Software-based quantification of contrast-enhanced ultrasound in focal liver lesions--a feasibility study

To compare software-based quantification of contrast-enhanced ultrasound (CEUS) examinations of focal liver lesions in the arterial and late phases with the enhancement patterns established by the sonologist.

The study cohort comprised 12 malignant and 21 benign hepatic lesions in 33 patients (18 female and 15 male; aged 57 +/- 13 years). All underwent dynamic real-time low mechanical index (<0.3) CEUS, which was stored as video sequences of the various enhancement phases. A software was used for analysis by using different regions of interest (ROI) in a double-blinded manner. The software generated and the visual enhancement patterns were compared, and the t-test was performed.

The videos containing the arterial phase had a mean length of 37.5 +/- 36.7 s and the late phase sequences a mean length of 15.2 +/- 9.2 s. In the arterial phase complete agreement between software and sonologist was 100%, 93.9% and 87.9% with regard to the entire lesion, its centre and its periphery, respectively. The late phase analysis revealed corresponding figures of 90.9%, 87.9% and 90.9%. In the late phase, benign lesions revealed a mean relative enhancement of +65.1 +/- 103.6% and malignant lesions -56.9 +/- 26.3% (p=0.0005) vis-à-vis liver parenchyma. All the malignant and 14% of the benign tumors showed hypo-enhancement of less than -10%.

The complete agreement between the quantitative analysis and the sonologist within the arterial and late phase showed excellent results. Software analysis of the late phase could dichotomise benign and malignant lesions. Objective establishment of iso-enhancement in the late phase excludes malignancy.