Validity of real time ultrasound in t
A prospectiv
Srinivasan Dasarathy1,*, Jaividhya Dasarat
Rocio Lopez4, Arthu
1Departments of Gastroenterology, Hepatology, Pathobiology, 9500 Euclid Avenue, NE4-208, Lerner Research Institute,
Conclusion:Real time ultrasound using a combination of sonographic findings has a high specificity but underestimates
the prevalence of hepatic steatosis when there is < 20% fat.
obtained as well as being non-invasive, well tolerated
and widely available [4]. Hepatic steatosis appears as a
diffuse increase in echogenicity (bright liver) and a num-
ber of sonographic alterations in the liver [5,6]. The
major limitation of US as a screening tool for hepatic
iver. Published by Elsevier B.V. All rights reserved.
who have taken part in this study declared that they do not have
anything to disclose regarding funding from industries or conflict of
interest with respect to this manuscript.
* Corresponding author. Tel.: +1 216 4443445; fax: +1 216 6361495.
E-mail address: dasaras@ccf.org (S. Dasarathy).
Abbreviations: NAFLD, Non-alcoholic fatty liver disease.
Journal of Hepatology 51 (20168-8278/$36.00  2009 European Association for the Study of the L 2009 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.
Keywords: Hepatic steatosis; Ultrasound; Sensitivity; Specificity
1. Introduction
Non-alcoholic fatty liver disease (NAFLD) is the
most common form of liver disease in the United States
[1–3]. The diagnosis of NAFLD is established by liver
biopsy but ultrasound (US) is being increasingly recog-
nized as a screening tool due to the useful information
Received 23 April 2009; received in revised form 2 July 2009; accepted 3
July 2009; available online 20 September 2009
Associate Editor: C.P. Day
q The underlying research reported in the study was funded in part
by the NIH Institutes of Health, Grant No. U DK 61732. The authorsCleveland Clinic Foundation, Cleveland, OH 44195, USA
2Department of Family Practice, Metro Health Medical Center, Cleveland, OH 44195, USA
3Department of Pathology, Metro Health Medical Center, Cleveland, OH 44195, USA
4Department of Quantitative Health Sciences, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
Background/Aims:Ultrasound is used to screen for hepatic steatosis, the most common liver disease in the United States.
However, few studies have prospectively evaluated the accuracy of ultrasound to diagnose hepatic steatosis. Therefore, a
double blinded prospective study was performed in consecutive patients undergoing liver biopsy to evaluate the accuracy of
ultrasound to diagnose hepatic steatosis.
Methods:Real time ultrasound was performed just prior to the biopsy by a single investigator masked to the clinical
diagnosis. The liver biopsy was reviewed by a pathologist masked to the clinical indication or sonographic findings.
Results:Of 73 consecutive patients studied, macrovesicular steatosis of any severity on biopsy was found in 46 (63%) and
micro vesicular fat found in 51 (69.9%). The overall impression of the sonographer for the presence of macrovesicular
hepatic steatosis of any degree had a sensitivity of 60.9% and a specificity of 100%. The sensitivity increased to 100%
and the specificity to 90% when there wasP20% of fat. The zonular distribution of the fat did not alter the diagnostic
accuracy of ultrasound. Ultrasound had a poor yield in the diagnosis of microvesicular fat with an overall sensitivity of
43% and a specificity of 73%. The combination of increased echogenicity and portal vein blurring on ultrasound had
the greatest sensitivity in the diagnosis of hepatic steatosis.doi:10.1016/j.jhep.2009.09.001he diagnosis of hepatic steatosis:
e studyq
hy2, Amer Khiyami3, Rajesh Joseph1,
r J. McCullough1
www.elsevier.com/locate/jhep
009) 1061–1067

nosed and those that are diagnosed are evaluated
appropriately [9,10]. However, this requirement for a
1062 S. Dasarathy et al. / Journal of Hepatology 51 (2009) 1061–1067screening test for NAFLD may not necessarily be clini-
cally appropriate due to the need for a liver biopsy to
confirm the diagnosis, the slow rate of progression of
disease, and the lack of established treatment protocols
[11]. In this clinical situation, one may need a test that
has a relatively high specificity to ensure that a large
population of false positive subjects is not subjected to
a liver biopsy due to the potential for morbidity and
mortality. The currently available data on the utility of
ultrasound in the diagnosis of hepatic steatosis are either
retrospective or done in a well defined population of
patients with known hepatic steatosis [4,12–19]. Fur-
thermore, hepatic steatosis has been used to refer to
macrovesicular steatosis while microvesicular steatosis
accompanies a number of hepatic disorders and often
occurs with macrovesicular steatosis in NAFLD [20].
The contribution of microvesicular fat to the sono-
graphic abnormalities in patients with hepatic steatosis
has not been systematically evaluated. A number of
sonographic abnormalities suggest hepatic steatosis but
the predictive role of each of these findings has not been
determined in a prospective manner. Their role in iden-
tifying fibrosis and inflammation has also not been sys-
tematically evaluated prospectively in an unselected
population of subjects undergoing liver biopsy. There-
fore, the present study prospectively evaluated the diag-
nostic utility of real time ultrasound performed by a
clinical gastroenterologist in diagnosing the presence
and severity of hepatic steatosis as well as fibrosis and
inflammation in an unselected population of consecutive
patients undergoing liver biopsy.
