T1 T2 Mapping Research Articles

Integrated Reservoir Characterization Using Unsupervised Learning on Nuclear Magnetic Resonance (NMR) T1-T2 Logs

A novel interpretation workflow was developed using an automated unsupervised learning algorithm on nuclear magnetic resonance (NMR) T1-T2 log data to quantify fluid-filled porosity and saturation, producible oil volumes, and to characterize matrix pore sizes and formation wettability. Core porosity and saturation measurements, scanning electron microscope images (SEM), Rock-Eval pyrolysis, wettability measurements, and mercury injection capillary pressure (MICP) tests are compared with the NMR interpretation for calibration and validation. Understanding in-situ fluid types and volumetrics is key for reservoir characterization. The traditional static formation evaluation model based on triple-combo logs (density, neutron, resistivity, and gamma ray) has been widely used to characterize formations to provide cost-effective answers of lithology, total porosity, and water saturation. Nevertheless, the dynamic result from production often shows quite a different water cut than total water saturation because the static model cannot distinguish immobile hydrocarbons from producible oil. NMR log data show unique signatures of formation fluids, such as gas, immobile hydrocarbon, producible oil, T1-T2 immobile, and free water. The NMR data also provide a method to interpret fluid and matrix properties, including fluid viscosity, pore geometry, and fluid-pore interaction. However, due to the downhole environment and the resolution limitation of the logging tool, the signatures of the fluids are not always well separated. It is challenging to visually separate the signal contributions of different formation fluids on T1-T2 maps. An automated unsupervised learning algorithm based on non-negative matrix factorization (NMF) and hierarchical clustering (Venkataramanan et al., 2018) is implemented in the new workflow to separate T1-T2 signatures of different pore fluids, enabling fluid typing and providing quantitative fluid-filled porosities and associated saturations. T1-T2 signatures of separated fluids are used to characterize fluid mobility, pore sizes, and formation wettability. The new approach is successfully applied to multiple wells for a field case study to characterize the saturation and producibility of hydrocarbon and water, which routine petrophysical models are unable to distinguish. Results are corroborated with dynamic production data showing high free water and high residual oil. This is also validated by routine and special core analyses. Integration of NMR, MICP, and SEM gives pore-body and pore-throat-size distributions with body-to-throat ratio (BTR), increasing the precision of estimated formation permeability. A high T1/T2 ratio of the oil suggests that the formation is partially oil-wet. The wettability results from NMR are consistent with the core wettability test and production results. Understanding which portion of a reservoir contains mobile fluids impacts target zone selection and reserves estimation.

Determination of in situ hydrocarbon contents in shale oil plays. Part 1: Is routine Rock–Eval analysis reliable for quantifying the hydrocarbon contents of preserved shale cores?

An accurate determination of in situ hydrocarbon (oil) content is critical for the assessment of shale oil plays in terms of their total resources in place and recovery potential. Although correction of light hydrocarbon loss to the Rock–Eval S1 parameters on conventional core and cuttings samples has been recently attempted using preserved (e.g., sealed or pressure–preserved) cores, hydrocarbon evaporation loss during sample preparation and delay time before the actual commencement of Rock–Eval analysis has not received sufficient attention. In this study, a combination of petrophysical and geochemical techniques including Dean–Stark extraction, hydrogen nuclear magnetic resonance (1H-NMR) T1-T2 mapping, thermal desorption–gas chromatography (TD–GC) analysis, and Rock–Eval programmed pyrolysis were used in parallel on a set of 30 preserved shale cores to determine their total hydrocarbon contents. The preserved shale cores were analyzed in large pieces (e.g., 3–5 cm in size) by the former two petrophysical methods while using fine powder (e.g., <60 mesh) by the latter two thermal analytical methods. The total free hydrocarbon contents (equivalent of Rock–Eval S1) determined on the studied lacustrine shale samples with a Ro ranging from 1.00% to 1.51% followed the order of Dean–Stark (average 10.27 mg/g) ≈ NMR (10.34) ＞ TD–GC (6.65) ＞ Rock–Eval (3.93). The core crushing and grinding process required for both TD-GC and Rock–Eval pyrolysis analyses was found to cause a loss of approximately 35% to the in situ hydrocarbons. In addition, Rock–Eval analysis delay time (of 5 min) could lead to another 25% reduction to the total free hydrocarbons. In combination, sample preparation and analysis delay resulted in up to 60% reduction to the Rock–Eval S1 peaks for the preserved shale cores, and a 30% loss to the liquid (C6+) hydrocarbons in particular. To the best of our knowledge, this is the first reported observation that in situ light hydrocarbon contents can be severely underestimated by Rock–Eval and TD–GC analyses using powdered forms of preserved core samples. The extents of light hydrocarbon loss in conventional cores have been underestimated using the Rock–Eval S1 difference between preserved shale and its long–duration exposed replicates. Hence, when quantifying the hydrocarbon contents of the preserved shale samples, techniques utilizing larger rock pieces are highly recommended.

