Volumetric apparent diffusion coefficient histogram analysis for determining the degree of differentiation of periampullary carcinomas

Abstract

Background/Aim: The classification of periampullary adenocarcinomas into pancreatobiliary-type periampullary adenocarcinoma and intestinal-type periampullary adenocarcinoma (PPAC and IPAC, respectively) has gained significant acceptance in the medical community. A patient's prognosis is determined by the degree of differentiation of these tumor types. The objective of the present investigation was to assess the efficacy of volumetric apparent diffusion coefficient (ADC) histogram analysis in assessing the degree of differentiation for these two tumor types. Methods: This retrospective cohort research evaluated 54 PPAC (45 well-differentiated and nine poorly differentiated) and 15 IPAC (11 well-differentiated and four poorly differentiated) patients. Magnetic resonance imaging (1.5 T MRI) scans were used to evaluate the results. The features of the histogram for the ADC values were computed and incorporated several statistical measures, such as the mean, minimum, median, maximum, and percentiles in addition to the skewness, kurtosis, and variance. Results: In both PPAC and IPAC patients, the ADC values exhibited lower values in the poorly differentiated group when compared with the well-differentiated group. However, the changes between groups did not reach statistical significance. Among IPAC patients, the well-differentiated group had a larger kurtosis (P=0.048). In IPAC patients, the calculated value for the area under the curve (AUC) of kurtosis was determined to be 0.818. When the threshold was set at 0.123, the specificity and sensitivity were observed to be 90% and 75%, respectively. Conclusion: Our research indicates that the kurtosis of ADC is an effective indicator to determine the level of IPAC differentiation. Analysis of the histogram at increased b values can provide valuable insights to help determine the degree of differentiation of IPAC using a noninvasive technique.