Ultrasound is not bypassed and a brain tumor, however, it is rarely used. The fact that ultrasound can not pass through the skull. If he can easily penetrate through them, you may not be needed, many methods that are now there.
Ultrasound examination of the brain called the "M - echo". This method allows the displacement of so-called mid-brain structures. But such shifts are related, as a rule, with some three-dimensional form in it, for example, tumor.