An integrated radio frequency probe and cranial clamp for intraoperative magnetic resonance imaging: technical note

To design an integrated radio frequency (RF) head probe and cranial clamp for intraoperative magnetic resonance imaging (MRI) that do not interfere with the operating procedures.

A concept based on four inductively coupled rings was developed and applied for an intraoperative RF probe. The probe was integrated with a specially designed cranial clamp and incorporated into the intraoperative MRI system.

The design of the RF probe allows splitting the probe into two separate parts; the lower two rings and matching ring are permanently incorporated into the patient table, and the two upper rings can be removed to expose the patient's head during neurosurgery. The probe produces a homogeneous B1 field over the entire region of interest with sufficient sensitivity to obtain high quality images. The cranial clamp, made of MRI compatible materials, is asymmetrical to allow variable head positioning.

The described RF head probe and cranial clamp have been used successfully in more than 400 brain surgeries without compromising sterility of the operating area. Pre-, intra-, and postsurgical MRI scans have been obtained without a need to move a patient or reposition the head for imaging sessions. The images were of high quality and free of susceptibility or eddy currents artifacts. With minor modifications, the integrated RF probe and cranial clamp can be used successfully in other intraoperative MRI systems.