A simplified method to integrate metabolic images in stereotactic procedures using a PET/CT scanner

We have developed a method that needs only the computed tomography (CT) indicator box to coregister positron emission tomography (PET) images and integrates this information with magnetic resonance imaging. The study was performed using a PET/CT scanner. A standard CT bed adapter was attached to the scanner couch. Then, the patient, with the Leksell G frame fixed, was positioned into the scanner with the CT indicator box. PET images were acquired using either [ 18F]fluorodeoxyglucose or [ 11C]choline as radioisotopes. After acquisition, CT and PET images were exported in DICOM 3 standard and transferred to a dedicated workstation via data link. Homemade software was implemented for multimodal image fusion. PET images were overwritten to their corresponding CT point values using a threshold algorithm, maintaining the stereotactic CT markers. The use of a CT indicator simplifies the procedure, because there is no need for a radioactive solution filling the indicator box. This method was tested first using a phantom and then in patients. The localization accuracy of the PET images is limited only by the slice thickness.