Liver Graft and Spleen Elastography After Living Liver Transplantation: Our First Results

Impact of probe-induced abdominal compression on two-dimensional shear wave elastography measurement of split liver transplants in children

PURPOSE

To evaluate the effect of probe-induced abdominal compression of split liver transplants (SLT) in children on 2D-shear wave elastography (SWE) values.

MATERIALS AND METHODS

Data from 11 children (4.7 ± 4.8 years) who had undergone SLT and SWE were evaluated retrospectively. Elastograms were obtained with probes placed in an epigastric, midline position on the abdominal wall, with no and slight compression, using convex and linear transducers. For each identically positioned probe and condition, 12 serial elastograms were obtained and the SLT diameter was measured. Liver stiffness and degree of SLT compression were compared.

RESULTS

Slight probe pressure resulted in SLT compression, with a shorter distance between the cutis and the posterior margin of the liver transplant than in the measurement with no pressure (curved array, 5.0 ± 1.1 vs. 5.9 ± 1.3 cm, mean compression 15 %± 8 %; linear array, 4.7 ± 0.9 vs. 5.3 ± 1.0 cm, mean compression 12 %± 8 %; both p < 0.0001). The median liver stiffness was significantly greater with slight pressure than with no pressure (curved transducer, 13.38 ± 3.0 vs. 7.02 ± 1.7 kPa, p < 0.0001; linear transducer, 18.53 ± 7.1 vs. 9.03 ± 1.5 kPa, p = 0.0003).

CONCLUSION

Slight abdominal compression can significantly increase SWE values in children with left-lateral SLT. To obtain meaningful results and reduce operator dependency in free-hand examinations, probe pressure must be controlled carefully.

KEY POINTS

· Probe-induced compression can increase elastography values in split liver transplants in children. · In free-hand examination, probe pressure must be controlled carefully. · Pressure loading can be determined indirectly by the anteroposterior transplant diameter.

CITATION FORMAT

· Groth M, Fischer L, Herden U et al. Impact of probe-induced abdominal compression on two-dimensional shear wave elastography measurement of split liver transplants in children. Fortschr Röntgenstr 2023; 195: 905 - 912.

Evaluation of liver stiffness measurement-based scores in liver transplantation recipients

Combining bioclinical parameters with liver stiffness measurement (LSM) has improved the diagnostic performance of vibration-controlled transient elastography (VCTE) for detection of advanced fibrosis in patients with chronic liver disease. However, this approach has not yet been tested in liver transplantation (LT) recipients. Thus, the aim of this study was to evaluate the diagnostic performance of combining LSM-based scores with LSM alone for the detection of advanced fibrosis in LT recipients. Adult LT recipients with a liver biopsy, VCTE, and clinical data necessary to construct LSM-based fibrosis models (FibroScan-AST [FAST], AGILE-3+, and AGILE-4) were included ( n = 132). The diagnostic statistics for advanced fibrosis (fibrosis stage 0-2 vs. 3-4) were determined by optimal cut-off using the Youden index. The area under the receiver operating characteristic curve (AUROC) for LSM was 0.94 (95% confidence interval [95% CI], 0.89-0.99), FAST was 0.65 (95% CI, 0.50-0.79), AGILE-3+ was 0.90 (95% CI, 0.83-0.97), and AGILE-4 was 0.90 (95% CI, 0.83-0.97). No statistically significant differences were noted between the AUROC of LSM versus LSM-based scores. The false-positive rates for AGILE-3+ and AGILE-4 were 14.5% and 11.8% compared with 8.3% for LSM alone. The false-positive rates in LSM-based scores were higher among patients with diabetes mellitus, higher AST levels, and lower platelet counts. The LSM-based scores did not improve the diagnostic performance of LSM alone in LT recipients for the detection of advanced fibrosis. This lack of improvement in diagnostic performance results from the impact of immunosuppression on bioclinical profile and underscores the importance of developing LSM-based scores that are specific to LT patients.