Biology Reference
In-Depth Information
3.2 MHz and a linear probe with a receiving frequency of 5 MHz. A focal zone was
always set at the level of the deepest portion of the lesion to be examined. The
mechanical index was always less than 0.1 (acoustic pressure
45 kPa). A bolus
intravenous injection of the contrast medium composed of sulfur hexafluoride
encapsulated by a shell of phospholipids (SonoVue
®
-Bracco) at a dosage of
0.03 ml/kg b.w. into the cephalic vein, followed by a saline flush at a dosage of
5 ml for the dogs and 2.5 ml for the cats, was performed. Regional blood perfusion
was visualized in the region of interest for 2 min after intravenous injection. Tissue
echogenicity of the considered liver lesions was evaluated during the arterial phase,
peak liver enhancement, and portal phase and was then compared with normal
surrounding liver tissue. Each diagnostic examination was recorded digitally. The
collected data from the region of interest were then elaborated using commercial
software (
Qontrast
®
-Bracco
), and time-intensity curves were constructed using the
gamma variate model. The peak intensity P (percentage of the signal intensity, SI),
time to peak in seconds (TTP), regional blood flow RBF (ratio between the regional
blood volume and the medium transit time), and the medium transit time (MTT) in
seconds were calculated. Contrast-enhancement patterns during the arterial and
portal phases of the benign and malignant lesions were studied with Fischer's exact
test. Values for
P
<
0.05 were considered significant.
<
18.3 Results
Sixteen hepatic focal lesions were evaluated: 12 were single and four were multiple.
Ten lesions were described as benign: nodular hyperplasia (four cases), hydropic
degeneration (two cases), simple cystic lesions (three cases), and eosinophilic
infiltrate (one case). The other six lesions were malignant: hepatocellular carcinoma
(four cases), biliary carcinoma (one case), and lymphoma (one case). In one patient,
two different types of lesions were present. One benign lesion (cyst) and one
malignant lesion (hepatocellular carcinoma) belonged to the two feline patients.
Two cases of nodular hyperplasia were hypoechoic and two were hyperechoic by
fundamental US. Hydropic degeneration nodules were always hypoechoic. Hepatic
cysts appeared as anechoic cavitary lesions with a thin capsule, characterized by
distal enhancement. Eosinophilic infiltrate was characterized by multiple, small,
hypoechoic, poorly defined nodules. Among the malignant lesions, two hepatocellular
carcinomas were hypoechoic, while the other two showed a mixed echotexture.
Biliary carcinoma appeared as multiple nodular target lesions, and lymphoma
appeared as a hypoechoic focal lesion.
During CEUS examination, two cases of nodular hyperplasia were hyperechoic
during the arterial phase, while the other two were hypoechoic. During the portal
phase, three of these were isoechoic, while one was hyperechoic (data media:
P: 36.7%, TTP: 49.6 s, RBF: 45.9, MTT: 80.7 s; surrounding hepatic tissue:
34.7%, TTP: 53.5 s, RBF 43, MTT: 82 s). One case of hydropic degeneration
appeared hyperechoic during the arterial phase, while the other was hypoechoic.
