Comparative study between pSWE and 2D-SWE techniques integrated in the same ultrasound machine, with Transient Elastography as the reference method

To evaluate the feasibility of two elastographic methods, point Shear Wave Elastography (pSWE) and two dimensional Shear Wave Elastography (2D-SWE), integrated in the same ultrasound machine, for liver fibrosis (LF) assessment, using Transient Elastography (TE) as the reference method.

We included in the study 115 subjects in which LF was evaluated in the same session by TE (FibroScan, EchoSens), pSWE and 2D-SWE (Samsung-Medison RS85). Reliable liver stiffness (LS) measurements were defined: for TE the median value of 10 measurements with interquartile range (IQR/M)≤30%,while for pSWE and 2D-SWE the median value of 10 measurements, with a reliability measurement index (RMI)≥0.5 and IQR/M≤30%. For classification of LF severity we used TE as the reference method with the following cut-offs: F2≥7kPa, F3≥9.5kPa and F4≥12kPa.

Reliable measurements by TE were obtained in 98.2% of cases (113/115), by pSWE in 93.9% of cases (108/115) and by 2D-SWE in 92.1% of cases (106/115), so the final analysis included 101 patients. We divided the cohort into 3 groups: fibrosis 5.9 kPa [AUROC=0.95, 95%CI(0.89;0.98), p<0.0001, Se=94.1%, Sp=89.5%, PPV=82.1%, NPV=96.8%]; F4 LS >8 kPa [AUROC=0.98, 95%CI(0.94;0.99), p<0.0001, Se=94.4%, Sp=95.1%, PPV=81%, NPV=98.7%], while for 2D-SWE they were: F≥2 LS >6.1 kPa [AUROC=0.93, 95%CI(0.86;0.97), p<0.0001, Se=91.1%, Sp=80.6%, PPV=70.5%, NPV=94.7%]; F4 LS >7.6 kPa [AUROC=0.98, 95%CI(0.93;0.99), p<0.0001, Se=100%, Sp=91.5%, PPV=72%, NPV=100%]. We observed strong correlations between LS values obtained by TE and 2D-SWE (r=0.85), between TE and pSWE (r=0.88) and between pSWE and 2D-SWE (r=0.90) (p=0.37), respectively. There were no significant differences between the mean values obtained by pSWE and 2D-SWE (p=0.96).

The pSWE and 2D-SWE are feasible methods for assessing liver fibrosis, both techniques strongly correlating with TE results.