scholarly journals Study on Magnetic Resonance Characteristics of Coal Sample under Progressive Loads

2020 ◽  
Vol 10 (18) ◽  
pp. 6526 ◽  
Author(s):  
Zhengzheng Xie ◽  
Nong Zhang ◽  
Jin Wang ◽  
Zhe Xiang ◽  
Chenghao Zhang
Keyword(s):  
Magnetic Resonance ◽  
Coal Sample ◽  
Distribution Curve ◽  
Transverse Relaxation Time ◽  
T2 Distribution ◽  
Supporting Pressure ◽  
Damage Degree ◽  
Significant Difference ◽  
Pressure Area ◽  
Elastic Stage

With the characteristics of gradual instability in the supporting pressure area of roadway as the engineering background, this paper aims to explore the evolution law of pore and fracture in the coal sample under progressive loads. The low-field nuclear magnetic resonance (NMR) test was designed and conducted with the coal sample under different axial loads (0, 3, 5, 7, 9, and 11 MPa). The characteristic parameters such as the porosity, the pore size distribution, the transverse relaxation time (T2) distribution curve, and the magnetic resonance image (MRI) were obtained. As the test results show, significant difference in the NMR characteristics of the coal samples can be observed throughout the compaction stage and the elastic stage. In the compaction stage, the porosity of the coal samples decreases slightly; the T2 distribution curve moves to the smaller value as a whole, and the percolation pore (PP) displays a tendency to transform to the adsorption pore (AP). In the elastic stage, the porosity of the coal samples rises gradually as the load increases; the T2 distribution curve moves to the larger value as a whole, and the AP tends to transform to the PP. The MRI shows that some pores and fissures in the coal sample close up and disappear as the load increases gradually, while the main pores and fissures expand and perforate till the macro failure occurs. Compared with one-time loading, the progressive multiple loads can ensure the fracture of the coal sample to develop more fully and the damage degree higher. It indirectly reflects that the instability and failure of the coal under the progressive load has the stage characteristics, verifying that the coal in the supporting pressure area needs to be controlled in advance.

scholarly journals Experimental Study on the Damage and Degradation Characteristics of Red Sandstone after Dry and Wet Cycling by Low Magnetic Field Nuclear Magnetic Resonance (NMR) Technique

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Yuan Zhao ◽  
Jiangteng Li ◽  
Gang Ma
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Distribution Curve ◽  
Maximum Increase ◽  
Continuous Increase ◽  
Red Sandstone ◽  
Damage Degree ◽  
Number Of Cycles ◽  
Wet And Dry Cycles ◽  
Nuclear Magnetic

To study the damage evolution of rocks under the action of wet and dry cycles, nuclear magnetic resonance (NMR) technology was used to test red sandstone under different times of wet and dry cycles. The T 2 spectral distribution curve, porosity, spectral peak area, and damage distribution curve of the rock were obtained, and the quantitative relationship between porosity, damage degree, and number of cycles was established. The results show that with the increase of the number of wet and dry cycles, the T 2 spectral curve of rock gradually moves to the right, but the moving amplitude gradually decreases. The porosity and spectral area increase with the increase of the number of wet and dry cycles, coupled with a declining growth rate, and the maximum increase in porosity is 18.789%. The damage degree of rock increase with the increase of the number of cycles, but with the continuous increase of the number of cycles, the damage rate decreases, and finally the damage degree of rock tends to be a constant value.

Effect of aerobic capacity on the T2 increase in exercised skeletal muscle

2001 ◽  
Vol 90 (3) ◽  
pp. 897-902 ◽  
Author(s):  
Robert W. Reid ◽  
Jeanne M. Foley ◽  
R. C. Jayaraman ◽  
Barry M. Prior ◽  
Ronald A. Meyer
Keyword(s):  
Magnetic Resonance ◽  
Aerobic Power ◽  
Human Subjects ◽  
Transverse Relaxation Time ◽  
Work Rate ◽  
Resonance Imaging ◽  
Transverse Relaxation ◽  
Sedentary Group ◽  
Significant Difference ◽  
Muscle Water

