Diffusion-weighted imaging for the detection of mesenteric small bowel tumours with Magnetic Resonance--enterography

To retrospectively investigate the added value of diffusion-weighted MR imaging (DWI) for detecting mesenteric small bowel tumours (MSBTs) via MR-enterography.

MR-enterographies of 98 patients with suspected MSBTs were blindly analyzed by two independent readers for the presence of MSBTs. Four imaging sets including "standard" (Haste and TrueFisp), "standard + DWI," "standard + gadolinium-enhanced" and "standard + DWI + gadolinium-enhanced" were reviewed. Diagnostic performance of different readings were compared with McNemar's test.

Twenty-nine MSBTs were pathologically confirmed. For R1 (junior radiologist) sensitivity, specificity, PPV, NPV and accuracy for the detection of MSBTs via standard MRI were 52 % [95 % CI: 34 %-70 %] (15/29), 94 % [95 % CI: 89 %-100 %] (65/69), 79 % [95 % CI: 61 %-97 %] (15/19), 82 % [95 % CI: 74 %-91 %] (65/79) and 82 % [95 % CI: 74 %-89 %] (80/98), respectively. For R2 (senior radiologist) they were 76 % [95 % CI: 60 %-91 %] (22/29), 96 % [95 % CI: 91-100 %] (66/69), 88 % [95 % CI: 75 %-100 %] (22/25), 90 % [95 % CI: 84 %-97 %] (66/73) and 90 % [95 % CI: 84 %-96 %] (88/98), respectively. Adding DWI they were 72 % [95 % CI: 56 %-89 %] (21/29), 91 % [95 % CI: 85 %-98 %] (63/69), 78 % [95 % CI: 62 %-94 %] (21/27), 89 % [95 % CI: 81 %-96 %] (63/71) and 87 % [95 % CI: 80 %-94 %] (85/98) for R1 and 79 % [95 % CI: 65 %-94 %] (23/29), 97 % [95 % CI: 93 %-100 %] (67/69), 92 % [95 % CI: 81 %-100 %] (23/25), 92 % [95 % CI: 86 %-98 %] (67/73) and 92 % [95 % CI: 86 %-97 %] (90/98) for R2. Sensitivities for tumour detection were higher after adding DWI to standard MRI, although only for R1 was this significant (P = 0.03). Adding DWI to standard + gadolinium-enhanced MRI did not significantly increase MR performance.

DWI improves MSBT detection via MR-enterography compared to standard unenhanced MR-enterography, especially for unexperienced readers.

• MR-enterography is accurate for the detection of mesenteric small-bowel tumours. • Diffusion-weighted sequencing helps inexperienced readers detect small-bowel tumours with MR-enterography. • Diffusion-weighted sequencing adds value to standard MR-enterography when gadolinium is contraindicated.