Intraoperative ultrasound (iUS)

Intraoperative ultrasound (iUS) uses a probe placed on the brain or dura to image tissue in real time. Compared with intraoperative MRI it is fast, portable and inexpensive, and it can be repeated many times during a single operation.

When the probe is tracked by the navigation system, sweeps can be reconstructed into 3D volumes. Comparing a sweep taken before resection with one taken after shows how much the brain has moved, which can be used to update preoperative MRI.

Image quality depends on the operator and on artifacts such as blood in the resection cavity, which is one reason learning-based methods are used to interpret and register iUS volumes.