The increase in nuclear magnetic resonance transverse relaxation time (T2) of muscle water measured by magnetic resonance imaging after exercise has been correlated with work rate in human subjects. This study compared the T2 increase in thigh muscles of trained (cyclingV˙o 2 max = 54.4 ± 2.7 ml O2 · kg−1 · min−1, mean ± SE, n = 8, 4 female) vs. sedentary (31.7 ± 0.9 ml O2 · kg−1 · min−1, n = 8, 4 female) subjects after cycling exercise for 6 min at 50 and 90% of the subjects' individually determinedV˙o 2 max. There was no significant difference between groups in the T2 increase measured in quadriceps muscles within 3 min after the exercises, despite the fact that the absolute work rates were 60% higher in the trained group (253 ± 15 vs. 159 ± 21 W for the 90% exercise). In both groups, the increase in T2 of vastus muscles was twofold greater after the 90% exercise than after the 50% exercise. The recovery of T2 after the 90% exercise was significantly faster in vastus muscles of the trained compared with the sedentary group (mean recovery half-time 11.9 ± 1.2 vs. 23.3 ± 3.7 min). The results show that the increase in muscle T2varies with work rate relative to muscle maximum aerobic power, not with absolute work rate.

The Significant Difference with the Relationships of T2 and Moisture Distribution between Untreated and Esterified Poplar

2011 ◽  
Vol 704-705 ◽  
pp. 446-449
Author(s):  
Xiang Jun Wang ◽  
Ming Hui Zhang ◽  
Xi Ming Wang
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Moisture Content ◽  
Relaxation Times ◽  
Free Water ◽  
Transverse Relaxation Time ◽  
Moisture Distribution ◽  
Transverse Relaxation ◽  
Significant Difference

the moisture distribution in untreated and esterified poplar with Maleic anhydride was studied in the present paper employed nuclear magnetic resonance (NMR). The results show that relaxation times decrease with the the fall of moisture content, and there is a linear equation between the moisture content and transverse relaxation time in esterified wood. The content of bonding water and free water in the esterified wood decreased simultaneously during the drying.

scholarly journals Myocardial deformation in patients with a single left ventricle using 2D cardiovascular magnetic resonance feature tracking: a case–control study

2021 ◽  
Author(s):  
Fabian Strodka ◽  
Jana Logoteta ◽  
Roman Schuwerk ◽  
Mona Salehi Ravesh ◽  
Dominik Daniel Gabbert ◽  
...  
Keyword(s):  
Cardiovascular Magnetic Resonance ◽  
Magnetic Resonance ◽  
Left Ventricle ◽  
Feature Tracking ◽  
Systolic Function ◽  
Radial Strain ◽  
Left Ventricular ◽  
Lv Function ◽  
Significant Difference ◽  
Lv Volumes

AbstractVentricular dysfunction is a well-known complication in single ventricle patients in Fontan circulation. As studies exclusively examining patients with a single left ventricle (SLV) are sparse, we assessed left ventricular (LV) function in SLV patients by using 2D-cardiovascular magnetic resonance (CMR) feature tracking (2D-CMR-FT) and 2D-speckle tracking echocardiography (2D-STE). 54 SLV patients (11.4, 3.1–38.1 years) and 35 age-matched controls (12.3, 6.3–25.8 years) were included. LV global longitudinal, circumferential and radial strain (GLS, GCS, GRS) and strain rate (GLSR, GCSR, GRSR) were measured using 2D-CMR-FT. LV volumes, ejection fraction (LVEF) and mass were determined from short axis images. 2D-STE was applied in patients to measure peak systolic GLS and GLSR. In a subgroup analysis, we compared double inlet left ventricle (DILV) with tricuspid atresia (TA) patients. The population consisted of 19 DILV patients, 24 TA patients and 11 patients with diverse diagnoses. 52 patients were in NYHA class I and 2 patients were in class II. Most SLV patients had a normal systolic function but median LVEF in patients was lower compared to controls (55.6% vs. 61.2%, p = 0.0001). 2D-CMR-FT demonstrated reduced GLS, GCS and GCSR values in patients compared to controls. LVEF correlated with GS values in patients (p < 0.05). There was no significant difference between GLS values from 2D-CMR-FT and 2D-STE in the patient group. LVEF, LV volumes, GS and GSR (from 2D-CMR-FT) were not significantly different between DILV and TA patients. Although most SLV patients had a preserved EF derived by CMR, our results suggest that, LV deformation and function may behave differently in SLV patients compared to healthy subjects.

