Ultrasound-MRI Agreement in Individuals Undergoing Surveillance of Fontan-associated Liver Disease.

[OBJECTIVE] To assess agreement between abdominal ultrasound and MRI for the detection of focal liver lesions and manifestations of portal hypertension in patients with Fontan circulation.

[MATERIALS AND METHODS] To perform this single-center, retrospective study, we identified patients with Fontan circulation who underwent clinical abdominal ultrasound and MRI examinations within ±12 months between January 1, 2018 and June 30, 2023. Imaging reports were reviewed for the presence of liver lesions (specifically noting lesions >1 cm and radiologist-indicated suspicious lesions), features of portal hypertension (ie, presence of ascites and spleen length), abnormal liver contour, and liver stiffness. Intermodality agreement, sensitivity and specificity of ultrasound relative to MRI, and Spearman correlation were used to compare ultrasound and MRI measurements. Follow-up of detected lesions was also performed using electronic health records.

[RESULTS] There were 58 patients included. Agreement between MRI and ultrasound for the findings of Fontan-associated liver disease (FALD) was as follows: presence of a liver lesion of any size [k = 0.20 (95% CI: 0.08 to 0.32)], presence of a liver lesion >1 cm [k = 0.43 (95% CI: 0.18 to 0.68)], radiologist-indicated suspicious liver lesion(s) [k = 0.07 (95% CI: -0.13 to 0.27)], presence of ascites [k = 0.57 (95% CI: 0.32 to 0.81)], abnormal liver contour [k = 0.31 (95% CI: 0.03 to 0.59)], and spleen length [intraclass correlation coefficient = 0.81 (95% CI: 0.58 to 0.92)]. Sensitivity and specificity of ultrasound using MRI as the reference standard were as follows: 34% (95% CI: 20% to 50%) and 100% (95% CI: 77% to 100%) for the presence of a liver lesion of any size, and 39% (95% CI: 17% to 64%) and 98% (95% CI: 87% to 100%) for the presence of a liver lesion >1 cm. There was a poor correlation between ultrasound and MRI liver stiffness measurements [rho = 0.22 (95% CI: -0.14 to 0.53); P = 0.23]. Of 44 patients with liver lesions, 3 (6.8%) had biopsy-confirmed hepatocellular neoplasms, including 2 adenomas and 1 hepatocellular carcinoma. All 3 lesions were detected by both MRI and ultrasound.

[CONCLUSIONS] There is poor to fair agreement between ultrasound and MRI for detecting manifestations of FALD, with ultrasound having poor sensitivity compared with MRI. While ultrasound detected all 3 clinically important liver lesions in our study, our results raise questions about whether ultrasound is an appropriate screening tool for FALD in patients post-Fontan.