Type:
Educational Exhibit
Keywords:
Multicentre study, Not applicable, Prospective, Cerebrospinal fluid, Physics, Imaging sequences, MR, Neuroradiology brain, MR physics, Neuro
Authors:
Y. Wada1, Y. Kanazawa1, M. Harada1, N. Maeda1, Y. Matsumoto2, T. Abe3, H. Hayashi4, M. Miyoshi5, M. Carl6; 1Tokushima/JP, 2Tokushima-shi/JP, 3770-8509, --/JP, 4Kanazawa/JP, 5Hino/JP, 6Milwaukee/US
DOI:
10.26044/ecr2020/C-08766
Background
Ultrashort Echo Time Magnetic Resonance Imaging (UTE-MRI) is a technique using extremely short-TE(s) which enables the observation of a component signal having a short T2 [1]. In clinical practice, the shortest TE is set at between 0.04–1.0 ms, which is used for the imaging of cartilage and Achilles tendon (T2 = 0.3–0.7 ms); furthermore, bone, lung, and brain imaging are also used.
Myelin is a membrane structure rich in lipid components that wrap around nerve cell axons. The components are 70–80% lipid and 20–30% protein [2]. It is known in abundance in the white matter (WM) of the brain and spinal cord and acts to increase the speed of signal transmission. In addition, myelin content is known to be decreased when there is neurodegeneration in diseases such as Alzheimer's and in demyelinating diseases such as multiple sclerosis and leukodystrophies.
It has been recognized that brain structures including myelin and axon have a short T2 component, which is composed of lipids and proteins [3]. There have been reports of phantom studies which describe the measuring of T2 shorts such as myelin and axons using UTE-MRI. Because UTE-MRI can observe the short T2 signal, detailed information on myelin structure can be obtained and clinical application is being attempted [4].
After calculating short and long T2 components (T2,s and T2,l) using bi-exponential fitting to the acquired signal values, and then a Myelin Water Fraction (MWF) image can be derived from each T2 value. MWF is used as a measure of myelin content and has been proposed as a potential biomarker for many Central Nervous System (CNS) diseases. In this study, we created MWF images in which MWF is defined as the ratio of T2,s* to T2,l*. Moreover, because myelin includes lipids, an MWF image using CHEmical Shift Selective (CHESS) saturation RF pulse, e.g. fat-saturation (FS) was generated. The purpose of this study is to define a method to extract short T2* components (T2,s*) using UTE-MRI.