Diagnostic ultrasound ( PDFDrive )

88 PART II Abdominal and Pelvic Sonography
A
B
FIG. 4.20 Fungal Infection. “Bull’s-eye” fungal morphology in 24-year-old man with acute lymphoblastic leukemia and fever. (A) Sagittal
sonogram through the spleen shows focal hypoechoic target lesions. (B) The liver showed multiple masses. This magniied view shows a thick,
echogenic rim and a thin, hypoechoic inner rim with a dense echogenic nidus. Biopsy revealed pseudohyphae.
A
B
FIG. 4.21 Candidiasis. (A) Uniformly hypoechoic pattern. Multiple hypoechoic hepatic lesions are present in this young patient with acute
myelogenous leukemia. (B) Echogenic pattern after medical therapy. Small calciied lesion (arrow) is visualized in another immunocompromised
patient.
Sonographic features include a round or oval-shaped lesion,
absence of a prominent abscess wall, hypoechogenicity compared
to normal liver, ine low-level internal echoes, distal sonic
enhancement, and contiguity with the diaphragm 31,32 (Fig. 4.22).
All of these features, however, can be found in pyogenic abscess.
In a review of 112 amebic lesions, Ralls et al. 33 reported that
two sonographic patterns were signiicantly more prevalent in
amebic abscesses: (1) round or oval shapes in 82% versus 60%
of pyogenic abscesses, and (2) hypoechoic appearance with ine
internal echoes at high gain in 58% versus 36% of pyogenic
abscesses. Most amebic abscesses occur in the right lobe of the
liver. Diagnosis is made using a combination of the clinical
features, ultrasound indings, and serologic results. he indirect
hemagglutination test result is positive in more than 94% of
patients.
Amebicidal drugs are efective therapy. Symptoms improve
in 24 to 48 hours, and most patients are afebrile in 4 days. hose
who exhibit clinical deterioration may also beneit from catheter
drainage, although this is unusual. he majority of hepatic amebic
abscesses disappear with adequate medical therapy. 34 he time
from termination of therapy to resolution varies from 1.5 to 23
months (median, 7 months). 35 A minority of patients have residual
hepatic cysts and focal regions of increased or decreased
echogenicity.
Hydatid Disease
he most common cause of hydatid disease in humans is infestation
by the parasite Echinococcus granulosus, which has a
worldwide distribution. It is most prevalent in sheep- and cattleraising
countries, notably in the Middle East, Australia, and the
Mediterranean. Endemic regions in the United States include
the central valley in California, the lower Mississippi River Valley,
Utah, and Arizona. Northern Canada is also endemic. E. granulosus
is a tapeworm 3 to 6 mm in length that lives in the intestine