We read with interest the letter written by Lebray et al., 1 who reported that hepatic congestion can considerably increase hepatic elastometry, as measured by Fibroscan, to values that are unambiguously diagnostic for liver cirrhosis. We recently made the same observation, 2 and we would like to present more information on this topic.
We had the opportunity to study, before resection, liver stiffness in various subtypes of hepatocellular adenomas (HCAs). 3 In HCAs, fibrosis is usually absent. Indeed, hepatocyte nuclear factor 1␣-mutated HCAs (HNF1␣ HCAs) are often steatotic, whereas inflammatory hepatocellular adenomas (IHCAs) often present congestion, with sinusoidal dilatation as the initial step and passage of red blood cells in the space of Disse as the second step. Liver stiffness was measured by the acoustic radiation force impulse method (Siemens S2000). 4 The standard ultrasonographic probe offered elastography with a flexible metering box (2 ϫ 1 cm 2 ) at various depths (up to 5.5 cm), allowing the examination of specific areas, such as those within and outside tumors. The speed of the shear wave (m/s) was expressed as a median of 10 measurements. 5 Elasticity could also be expressed in kilopascals with the Young formula [elasticity ϭ 3v 2 , where is the density and v is the speed of the shear wave (m/s)]. The interquartile range/median (IQR/M) ratio was then calculated.
In the first case (HNF1␣ HCA), which was entirely and massively steatotic (Fig. 1A), the median speed was 1.05 m/s (3.34 kPa), and the IQR/M ratio was 0.18; in the second case (HNF1␣ HCA), which was mildly steatotic with sinusoidal dilatation (Fig. 1B), the median speed was 1.5 m/s (6.78 kPa), and the IQR/M ratio was 0.49; and in the third case (IHCA), which presented sinusoidal dilatation and major hepatic congestion (Fig. 1C), the speed was 3.17 (30.15 kPa), and the IQR/M ratio was 0.83. The median speed in the nontumoral liver [normal histology in cases 1 and 2 and mild steatosis (Ͻ5%) in case 3] was 1.28 (4.95 kPa), 1.2 (4.32 kPa), and 0.86 m/s (2.21 kPa) with IQR/M ratios of 0.14, 0.08, and 0.33, respectively.
These results indicate that (1) the speed measured in the nontumoral liver with the acoustic radiation force impulse method was in the range obtained with transient elastography, (2) massive steatosis does not increase stiffness, and (3) sinusoidal dilatation and hepatic congestion appear to play a major role in tissue elasticity. Hepatic congestion (case 3) in an IHCA is not homogeneously distributed, as reflected by the high IQR/M value.
The rationale that the velocity of the elastic shear wave that propagates through the underlying liver tissue is directly related to tissue stiffness, which is considered an index of the amount of fibrotic tissue, 6 is, however, too restrictive.