for magnetic resonance imaging of pancreatic adenocarcinoma in 15 patients. At enhanced T1-weighted spin-echo (SE) and enhanced T1-weighted gradient-echo (GRE) imaging, statistically significant increases in signal-to-noise ratio (S/N) for the pancreas (21% and 92%, respectively) and contrast-to-noise ratio (C/N) (91% and 209%, respectively) were found. The C/N at enhanced T1-weighted SE imaging was superior to that at unenhanced imaging, including T2-weighted SE imaging (P = .001). Subjective image analysis showed that delineation of the pancreas and pancreatic tumors was clearly improved (P = .05) on enhanced T1-weighted SE and GRE images compared with on unenhanced T1- and T2-weighted images. The liver enhanced 19% at T1-weighted SE imaging and 90% at T1-weighted GRE imaging. There was a significantly higher S/N increase in hepatic parenchyma than in pancreatic tissue at enhanced T1-weighted GRE imaging (P = .0026) but not at enhanced T1-weighted SE imaging.
The aim of this study was to evaluate fluorine-18 fluorodeoxyglucose positron emission tomography ([18F]FDG PET) as a tool for the differential diagnosis of pancreatic carcinoma while taking into account serum glucose level. A group of 106 patients with unclear pancreatic masses were recruited for the study. PET was performed following intravenous administration of an average of 190 MBq [18F]FDG. Focally increased glucose utilisation was used as the criterion of malignancy. In addition, the "standardised uptake value" (SUV) was determined 45 min after injection. Carcinoma of the pancreas was demonstrated histologically in 74 cases, and chronic pancreatitis in 32 cases. Employing visual evaluation, 63 of the 74 (85%) pancreatic carcinomas were identified by PET. In 27 of the 32 cases (84%) of chronic pancreatitis it was possible to exclude malignancy. False-negative results (n=11) were obtained mostly in patients with raised serum glucose levels (10 out of 11), and false-positives (n=5) in patients with inflammatory processes of the pancreas. Thus PET showed an overall sensitivity of 85%, a specificity of 84%, a negative predictive value of 71%, and a positive predictive value of 93%. In a subgroup of patients with normal serum glucose levels (n=72), the results were 98%, 84%, 96% and 93%, respectively. Quantitative assessment yielded a mean SUV of 6.4+/-3.6 for pancreatic carcinoma as against a value of 3.6+/-1.7 for chronic pancreatitis (P<0.001), without increasing the diagnostic accuracy. This shows PET to be of value in assessing unclear pancreatic masses. The diagnostic accuracy of PET examinations is very dependent on serum glucose levels.
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