Development of an NMR workflow for determining nano-petrophysical properties of marine and lacustrine mudrocks

Nuclear Magnetic Resonance (NMR) is a powerful method of pore structure and fluids characterization for a wide range of porous media due to its fast and non-destructive capabilities, but its utilities of nano-petrophysics (the properties of rocks and fluids, as well as their interactions, in the presence of predominantly nm-sized pores) for tight oil formations warrant more studies. In this work, a total of four cylindrically-shaped tight reservoir samples at 2.54 cm in diameter with four different lithologies in USA and China were selected for systematic NMR analyses with T2 relaxation time, T1-T2 mapping, NMR cryoporometry (NMRc), and magnetic resonance imaging (MRI) techniques, along with other supplemental tests of X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and vacuum-assisted water immersion porosimetry (WIP), to characterize their petrophysical properties. The results show that the effective porosity obtained from NMR was highly consistent with WIP. Three samples characterized by MRI showed that T2 spectra had a good response to the fluid distribution in the samples. In this study, T2 time was converted into the pore size by combining corrected NMR T2 spectrum and MIP pore-throat size distribution. Finally, The Katz-Thompson model was applied for NMR data to calculate the permeability at different inflection points (connected pore networks) to quantitatively evaluate their individual permeabilities and porosities. Furthermore, except for sample N9 (carbonate-rich Wolfcamp A mudrock), a satisfactory agreement was achieved between the results of K2C (cut-off time at the second inflection point) and helium method for permeability analyses.

A phase I/IIa clinical trial of third-generation autologous chondrocyte implantation (IK-01) for focal cartilage injury of the knee

Background/objectiveThe purpose of this study was to report the outcomes of a clinical trial conducted in Japan to assess the safety and effectiveness of third-generation autologous chondrocyte implantation (ACI) using IK-01 (CaReS™), which does not require flap coverage, in the treatment of patients with focal cartilage injury of the knee. MethodsThis was an open label, exploratory clinical trial. Patients were enrolled between June 2012 and September 2016. The primary endpoint of the study was the International Knee Documentation Committee (IKDC) score at 52 weeks after implantation. The IKDC, Lysholm, and visual analog scale (VAS) scores were evaluated at the time of screening and at 4, 12, 24, 36, and 52 weeks after implantation. Improvements from the baseline scores were evaluated using the equation “(postoperative score) − (preoperative score).” Magnetic resonance imaging (MRI) was performed at 2, 12, 24, and 52 weeks after implantation, and MRI measurements were evaluated using T1 rho and T2 mapping. ResultsNine patients were enrolled in this study and were examined for safety. Product quality did not satisfy the specification in one patient, and bacterial joint infection occurred in one patient. As a result, seven patients were included in the outcome analyses. The mean IKDC score significantly improved from 36.4 preoperatively to 74.1% at 52 weeks after implantation (p < 0.0001). The mean Lysholm and VAS scores also significantly improved from 39.6 to 57.4 to 89.6 and 22.9, respectively, after surgery. In the MRI evaluation, the T1 rho and T2 values of the implanted area were similar to those of the surrounding cartilage at 52 weeks after implantation. ConclusionsThird generation ACI (IK-01) can be an effective treatment option for focal cartilage defects of the knee; however, surgeons must pay careful attention to the risk of postoperative joint infection.

Simultaneous Multi-Slice Cardiac MR Multitasking for Motion-Resolved, Non-ECG, Free-Breathing T1-T2 Mapping.

The aim of this study is to simultaneously quantify T1/T2 across three slices of the left-ventricular myocardium without breath-holds or ECG monitoring, all within a 3 min scan. Radial simultaneous multi-slice (SMS) encoding, self-gating, and image reconstruction was incorporated into the cardiovascular magnetic resonance (CMR) Multitasking framework to simultaneously image three short-axis slices. A T2prep-IR FLASH sequence with two flip angles was designed and implemented to allow B1+-robust T1 and T2 mapping. The proposed Multitasking-SMS method was validated in a standardized phantom and 10 healthy volunteers, comparing T1 and T2 measurements and scan-rescan repeatability against corresponding reference methods in one layer of phantom vials and in 16 American Heart Association (AHA) myocardial segments. In phantom, Multitasking-SMS T1/T2 measurements showed substantial correlation (R2 > 0.996) and excellent agreement [intraclass correlation coefficients (ICC) ≥ 0.999)] with reference measurements. In healthy volunteers, Multitasking-SMS T1/T2 maps reported similar myocardial T1/T2 values (1,215 ± 91.0/41.5 ± 6.3 ms) to the reference myocardial T1/T2 values (1,239 ± 67.5/42.7 ± 4.1 ms), with P = 0.347 and P = 0.296, respectively. Bland–Altman analyses also demonstrated good in vivo repeatability in both the multitasking and references, with segment-wise coefficients of variation of 4.7% (multitasking T1), 8.9% (multitasking T2), 2.4% [modified look-locker inversion recovery (MOLLI)], and 4.6% (T2-prep FLASH), respectively. In summary, multitasking-SMS is feasible for free-breathing, non-ECG, myocardial T1/T2 quantification in 16 AHA segments over 3 short-axis slices in 3 min. The method shows the great potential for reducing exam time for quantitative CMR without ECG or breath-holds.

