Liver Stiffness Predicts Portal Hypertension in HCV Cirrhosis
FLORENCE, Italy, May 3 -- An ultrasound measurement of liver thickness
-- also known as liver stiffness -- predicted portal hypertension in
patients with hepatitis C-related cirrhosis, researchers here found. Action
In a comparison with the standard technique, measuring the hepatic venous
pressure gradient, there was a statistically significant positive
correlation between the ultrasound technique and the gradient measurement.
Nevertheless, the positive correlation applied only to hepatic venous
pressure gradient levels of less than 10 or 12 mm Hg, Massimo Pinzani, M.D.,
Ph.D., of the University of Florence, and colleagues, reported in the May
issue of Hepatology.
Although pressure gradient measurement is the gold standard for assessing
portal hypertension, the technique is invasive, expensive, and requires
technical expertise found only in large tertiary care centers, Dr. Pinzani
In search of a better method, the researchers evaluated transient
elastography, a rapid, noninvasive ultrasound technique, to measure liver
stiffness, and compared its accuracy with that of measuring hepatic venous
In transient elastography, the tip of an ultrasound probe is placed between
two intercostal spaces at the level of the right lobe of the liver. A
low-amplitude vibration induces an elastic shear wave throughout the liver
tissue. Pulse-echo ultrasound permits measurement of wave velocity, which
corresponds directly with liver stiffness across the organ, reflecting a
larger sample than liver biopsy.
From March 1, 2005 to July 1, 2006, 61 patients (ages 32 to 75) with
diagnosed or suspected cirrhosis from chronic HCV infection underwent
transient elastography, followed by a hepatic venous pressure gradient
measurement and liver biopsy. Patients with a body mass index of 35 kg/m2 or
higher were excluded.
Overall, a strong relationship between liver stiffness and pressure gradient
measurements was found in the total population (r=0.81, P<0.0001).
However, although the correlation was excellent for pressure gradient values
less than 10 mm Hg or less than 12 mm Hg (r=0.81, P<0.0003 and r=0.91,
P<0.0001, respectively), linear regression analysis was not optimal for
values =10 mm Hg (r2=0.35, P<0.0001) or =12 mm Hg (r2=0.17, P=0.02).
The researchers also noted a correlation between liver stiffness and the
presence of esophageal varices (P=0.002), although the negative and positive
predictive values for their detection were unsatisfactory, at 66% and 77% in
a population where the prevalence of varices was 64% (30 of 47 patients),
respectively, they said.
Moreover, they added, this study failed to demonstrate a correlation between
liver stiffness and the size of esophageal varices.
The researchers noted that whereas the correlation between the two
measurements seemed optimal only for hepatic venous pressure gradient values
less than 10 and 12 mm Hg, this important observation suggests that beyond a
certain degree of portal pressure, the development of portal hypertension
becomes at least partially independent of the simple accumulation of the
fibrillar extracellular matrix responsible for the increase in liver
The measurement of liver stiffness by this ultrasound technique may
represent a reliable noninvasive method for screening patients to be given
standard testing, including upper GI endoscopy and hemodynamic studies, the
researchers said. However, they added, the technique is not good enough to
replace endoscopy for detection of esophageal varices.
Finally, they noted, these results need to be validated in larger
populations, especially among those patients with a body mass index greater
than 30 kg/m2 for whom liver stiffness reproducibility may not be optimal.
In an accompanying editorial, Joseph K. Lim, M.D., and Roberto J. Groszmann,
M.D., of Yale, praised the study as the first to evaluate the correlation
between liver stiffness and clinically significant portal hypertension, as
reflected by both direct pressure gradient measurement and identification of
esophageal varices on upper GI endoscopy.
However, to date, they said, direct measurement of hepatic venous pressure
gradient remains the gold standard for the diagnosis and staging of portal
Although the use of noninvasive modalities is attractive, additional
validation studies measuring diagnostic accuracy in a representative
American population are needed prior to regulatory approval, they wrote.
Of note, they said, the mean BMI of patients in this study was 23, and those
with a BMI of 35 kg/m2 or greater were excluded, which contrasts with the
higher means reported in large U.S. trials for HCV therapy.
Liver-stiffness measurement represents one of several noninvasive tools that
appear to be useful in diagnosing and staging liver fibrosis in selected
patients, although the current data supporting its role in evaluating the
consequences of portal hypertension remain unconvincing, Drs. Lim and
"Additional data in carefully designed studies will help define its
appropriate role in clinical practice," they added.
Primary source: Hepatology
Vizzutti F, et al "Liver Stiffness Measurement Predicts Portal Hypertension
in Patients with HCV-Related Cirrhosis" Hepatology 2007; 45: 1290-1297.
Additional source: Hepatology
Lim, JK, Groszmann RJ "Transient Elastography for Diagnosis of Portal
Hypertension in Liver Cirrhosis: Is There Still a Role for Hepatic Venous
Pressure Gradient Measurement?" Hepatology 2007; 45: 1087-1089.