2. Patients and methods
Seventy-five consecutive patients undergoing an elective liver
biopsy for clinical indications of abnormal liver function or clinical
suspicion of liver disease being performed in the Gastroenterology
division of Metro Health Medical Center, Cleveland, OH had a real
time US by a single investigator (SD) masked to the clinical indication
for the liver biopsy as part of confirmation of the site of the biopsy just
prior to the procedure. All patients were determined to have normal
renal function since one of the sonographic criteria depended on a
comparison of the echogenicity of the renal cortex with that of the
liver. Real time ultrasound was performed using a Sonosite Micro-steatosis has been the modest sensitivity of 67% and
specificity of 77% that would result in an incorrect diag-
nosis in up to 33% of patients [7]. In patients with
chronic hepatitis C, ultrasound had a sensitivity of
60% and a specificity of 79% making it a relatively inac-
curate test [8]. It must be reiterated that the relative util-
ity of ultrasound as a diagnostic tool depends on the
clinical setting in which it is being used. Screening
asymptomatic patients requires a test with a high sensi-
tivity and specificity so that few patients are undiag-maxx (Sonosite Inc., Bothell, WA). The technical parameters includinggain adjustment, placement of focal zone and the optimum location of
the transducer were optimized for each patient. A percutaneous liver
biopsy was then performed using an 18G Bard Monopty biopsy gun
(Bard Biopsy Systems, Tempe, AZ) with a single pass by the percuta-
neous route in the right lower intercostal space. Hematoxylin and eosin
stained slides were used for assessing the type and degree of steatosis as
well as any necroinflammatory changes. Only biopsies deemed to be
sufficient specimens were reviewed by a clinical pathologist (AK)
who was masked to the clinical indication and the sonographic find-
ings. A quantitative score was assigned based on the estimated percent-
age of hepatocytes involved in increments of 5%. The pattern of
steatosis was judged as either predominantly macrovesicular if >75%
of involved hepatocytes contained fat droplets larger than the hepato-
cyte nucleus and displaced the nucleus to one side or predominantly
microvesicular if greater than 75% of involved hepatocytes contained
fat droplets smaller than the hepatocyte nucleus and without signifi-
cant nuclear displacement. Biopsies showing at least 25% of each type
of fatty change were designated to show a mixed pattern. The necroin-
flammatory changes (portal inflammation, piecemeal necrosis, and lob-
ular inflammation and necrosis) and degree of fibrosis were evaluated
as part of histological examination and were related to the sonographic
findings. The diagnosis of NASH and steatosis were made using previ-
ously described criteria [21]. Significant alcohol intake was defined
as >20 g/day for women and >30 g/day for men. The elective liver
biopsy was performed in all patients after at least 6 months of absti-
nence from alcohol. Serological and biochemical assays were used to
diagnose the etiology of liver disease. Adequate liver biopsy was not
obtained in 2 patients and they were excluded from the analyses. Sever-
ity of hepatic steatosis classified as mild if the area of involvement by
fat was 5–35%, moderate when the involvement was > 35–65% and
severe when the involvement was >65%.
The US results were interpreted by one of the investigators (SD)
with previous experience in performing and interpreting hepatic ultra-
sound [22–24]. The results were initially categorized into the presence
or absence of hepatic steatosis based on the overall impression using
the sonographic abnormalities [5]. An attempt was also made to differ-
entiate the degree of steatosis during ultrasound interpretation into no
fat, mild fatty liver and severe fatty liver. The liver image was assessed
to be normal if the texture was homogenous, exhibited fine level echoes
and isoechoic compared to the renal cortex and adequate visualization
of the hepatic vessels and diaphragm. The sonographic findings that
were specifically evaluated included the hepatorenal contrast, bright
hepatic echoes, deep attenuation, vessel blurring and non-specific find-
ings of heterogeneous echoes. The diagnosis of hepatorenal echo con-
trast was based on evidence of sonographic contrast between the liver
and right renal cortex in the midaxillary line. The diagnosis of bright
liver was based on abnormally intense, high level echoes arising from
the hepatic parenchyma, deep attenuation was based on evident atten-
uation of echo penetration into the deep portion of the liver and
impaired visualization of the diaphragm. Vessel blurring was based
on an impaired visualization of the borders of the intrahepatic vessels
and narrowing of their lumen.
Predefined criteria for determining the severity of hepatic steatosis
included the presence of bright echoes or increased hepatorenal contrast
indicative ofmild steatosis, presence of both bright echoes and increased
hepatorenal contrast aswell as vessel blurring indicative ofmoderate ste-
atosis and severe steatosis was considered to be present when in addition
to the criteria for moderate steatosis, there was evidence of posterior
beam attenuation and non-visualization of the diaphragm. The liver
image was assessed to be normal if the texture was homogenous, exhib-
ited fine level echoes and isoechoic compared to the renal cortex and ade-
quate visualization of the hepatic vessels and diaphragm.
2.1. Statistical analyses
Descriptive statistics were computed for all factors. These include
means, standard deviations and percentiles for continuous variables
and frequencies for categorical factors. Wilcoxon’s rank sum test was
used to compare fat levels between presence and absence of specific ultra-
sound criteria and p < 0.05 accepted as the significance levels. The sensi-
tivity and specificity of each ultrasound criterion in predicting the
macrovesicular fat was calculated for the histological severity. In addi-
tion, receiver operating characteristics (ROC) analysis was performed