scholarly journals AB1093 INTEROBSERVER AGREEMENT IN MAGNETIC RESONANCE OF SACROILIAC JOINTS ABOUT ACTIVE SACROILIITIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1835.1-1836
Author(s):  
A. C. Genç ◽  
F. Turkoglu Genc ◽  
A. B. Kara ◽  
Z. Ozturk ◽  
D. Karatas ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Interobserver Agreement ◽  
Corporate Strategy ◽  
Axial Spondyloarthritis ◽  
Musculoskeletal Diseases ◽  
P Value ◽  
Mri Findings ◽  
Expert Radiologist ◽  
Significant Difference ◽  
Active Sacroiliitis

Background:Axial spondyloarthritis has characteristic clinical features such as enthesitis, sacroiliitis and spondylitis, and extra-articular manifestations(1). Magnetic resonance imaging (MRI) of sacroiliac (SI) joints is used to detect early sacroiliitis(2). Health institutions in our country carry out some of the radiology reporting services by outsourcing for reasons such as high cost and insufficient number of radiologists(3).Objectives:We decided to evaluate the interobserver agreement in active MRI findings of SI between radiologist of outsourcing radiology services and local/expert radiologist in musculoskeletal diseases.Methods:Between the years of 2015 and 2019, 8100 sacroiliac MRIs were taken at our center. The MRI of 1150 patients who were reported as active or chronic sacroiliitis from these sacroiliac MRIs or whose MRI was considered by the primary physician in favor of sacroiliitis was included in the study. Concordance between Evaluation and Service Procurement was examined using Kappa (k) coefficients. Mc Nemar test was used to compare the evaluation result between two observers. A p-value <0.05 was considered significant. Analyses were performed using commercial software (IBM SPSS Statistics, Version 23.0. Armonk, NY: IBM Corp.)Results:Of the 1150 patients examined in the study, 526 (45.7%) were male and 624 (54.3%) were female. The general average age is 37.20 ± 11.65 and the average age of men and women is 34.98 ± 11.19 and 39.07 ± 11.71 respectively. A statistically significant difference was found between the expert radiologists and outsourcing radiologist reports. In other words, a high level of compatibility was not found among the evaluators (p <0.001). When the consistency between expert radiologist and outsourced radiologist reports was examined, it was observed that there was a medium level of concordance (k = 0.589).Conclusion:The diagnosis of a spondyloarthropathy may be delayed for some reasons. In addition to the insidious course of the disease, being contented with an outsourced radiologist report may delay diagnosis. If the patient’s clinic and MRI report are not consistent, the patient should not be removed from follow-up.References:[1]Braun J. ‘Axial spondyloarthritis including ankylosing spondylitis’ Rheumatology (Oxford). 2018 1;57(suppl_6):vi1-vi3[2]Jans L, Egund N, Eshed I, Sudoł-Szopińska I, Jurik AG. Sacroiliitis in Axial Spondyloarthritis: Assessing Morphology and Activity. Semin Musculoskelet Radiol. 2018;22: 180–188.[3]Quélin B, Duhamel F. Bringing Together Strategic Outsourcing and Corporate Strategy: European Management Journal. 2003. pp. 647–661. doi:10.1016/s0263-2373(03)00113-0OUTSOURCING RADIOLOGIST REPORTSTOTALpNOT ACTIVE SACROILIITISACTIVE SACROILIITISEXPERT RADIOLOGIST REPORTSNOT ACTIVE SACROILIITIS508178686<0.0010.589ACTIVE SACROILIITIS59405464TOTAL5675831150Disclosure of Interests:None declared

scholarly journals Estimation of the permeability of hydrocarbon reservoir samples using induced polarization and nuclear magnetic resonance methods

Geophysics ◽  
2019 ◽  
Vol 84 (2) ◽  
pp. MR73-MR84 ◽  
Author(s):  
Fatemeh Razavirad ◽  
Myriam Schmutz ◽  
Andrew Binley
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Mechanistic Model ◽  
Transverse Relaxation Time ◽  
Induced Polarization ◽  
Permeability Model ◽  
Transverse Relaxation ◽  
Hydrocarbon Reservoir ◽  
Nuclear Magnetic

