Impact of Liver and Whole-Body Diffusion-Weighted MRI for Neuroendocrine Tumors on Patient Management: A Pilot Study

Background: Computed tomography scan is the current standard cross-sectional imaging modality for neuroendocrine tumor (NET) workup. Diffusion-weighted magnetic resonance imaging (DW-MRI) has proven to be more sensitive than standard sequences to diagnose liver metastases; whole-body DW-MRI may be more sensitive than whole-body MRI. Clinical implications have not yet been assessed. Thus, we evaluated radiological and clinical contributions of liver and whole-body DW-MRI to manage NETs. Methods: Twenty-five abnormal liver and 22 abnormal whole-body standard MRIs were first analyzed retrospectively. MR images were then reanalyzed after adding DW sequences. The standard of reference for metastasis confirmation was a combination of radiological follow-up and histological proof. Clinical impact was defined as MRI changes of liver invasion (unilobar to bilobar and/or 50% of liver) or therapeutic management changes made during a dedicated multidisciplinary meeting after whole-body MRI. Results: Thirty-two patients with mainly small intestine NETs (24/32) were studied. Adding DW to standard liver MRI yielded additional findings for 45% of the patients with 1.78 times more new lesions, mainly infracentimetric; it induced a management change for 18% of the patients. DW sequences added to whole-body MRI yielded additional findings for 71% of the patients, with 1.72 times more lesions, mainly infracentimetric, and induced a change in management for 19% of the patients. Conclusion: Adding DW sequences to standard MRI revealed additional metastases and led to modifications of patient management. Prospective studies are needed to confirm these results.