Relative attenuation measurements of ultrasound in the liver using the zerocrossing method

The zerocrossing method for measurement of the frequency dependence of ultrasound attenuation was used to study the livers of 10 healthy subjects and 9 patients. Increased attenuation in vivo was observed in 5 patients who were seen to have a 'bright liver' during B-scanning. Normal attenuation was seen in 3 patients who had pathologic liver biopsies, but normal B-scan images. Increased attenuation was seen in one patient who had a nodular appearance of the liver during B-scanning; biopsy showed steatosis. These results indicate that the zerocrossing method makes it possible to quantify some of the changes seen in the B-scan image. A detailed description, including block diagrams, is given of a zerocrossing detector which can be connected to a commercially available scanner (Brüel & Kjaer Ultrasound Scanner Type 1846).