<unk>  is a technique for scanning the brain using high-frequency sound waves. It is used almost exclusively in babies because their fontanelle (the soft spot on the skull) provides an "acoustic window". A different form of<unk> -based brain scanning, transcranial Doppler, can be used in any age group. This uses Doppler<unk>  to assess blood flow through the major arteries in the brain, and can scan through bone. It is not usual for this technique to be referred to simply as<unk> ". Additionally,<unk>  can be used for intra-operative imaging in adults undergoing neurosurgery once the skull has been opened, for example to help identify the margins of a tumour.
Cranial ultrasound
Brain biopsy
Transcranial pulsed ultrasound
Magnetic resonance imaging of the brain
Hemoencephalography
Audiometry
Cranio-corpography
Magnetoencephalography