Differentiation Of The Histological Subtypes Of Periampullary Adenocarcinoma:Whole-tumor Histogram Analysis Of The Apparent Diffusion Coefficient

Purpose:To investigate whether whole-tumor histogram analysis of apparent diffusion coefficient（ADC）is helpful for distinguishing intestinal-type periampullary adenocarcinoma from pancreatobiliary-type periampullary adenocarcinoma.Materials and Methods:From January 2015 to October 2018,476 consecutive patients suspected with periampullary neoplasm and performed with MR scan were reviewed in this retrospective study.Only MR imaging acquired at 3T with different diffusion weighted imaging（b value,800,1000 s/mm²）and patients confirmed with periampullary adenocarcinoma were further analyzed.Then,the mean,5th,10th,25th,50th,75th,90th,95th percentiles of ADC values and ADC_min,ADC_max,kurtosis,skewness,and entropy were obtained from histogram analysis.Comparisons were made by independent Student’s t-test or Mann–Whitney U-test.Multiple receiver operating characteristic（ROC）curves analysis was used to determine and compare the diagnostic value of each significant parameter.Results:Finally,40 patients with histopathological confirmed intestinal-type（n=17）and pancreatobiliary-type（n=23）periampullary adenocarcinoma were enrolled.The mean,10th,25th,50th,75th,90th,95th percentiles and ADC_max derived from ADC₁₀₀₀ were significantly lower in the pancreatobiliary-type group than in intestinal-type group（P<0.05）.Yet those derived from ADC₈₀₀00 showed no significant difference between two groups.The75th percentile of ADC₁₀₀₀ values achieved the highest AUC for differentiating the two subtypes(AUC,0.781;Sensitivity,91%;Specificity,59%;cut-off value,1.50×10^-3mm²/s).Conclusion:Whole-tumor ADC histogram analysis at b value of 1000 s/mm² might be helpful for differentiating the histological subtypes of periampullary adenocarcinoma before surgery.