Computer coregistration of positron emission tomography and magnetic resonance images in head and neck cancer.

Purpose: Early experience has shown that positron-emission tomography (PET) is a useful technique for the detection of occult squamous cell carcinoma of the head and neck. Although highly sensitive, PET lacks definition of anatomic detail and therefore does not localize pathology precisely. To circumvent this limitation, a computerized coregistration technique has been developed at the University of California-Los Angeles to correlate PET and magnetic resonance images (MRI). This method allows accurate, precise anatomic localization of areas of heightened glucose metabolism, including subclinical tumors.

Materials And Methods: The technique uses a coregistration computer program that precisely superimposes the PET scan with the corresponding MRI image.

Results: Two cases are presented in which PET-MRI coregistration was used to anatomically define the areas of heightened glucose metabolism. Large tumors were selected because the precision of the method can be verified.

Conclusion: The coregistration technique is a valuable addition to PET imaging, particularly in its ability to anatomically localize PET findings. The most important application of this technique is to facilitate the biopsy of subclinical lesions identified on PET.