Harmonic hepatic US with microbubble contrast agent: initial experience showing improved characterization of hemangioma, hepatocellular carcinoma, and metastasis.
OBJECTIVE
To characterize blood flow in focal hepatic lesions with harmonic ultrasonographic (US) imaging and a microbubble contrast agent.


METHODS
Thirty patients with known hepatic masses were examined after injection of a perfluorocarbon microbubble agent. Tumor vascularity was assessed with continuous, harmonic gray-scale imaging with a low mechanical index (MI). Tumor vascular volume was assessed with brief, high-MI insonation called interval-delay imaging, which caused microbubble destruction. As the total contrast agent volume in the liver reflects the total vascular volume, quantitation of lesion enhancement relative to normal hepatic enhancement helped determine the vascular volume of the tumor relative to that of normal parenchyma.


RESULTS
Low-MI continuous harmonic imaging showed lesional vessels in hepatocellular carcinomas, minimal or no vessels in hemangiomas, and variable vascularization in metastases. High-MI interval-delay imaging showed greater enhancement in hepatocellular carcinomas than in normal liver (P <.02) and showed less enhancement in hemangiomas than in normal liver (P <.02). Enhancement in metastases was greater in the margins than in the center; as a result, the lesions appeared smaller (P <.03) and less well defined on the interval-delay images.


CONCLUSIONS
Contrast-enhanced harmonic imaging appears superior to conventional Doppler US for hepatic mass characterization. Low-MI continuous and high-MI interval-delay imaging can help assess tumor vascular pattern and microvascular volume.
Wilson
S R
SR
Department of Medical Imaging, Toronto General Hospital, 200 Elizabeth St, Toronto, Ontario M5G 2C4, Canada. stephanie.wilson@uhn.on.ca
Burns
P N
PN
Muradali
D
D
Wilson
J A
JA
Lai
X
X
D000328:Adult; D000368:Aged; D000388:Air; D000418:Albumins; D001810:Blood Volume / Q000502:physiology; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000000981:diagnostic imaging*; D003287:Contrast Media; D005260:Female; D005466:Fluorocarbons; D005500:Follow-Up Studies; D006391:Hemangioma / Q000098:blood supply / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008099:Liver / Q000098:blood supply / Q000000981:diagnostic imaging*; D008113:Liver Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000556:secondary; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D012039:Regional Blood Flow / Q000502:physiology; D016037:Single-Blind Method; D013997:Time Factors; D018608:Ultrasonography, Doppler
D000418:Albumins; D003287:Contrast Media; C099458:FS 069; D005466:Fluorocarbons