The role of sound touch elastography in assessment of liver fibrosis in chronic liver disease keeping APRI as the reference standard

Purpose The study aims to determine the role of Sound Touch Elastography [STE] technique in staging liver fibrosis and predicting clinically significant gastro-esophageal varices among patients with chronic liver disease [CLD] keeping aspartate aminotransferase to platelet ratio index [APRI] as the reference standard.Methods A prospective short-term study including 60 eligible patients with CLD were staged as non-significant fibrosis [NSF], significant fibrosis [SF] and cirrhosis [C] based on APRI values. STE was performed on each patient obtaining multiple readings as per pre-defined standards. The intra-observer reliability between each measurement and its association with APRI staging was evaluated using relevant statistical variables. Further, Youden's index was used to define the optimum cut-off values on STE in differentiating the stages of fibrosis and in predicting clinically significant gastro-esophageal varices.Results Based on APRI cut-off values, 41.7% [n = 25] of the study population had cirrhosis, while 45% [n = 27] had significant fibrosis and 13.3% [n = 8] had NSF. The STE values in kPa showed a positive correlation with APRI values [(rs) = 0.837, p < 0.001]. The intra-class correlation estimates based on a mean rating [k = 5] was found to be 0.97 [0.95-0.99], implying an excellent agreement between the measurements. Optimum cut-off values in staging SF and C were 7.26 kPa [J = 0.73, sensitivity-85.19%, specificity-87.5%; 95% CI] and 13.79 kPa [J = 0.84, sensitivity-96.0%, specificity-88.89%; 95% CI]. The AUROC for each of these stages were 0.926 [0.785-0.987] and 0.976 [0.890-0.999], respectively. 23.3% [n = 14] of the study population had clinically significant gastro-esophageal varices with a value above 18.84 kPa [J = 0.88] showing a sensitivity of 92.85% and a specificity of 95.65% in predicting the same.Conclusion The novel STE technique shows good accuracy in staging liver fibrosis as determined by APRI values and in prediction of clinically significant gastro-esophageal varices with excellent reliability. It shows promising prospects and can be integrated widely in clinical practice for assessment and staging of fibrosis in CLD.