Intrasurgical dignity assessment of hepatic tumors using semi-quantitative strain elastography and contrast-enhanced ultrasound for optimisation of liver tumor surgery.

OBJECTIVE

To evaluate the efficacy of strain elastography (SE) using semi-quantitative measurement methods compared to constrast enhanced ultrasound during liver tumor surgery (Io-CEUS) for dignity assessment of focal liver lesions(FLL).

MATERIAL AND METHODS

Prospective data acquisition and retrospective analysis of US data of 100 patients (116 lesions) who underwent liver tumor surgery between 10/2010 and 03/2016. Retrospective reading of SE color patterns was performed establishing groups depending on dominant color (>50% blue = stiff, inhomogenous, >50% yellow/red/green = soft tissue). Semi-quantitative analysis was performed by Q-analysis based on a scale from 0 (soft) to 6 (stiff). 2 ROIs were placed centrally, 5 ROIs in the lesion's surrounding tissue. Io-CEUS was performed by bolus injection of 5-10 ml sulphurhexaflourid microbubbles evaluating wash-in- and -out- kinetics in arterial, portal venous and late phase. Histopathology after surgical resection served as goldstandard.

RESULTS

100 patients (m: 65, f: 35, mean age 60.5 years) with 116 liver lesions were included. Lesion's size ranged from 0.5 to 8.4 cm (mean 2.42 cm SD±1.44 cm). Postoperative histology showed 105 malignant and 11 benign lesions. Semi-quantitative analysis showed central indurations of >2.5 in 76/105 cases suggesting malignancy. 7 benign lesions displayed no central indurations correctly characterized benign by SE. ROC-analysis and Youden index showed a sensitivity of 72.4% and specificity of 63.6% assuming a cut-off of 2.5. Io-CEUS correctly characterized 103/105 as malignant. Sensitivity was 98%, specificity 72.7%.

CONCLUSION

Strain elastography is a valuable tool for non-invasive characterization of FLLs. Semi-quantitative intratumoral stiffness values of >2.5 suggested malignancy. However, sensitivity of Io-CEUS in detecting malignant lesions was higher compared to SE. In conclusion SE should be considered for routine use during intraoperative US in addition to Io-CEUS for optimization of curative liver surgery.