Relaxation Behavior of Laser-Polarized 129Xe Gas: Size Dependency and Wall Effect of the T1 Relaxation Time in Glass and Gelatin Bulbs

2001 ◽  
Vol 150 (2) ◽  
pp. 156-160 ◽  
Author(s):  
Hideaki Fujiwara ◽  
Atsuomi Kimura ◽  
Yasuhiro Yanagawa ◽  
Takashi Kamiya ◽  
Mineyuki Hattori ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Relaxation Behavior ◽  
Wall Effect ◽  
T1 Relaxation Time ◽  
Size Dependency ◽  
T1 Relaxation

T1 Relaxation Time of Achilles Tendon at 3 Tesla with Special Reference to Relevant Clinical Score: A Preliminary Study

2020 ◽  
Vol 16 (2) ◽  
pp. 164-173
Author(s):  
Zeineb Tbini ◽  
Mokhtar Mars ◽  
Mouna Bouaziz
Keyword(s):  
Relaxation Time ◽  
Achilles Tendon ◽  
Clinical Score ◽  
3 Tesla ◽  
Acquisition Time ◽  
Short Term ◽  
T1 Relaxation Time ◽  
T1 Relaxation ◽  
Spin Echo Sequence ◽  
Significant Difference

Purpose: The purpose of this study was to investigate T1 relaxation time of the human Achilles tendon, to test its short-term repeatability as well as the minimal detectable change, and to assess the extent that correlate with clinical symptoms. Methods: Twenty asymptomatic volunteers and eighteen patients with clinically and sonographically confirmed tendinopathy were scanned for ankle using a 3 Tesla (T) MR scanner. T1 maps were calculated from a variable flip angle gradient echo Ultra-short echo time sequence (VFA-GE UTE) and inversion recovery spin echo sequence (IR-SE) using a self-developed matlab algorithm in three regions of interest of Achilles Tendon (AT). Signal to Noise Ratio (SNR) between the two sequences was evaluated. INTRA-class Correlation Coefficient (ICC), Coefficient of Variation (CV) and the Least Significant Change (LSC) were calculated, to test short-term repeatability of T1. Subjects were assessed by the VISA-A clinical score. P values less than 0.005 were considered statistically significant. Results: Mean T1 values were 427.09 ± 53.37 ms and 528.70 ± 103.50 ms using IR-SE sequence and 575.43 ± 110.60 ms and 875.81 ± 425.77 ms with VFA-GE UTE sequence in the whole AT for volunteers and patients, respectively. : T1 values showed a significant difference between volunteers and patients (P=0.001). Regional variation of T1 in healthy and tendinopathic AT were greater for VFA-GE UTE sequence than for IR-SE sequence. VFA-GE UTE sequence showed clearly higher SNR compared to IR-SE sequence. Short-term repeatability of T1 values for volunteers showed an LSC of 22% and 14% for IR-SE sequence and VFA-GE UTE sequence, respectively. For patients, LSC was 14% and 5% for IR-SE sequence and VFA-GE UTE sequence, respectively. There was no correlation between T1 and VISA-A clinical score (p>0.005). Conclusion: VFA-GE UTE sequence used for T1 mapping calculation demonstrated short acquisition time and clearly high SNR. Results revealed that T1 relaxation time can be used as a biomarker to differentiate between healthy and pathologic Achilles tendon. However, T1 showed no correlation with the VISA-A clinical score.

scholarly journals Blood-brain barrier breakdown in non-enhancing multiple sclerosis lesions detected by 7-Tesla MP2RAGE ΔT1 mapping

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249973
Author(s):  
Seongjin Choi ◽  
Margaret Spini ◽  
Jun Hua ◽  
Daniel M. Harrison
Keyword(s):  
Multiple Sclerosis ◽  
Relaxation Time ◽  
White Matter ◽  
Blood Brain Barrier ◽  
White Matter Lesions ◽  
Brain Barrier ◽  
7 Tesla ◽  
T1 Relaxation Time ◽  
T1 Relaxation ◽  
Blood Brain

Although the blood-brain barrier (BBB) is altered in most multiple sclerosis (MS) lesions, gadolinium enhancement is seen only in acute lesions. In this study, we aimed to investigate gadolinium-induced changes in T1 relaxation time in MS lesions on 7-tesla (7T) MRI as a means to quantify BBB breakdown in non-enhancing MS lesions. Forty-seven participants with MS underwent 7T MRI of the brain with a magnitude-prepared rapid acquisition of 2 gradient echoes (MP2RAGE) sequence before and after contrast. Subtraction of pre- and post-contrast T1 maps was used to measure T1 relaxation time change (ΔT1) from gadolinium. ΔT1 values were interrogated in enhancing white matter lesions (ELs), non-enhancing white matter lesions (NELs), and normal appearing white matter (NAWM) and metrics were compared to clinical data. ΔT1 was measurable in NELs (median: -0.139 (-0.304, 0.174) seconds; p < 0.001) and was negligible in NAWM (median: -0.001 (-0.036, 0.155) seconds; p = 0.516). Median ΔT1 in NELs correlated with disability as measured by Expanded Disability Status Scale (EDSS) (rho = -0.331, p = 0.026). Multiple measures of NEL ΔT1 variability also correlated with EDSS. NEL ΔT1 values were greater and more variable in patients with progressive forms of MS and greater in those not on MS treatment. Measurement of the changes in T1 relaxation time caused by contrast on 7T MP2RAGE reveals clinically relevant evidence of BBB breakdown in NELs in MS. This data suggests that NEL ΔT1 should be evaluated further as a biomarker for disease severity and treatment effect in MS.

