Transient Elastography in Acute Cellular Rejection Following Liver Transplantation: Systematic Review.

BACKGROUND: Transient elastography (TE) is a noninvasive technique that measures liver stiffness. When an inflammatory process is present, this is shown by elevated levels of stiffness. Acute cellular rejection (ACR) is a consequence of an inflammatory response directed at endothelial and bile epithelial cells, and it is diagnosed through liver biopsy. This is a systematic review of the viability of TE in ACR following liver transplantation.

METHODS: The Cochrane Library, Embase, and Medline PubMed databases were searched and updated to November 2016. The MESH terms used were "Liver Transplantation," "Graft Rejection," "Elasticity Imaging Techniques" (PubMed), and "Elastography" (Cochrane and Embase).

RESULTS: Seventy studies were retrieved and selected using the PICO (patient, intervention, comparison or control, outcome) criteria. Three prospective studies were selected to meta-analysis and evaluation. A total of 33 patients with ACR were assessed with TE. One study showed a cutoff point of >7.9 kPa to define graft damage and <5.3 kPa to exclude graft damage (receiver operating characteristic 0.93; P < .001). Another study showed elevated levels of liver stiffness in ACR patients. However, in this study, no cutoff point for ACR was suggested. The final prospective study included 27 patients with ACR at liver biopsy. Cutoff points were defined as TE > 8.5 kPa, moderate to severe ACR, with a specificity of 100% and receiver operating characteristic curve of 0.924. The measurement of TE < 4.2 kPa excludes the possibility of any ACR (P = .02).

CONCLUSIONS: TE may be an important tool for the severity of ACR in patients following liver transplantation. Further studies should be performed to better define the cutoff points and applicability of the exam.