Acoustic liver biopsy using endoscopic ultrasound.
Acoustic liver biopsy using endoscopic ultrasound.
Andanappa HK, Dai Q, Korimilli A, Panganamamula K, Friedenberg F, Miller L.
Section of Gastroenterology, Department of Medicine, Temple University Hospital,
3401 N Broad Street, Philadelphia, PA 19140, USA.
BACKGROUND: Transabdominal ultrasound cannot be used to quantitate fibrosis in
patients with cirrhosis because of variability in the abdominal wall thickness
and variability in the components of the abdominal wall (fat versus muscle).
Endoscopic ultrasound through the gastric wall is always at a constant distance,
approximately 3 mm, away from the liver when the transducer is just below the
gastroesophageal junction, thereby eliminating this variability. PURPOSE: To
differentiate between cirrhotic and noncirrhotic liver using endoluminal
ultrasound. METHODS: Eleven patients without known liver disease and eight
patients with cirrhosis underwent endoscopic ultrasound using an Olympus linear
ultrasound scope. The gain, contrast, frequency, and acoustic power were kept
constant on the Aloka ultrasound processor. Videotaped images of the liver were
recorded and then digitized on Image-Pro Plus software. The brightness of the
image was adjusted to a standard brightness for each image and an area of
interest was chosen using Photoshop 7.0. Vessels and artifacts were eliminated
digitally and a histogram was produced using Photoshop to quantitate the pixel
density for the area of interest from 0 (black) to 255 (white). Approximately
250,000 pixels were evaluated for each subject. The mean +/- standard deviation
(SD) pixel density of the noncirrhotic subjects was evaluated against the
cirrhotic patients using a Student unpaired t-test. RESULTS: The mean
echogenecity in patients with cirrhosis was 116.85 and the mean echogenecity in
patients without cirrhosis was 92.75 (P < 0.002). The mean standard deviation of
the pixel density in patients with cirrhosis was 19.08 and the mean standard
deviation of the pixel density in patients without cirrhosis was 13.25 (P <
0.0004). Using these criteria the subjects with cirrhosis were segregated from
the noncirrhotic subjects (normal subjects and the subjects with steatosis) with
100% sensitivity and 100% specificity.
CONCLUSION: A new method of evaluating the liver parenchyma (acoustic liver
biopsy) that takes advantage of the proximity of the endoscopic ultrasound
transducer to the liver and uses commercial image analysis technology that is
inexpensive and widely available was developed. This is a preliminary study of
this new technology, which demonstrates that endoscopic ultrasound, can be
standardized in order to image, analyze, and compare the mean echogenecity and
mean standard deviation of the pixel density in the liver in order to
distinguish cirrhotic patients from patients without cirrhosis.
PMID: 18270828 [PubMed - indexed for MEDLINE]
http://www.ncbi.nlm.nih.gov/pubmed/18270828