Comparison of abdominal MRI with diffusion-weighted imaging to 68Ga-DOTATATE PET/CT in detection of neuroendocrine tumors of the pancreas

Purpose

The aim of the study was to evaluate contrast-enhanced MRI, diffusion-weighted MRI (DW MRI), and ⁶⁸Ga-DOTATATE positron emission tomography (PET)/CT in the detection of intermediate to well-differentiated neuroendocrine tumors (NET) of the pancreas.

Methods

Eighteen patients with pathologically proven pancreatic NET who underwent MRI including DW MRI and PET/CT within 6 weeks of each other were included in this retrospective study. Two radiologists evaluated T2-weighted (T2w), T2w?+?DW MRI, T2w?+?contrast-enhanced T1-weighted (CE T1w) MR images, and PET/CT for NET detection. The sensitivity and level of diagnostic confidence were compared among modalities using McNemar’s test and a Wilcoxon signed rank test. Apparent diffusion coefficients (ADC) of pancreatic NETs and normal pancreatic tissue were compared with Student’s t test.

Results

Of the NETs, 8/23 (34.8 %) and 9/23 (39.1 %) were detected on T2w images by observers 1 and 2, respectively. Detection rates improved significantly by combining T2w images with DW MRI (observer 1: 14/23?=?61 %; observer 2: 15/23?=?65.2 %; p?p?p??3?mm²/s) was statistically significantly lower than that of normal pancreatic tissue (1.48?±?0.39?×?10^?3?mm²/s).

Conclusion

DW MRI is a valuable adjunct to T2w imaging and comparable to CE T1w imaging in pancreatic NET detection, quantitatively differentiating between NET and normal pancreatic tissue with ADC measurements. ⁶⁸Ga-DOTATATE PET/CT is more sensitive than MRI in the detection of pancreatic NET.