Factors that influence the correlation of acoustic radiation force impulse (ARFI), elastography with liver fibrosis

To establish the influence of different factors on the correlation between liver stiffness (LS) measurements by ARFI and liver fibrosis, evaluated by liver biopsy (LB). We assessed the following factors: the success rate (SR) and interquartile range (IQR) interval, the place where ARFI was performed, liver steatosis, the quality of the specimen obtained by LB.

We studied 471 patients: 82 with LB, 82 healthy volunteers and 307 with cirrhosis. We performed 10 valid ARFI measurements, a median value was calculated, expressed in meters/second.

Valid measurements were not obtained in 11 patients. There was a direct, strong, correlation (r=0.694) between ARFI and fibrosis (p<0.0001). There were no statistically significant differences between the mean ARFI values obtained in segments V vs. VIII (p=0.89). Considering the IQR and SR, the correlation of ARFI with fibrosis was: for IQR<30% and SR ≥ 60%: r=0.722 and for IQR>30% and/or SR ≤ 60%: r=0.268 (p=0.0001). The quality of the liver specimen (2-3 cm long vs. >3 cm) did not influence the correlation of ARFI with fibrosis.

To obtain the best correlation between ARFI and fibrosis, IQR must be <30% and SR ≥ 60%. These technical parameters must be introduced to improve the ARFI value for LS evaluation.