T2*

T2*

An MRI term for the time constant for the loss of phase coherence among spins oriented at an angle to the static magnetic field, which is due to a combination of magnetic field inhomogeneities and spin-spin relaxation, resulting in a rapid loss of transverse magnetisation and the MRI signal. The value of T2* is < T2.
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References in periodicals archive ?
The measured parameters compared between the two groups included T1, T2, T2* relaxation times, fat fraction (FF), and cross-sectional area (CSA) of the quadriceps femoris and the hamstring muscles.
The noninvasive MR imaging techniques enable to capture the information of changes in microstructure and perfusion at the cellular or fascicular level.[3],[4],[5] These quantitative MR imaging techniques include T1-mapping, T2-mapping, and multi-echo mDixon-Quant imaging, from which parameters (T1, T2, and T2*) derived are the characteristic indicators of the tissue composition and the metabolic changes; both fat fraction (FF) and cross-sectional area (CSA) of the muscle are two quantitative markers of the muscular strength and damage.[6],[7],[8] We hypothesized that these quantitative MR imaging techniques could reflect structural and functional changes at the microscopic level of skeletal muscles.
The T2* and FF map were acquired from the mDixon-Quant sequence.
Two independent sample t -test was used to compare the difference in the muscle's T1, T2, T2* relaxation times, and FF and CSA between two groups.
ICC was as follows: T1 value ranged from 0.758 to 0.975; T2 value ranged from 0.842 to 0.994; T2* value ranged from 0.763 to 0.963.
Intra-tumor microcalcification, hemorrhage, or other T2* change such as macrophage and free radical of NIPT may be related to relative low signal intensity on T2-weighted images.
Biochemical changes of early stage Achilles tendinopathy may affect T2* values of AT and thus can be caught and quantified with UTE sequences [8].
Therefore, the aim of this study was to investigate the capability of quantitative 3D-UTE-T2* in evaluating diseased AT and analyze the correlation between T2* value and American Orthopaedic Foot and Ankle Society (AOFAS) score or Achilles tendon Total Rupture Score (ATRS).
All the participants were examined on a 3T MR scanner (Discovery 750, GE Healthcare, Waukesha, WI, USA) to get monoexponential calculation of T2* in the human AT in vivo.
T2* value of each region is calculated by fitting the acquired signal at different echo time to a single exponential decay model (Figure 2).
An independent sample f-test was used to compare the differences of T2* values between two groups.
The aim of this study is to explore the possibility of T2* weighted images (T2*WI) as another sequence in addition to T1WI to determine the process of bone fusion of the radial epiphysis and explore new findings.