CHICAGO - Contrast-enhanced ultrasound (CEUS) significantly improves the diagnostic performance of radiologists characterizing hypoechoic focal lesions in fatty livers, according to researchers from the University of Palermo in Italy.
"And it also reduces the need for further radiological workup in this clinical setting," said Dr. Tommaso Bartolotta. He presented the research Tuesday at the 2006 RSNA meeting.
The presence of diffuse liver disease such as steatosis may alter the grayscale ultrasound appearance of hepatic tumors, which mainly appear as hypoechoic lesions regardless of their nature. This makes the right diagnosis challenging, Bartolotta said.
To assess the diagnostic performance of CEUS in characterizing hypoechoic focal hepatic lesions in fatty liver and to determine if the technique may reduce the need for further radiological workup in, the researchers studied 105 consecutive patients with 105 hypoechoic (52 malignant and 53 benign) focal hepatic lesions in a fatty liver.
The standard of reference was histological evaluation of a resected specimen (10 cases), core biopsy (40 cases), or typical helical CT and/or MRI findings (55 cases). Ultrasound exams were performed using either a HDI 5000 or iU22 (Philips Medical Systems, Andover, MA) and intravenous administration of the SonoVue (Bracco, Milan, Italy) ultrasound contrast agent.
The baseline conventional ultrasound study included color and power Doppler examination. Pulse-inversion harmonic imaging (PIHI) was then performed at a very low mechanical index (0.05-0.08) following a 2.4 mL injection of SonoVue.
All the ultrasound studies were digitally stored for offsite image analysis. Two independent and experienced radiologists, who were not involved in the scanning and were blinded to the final diagnosis, first reviewed the baseline ultrasound studies alone and then the CEUS scans. The readers classified each lesion as malignant or benign based on a five-point scale of confidence by means of established diagnostic criteria. They also recorded whether further imaging was needed for lesion characterization.
Diagnostic confidence significantly improved for both after reviewing CEUS; the area under the ROC curve (Az) grew from 0.706 to 0.999 for the first reader and 0.665 to 0.99 for the second reader (p < 0.0001). Inter-reader agreement also increased from a weighted k of 0.748 at the baseline ultrasound to 0.882 at CEUS.
Correctly characterized lesions increased from 27 of 105 (27.5%) to 94 of 105 (89.5%) for the first reader and from 19 of 105 (18.1%) to 93 of 105 (88.6%) for the second reader after considering the CEUS scans (p < 0.0001), Bartolotta said.
The number of cases for which a further imaging study was requested to characterize the lesion significantly decreased from 93 of 105 (88.6%) to 26 of 105 (24.8%) for the first reader and from 96 of 105 (91.4%) to 40 of 105 (38.1%) for the second reader (p < 0.0001), according to Bartolotta.
By Erik L. Ridley
AuntMinnie.com staff writer
November 28, 2006
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