We have evaluated several published models using induced polarization (IP) and nuclear magnetic resonance (NMR) measurements for the estimation of permeability of hydrocarbon reservoir samples. IP and NMR measurements were made on 30 samples (clean sands and sandstones) from a Persian Gulf hydrocarbon reservoir. We assessed the applicability of a mechanistic IP-permeability model and an empirical IP-permeability model recently proposed. The mechanistic model results in a broader range of permeability estimates than those measured for sand samples, whereas the empirical model tends to overestimate the permeability of the samples that we tested. We also evaluated an NMR permeability prediction model that is based on porosity [Formula: see text] and the mean of the log transverse relaxation time ([Formula: see text]). This model provides reasonable permeability estimations for the clean sandstones that we tested but relies on calibrated parameters. We also examined an IP-NMR permeability model, which is based on the peak of the transverse relaxation time distribution, [Formula: see text] and the formation factor. This model consistently underestimates the permeability of the samples tested. We also evaluated a new model. This model estimates the permeability using the arithmetic mean of log transverse NMR relaxation time ([Formula: see text]) and diffusion coefficient of the pore fluid. Using this model, we improved estimates of permeability for sandstones and sand samples. This permeability model may offer a practical solution for geophysically derived estimates of permeability in the field, although testing on a larger database of clean granular materials is needed.

Pituitary volume in children with growth hormone deficiency, idiopathic short stature and controls

2016 ◽  
Vol 29 (10) ◽  
Author(s):  
Marion Kessler ◽  
Michael Tenner ◽  
Michael Frey ◽  
Richard Noto
Keyword(s):  
Growth Hormone ◽  
Magnetic Resonance ◽  
Growth Hormone Deficiency ◽  
Short Stature ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Magnetic Resonance Images ◽  
Idiopathic Short Stature ◽  
Hormone Deficiency ◽  
Significant Difference

AbstractBackground:The objective of the study was to describe the pituitary volume (PV) in pediatric patients with isolated growth hormone deficiency (IGHD), idiopathic short stature (ISS) and normal controls.Methods:Sixty-nine patients (57 male, 12 female), with a mean age of 11.9 (±2.0), were determined to have IGHD. ISS was identified in 29 patients (20 male, 9 female), with a mean age of 12.7 (±3.7). Sixty-six controls (28 female, 38 male), mean age 9.8 (±4.7) were also included. Three-dimensional (3D) magnetic resonance images with contrast were obtained to accurately measure PV.Results:There was a significant difference in the mean PV among the three groups. The IGHD patients had a mean PV 230.8 (±89.6), for ISS patients it was 286.8 (±108.2) and for controls it was 343.7 (±145.9) (p<0.001). There was a normal increase in PV with age in the ISS patients and controls, but a minimal increase in the IGHD patients.Conclusions:Those patients with isolated GHD have the greatest reduction in PV compared to controls and the patients with ISS fall in between. We speculate that a possible cause for the slowed growth in some ISS patients might be related to diminished chronic secretion of growth hormone over time, albeit having adequate pituitary reserves to respond acutely to GH stimulation. Thus, what was called neurosecretory GHD in the past, might, in some patients, be relative pituitary hypoplasia and resultant diminished growth hormone secretion. Thus, PV determinations by magnetic resonance imaging (MRI) could assist in the diagnostic evaluation of the slowly growing child.

scholarly journals Is Postural Control Different in Boys and Girls? Comparison Between Sex

2020 ◽  
Vol 27 (4) ◽  
pp. 385-391
Author(s):  
Jessica Caroliny de Jesus Neves ◽  
Aryane Karoline Vital Souza ◽  
Dirce Shizuko Fujisawa
Keyword(s):  
Physical Activity ◽  
Postural Control ◽  
Test Performance ◽  
Center Of Pressure ◽  
Cross Sectional Study ◽  
Lateral Velocity ◽  
Cross Sectional ◽  
Stage Of Development ◽  
Significant Difference ◽  
Pressure Area

ABSTRACT The purpose of this study was to compare the postural control between eight-year-old boys and girls, considering the nutritional classification and level of physical activity. This was a cross-sectional study, with a sample of 346 participants, classified by the WHO AnthroPlus software, evaluated on the force platform and the Questionnaire Physical Activity for Children. The results demonstrated that girls showed lower values in relation to the opposite sex (p<0.001), in the center of pressure area (COP) (girls: 11.88 vs boys: 15.86cm2), Antero-posterior Amplitude (girl: 5.40 vs boy: 6.05cm), Medial-lateral Amplitude (girl: 3.97 vs boy: 4.40cm), Antero-posterior velocity (girl: 3.98 vs boy: 4.94cm/s), Medial-lateral velocity (girl: 3.98 vs boy: 4.59cm/s), Antero-posterior frequency (girl: 0.70 vs boy: 0.84Hz). Physical activity was associated with male sex (p=0.001; X2=11.195; odds ratio=0.372). In relation to the center of pressure of sedentary children, girls showed better postural control (p<0.001), but when we analyzed the center of pressure of both sexes who were active there was no statistically significant difference (p=0.112). The Z score of both sexes presented no difference in the center of pressure area (p=0.809 and p=0.785 respectively). Girls showed better postural control, while boys are more active; when both sexes performed physical activity COP area was similar. Therefore, special care should be taken when assessing postural control in boys and girls due to their differences in test performance and stage of development. As for interventions, exercise should be considered for better performance of the COP.

