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.
