Diagnosis Of Focal Hepatic Lesions With Contrast-Enhanced Gray-Scale Ultrasonography

Objective The purpose of this study was to investigate the role of real time gray-scale contrast-enhancement ultrasonography(CE-US) and new contrast agent in evaluating the perfusion and contrast enhancement patterns of focal hepatic lesions .Materials and methods The study population consisted of 36 consecutive patients with solid focal hepatic lesions that were considered indeterminate at baseline gray-scale ultrasonography (US) during routine clinical work-up. 26 males and 10 females were enrolled in this study, ranging in age from 30 to 79 years(medium age, 53years).CE-US were performed on 36 nodular hepatic lesions: 16 hepatic cellular carcinomas(HCC),8 metastases, 6 hemangiomas, 3 hepatic abscesses, 2 inflammatory necrotic nodules and 1 focal nodular hyperplasis.First of all, a baseline US of the liver, using the gray scale and color Doppler flow imaging(CDFI) was performed to identify the focal liver lesions and diagnosis was made according to the location, size, shape, number, and echo features of the lesion. When the suspected lesion was identified , the contrast-specific mode was initiated and a low mechanical index (MK0.09)was selected to avoid disrupting microbubbles .After a venous bolus injection of 2.4ml of SonoVue at a strength of 5mg/ml ,contrasted image was used to studylesion enhancement in the arterial , portal and delay phases. The entire examination was recorded on digital video clips. The comparisons with conventional color Doppler US and dynamic CT were made.Result In HCC ,the presence of intratumoral vessels in the arterial phase and homogeneous or hetergeneous enhancement in the portal phase were typical patterns. With intratumoral vessels and homogeneous or hetergeneous enhancement for HCC, the following diagnostic indications emerged: sensitivity, 68%, 87.5%; specificity,60%, 78.6%;and diagnostic accuracy,72%, 83.3%. In metastases, the presence of ring enhancement in the portal phase was typical pattern and the sensitivity , specificity and diagnostic accuracy were 50% , 90.9%, 80.0% respectively. In hemangioma, peripheral nodular enhancement in the portal phase was typical pattern and the sensitivity, specificity and diagnostic accuracy of diagnosis based on the enhancement pattern for hemangioma were 66.7%, 100%, 93.3% respectively. In the delay phase ,83.8% of benign lesions and 4.2% of malignant lesions showed residual enhancement and there was statistical difference between benign and malignant lesions(P<0.05). In the perfusion process of liver lesions, malignant lesions showed early arterial enhancement and immediate wash-out, while benign lesions presented with slow enhancement and wash-out. After injection SonoVue, The time of beginning enhancement in malignant lesions was 14.9 ± 4.7s and there was no statistical difference compared with that of benign lesions (18.1±5.8s) (P>0.05), The time of peak enhancement and reducing enhancement in malignant lesions (34.0 ± 10.3s, 71.6 ± 17.5s)vvere obviously earlier than those of benign lesions(81.6 ± 32.3s, 313.5 ± 105.2s) (P< 0.05).Compared with CDFI, the blood flow detecting rates before and after SonoVue administration in the benign lesions were 33.3% and 66.7% respectively, those in the malignant group were 62.5% and 87.5% and there were distinguished improvements after enhancement(P<0.05).CE-US was superior to conventional US and dynamic CT in detecting more minute (d≤ 1.0cm)lesions.Conclusion CE-US is useful for differentiation between liver benign andmalignant lesions. The typical HCC features are intratumoral vessels in the arterial phase, homogeneous or hetergeneous enhancement in the portal phase and immediate enhancement and wash-out. The typical metastasis feature was ring enhancement and peripheral nodular enhancement may provide a more reliable diagnosis for hemangioma. The time of peak and reducing enhancement in dynamic CE-US are important in differentiating benign and malignant lesions. The blood detecting rate distinctly improved after enhancement. CE-US is superior to conventional US and dynamic CT in detecting more minute (d≤ 1.0cm)Iesions.