External landmarking tool lets imagers fuse PET, SPECT, MR, CT

March 6, 2004

Obtaining cleanly fused cerebral PET and CT images no longer requires a multimillion-dollar hybrid scanner. Austrian researchers have developed an external frame that can facilitate fusion of those modalities and also MR or SPECT. Researchers from the

Obtaining cleanly fused cerebral PET and CT images no longer requires a multimillion-dollar hybrid scanner. Austrian researchers have developed an external frame that can facilitate fusion of those modalities and also MR or SPECT.

Researchers from the University Clinic Innsbruck use a rigid, lightweight frame to fix reference points around a patient's face. A customized mouthpiece, similar to those used by athletes, and a vacuum pump hold the frames in an identical position during each scan. Different materials are used as markers for each type of scan.

Once two or more image sets are acquired, software registers the reference points and overlays the various modality data. In initial trials with 49 patients, the coregistration was accurate to within 0.9 to 1.4 mm, according to Prof. Reto Bale, leader of the interdisciplinary team working on coregistration and interventional procedures.

Beyond matching functional and anatomic data for analysis of epilepsy and other conditions, the frame can also be used for real-time surgical guidance and to plan radiotherapy.

The tool is still in development, and the software can coregister only images obtained using the reference frame, Bale said. Making a custom mouthpiece for each patient costs about $60, but the mouthpieces are reusable and can be attached to whatever modality frame is needed. Because positioning relies on the mouthpiece being held in place with suction, patients need enough upper teeth to hold the mouthpiece firmly.