Simple parameters of synthetic MRI for assessment of bone density in patients with spinal degenerative disease.

Good bone quality is the key to avoiding osteoporotic fragility fractures and poor outcomes after lumbar instrumentation and fusion surgery. Although dual-energy x-ray absorptiometry (DEXA) screening is the current standard for evaluating osteoporosis, many patients lack DEXA measurements before undergoing lumbar spine surgery. The present study aimed to investigate the utility of using simple quantitative parameters generated with novel synthetic MRI to evaluate bone quality, as well as the correlations of these parameters with DEXA measurements. This prospective study enrolled patients with symptomatic lumbar degenerative disease who underwent DEXA and conventional and synthetic MRI. The quantitative parameters generated with synthetic MRI were T1 map, T2 map, T1 intensity, proton density (PD), and vertebral bone quality (VBQ) score, and these parameters were correlated with T-score of the lumbar spine. There were 62 patients and 238 lumbar segments eligible for analysis. PD and VBQ score moderately correlated with T-score of the lumbar spine (r = -0.565 and -0.651, respectively; both p < 0.001). T1 intensity correlated fairly well with T-score (r = -0.411, p < 0.001). T1 and T2 correlated poorly with T-score. Receiver operating characteristic curve analysis demonstrated area under the curve values of 0.808 and 0.794 for detecting osteopenia/osteoporosis (T-score ≤ -1.0) and osteoporosis (T-score ≤ -2.5) with PD (both p < 0.001). PD and T1 intensity values generated with synthetic MRI demonstrated significant correlation with T-score. PD has excellent ability for predicting osteoporosis and osteopenia.

Segmental analysis of microvascular dysfunction and tissue characterization in hypertrophic cardiomyopathy by magnetic resonance imaging

Abstract Funding Acknowledgements Type of funding sources: None. Background While left ventricular hypertrophy (LVH) and myocardial fibrosis are frequently evaluated in hypertrophic cardiomyopathy (HCM), microvascular dysfunction is often overlooked. The aim of this study was to assess the association between wall thickness, microvascular dysfunction and tissue characteristics in HCM patients (P), comparing individual myocardial segments. Methods Prospective evaluation of adult P with HCM (P with "end-stage" HCM, prior septal reduction therapy or epicardial coronary artery disease were excluded). All underwent a cardiac magnetic resonance (CMR) protocol (1.5-T), from which the following parameters were analysed: maximal LV wall thickness (MLVWT), T1 and T2 mapping, extracellular volume (ECV), late gadolinium enhancement (LGE) and stress perfusion. Results were stratified according to the 16 American Heart Association segments. Multivariate regression analyses for perfusion defects and tissue characteristics were performed. Results 75 P (total of 1200 myocardial segments analysed), 63% male, mean age 55 ± 15 years, MLVWT of 20 ± 4.5mm (61% asymmetric septal LVH, 29% apical LVH and 8% concentric LVH). 28% presented LV outflow tract obstruction. MLVWT was greater in the basal and mid septum (table 1). Among the 424 segments (35.3%) with a perfusion defect, 286 (23.8%) had a defect only in the endocardial layer and 138 (11.5%) in both endocardial and epicardial layers with defects more often detected in hypertrophied segments. This association was verified in segments with MLVWT 12-14mm and MLVWT ≥15mm (OR 7.83, 95% CI 5.75-10.67, p &amp;lt; 0.001) (table 2). Among the 660 segments with normal MLVWT (≤11mm), 123 (19%) presented perfusion defects. A perfusion defect was more frequent in segments of obstructive HCM P (OR 1.48, 95% CI 1.13-1.92, p = 0.004). Microvascular dysfunction was associated with changes in tissue characteristics. For the same thickness, segments with perfusion defects had a higher T1 mapping (β-estimate 20.91, 95% CI 16.87-24.96, p &amp;lt; 0.001) and T2 mapping mean values than those without. Furthermore, regardless of MLVWT, segments with perfusion defects had LGE more often (OR 4.16, 95% CI 3.19-5.41, p &amp;lt; 0.001) and a higher ECV. On the other hand, among the 424 segments with a perfusion defect, 115 (27%) did not present LGE. MLVWT was associated with tissue characteristics. Comparing to non-hypertrophied segments, T1 mapping mean value was higher in segments with MLVWT 12-14mm and with ≥15mm (β-estimate 37.71, 95% CI 31.2-44.21, p &amp;lt; 0.001). Segments with MLVWT ≥15mm showed a significantly superior ECV mean value comparing to non-hypertrophied segments. LGE was more frequent in the more hypertrophied segments: MLVWT 12-14mm and ≥15mm (OR 9.02, 95% CI 6.42-12.67, p &amp;lt; 0.001) (Table 2). Conclusion Microvascular dysfunction is more prevalent in obstructive HCM, particularly in the more hypertrophied segments. The presence of microvascular dysfunction is associated with diffuse tissue abnormalities and replacement fibrosis. Abstract Table 1: Characteristics of AHA segments Abstract Table 2: Multivariable analyses

