Registering Molecular Imaging Information into Anatomic Images with Improved Spatial Accuracy

To make molecular imaging useful in the clinic, accurate image registration must be done to correlate nano-scale events to macro-scale anatomy. The 3D volumetric image registration technique uses visual and quantitative measures to identify the most homogeneous color distribution on a volumetric anatomical landmark. Four phantom PET/CT images were acquired with 5.0 plusmn 0.1 mm shift interval. The image registration shift was compared with the positioning shift. An accuracy of 0.1deg and 0.1 mm was achieved. Cranial PET/CT images from 39 patients were examined. It was found that the average head motion was 0.5-1deg and 1-3 mm, even with a stringent head holder. This small but significant misalignment is beyond the capability of conventional visual-based fusion methods used clinically. The 100 mum accuracy is a step forward to register molecular activities to anatomy for high precision interventions