MSCT and MRI vie for intraoperative guidance role

Multislice CT could prove more advantageous than MRI for intraoperative guidance, elucidating minimally invasive approaches in head, neck, and body interventions, according to researchers at the Center for Surgical Advancement in Celebration, FL.

"Interventional MR has never really fulfilled its promise," said principal investigator Dr. Gary M. Onik, an interventional radiologist and director of surgical imaging at the CSA's Celebration Health/Florida Hospital.

Intraoperative guidance with 1.5T and 3T MR scanners has overcome most limitations posed by low-field systems, and it has already proved its worth in the neurosurgical setting. Research at the National Institutes of Health, Johns Hopkins University, Brigham and Women's Hospital, and the University of Essen in Germany has produced steady, though preliminary, progress in MR guidance and intravascular catheters.

But MR-guided interventions are generally complex and expensive to run, and they require MR-compatible operation rooms. MSCT, on the other hand, has most of MR's imaging capabilities and none of its constraints, adapting easily into the OR environment, Onik said.

MSCT provides OR physicians with valuable speed and visualization capabilities. Surgeons - working always against the clock - can perform thoraco-abdominal interventions in minutes, without compromising image quality, he said.

To date, Onik and colleagues have prospectively enrolled 26 patients who have undergone abdominal, chest, and brain surgeries under intraoperative guidance and monitoring with a 16-slice scanner. The fully OR-integrated system includes a mechanized arm that guides several surgical instruments, a table specially designed as a patient-immobilization device and respiratory-gating platform, and fluoroscopy and ultrasound equipment for simultaneous multimodality scanning and monitoring.

The MSCT intraoperative setting can guide laparoscopic and thoracoscopic procedures to remove occult pathology and to displace organs to prevent them from thermal injury or bleeding during cryo or radiofrequency ablation procedures. It also allows simultaneous monitoring and control of outcomes such as complete tumor resections and complications. The CSA team will present its preliminary findings at the 2005 American Roentgen Ray Society meeting in May, Onik said.

Researchers have worked out ways to minimize the system's shortcomings. Though radiation exposure is a secondary concern in patients treated for cancer, alternative guidance and monitoring with ultrasound lessens the need for CT. CSA physicians have also developed patient-protective pads to cut radiation exposure. A special device in the works will allow manipulation of surgical instruments outside the scan's gantry, Onik said.

The idea is not new. Intraoperative CT has been proposed since the early 1980s, and the first experiences with patients were documented in the early 1990s. CSA's sophisticated intraoperative MSCT setting, however, is allegedly the only one of its kind, Onik said. He has already been contacted by other institutions interested in the technology and plans to implement the system in a mobile operating room to bring it to smaller hospitals.

The technology is also proving effective with minimally invasive surgery.

"We have been able to monitor lesions and guide the laparoscopic surgeon down to the pathology to remove it with minimal invasiveness. Intraoperative MSCT had a major impact on the ability of our surgeons to take patients who would have otherwise been candidates for open surgery," he said.

For more information from the Diagnostic Imaging archives:

Intraoperative high-field MR revamps neurosurgery

Clinicians weigh 64-slice CT's revolutionary potential

Three-D ultrasound evolves in interventional radiology

MR moves into the OR to visualize pathology and guide therapy

An encore for Gary Onik