Continuous MR bone density measurement using water- and fat-suppressed projection imaging (WASPI) for PET attenuation
1Center for Advanced Medical Imaging Sciences, Department of Imaging, Massachusetts General Hospital, Boston, MA 02114, USA. Department of Radiology, Harvard Medical School, Boston, MA 02115, USA. Departments of Radiology, Psychiatry, Stony Brook Medicine, Stony Brook, NY 11794, USA.
Abstract:
Due to the lack of signal from solid bone in normal MR sequences for the purpose of MR-based attenuation correction, investigators have proposed using the ultrashort echo time (UTE) pulse sequence, which yields signal from bone. However, the UTE-based segmentation approach might not fully capture the intra- and inter-subject bone density variation, which will inevitably lead to bias in reconstructed PET images. In this work, we investigated using the water- and fat-suppressed proton projection imaging (WASPI) sequence to obtain accurate and continuous attenuation for bones. This approach is capable of accounting for intra- and inter-subject bone attenuation variations. Using data acquired from a phantom, we have found that that attenuation correction based on the WASPI sequence is more accurate and precise when compared to either conventional MR attenuation correction or UTE-based segmentation approaches.
