Comparison of acquired diffusion weighted imaging and computed diffusion weighted imaging for detection of hepatic metastases.

Objective: To compare the accuracy of acquired diffusion weighted imaging (DWI) (b=1000 s/mm(2)) with that of computed DWI (b=1000 s/mm(2)) for the detection of hepatic metastases.

Methods: Two hundred and sixty patients underwent abdominal magnetic resonance imaging (MRI) at 3.0 T for the evaluation of hepatic metastasis, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), heavily T2WI, DWI with b-values of 0, 500, 1000 s/mm(2), and three-dimensional dynamic contrast-enhanced MRI with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA), and 190 patients were included in the final study. Computed DWI (=1000 s/mm(2)) was synthesized from lower b-values (b=0 and 500 s/mm(2)). Two groups were assigned and compared: group A (acquired DWI) and group B (computed DWI). Diagnostic performance using each imaging set was evaluated by receiver operating characteristic (ROC) curve analysis.

Results: A total of 76 hepatic metastases were confirmed. The area under the ROC curve (Az) of group A was larger than that of group B (Observer 1; 0.919-0.915, Observer 2; 0.926-0.901), but there were no significant differences (observer 1, P=0.500; observer 2, P=0.190). There were 5 metastases visualized in group A, but these were difficult to detect in group B. However, there were 2 metastases that were better visualized in group B than in group A.

Conclusion: There were no significant differences between acquired DWI and computed DWI in the detection of hepatic metastasis.