@article {Boutchko2062, author = {Rostyslav Boutchko and David Saloner and Grant Gullberg}, title = {Respiratory motion correction in cardiac PET-MR by optical monitoring and incorporation of MRI data}, volume = {52}, number = {supplement 1}, pages = {2062--2062}, year = {2011}, publisher = {Society of Nuclear Medicine}, abstract = {2062 Objectives We propose a method to enable respiratory motion correction in cardiac PET-MRI with optical fiducial markers. We assume that the different modality studies are performed with MRI preceding the PET. We also assume that incorporating the instantaneous position of the heart in the reconstruction improves the quality of PET images. The underlying hypothesis is that positions of some points on the surface of a body are uniquely related to the position of the heart. Methods Respiration is traced by visual or infrared monitoring of the positions of fiducial markers placed on the patient{\textquoteright}s chest/abdominal area. The optical markers are merged with MR markers. The coordinates of fiducial markers, R_f, can be obtained by using multiple cameras and validated with the same coordinates extracted from cine MR data. At the same time, a 3D position of a point inside the heart, R_a, is determined from the MR images only. A mapping that converts R_f into R_a is established using the MR data as the teaching set. When the patient is moved to the PET or SPECT scanner, R_f data obtained from the optical marker-tracing system are used to predict the instantaneous position of R_a. This information is then incorporated in PET reconstruction. Results Feasibility of the proposed approach was considered by predicting the position of the edge of interventricular septum from the positions of three fiducial markers. Both the anatomic landmark and fiducial marker positions were determined from MRI images of five subjects. For each subject, six single breathhold datasets were acquired and processed. Linear least squares approximation was used to model the mapping. The results show that the position of the heart{\textquoteright}s center can be predicted with 2-3 cm accuracy from three fiducial markers. Conclusions An anatomic landmark inside the heart can be represented as a linear function of fiducial marker coordinates. The accuracy of the prediction may be improved by increasing the training set and changing the approximation method Research Support NIH R01HL50663 \& R01EB0012}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/52/supplement_1/2062}, eprint = {https://jnm.snmjournals.org/content}, journal = {Journal of Nuclear Medicine} }