Ultrasound imaging of liver metastases in the delayed parenchymal phase following administration of Sonazoid™ using a destructive mode technique (Agent Detection Imaging™)

Aim

To determine whether delayed-phase liver imaging using a destructive imaging mode is able to provide similar information to phase-inversion imaging regarding detection and conspicuity of liver metastases.

Material and methods

Patients with a known primary malignancy with suspected liver metastases were recruited. Ultrasound was performed at baseline, and up to 5min after the administration of Sonazoid™, using phase-inversion imaging at both low and high mechanical indices (MI) and at 10–15min using destructive imaging. One of four doses of Sonazoid™ was used: 0.008, 0.08, 0.12, and 0.36μl/kg of body weight. Two observers documented lesion number and conspicuity subjectively, and divided the patients into group A (no lesions), group B (one to seven lesions), and group C_I–III (more than eight lesions, subdivided with increasing lesion number) depending on the number of lesions and categories I–IV based on lesion conspicuity. These parameters were compared with contrast-enhanced computed tomography (CECT) as the reference standard.

Results

Sixteen patients were examined (six women, 10 men), mean age 67.3 years (range 48–83 years). Based on CECT imaging, the division was as follows: group A n=1, group B n=8, group C_I n=1, group C_II n=4, group C_III n=2. The accuracy of baseline ultrasound versus CECT was 75% (in 12 of the 16 patients the group concurred) and the accuracy for contrast-enhanced ultrasound (CEUS) versus CECT was 93.8% (15/16). There was a significant improvement in lesion conspicuity for both low (p=0.0029) and high MI phase-inversion (p=0.0004) and destructive (p=0.0015) CEUS imaging in comparison with baseline ultrasound. Artefact was noted at higher doses of Sonazoid™; and no side effects were recorded.

Conclusion

Following a single, intravenous injection of Sonazoid™, the properties of this microbubble allow for a and robust examination of the liver using two different techniques with comparable results.