Delay before the hepatocyte phase of Gd-EOB-DTPA-enhanced MR imaging: Is it possible to shorten the examination time?

Aim: To examine if it is possible to shorten the examination time of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB)-enhanced MRI by omitting hepatocyte-phase images of 20-min delay time (Im-20) for detecting focal liver lesions. Four hundred ninety-five malignant focal liver lesions observed on Im-20 in 265 patients were included. The hepatocyte phase was obtained 10 min (Im-10) and 20 min (Im-20) after Gd-EOB injection. Liver enhancement was evaluated using a 4-point scale [excellent/good/poor/non-diagnostic; visual liver-spleen contrast (V-LSC)] and a quantitative liver-spleen contrast ratio (Q-LSC). Two radiologists evaluated lesion conspicuity for assessing the sensitivity of lesion detection. As Im-20 was used as the standard of reference for the lesions, Im-20 artificially had 100% sensitivity. The results showed that although sensitivities and Q-LSC significantly increased from Im-10 to Im-20 (sensitivity/mean Q-LSC: Im-5, 81%/1.4 Im-10, 96%/1.7: Im-20, 100%/1.9), the sensitivity of Im-10 achieved 100% (the same as Im-20) in patients with good/excellent V-LSC or Q-LSC of more than 1.5. On Im-10, 202 patients (77%) were assigned as having good/excellent V-LSC (78%), and 161 (61%) were assigned as having Q-LSC of more than 1.5. We concluded that Im-20 can be omitted in at least 61% of the patients. (orig.)