Diagnostic ultrasound ( PDFDrive )

CHAPTER 4 The Liver 85
A
B
C
D
FIG. 4.17 Acute Hepatitis. (A) Sagittal and (B) transverse images of the left lobe of the liver show marked increased thickness and echogenicity
of the soft tissue surrounding the portal vein branch, called periportal cufing. (C) Sagittal and (D) transverse views of the gallbladder with marked
mural thickening, such that the lumen is virtually obliterated. The gallbladder wall shows a multilayered appearance with extensive hypoechoic
pockets of edema luid. (With permission from Wilson SR. The liver. In Gastrointestinal disease. 6th series. Test and syllabus. Reston, VA: American
College of Radiology; 2004. 26 )
necrosis. Death occurs if the loss of hepatic parenchyma is greater
than 40%.
Chronic hepatitis is deined as the persistence of biochemical
abnormalities beyond 6 months. It has many causes other than
viral, including metabolic (e.g., Wilson disease, alpha-1 antitrypsin
deiciency, hemochromatosis), autoimmune, and drug
induced. he prognosis and treatment of chronic hepatitis depend
on the speciic cause.
In acute hepatitis, there is difuse swelling of the hepatocytes,
proliferation of Kupfer cells lining the sinusoids, and iniltration
of the portal areas by lymphocytes and monocytes. he
sonographic features parallel the histologic indings. he liver
parenchyma may have a difusely decreased echogenicity, with
accentuated brightness of the portal triads or periportal cuing
(Figs. 4.17 and 4.18A and B). Hepatomegaly and thickening
of the gallbladder wall are associated indings (Figs. 4.17 and
4.18C and D). In most patients the liver appears normal. 26 Most
cases of chronic hepatitis are also sonographically normal.
When cirrhosis develops, sonography may demonstrate a
coarsened echotexture and other morphologic changes of
cirrhosis.
Bacterial Diseases
Pyogenic bacteria reach the liver by several routes, the most
common being direct extension from the biliary tract in patients
with suppurative cholangitis and cholecystitis. Other routes are
through the portal venous system in patients with diverticulitis
or appendicitis and through the hepatic artery in patients with
osteomyelitis and subacute bacterial endocarditis. Pyogenic
bacteria may also be present in the liver as a result of blunt or
penetrating trauma. No cause can be found in approximately
50% of hepatic abscesses; the rest are mainly caused by anaerobic
infection. Diagnosis of bacterial liver infection is oten delayed.
he most common presenting features of pyogenic liver abscess
are fever, malaise, anorexia, and right upper quadrant pain.
Jaundice may be present in approximately 25% of these patients.
Sonography has proved to be extremely helpful in the detection
of liver abscesses. he ultrasound features of pyogenic abscesses