The value of contrast enhanced ultrasonography in detection of liver metastases from colorectal cancer: a prospective double-blinded study

Can contrast-enhanced ultrasonography replace multidetector-computed tomography in the detection of liver metastases from colorectal cancer?

PURPOSE

To compare the sensitivity and specificity of contrast-enhanced ultrasonography (CEUS) and 4-slice multidetector-computed tomography (MDCT) in the detection of liver metastases in patients with colorectal cancer (CRC).

MATERIALS AND METHODS

Candidates for this prospective study were 461 consecutive patients referred to the Department of Colorectal Surgery, Aarhus University Hospital with primary or local recurrence of CRC. The patients underwent liver ultrasonography (US), CEUS, MDCT and intraoperative ultrasonography (IOUS). Fine-needle biopsy was performed on all suspicious lesions. The examinations were interpreted blindly and the combination of US, CEUS, biphasic MDCT, IOUS, follow up and biopsy was the gold standard.

RESULTS

Three hundred and sixty-five patients were included. All patients had undergone preoperative US, CEUS and MDCT and 65.5% had received IOUS. The gold standard found liver metastases in 54 patients (14.8%). Multidetector CT found significantly more metastases than CEUS in 15 (28%) of the patients (p=0.02). In a patient-by-patient analysis MDCT had a non-significantly higher sensitivity in the detection of liver metastases compared to CEUS (0.89 versus 0.80, p=0.06). The specificity of CEUS (0.98) was slightly better than that of MDCT (0.94) (p=0.02).

CONCLUSION

Multidetector CT found significant more metastases than CEUS, and MDCT had in patient-by-patient analysis a non-significant better sensitivity (p=0.06) in detecting liver metastases in patients with CRC.

Focal liver lesions: role of contrast-enhanced ultrasound

The introduction of microbubble contrast agents and the development of contrast-specific techniques have opened new possibilities in liver imaging. Initially, only intermittent imaging with Doppler detection was available. Second-generation contrast agents and low mechanical index real-time scanning techniques are decisive advances that enable convenient liver examinations with high sensitivity and specificity. Hepatic lesions usually show typical perfusion and enhancement patterns through the various contrast phases, which help their characterization. Several published studies and the daily clinical routine show that, as opposed to conventional ultrasound (US), contrast-enhanced US can substantially improve detection and differentiation of focal liver lesions. Today, contrast-enhanced US is the dynamic imaging modality of choice for differentiation of focal liver lesions. Contrast uptake patterns of the most relevant liver lesions, as well as important clinical indications are presented and discussed.