New utility for registration of the CT and PET data in PET/CT

1497 Objectives Misalignment between the CT and PET data can degrade PET quantification in PET/CT. Misalignment caused by the breathing and cardiac motion can be mitigated with average CT (ACT). The aim of this study was to design a new utility to resolve the remaining patient motion between the CT and PET data not accounted for by ACT and by the commercial software, to further improve quantitation of the PET data. Methods Our design included the following three features not available in the commercial software from the equipment manufacturer: (1) a different amount of alignment can be applied to each part of the body in the CT data, (2) the boundary between two adjacent body sections can be adjusted for smooth transition, and (3) a new CT data set after alignment can be generated for attenuation correction (AC) of the PET data and for localization with the PET data. The commercial software can only align the whole CT data set with the PET data by rigid body translation and rotation, and it does not generate the CT data after alignment for localization with the PET data. The physician may sometimes be confused with the new PET data set displayed with the original misaligned CT data (and without the aligned CT data) even though the PET data may be properly attenuation corrected. Results The software has been successfully developed and has been applied on one pediatric patient with misalignment in the head and one patient with misalignment in both the thorax and the abdomen. Both registrations after application of the software showed improved quantitation of the PET data. Conclusions We have developed a new utility to correct for the misalignment between the CT and the PET data, and to generate the registered CT data for improving quantitation of the PET data.