Objectives: To determine magnetic resonance imaging (MRI) signal and enhancement characteristics of endocrine pancreatic tumours (ETPs) and which MR sequences show them most consistently.
Methods: Fifty-five consecutive patients with 68 ETPs underwent 1.5-T abdominal MRI comprising T2-weighted, unenhanced T1-weighted and dynamic T1-weighted after injection of gadopentetate dimeglumine sequences. Twenty-one patients underwent diffusion-weighted imaging (DWI). Two radiologists identified the number, location, size, signal and enhancement patterns of ETPs, and determined a confidence scale indicating the presence of tumours on DWI. The results were compared with echo-endoscopy (endoscopic ultrasound) findings.
Results: The detection sensitivity was 95%, similar to that of echo-endoscopy. T2-weighted and T1-weighted sequences at the arterial phase had the highest contrast-to-noise ratio (CNR) median value. On DWI, the mean sensitivity was 65%. The mean apparent diffusion coefficient (ADC) value of ETP was significantly lower than in the normal parenchyma.
Conclusion: In suspected ETP, MRI is a sensitive method, similar to echo-endoscopy and could be recommended as the first imaging technique. T2-weighted sequences and T1-weighted sequences in the arterial phase are the optimal pulse sequences. The quantitative assessment of ADC values is a promising tool for the characterisation of pancreatic lesions.