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Contrast-enhanced ultrasound can guide the therapeutic strategy by improving the detection of colorectal liver metastases

Mikael Sawatzki, Ulrich Gueller, Sabine Guesewell, Daniela B. Husarik, David Semela & Stephan Brand

abstract

BACKGROUND & AIMS
CT may miss up to 30% of cases of colorectal liver metastases (CRLMs). We assessed the impact of contrast-enhanced ultrasound (CEUS) on the detection of CRLMs and on changes to the therapeutic strategy; additionally, we assessed the accuracy of CEUS in differentiating unclear focal liver lesions (FLLs) compared to staging-CT.

METHODS
We prospectively analyzed all patients with newly diagnosed and histologically confirmed colorectal cancer (CRC) at our tertiary gastroenterological center between December 2015 and May 2019. CEUS was performed in a total of 296 patients without CRLMs after staging-CT using the contrast agent (SonoVue®). Standard of reference was obtained by MRI or histology to diagnose CRLMs missed by CT. Benign FLLs were confirmed by MRI or follow-up CT (mean follow-up interval: 18 months).

RESULTS
Eight additional CRLMs were detected by CEUS (overall 2.7%; sensitivity 88.9%, specificity 99.0%, positive predictive value 100%, negative predictive value 99.6%). All patients with CRLMs detected only by CEUS were in tumor stage T3/T4 (4.0% additionally detected CRLMs). The number needed to screen to detect 1 additional CRLM by CEUS was 37 in all patients and 24.5 in T3/T4-patients. When results were reviewed by a board-certified radiologist and oncologist, the therapeutic strategy changed in 6 of these 8 patients. Among the 62 patients (20.9%) with unclear FLLs after staging-CT, CEUS determined the dignity (malignant vs. benign) of 98.4% of the FLLs.

CONCLUSION
Overall, CEUS detected 2.7% additional CRLMs (including 4.0% in tumor stage T3/T4) with a significant impact on the oncological therapeutic strategy for 75% of these patients. Patients with tumor stage T3/T4 would particularly benefit from CEUS. We propose CEUS as the first imaging modality for CT-detected lesions of unknown dignity.

LAY SUMMARY
In patients with newly diagnosed colorectal cancer, contrast-enhanced ultrasound (CEUS) detected additional liver metastases after computed tomography (CT). In the majority of these patients, the oncological therapy was changed after obtaining the CEUS results. After staging-CT, 21% of hepatic lesions remained unclear. In these cases, CEUS was accurate to either reveal or exclude liver metastasis in nearly all patients and could reduce costs (e.g., number of MRI scans).
   
citation Sawatzki M, Gueller U, Guesewell S, Husarik D B , Semela D, Brand S. Contrast-enhanced ultrasound can guide the therapeutic strategy by improving the detection of colorectal liver metastases. J Hepatol 2021; 74:419-427.
   
type journal paper/review (English)
date of publishing 12-2-2021
journal title J Hepatol (74/2)
ISSN electronic 1600-0641
pages 419-427
PubMed 33065168
DOI 10.1016/j.jhep.2020.09.036
contact Mikael Sawatzki