Navigated intraoperative ultrasound in neuro-oncology: volumetric accuracy and correlation with high-field MRI.

Objective: The use of intraoperative techniques to detect residual tumors has recently become increasingly important. Intraoperative MRI has long been considered the gold standard; however, it is not widely used because of high equipment costs and long acquisition times. Consequently, real-time intraoperative ultrasound (ioUS), which is much less expensive than MRI, has gained popularity.