Inclusion Criteria:

- Histologically confirmed colorectal tumor

- first line treatment by a bevacizumab based chemotherapy

- Target hepatic metastases of size lower than 5 cm and higher than 5 mm detected by
conventional ultrasonography and CT or MRI

- Life expectancy > 2 months

- OMS status =< 2

- Major surgery, open biopsy, or significant traumatic injury within 28 days prior to
Day 0

- informed consent signed

Exclusion Criteria:

- no target hepatic lesion detected by conventional ultrasonography

- Prior bevacizumab treatment

- Prior chemotherapy treatment for advanced disease

- Clinically significant cardiac disease (e.g. myocardial infarction or stroke within
12 months, unstable angina, New York Heart Association (NYHA) Grade II or greater
congestive heart failure not well controlled with medication, endocarditis and
prosthetic valve) and any contraindications in sulphur hexafluoride administration

- Blood pressure >= 180/110 mmHg

- Daily and chronic treatment by aspirin or AINS

- Anticipation of need for major surgical procedure within 7 days prior day 0

- Urine protein > 1g/24 Hours

- Any contraindication in enhancing bevacizumab treatment

- Serious, uncontrolled, concurrent infection(s) or illness(es)

- pregnant and lactating woman