Contrast-enhanced US useful for differentiating focal liver lesions

(Radiology Review) All three vascular phases should be assessed when sonographic contrast agents are used to differentiate benign from malignant focal liver lesions, according to Dr. Carlos Nicolau from Hospital Clinic, Barcelona, and colleagues. They evaluated the accuracy of tumoral vascularity display in liver tumors using contrast-enhanced sonography, and their study is published in the American Journal of Roentgenology (January 2006, Vol. 186:1, pp. 158-167).

Although CT and MR imaging with contrast agents are more accurate for determining tumoral vascularity, the authors explained that new ultrasound techniques such as harmonic imaging and contrast agents enable tumor vascularity display. In addition, the low cost, noninvasiveness, and ready availability now make sonography a viable alternative.

The SonoVue (Bracco, Milan, Italy) contrast agent has a highly flexible shell that allows continuous real-time imaging of contrast enhancement during the arterial, portal, and late vascular phases, because a low mechanical index is used, they stated.

Fine-needle biopsy or dynamic CT or MR imaging was used in 152 patients to determine the final diagnosis for 152 solid focal liver lesions. "The final diagnoses were metastasis for 24, hepatocellular carcinoma for 75, focal nodular hyperplasia for 13, regenerating or dysplastic nodule for 14, hemangioma for 22, cholangiocarcinoma for two, and another focal liver lesion for two," the authors reported.

Sonography was performed following a bolus injection of 2.4 mL of SonoVue, and lesions were evaluated in the arterial, portal, and late vascular phases. Lesions then were classified as benign or malignant, and each classification was correlated with the final diagnosis.

Based on results, when all vascular phases were used to differentiate between malignant and benign lesions the sensitivity was 98% and accuracy was 92.7%, compared with 78.4% and 80.9% for late phase alone. This improvement in results was more significant in patients with chronic liver disease, they stated.

"For differentiating between benign and malignant focal liver lesions, evaluation of SonoVue enhancement in all three vascular phases is superior to evaluation of SonoVue enhancement in the late phase alone, especially in patients with chronic liver disease," the authors concluded.

"Importance of Evaluating All Vascular Phases on Contrast-Enhanced Sonography in the Differentiation of Benign from Malignant Focal Liver Lesions"
Carlos Nicolau et al
Diagnosis Imaging Center, Hospital Clinic
Villarroel 170, Barcelona 08036, Spain
AJR January 2006; 186:158-167

By Radiology Review
January 19, 2006

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