# Differentiation of Autoimmune Pancreatitis From Pancreatic Ductal Adenocarcinoma by Diffusion-Weighted Magnetic Resonance Imaging With Weighted Diffusion Subtraction

## TL;DR

This study shows that adding a new imaging technique called weighted diffusion subtraction improves the ability to tell apart two types of pancreatic diseases using MRI.

## Contribution

The study introduces weighted diffusion subtraction as a novel enhancement to diffusion-weighted MRI for differentiating autoimmune pancreatitis from pancreatic cancer.

## Key findings

- Adding weighted diffusion subtraction significantly improved diagnostic accuracy compared to using diffusion-weighted imaging alone.
- Radiologists had higher confidence scores when using weighted diffusion subtraction in distinguishing between the two conditions.
- The inter-reader agreement was substantial in both groups, indicating consistent diagnostic reliability.

## Abstract

Purpose

Weighted diffusion subtraction (WDS) is a new imaging technique derived from a pair of diffusion-weighted images (DWIs) using low and high b values. This study assesses the diagnostic performance of WDS in distinguishing pancreatic ductal adenocarcinoma (PDAC) from autoimmune pancreatitis (AIP) by comparing the efficacy of DWI alone compared to DWI with WDS.

Methods

The patient cohort consisted of 10 patients diagnosed with AIP and 28 patients diagnosed with PDAC. Two blinded radiologists reviewed the MRI images and assessed their diagnostic accuracy and confidence levels. Differences between groups A (DWI alone) and B (DWI added WDS) were assessed, and a receiver operating characteristic (ROC) curve analysis was performed. Inter-reader agreement was analyzed using weighted κ statistics, and apparent diffusion coefficient (ADC) values were calculated for both AIP and PDAC.

Results

In diagnostic accuracy, Group B demonstrated significantly higher area under the curve (AUC) values than Group A for both readers. The inter-reader agreement was evaluated as “substantial” in both groups. The mean confidence scores for Group B were significantly higher than those for Group A for both readers.

Conclusion

The addition of WDS to DWI may enhance the visual differentiation between AIP and PDAC, potentially improving diagnostic accuracy and confidence.