[Detection of liver metastases--comparison of contrast--enhanced ultrasound using first versus second generation contrast agents].

Aim: To compare detection rates for liver metastases for conventional ultrasound, US using tissue harmonic imaging (THI), echo-enhanced pulse inversion harmonic imaging using Optison and Levovist.

Method: In 73 patients with histologically proven gastrointestinal tumors spiral CT (S-CT), conventional US, US in the THI-mode, echo-enhanced ultrasound in the portal venous phase (ECI Optison ) and in the liver specific late phase (ECI Levovist) were performed and reviewed by blinded readers.

Results: 73 patients (25 female, 48 male, age 63 +/- 11) were included. S-CT detected 158 liver metastases. Conventional US detected 117, THI 119, ECI Optison 169 and ECI Levovist 166 liver metastases. Especially for small (< 2 cm) liver metastases and metastases near the diaphragm echo-enhanced ultrasound exceeded conventional US (p < 0.001). Between both echo enhancers there was no significant difference.

Conclusion: Using echo enhancers increases the ultrasound detection rate significantly. Examination in the portalvenous phase using a second generation enhancer (Optison) is equal to a late-phase examination using Levovist.