scholarly journals Lateral diffusion of manganese in the rat brain determined by T1 relaxation time measured by 1H MRI

2011 ◽  
Vol 61 (3) ◽  
pp. 259-266 ◽  
Author(s):  
Yoshiteru Seo ◽  
Akira Takamata ◽  
Takashi Ogino ◽  
Hironobu Morita ◽  
Masataka Murakami
Keyword(s):  
Relaxation Time ◽  
Rat Brain ◽  
Lateral Diffusion ◽  
T1 Relaxation Time ◽  
T1 Relaxation

S11-4 Associations between exposure to MN and T1 relaxation time in magnetic resonance imaging

2016 ◽  
Author(s):  
Anne Lotz ◽  
Beate Pesch ◽  
Clara Quetscher ◽  
Chien-Lin Yeh ◽  
Martin Lehnert ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Resonance Imaging ◽  
T1 Relaxation Time ◽  
T1 Relaxation

Atherosclerotic Lesions Rich in Macrophages or Smooth Muscle Cells Discriminated in Rabbit Iliac Arteries Based on T1 Relaxation Time and Lipid Content

2010 ◽  
Vol 17 (2) ◽  
pp. 230-238 ◽  
Author(s):  
Yasuyoshi Kuroiwa ◽  
Atsushi Yamashita ◽  
Tosiaki Miyati ◽  
Eiji Furukoji ◽  
Misaki Takahashi ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Relaxation Time ◽  
Smooth Muscle Cells ◽  
Lipid Content ◽  
Muscle Cells ◽  
T1 Relaxation Time ◽  
Iliac Arteries ◽  
T1 Relaxation ◽  
Atherosclerotic Lesions

scholarly journals Normal-Appearing Brain T1 Relaxation Time Predicts Disability in Early Primary Progressive Multiple Sclerosis

2007 ◽  
Vol 64 (3) ◽  
pp. 411 ◽  
Author(s):  
Francesco Manfredonia ◽  
Olga Ciccarelli ◽  
Zhaleh Khaleeli ◽  
Daniel J. Tozer ◽  
Jaume Sastre-Garriga ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Relaxation Time ◽  
Progressive Multiple Sclerosis ◽  
Primary Progressive Multiple Sclerosis ◽  
T1 Relaxation Time ◽  
Primary Progressive ◽  
T1 Relaxation ◽  
Early Primary

MTR and T1 provide complementary information in MS NAWM, but not in lesions

2000 ◽  
Vol 6 (5) ◽  
pp. 327-331 ◽  
Author(s):  
C M Griffin ◽  
G JM Parker ◽  
G J Barker ◽  
A J Thompson ◽  
D H Miller
Keyword(s):  
Relaxation Time ◽  
White Matter ◽  
Mixed Model ◽  
Relaxation Times ◽  
Tissue Type ◽  
Tissue Characterisation ◽  
Complementary Information ◽  
T1 Relaxation Time ◽  
T1 Relaxation ◽  
The Relationship

MTR and T1 relaxation times are abnormal in MS lesions and NAWM, and may reflect tissue damage such as demyelination and axonal loss. Their relationship and potential to provide complementary information in tissue characterisation is explored. The aim of this study was to document the relationship between magnetisation transfer ratio (MTR) and T1 relaxation time in Multiple Sclerosis (MS) lesions and normal appearing white matter (NAWM) in order to determine whether the combination provides a more comprehensive tissue characterisation than either parameter in isolation. Ten patients with relapsing remitting MS and 10 age matched healthy controls underwent imaging using a protocol which included the measurement of both MTR and T1 relaxation times. The MTR and T1 values were compared statistically using a commonly adopted correlation approach and a mixed-model regression approach. There was a strong correlation between MTR and T1 in MS lesions (r=0.74). The correlation was seen equally in T1 hypointense and isointense lesions. The relationship was much weaker in MS NAWM (r=0.24) and no correlation was found in control white matter (r=0.06). Mixed-model regression analysis confirmed that the relationship between T1 and MTR is strongly dependent upon tissue type (MS lesion, MS NAWM, or control white matter). The relationship between MTR and T1 relaxation time measurements varies markedly between pathological and normal tissue types. In MS, the complementary information obtained from MTR and T1 is most apparent in NAWM. The results emphasise the potential for combinations of MR parameters to improve tissue characterisation, which in turn should improve understanding of disease pathology and treatment monitoring.

Sign in / Sign up

Export Citation Format

Share Document