Ultrashort time to echo magnetic resonance techniques for the musculoskeletal system

Abstract

Magnetic resonance (MR) imaging has been widely implemented as a non-invasive modality to investigate musculoskeletal (MSK) tissue disease, injury, and pathology. Advancements in MR sequences provide not only enhanced morphologic contrast for soft tissues, but also quantitative biochemical evaluation. Ultrashort time to echo (UTE) sequence, in particular, enables novel morphologic and quantitative evaluation of previously unseen MSK tissues. By using short minimum echo times (TE) below 1 msec, the UTE sequence can unveil short T2 properties of tissues including the deepest layers of the articular cartilage, cartilaginous endplate at the discovertebral junction, the meniscus, and the cortical bone. This article will discuss the application of UTE to evaluate these MSK tissues, starting with tissue structure, MR imaging appearance on standard versus short and ultrashort TE sequences, and provide the range of quantitative MR values found in literature.

Advancements in magnetic resonance imaging‐based biomarkers for muscular dystrophy

“…Conventional scanning protocols are unable to separate fibrosis (which is largely composed of collagen) from fat in part because of the similarity in their T1 and T2 values. However, scanning protocols with ultrashort echo times (UTE) have been developed that may be effective in isolating highly proteinaceous tissues such as collagen that have shorter T2 times compared with fat . Although human studies of UTE sequences have centered primarily on cartilage, bone, tendon, and ligaments, several studies of UTE sequences in muscle have been able to distinguish fibrotic tissue from surrounding fat and water in healthy volunteers without the use of intravenous contrast .…”

“…However, scanning protocols with ultrashort echo times (UTE) have been developed that may be effective in isolating highly proteinaceous tissues such as collagen that have shorter T2 times compared with fat. 96 Although human studies of UTE sequences have centered primarily on cartilage, bone, tendon, and ligaments, several studies of UTE sequences in muscle have been able to distinguish fibrotic tissue from surrounding fat and water in healthy volunteers without the use of intravenous contrast. 97,98 These techniques have not yet been studied specifically in the muscular dystrophy population.…”

Quantitative Imaging in Inflammatory Arthritis: Between Tradition and Innovation

“…Ultrashort echo time (UTE) and the most recent zero echo time (ZTE) allow the detection of rapidly decaying transverse magnetization in the so-called short T2 tissues such as cortical bone, tendons, and fibrocartilage. 60,109 With two-dimensional (2D) UTE, echo times 10 to 20 times shorter than routine sequences can be achieved applying half-width radiofrequency pulses followed by early slice selection gradients. 109 Interesting results emerged from a study on 25 patients with spondyloarthritis comparing US with UTE (i.e., echo times between 0.07 and 16 ms), conventional T1-weighted spin-echo, gradient-echo, and postcontrast imaging for pathologic changes in the Achilles tendon.…”

Cartilage Imaging: Techniques and Developments

“…Because increased T2 is associated with cartilage damage, artifact from the magic angle effect is a potential source of error. 38 Ultrashort echo time techniques facilitate imaging of tissues with short transverse relaxation times such as deep and calcified cartilage layers and diskovertebral junctions, 39 where T2 measurements were shown to be unreliable. 40 Articular cartilage T2 values reflect the water content, collagen content, and collagen fiber orientation in the cartilage matrix, with longer T2 and shorter T2 Ã values thought to represent cartilage degeneration.…”