The influence of acute physical effort on liver stiffness estimation using Virtual Touch Quantification (VTQ). Preliminary results.

Abstract

Food intake and acutely decompensated cardiac failure may impair liver stiffness estimations, mainly because these methods are influenced by liver blood flow variation encountered in these conditions. It is well known that also during physical effort liver blood flow changes, due to the redistribution of blood flow mainly to the skeletal muscles. The aim of this study is to assess the change of liver shear- wave velocities immediately after cessation of an acute physical effort. A secondary aim was to find the proper timing for accurate liver stiffness estimation after physical exhaustion. Liver shear-wave velocities were measured using virtual touch quantification (VTQ) in seven apparently healthy volunteers, in fasting conditions. All subjects underwent a complete abdominal ultrasound study, including the liver VTQ. Then, all subjects performed a spiroergometry and thereafter, another series of three liver shear-wave velocity measurements were performed: immediately after spiroergometry, five min, and ten min after spiroergometry, respectively. Before spiroergoemetry, the mean liver shear-wave velocity was 1.05+/-0.12 m/sec. Immediately after spiroergometry, mean liver shear-wave velocities increased significantly, measuring 1.34+/-0.16 m/sec (p <0.01). The mean liver shear-wave velocities at five and ten minutes after exhausting were 1.23+/-0.14 m/sec and 1.05+/-0.11 m/sec respectively. Liver stiffness estimation using VTQ was influenced by acute physical exercise in our study group. Despite the small number of subjects, the preliminary results show that if patients had done physical effort before VTQ elastography, they should rest at least ten minutes before reliable liver stiffness estimations can be performed.