Liver tumors: utility of characterization at dual-frequency US.
OBJECTIVE
To evaluate the potential utility of a technique for analysis of ultrasonographic (US) images obtained at two center frequencies in a phantom model and in a clinical study of liver tumors.


METHODS
A US phantom was built that contained target regions with polystyrene scatterers both smaller and larger than scatterers in the background material. High- and low-frequency US images of target regions were obtained, and changes in the contrast-to-noise ratio (CNR) of the targets relative to the background were determined. In a clinical evaluation, 12 hemangiomas, 13 liver metastases, one adenoma, and two hepatomas were evaluated in a similar manner, and the results were correlated with the histologic findings in resected lesions.


RESULTS
For targets containing scatterers smaller than those in the background, there was an increase in CNR of higher frequency images. The converse was true for target regions having scatterers larger than those in the background. Liver metastases generally showed an increase in CNR of higher frequency images, whereas hemangiomas generally showed somewhat decreased CNR of higher frequency images, differing significantly from metastases (P < .01-.001).


CONCLUSIONS
Changes in CNRs of relatively high- and low-frequency US images may give useful information on the frequency dependence of backscattering, which is descriptive of the histologic findings in lesions and which is not evident with conventional US images.
Sommer
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Department of Radiology, Stanford University Medical Center, CA 94305-5621, USA.
Olcott
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Tai
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D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging; D005260:Female; D006391:Hemangioma / Q000000981:diagnostic imaging; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D014463:Ultrasonography / Q000379:methods