Super delayed phase imaging in gadoxetic acid-enhanced MRI: investigating factors contributing to improved liver contrast

Objectives: To assess whether extended delayed phase imaging, performed after gadoxetic acid administration for 60-120 min (termed as super delayed phase [SDP]), improves liver contrast and nodule visibility in patients with chronic liver disease and to identify predictors for contrast enhancement.

Methods: In this retrospective study, 116 patients with chronic liver disease were selected from 6933 gadoxetic acid-enhanced MRI examinations, which included SDP images. The liver-to-spleen contrast (LSC) was quantitatively evaluated, and factors influencing the improvement of LSC were analyzed. By comparing the standard hepatobiliary phase images at 20 min post-contrast (HBP20) with SDP images, nodule visibility was evaluated by two readers who were blinded to the study.

Results: SDP significantly enhanced LSC (SDP: 1.81 ± 0.48 vs HBP20: 1.50 ± 0.34, p < 0.001) and improved nodule visibility in patients with initially poor LSC. Total bilirubin levels and visible biliary excretion during HBP20 are predictors of LSC enhancement. Furthermore, nodule visibility scores significantly increased in the group with poor initial contrast (Reader 1: from 2.92 ± 1.57 to 3.79 ± 1.44; Reader 2: from 2.34 ± 1.42 to 3.36 ± 1.57, p < 0.001).

Conclusion: SDP enhanced liver contrast and nodule detection in patients with chronic liver disease, particularly in those with impaired liver function. Total bilirubin levels and visible biliary excretion during HBP20 are useful predictors of improvement. This technique may improve the diagnostic utility of MRI for hepatocarcinogenesis in cirrhotic nodules, specifically for detecting precursors of hepatocellular carcinoma, in cirrhotic patients with compromised liver function.

Key points: Question In gadoxetic acid-enhanced MRI, inadequate liver contrast can occur in patients with impaired liver function, potentially limiting the diagnostic value of the examination. Findings SDP images improved liver parenchymal signal intensity and visibility of hepatocellular carcinoma, even in cases with impaired liver function. Clinical relevance The addition of SDP imaging in gadoxetic acid-enhanced MRI improves liver contrast and early detection of hepatocellular carcinoma, especially in patients with impaired liver function, such as Child-Pugh B or C, aiding in making appropriate treatment decisions.