Short Echo Times and Multiple Echoes to Image, Quantitate and Classify Fast-Relaxing Anatomy

Ethan M. Johnson¹, Jinyi Qi², Urvi Vyas¹, Kim R. Butts Pauly¹, John M. Pauly¹

Pulse sequences using very short echo times (UTE, CUTE, DUTE, etc.) have been applied variously to image tissues with short spin-spin relaxation (<I>T</I>₂) times. With consideration of the consequences short-<I>T</I>₂ times have for excitation and encoding, a UTE-style pulse sequence capable of visualising bone and other fast-relaxing structures is developed. The acquired images show features that facilitate tissue classification, which is useful, e.g., for MR-PET and high-frequency focussed-ultrasound. To demonstrate, bone, soft tissue and air are classified from 1/<I>T</I>₂ and signal level, from which a linear attenuation coefficient map useful for PET reconstruction is generated.