Abstract
BackgroundHepatic lesions often present diagnostic connundrums with conventional MR techniques. Hepatobiliary phase contrast-enhanced imaging with gadoxetic acid can aid in the characterization of such lesions. However, quantitative measures describing late-phase enhancement must be assessed relative to their accuracy of hepatic lesion classification.Purpose: To compare quantitative parameters in gadoxetic acid contrast-enhanced dynamic and hepatobiliary phase imaging versus apparent diffusion coefficients in hepatic lesion characterization.Material and Methods57 patients with focal hepatic lesions on gadoxetic acid MR were included. Lesion enhancement at standard post-contrast time points and in the hepatobiliary phase (HB; 15 and 25 minutes post-contrast) was assessed via calculation of contrast (CR) and enhancement ratios (ER). Apparent diffusion coefficient (ADC) values were also obtained. Values for these parameters were compared among lesions and ROC analyses performed.Results: HB enhancement was greatest with FNH and adenomas. HB ER parameters but not HB CR could distinguish HCC from benign entities (0.9 ER ROC AUC versus 0.5 CR ROC AUC). There was no statistically significant difference found between the 15 and 25 minutes HB time points in detection of any lesion (p>0.4). ADC values were statistically significantly higher with hemangiomas (p<0.05) without greater accuracy in lesion detection relative to HB phase parameters.ConclusionHepatobiliary phase gadoxetic acid contrast-enhanced MR characterizes focal hepatic lesions more accurately than ADC and conventional dynamic post-contrast time point enhancement parameters. ER values are generally superior to CR. No discernible benefit of 25 minute versus 15 minute delayed imaging is demonstrated.
Highlights
Conventional dynamic contrast-enhanced MRI suffers limitations in characterization of focal hepatic lesions secondary to overlapping enhancement characteristics or variable appearances of lesions [1,2]. This shortcoming of cDCE-MRI has been improved through the utilization of additional hepatic MR imaging techniques such as diffusion-weighted imaging (DWI) [3] and hepatocyte-specific contrast agents [4]
21 hemangiomas, 18 hepatocellular carcinomas (11 of which were evaluated in cirrhotic livers), 10 hepatic adenomas, and 8 cases of focal nodular hyperplasia were assessed
Adenomas and focal nodular hyperplasia (FNH) could be differentiated with statistical significance from hepatocellular carcinomas (HCC) utilizing enhancement ratios (ER) in HB1 and HB2
Summary
Conventional dynamic contrast-enhanced MRI (cDCE-MRI) suffers limitations in characterization of focal hepatic lesions secondary to overlapping enhancement characteristics or variable appearances of lesions [1,2]. This shortcoming of cDCE-MRI has been improved through the utilization of additional hepatic MR imaging techniques such as diffusion-weighted imaging (DWI) [3] and hepatocyte-specific contrast agents [4]. Hepatobiliary phase contrast-enhanced imaging with gadoxetic acid can aid in the characterization of such lesions. Purpose: To compare quantitative parameters in gadoxetic acid contrast-enhanced dynamic and hepatobiliary phase imaging versus apparent diffusion coefficients in hepatic lesion characterization
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