scholarly journals Usefulness of Grayscale Values of Hypoechoic Lesions Matched with Target Lesions Observed on Magnetic Resonance Imaging for the Prediction of Clinically Significant Prostate Cancer

2021 ◽  
Author(s):  
Dong Gyun Kim ◽  
Jeong Woo Yoo ◽  
Kyo Chul Koo ◽  
Byung Ha Chung ◽  
Kwang Suk Lee
Keyword(s):  
Magnetic Resonance Imaging ◽  
Prostate Cancer ◽  
Magnetic Resonance ◽  
Area Under The Curve ◽  
Imaging Data ◽  
Resonance Imaging ◽  
Scoring Method ◽  
Significant Difference ◽  
Picture Archiving And Communication ◽  
Clinically Significant

Abstract INTRODUCTION: To analyze grayscale values for hypoechoic lesions matched with target lesions evaluated using prebiopsy magnetic resonance imaging (MRI). METHODS We collected data on 420 target lesions in patients who underwent MRI/transrectal ultrasound fusion biopsies. Images of hypoechoic lesions that matched the target lesions on MRI were stored in a picture archiving and communication system, and their grayscale values were estimated using the red/green/blue scoring method through an embedded function. We analyzed imaging data using grayscale values. RESULTS Of the 420 lesions, 261 (62.1%) were prostate cancer lesions. Grayscale ranges (42.6–91.8) were significant predictors of clinically significant prostate cancer (csPC) in multivariable logistic regression analyses. Area under the curve for detecting csPC using grayscale values along with conventional variables was 0.839, which was significantly higher than that for detecting csPC using only conventional variables (0.828; p = 0.036). Subgroup analysis revealed a significant difference for PI-RADS 3 lesions between grayscale values for benign and cancerous lesions (p = 0.008). Grayscale values were the only significant predictive factor (p = 0.005) for csPC. CONCLUSIONS Distribution of grayscale values according to PI-RAD 3 scores was useful, and the grayscale range (42.6–91.8) was an important factor for csPC diagnosis.

scholarly journals Agreement of Magnetic Resonance Imaging With Computed Tomography in the Assessment for Acute Skull Fractures in a Canine and Feline Cadaver Model

2021 ◽  
Vol 8 ◽  
Author(s):  
Silke Hecht ◽  
Kimberly M. Anderson ◽  
Aude Castel ◽  
John F. Griffin ◽  
Adrien-Maxence Hespel ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Computed Tomography ◽  
Magnetic Resonance ◽  
Head Trauma ◽  
Imaging Modality ◽  
Small Animal ◽  
Skull Fractures ◽  
Resonance Imaging ◽  
Significant Difference ◽  
Mri Sequences

Computed tomography (CT) is the imaging modality of choice to evaluate patients with acute head trauma. However, magnetic resonance imaging (MRI) may be chosen in select cases. The objectives of this study were to evaluate the agreement of MRI with CT in the assessment for presence or absence of acute skull fractures in a canine and feline cadaver model, compare seven different MRI sequences (T1-W, T2-W, T2-FLAIR, PD-W, T2*-W, “SPACE” and “VIBE”), and determine agreement of four different MRI readers with CT data. Pre- and post-trauma CT and MRI studies were performed on 10 canine and 10 feline cadaver heads. Agreement of MRI with CT as to presence or absence of a fracture was determined for 26 individual osseous structures and four anatomic regions (cranium, face, skull base, temporomandibular joint). Overall, there was 93.5% agreement in assessing a fracture as present or absent between MRI and CT, with a significant difference between the pre and post trauma studies (99.4 vs. 87.6%; p &lt; 0.0001; OR 0.042; 95% CI 0.034–0.052). There was no significant difference between dogs and cats. The agreement for the different MRI sequences with CT ranged from 92.6% (T2*-W) to 94.4% (PD-W). There was higher agreement of MRI with CT in the evaluation for fractures of the face than other anatomic regions. Agreement with CT for individual MRI readers ranged from 92.6 to 94.7%. A PD-W sequence should be added to the MR protocol when evaluating the small animal head trauma patient.

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