Contrast-Enhanced Ultrasound (CEUS) for the characterization of focal liver lesions - prospective comparison in clinical practice: CEUS vs. CT (DEGUM multicenter trial). Parts of this manuscript were presented at the Ultrasound Dreiländertreffen 2008, Davos

Abstract

Aim: The aim of our study was to evaluate the diagnostic value of Contrast-Enhanced Ultrasound (CEUS) for the characterization of focal liver lesions in a prospective multi-center study in clinical practice. For this purpose CEUS was compared with the spiral-CT (SCT), the standard radiological method.

Material and methods: 1349 patients with unclear liver lesions after fundamental ultrasound diagnostics including color doppler analysis were examined with standardized CEUS (pulse inversion method, mechanical index < 0.4) from May 2004 to December 2006 in 14 hospitals in a prospective study. The enhancement of contrast medium in the liver tumors was analyzed according to known tumor-specific vascular patterns, using standardized documentation and analysis methods for the differentiation of tumor differentiation (malign or benign) and tumor specification (entity). A subcollective of 267 patients was additionally examined by standardized SCT method. Final diagnosis was based on histology, SCT or MRI in typical findings of liver hemangioma and FNH and on proved clinical data and additional follow up.

Results: The subcollective of 267 patients was divided in two subgroups. In 109 of these patients (subgroup A) there was no histological verification, diagnoses based on clear SCT-findings in 79 cases of hemangioma or FNH, as well as in 20 cases with a clear clinical diagnosis. 6 cases (5.5 %) remained unclear. In this subgroup the assessment of tumor differentiation was concordant with CEUS in 90 cases, discordant in 19 cases and the assessment of tumor specification was concordant in 82 and and discordant in 27 cases. In 158 patients (subgroup B) a histological finding was also present, only in 4 cases no definitive tumor diagnosis was achieved. In this subgroup assessment of tumor differentiation with CEUS and SCT was concordant in 124 cases and discordant in 30 cases (CEUS/SCT: sensitivity 94.0 / 90.7 %, specificity 83.0 / 81.5 %, PPV 91.6 / 91.5 %, NPV 87.5 / 80.0 %, accuracy 90.3 / 87.8 %). Tumor specification matched in 103cases and were different in 51 cases (CEUS/SCT: sensitivity 95.3 / 90.6 %, specificity 83.7 / 81.6 %, PPV 92.7 / 91.4 %, NPV 89.1 / 80.0 %, accuracy 91.6 / 87.7 %). A statistically significant difference could not be established. The analysis of particular tumor specification showed a statistically non significant slight advantage in tumor differentiation for CEUS in the case of hemangioma, FNH, HCC and metastases.

Conclusion: In a multi-center approach under routine clinical conditions, this prospective study demonstrates CEUS to be of equal rank to the CT-scan in regard to the assessment of tumor differentiation and specification. No statistically significant differences could be established. CEUS should be employed before computed tomography is performed for the differentiation of liver tumors, because radiation exposure and invasive biopsies can be avoided in veritable numbers of cases, when precise clinical evaluation of the findings is implemented.