The Agfa Mayneord lecture: MRI of short and ultrashortT₂andT₂* components of tissues, fluids and materials using clinical systems

Abstract

ABSTRACT. A variety of techniques are now available to directly or indirectly detect signal from tissues, fluids and materials that have short, ultrashort or supershort T 2 or T 2 * components. There are also methods of developing image contrast between tissues and fluids in the short T 2 or T 2 * range that can provide visualisation of anatomy, which has not been previously seen with MRI. Magnetisation transfer methods can now be applied to previously invisible tissues, providing indirect access to supershort T 2 components. Particular methods have been developed to target susceptibility effects and quantify them after correcting for anatomical distortion. Specific methods have also been developed to image the effects of magnetic iron oxide particles with positive contrast. Major advances have been made in techniques designed to correct for loss of signal and gross image distortion near metal. These methods are likely to substantially increase the range of application for MRI.

UTE imaging in the musculoskeletal system

“…A family of clinically compatible sequences is capable of providing TE values less than 1 msec . These can be collectively referred to as the ultrashort TE (UTE) group of sequences, although zero TE (ZTE) is also a member of this family.…”

New Techniques in MR Imaging of the Ankle and Foot

“…Ultrashort echo time (UTE) MRI is represented by a group of pulse sequences capable of providing TE values less than 1 millissecond (ms) 40,41 . Conventional MRI sequences employ relatively long echo times, resulting in limited opportunity to encode decaying signal of short T2 tissues before that signal reaches zero.…”

MRI of fast-relaxing spins

“…To date, the translation of FID-based MRI methods into routine preclinical and clinical use has been slowed by the need for specialized hardware (e.g., fast switching between transmit and receive modes) and the technical challenges associated with reconstructing images from FID projections. Despite increased technical demands, interest in FID-based imaging methods has steadily increased in recent years, due in large part to the many pioneering works by Graeme Bydder and others who have demonstrated the utility of FID-based sequences to capture important short-lived signals in tissues (for reviews, see [1, 2]).…”