Miscible Fluid Displacement in Rock Cores Evaluated with NMR T2 Relaxation Time Measurements

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.

Download Full-text

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

Journal of Magnetic Resonance Imaging ◽

10.1002/jmri.25104 ◽

2015 ◽

Vol 43 (6) ◽

pp. 1417-1422 ◽

Cited By ~ 9

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

Download Full-text

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

Acta Radiologica ◽

10.1177/02841851960371p160 ◽

1996 ◽

Vol 37 (1P1) ◽

pp. 278-287 ◽

Cited By ~ 7

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.

Download Full-text

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

10.21203/rs.3.rs-22995/v2 ◽

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.

Download Full-text

The Effect of Intraventricular Hemorrhage on Brain Development in Premature Infants: A Synthetic MRI Study

Frontiers in Neurology ◽

10.3389/fneur.2021.721312 ◽

2021 ◽

Vol 12 ◽

Author(s):

Chunxiang Zhang ◽

Xin Zhao ◽

Meiying Cheng ◽

Kaiyu Wang ◽

Xiaoan Zhang

Keyword(s):

Relaxation Time ◽

Premature Infants ◽

Intraventricular Hemorrhage ◽

Brain Volume ◽

Relaxation Times ◽

T2 Relaxation Time ◽

T2 Relaxation ◽

T1 And T2 ◽

The Brain ◽

Synthetic Mri

Objectives: Synthetic MRI can obtain multiple parameters in one scan, including T1 and T2 relaxation time, proton density (PD), brain volume, etc. This study aimed to investigate the parameter values T1 and T2 relaxation time, PD, and volume characteristics of intraventricular hemorrhage (IVH) newborn brain, and the ability of synthetic MRI parameters T1 and T2 relaxation time and PD to diagnose IVH.Materials and methods: The study included 50 premature babies scanned with conventional and synthetic MRI. Premature infants were allocated to the case group (n = 15) and NON IVH (n = 35). The T1, T2, PD values, and brain volume were obtained by synthetic MRI. Then we assessed the impact of IVH on these parameters.Results: In the posterior limbs of the internal capsule (PLIC), genu of the corpus callosum (GCC), central white matter (CWM), frontal white matter (FWM), and cerebellum (each p < 0.05), the T1 and T2 relaxation times of the IVH group were significantly prolonged. There were significant differences also in PD. The brain volume in many parts were also significantly reduced, which was best illustrated in gray matter (GM), cerebrospinal fluid and intracranial volume, and brain parenchymal fraction (BPF) (each p < 0.001, t = −5.232 to 4.596). The differential diagnosis ability of these quantitative values was found to be excellent in PLIC, CWM, and cerebellum (AUC 0.700–0.837, p < 0.05).Conclusion: The quantitative parameters of synthetic MRI show well the brain tissue characteristic values and brain volume changes of IVH premature infants. T1 and T2 relaxation times and PD contribute to the diagnosis and evaluation of IVH.

Download Full-text