Shear-Wave Elastography—A Diagnostic Tool for Surveillance of Fontan-Associated Liver Disease

Objectives: Liver fibrosis is increasingly recognized as a potentially serious morbidity associated with Fontan circulation (Fontan-associated liver disease [FALD]). Modalities for diagnosis and surveillance are still under investigation. Liver fibrosis results in increased liver stiffness, which can be assessed by ultrasound-based elastography. Liver stiffness correlates with the degree of fibrosis in patients with chronic liver disease. Image acquisition usually requires periods of breath holding, which can be challenging in younger children. The purpose of this study was to assess the value of shear-wave elastography as a potential diagnostic tool for FALD. The effect of breathing technique and interobserver variation was of special interest.

Methods: Liver elastography was performed with shear-wave elastography (GE Healthcare) in 25 healthy subjects (10 males and 15 females). Different techniques for image acquisition (spontaneous breathing, breath hold, and Valsalva maneuver) and interobserver agreement were analyzed. Liver stiffness of healthy subjects was compared with 34 Fontan patients.

Results: In healthy subjects, liver stiffness obtained with breath hold technique was 4.70 ±0.56 kPa compared with 4.87 ±0.53 kPa with spontaneous breathing. Bland–Altman analysis revealed a bias of 0.17 kPa with acceptable limits of agreement (LoA) between −0.79 and 1.13 kPa. Measurements while performing a Valsalva maneuver resulted in slightly higher values (bias 0.30 kPa, LoA −1.35 to 1.94 kPa). Superficial measurements compared with those in 3 to 5 cm depth as recommended by the manufacturer showed lower stiffness values (bias −0.62 kPa, LoA −1.89 to 0.65 kPa). Interobserver agreement with spontaneous breathing revealed a bias of 0.41 kPa with LoA of −0.90 to 1.72 kPa. Liver stiffness was higher in Fontan patients compared with healthy subjects (9.07 ± 5.47 vs. 4.87 ±0.53 kPa, p < 0.001).

Conclusion: Liver elastography might be a valuable diagnostic tool for surveillance of FALD. Images can be sampled without breath hold and therefore shear-wave elastography is also suitable for smaller children. Liver stiffness is higher in Fontan patients but might be explained by higher venous pressure. The relationship between liver stiffness and the histologic grade of fibrosis still needs to be determined.

No conflict of interest has been declared by the author(s).