scholarly journals Magnetic resonance imaging in skeletal muscle following denervation and electrical stimulation

1996 ◽  
Vol XXVIII (1-2) ◽  
pp. 19-23
Author(s):  
Т. Mokrusch
Keyword(s):  
Electrical Stimulation ◽  
Relaxation Time ◽  
Signal Intensity ◽  
T2 Relaxation Time ◽  
Denervated Muscle ◽  
T2 Relaxation ◽  
New Type ◽  
Chronic Denervation ◽  
Mri Evaluation ◽  
Distinct Increase

Following chronic denervation, MRI evaluation of fast rabbit muscles revealed a distinct increase of signal intensity and T2 relaxation time. These changes were missing or less pronounced after treatment with a new type of electrical stimulation, which previously had proved effective in avoiding muscle atrophy. One month after denervation, there was a slight increase of signal intensity as well in the stimulated as in the untreated animals, after two months, however, the increase was statistically significant only in the non-stimulated muscles. T2 relaxation time showed a slight increase after one month of therapy, while there was a significant increase after one and two months without therapy. After 36 months of electrical stimulation, there was no increase of T2 at all. The results indicate 1), that MRI can be used when monitoring stimulation effects on denervated muscle, and 2), that, for this purpose, T2 relaxation time is more useful than signal intensity.

NIMG-53. RATIO OF T1-WEIGHTED TO T2-WEIGHTED SIGNAL INTENSITY AND IDH MUTATION IN GLIOMA

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi141-vi141
Author(s):  
Manabu Kinoshita ◽  
Masato Uchikoshi ◽  
Koji Takano ◽  
Mio Sakai ◽  
Hideyuki Arita ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Signal Intensity ◽  
Surrogate Marker ◽  
Radiological Feature ◽  
Lower Grade ◽  
Idh Mutation ◽  
T2 Relaxation Time ◽  
T2 Relaxation ◽  
Mutation Status ◽  
T1 And T2

Abstract INTRODUCTION Identifying IDH mutation status before treatment is essential for Lower-grade glioma (LrGG) treatment. We have previously revealed that IDH mutated LrGG consists of tumor tissues with significantly longer T1 and T2 relaxation time and is a useful radiological feature to identify IDH mutation status. The ratio of T1-weighted to T2-weighted signal intensity (rT1/T2) is a way to retrieve semi-quantitative relaxation time information of the tissue bypassing the need to perform relaxometry. This investigation aimed to elucidate the correlation between rT1/T2 and T1-, T2-relaxation time (-relax) in glioma tissue and to explore the possibility of rT1/T2 as a radiological surrogate marker to identify IDH mutation status in LrGG. MATERIALS AND METHODS We analyzed 8 LrGGs (IDHwt:4, IDHmt:2, IDHmt&1p19q-CODEL:2) in which relaxometry was performed. rT1/T2 maps were reconstructed as described in previous literature. Regions-of-interest were designed based on T2WI and FLAIR. The correlations between rT1/T2 and T1- and T2-relax were analyzed. Furthermore, We also investigated the correlation of IDH mutation status and rT1/T2. RESULTS 106,488 voxels were analyzed. The correlation between rT1/T2 and T1- and T2-relax were rT1/T2=1.6e-0.0003T1-relax and rT1/T2=1.2e-0.002T2-relax (R=0.77 and 0.70). rT1/T2 of IDH-wildtype tumor was significantly higher than that of IDH-mutant tumor (1.0 vs. 0.75, p< 0.0001). Voxel-wise analysis of rT1/T2 map was able to discriminate IDH-wildtype tumor from the mutant tumor with an AUC of 0.82. CONCLUSIONS rT1/T2, which can be calculated from MRI acquired during routine clinical practice, is a promising radiological surrogate marker to identify IDH mutation status in LrGG.

scholarly journals T1 and T2∗ relaxation time in the parcellated myocardium of healthy Taiwanese participants: A single center study

2020 ◽  
Author(s):  
Chih-Chien Tsai ◽  
Shu-Hang Ng ◽  
Yao-Liang Chen ◽  
Yu-Hsiang Juan ◽  
Chao-Hung Wang ◽  
...  
Keyword(s):  
Relaxation Time ◽  
T2 Relaxation Time ◽  
Single Center ◽  
T2 Relaxation ◽  
Single Center Study ◽  
T1 And T2 ◽  
Center Study

scholarly journals T2 Relaxation Time of Cartilage at MR Imaging: Comparison with Severity of Knee Osteoarthritis

Radiology ◽  
2004 ◽  
Vol 232 (2) ◽  
pp. 592-598 ◽  
Author(s):  
Timothy C. Dunn ◽  
Ying Lu ◽  
Hua Jin ◽  
Michael D. Ries ◽  
Sharmila Majumdar
Keyword(s):  
Relaxation Time ◽  
Mr Imaging ◽  
Knee Osteoarthritis ◽  
T2 Relaxation Time ◽  
T2 Relaxation

Textural and pore size analysis of carbonates from integrated core and nuclear magnetic resonance logging: An Arbuckle study

2015 ◽  
Vol 3 (1) ◽  
pp. SA77-SA89 ◽  
Author(s):  
John Doveton ◽  
Lynn Watney
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Pore Size ◽  
Relaxation Times ◽  
T2 Relaxation Time ◽  
T2 Relaxation ◽  
Nmr Logging ◽  
The Core ◽  
Nuclear Magnetic

