Diagnostic Role of Diffusion Weighted MRI in Characterization of Pancreatic Tumors

Abstract

Pancreatic cancer is one of the most fatal cancers. Stage of the disease greatly affects the prognosis of the disease that makes early diagnosis crucial in the management of pancreatic cancers.

Ultrasound (US) has a limited role in pancreatic evaluation as the overlying gas from the transverse colon and stomach makes visualizing pancreatic parenchyma difficult or even impossible. However, US can help identify biliary ductal dilation in patients with a pancreatic head mass. Most focal pancreatic lesions are hypoechoic compared to normal parenchyma.

In pancreatic neoplasms, Multidetector Computed Tomography (MDCT) accu- rately depicts the tumor morphology, ductal anatomy, and its relationship to surrounding organs and vascular structures.

Magnetic Resonance Imaging (MRI) is a powerful imaging technique for evaluating pancreatic neoplasms. Improvements in MR pulse sequences have resulted in a highly reliable means of detecting and staging pancreatic neoplasms and distinguishing malignant from benign pancreatic disease processes.

Diffusion Weighted Magnetic Resonance Imaging (DW- MRI) in the pancreas is a new imaging technique. It has the advantage that it can be obtained without breath-holding, using respiratory triggered technique. It is simple and non invasive with no need to use contrast media and it provides information that reflects tissue cellularity which can be used in detection of tumor aggressiveness and response to treatment.

Diffusion-Weighted Imaging (DWI) allows the assessment of random molecular motion in biologic tissues and generates representative apparent diffusion coefficient (ADC) values.

Several studies have shown that DWI can provide additional information for focal pancreatic lesions by demonstrating more restricted diffusion in solid malignant tumors than in benign inflammatory or cystic lesions, which can be indicated by a decreased ADC.