Zero TEMR bone imaging in the head

Abstract

PD-weighted ZT imaging provides robust and efficient depiction of bone structures in the head, with an excellent contrast between air, soft-tissue, and bone. Besides structural bone imaging, the presented method is expected to be of relevance for attenuation correction in positron emission tomography (PET)/MR and MR-based radiation therapy planning.

Effect of head motion on MRI B0 field distribution

“…In fact, this approach has been proposed to correct the EPI distortion of a moving phantom (40). For human subjects, anatomical scans revealing the air cavities against bone and soft tissue may support this predictive model, e.g., scans based on ultrashort or zero echo-time designs (41–43). The influence of the neck and torso can potentially be modeled using simplified geometry with appropriate susceptibility values (41).…”

Ultrashort echo time and zero echo time MRI at 7T

“…Zero echo time (ZTE) and ultrashort echo time (UTE) pulse sequences use specialized acquisition and reconstruction techniques to enable detection of ultrashort-T2 components in vivo. These sequences allow for direct visualization of tendons ( $T_2^{\ast }\approx 1\text{ms}$) (1–7), cortical bone ( $T_2^{\ast }\approx 0.4\text{ms}$) (8–16), and lung parenchyma ( $T_2^{\ast }\approx 0.5-3\text{ms}$) (17–22), as well as components in myelin ( $T_2^{\ast }\approx 0.1-0.4\text{ms}$ (23–25)) and ligaments (26) (up to 80% fraction of $T_2^{\ast }\approx 1\text{ms}$ (27)).…”

Attenuation Correction of PET/MR Imaging

“…The majority of these approaches rely on UTE or ZTE MR techniques that have very short or zero echo times 23,24,27,30,47,48 . These approaches potentially will provide lung, bone and soft tissue maps allowing for accurate patient specific attenuation correction.…”

“…Wiesinger et al proposed a ZTE method to image bone 47 . Imaging parameters of the ZTE protocol were chosen to generate proton density weighted images.…”