The T2 relaxation times recorded by nuclear magnetic resonance (NMR) logging are measures of the ratio of the internal surface area to volume of the formation pore system. Although standard porosity logs are restricted to estimating the volume, the NMR log partitions the pore space as a spectrum of pore sizes. These logs have great potential to elucidate carbonate sequences, which can have single, double, or triple porosity systems and whose pores have a wide variety of sizes and shapes. Continuous coring and NMR logging was made of the Cambro-Ordovician Arbuckle saline aquifer in a proposed CO2 injection well in southern Kansas. The large data set gave a rare opportunity to compare the core textural descriptions to NMR T2 relaxation time signatures over an extensive interval. Geochemical logs provided useful elemental information to assess the potential role of paramagnetic components that affect surface relaxivity. Principal component analysis of the T2 relaxation time subdivided the spectrum into five distinctive pore-size classes. When the T2 distribution was allocated between grainstones, packstones, and mudstones, the interparticle porosity component of the spectrum takes a bimodal form that marks a distinction between grain-supported and mud-supported texture. This discrimination was also reflected by the computed gamma-ray log, which recorded contributions from potassium and thorium and therefore assessed clay content reflected by fast relaxation times. A megaporosity class was equated with T2 relaxation times summed from 1024 to 2048 ms bins, and the volumetric curve compared favorably with variation over a range of vug sizes observed in the core. The complementary link between grain textures and pore textures was fruitful in the development of geomodels that integrates geologic core observations with petrophysical log measurements.

T2* relaxation time in Achilles tendinosis and controls and its correlation with clinical score

2015 ◽  
Vol 43 (6) ◽  
pp. 1417-1422 ◽  
Author(s):  
Anna Gärdin ◽  
Pawel Rasinski ◽  
Johan Berglund ◽  
Adel Shalabi ◽  
Helene Schulte ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Clinical Score ◽  
T2 Relaxation Time ◽  
T2 Relaxation ◽  
Achilles Tendinosis

Proton MR Spectroscopy and MR Imaging in Acute and Chronic Multiple Sclerosis — Ringlike Appearances in Acute Plaques

1996 ◽  
Vol 37 (1P1) ◽  
pp. 278-287 ◽  
Author(s):  
A.-M. Landtblom ◽  
L. Sjöqvist ◽  
B. Söderfeldt ◽  
H. Nyland ◽  
K.-Å. Thuomas
Keyword(s):  
Multiple Sclerosis ◽  
Relaxation Time ◽  
Mr Imaging ◽  
Brain Lesions ◽  
T2 Relaxation Time ◽  
Healthy Individuals ◽  
T2 Relaxation ◽  
Proton Mrs ◽  
Proton Mr Spectroscopy ◽  
The Core

Purpose: We wanted to compare the metabolite status of brain lesions in different clinical subtypes of multiple sclerosis (MS). Two acute MS lesions with ringlike appearances were also investigated. Material and Methods: Twenty-three clinically stable MS patients, 2 patients with acute relapses, and 15 healthy individuals were examined by MR imaging and localized proton MRS. Results: No metabolite differences were seen in plaques of different subtypes. Decreased NAA/Cr and NAA/choline ratios as well as increased inositol/Cr ratios were observed in the plaques of the clinically stable or chronic active MS patients as compared with controls. The ring plaques had hyperintense cores with surrounding halos, separated from the cores by rings with low signal intensity in T2-weighted images. The core exhibited a prolonged T2 relaxation time. Proton spectra initially contained lactate. Conclusion: No differences between the metabolite status of nonacute plaques in different clinical subtypes could be detected. The ring plaques contained lactate signals indicating oedema, inflammation, and macrophage invasion, and may be transition forms between acute oedematous lesions and chronic demyelinated plaques.

scholarly journals Alterations in articular cartilage T2 star relaxation time following mechanical disorders: in vivo canine supraspinatus tendon resection models

2020 ◽  
Author(s):  
Dokwan Lee ◽  
Ki-Taek Hong ◽  
Tae Seong Lim ◽  
Eugene Lee ◽  
Ye Hyun Lee ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Articular Cartilage ◽  
Motion Tracking ◽  
Supraspinatus Tendon ◽  
Quantitative Mri ◽  
Joint Mechanics ◽  
T2 Relaxation Time ◽  
T2 Relaxation ◽  
Positive Correlations

Abstract Background: The role of altered joint mechanics on cartilage degeneration in in vivo models has not been studied successfully due to a lack of pre-injury information. We aimed 1) to develop an accurate in vivo canine model to measure the changes in joint loading and T2 star (T2*) relaxation time before and after unilateral supraspinatus tendon resections, and 2) to find the relationship between regional variations in articular cartilage loading patterns and T2* relaxation time distributions.Methods: Rigid markers were implanted in the scapula and humerus of tested dogs. The movement of the shoulder bones were measured by a motion tracking system during normal gaits. In vivo cartilage contact strain was measured by aligning 3D shoulder models with the motion tracking data. Articular cartilage T2* relaxation times were measured by quantitative MRI scans. Articular cartilage contact strain and T2* relaxation time were compared in the shoulders before and three months after the supraspinatus tendon resections.Results: Excellent accuracy and reproducibility were found in our in vivo contact strain measurements with less than 1% errors. Changes in articular cartilage contact strain exhibited similar patterns with the changes in the T2* relaxation time after resection surgeries. Regional changes in the articular cartilage T2* relaxation time exhibited positive correlations with regional contact strain variations three months after the supraspinatus resection surgeries.Conclusion: This is the first study to measure in vivo articular cartilage contact strains with high accuracy and reproducibility. Positive correlations between contact strain and T2* relaxation time suggest that the articular cartilage extracellular matrix may responds to mechanical changes in local areas.

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