The diagnostic value of quantitative imaging for acute myocardial infarction

To explore the diagnostic performance of cardiac magnetic resonance imaging (CMR) with T1 mapping and T2 mapping for detection of acute phase of ischemic cardiomyopathy. Twenty-four patients with acute myocardial infarction (AMI) detected by coronary angiography from May 2020 to April 2021 in Tianjin First Center Hospital were selected. All patients underwent CMR (Philips Ingenia 3.0-T) at (9±4) days after definite diagnosis, which was defined as the first diagnosis. After 3 months and 6 months of chronic myocardial infarction (CMI) phase, one CMR was performed. On the same period with age and sex matching, a total of 26 cases of healthy volunteers and outpatient with non-specific chest pain and CMR examination without abnormality as control group. Plain scan included Cine, T2-weighted (STIR), and native T1/T2 mapping. The enhanced scan included perfusion, late gadolinium enhancement, post-T1 mapping. The changes of myocardial quantitative parameters before and after myocardial infarction were compared. Receiver operator characteristic curves (ROC curve) were developed to evaluate, compare, and distinguish the changes in the AMI group and the CMI group after 6 months. Pre-enhanced T1 value, T2 value and extracellular volume (ECV) of AMI group were significantly higher than those of control group [pre-enhanced T1 value (ms): 1 438.7±173.4 vs. 1 269.2±42.3, pre-enhanced T2 value (ms): 49.8±9.3 vs. 21.7±4.0 , ECV (%): 33.2±10.2 vs. 27.2±2.1, all P < 0.05]. ECV was significantly higher in AMI (%: 33.2±10.2 vs. 27.2±2.1), but stabilized after 3 months (%: 33.2±10.2 vs. 32.4±5.1), and after 6 months later (%: 27.7±4.9 vs. 32.4±5.1), there were no significant difference (all P > 0.05). Pre-enhanced T1 and T2 values were significantly higher in AMI, lower after 3 months, but significantly decreased after 6 months [pre-enhanced T1 values (ms): 1 438.7±173.4 vs. 1 272.1±25.2, pre-enhanced T2 values (ms): 49.8±9.3 vs. 29.0±4.0, all P < 0.05]. The ROC curve showed that the specificity of pre-enhanced T1 and T2 values between AMI and CMI were 100%, and the sensitivity were 72.7%, 100%, respectively, pre-enhanced T1 and T2 value could be better distinguish between AMI and CMI diagnosis method. T1 mapping and T2 mapping with ECV can clearly diagnosis ischemic cardiomyopathy, especially pre-enhanced myocardial T1 and T2 values which is non-invasive diagnosis method of AMI, and can distinguish AMI or CMI, has a great significance to the patient's clinical treatment and follow-up.

A Radiomic MRI based Nomogram for Prediction of Heart Failure with Preserved Ejection Fraction in Systemic Lupus Erythematosus Patients: Insights From a Three-Center Prospective Study.

Myocardial T1 and extracellular volume (ECV) fraction values have important roles in the prognostication of heart failure with preserved ejection fraction (HFpEF). However, the traditional mean quantification of intensity levels is not sufficient. To evaluate a T1 map-based radiomic nomogram as a long-term prognosticator for HFpEF in systemic lupus erythematosus (SLE) patients. Prospective. A total of 115 SLE patients and 50 age- and gender-matched controls. A 3.0T scanner; cine imaging, precontrast and post-contrast T1 mapping and T2 mapping sequences. A radiomic nomogram was developed based on precontrast T1 mapping. Three independent readers assessed and compared the ECV value and the value of the radiomic nomogram for predicting HFpEF in SLE patients. Cox proportional hazard models, Youden index for determining cut-off values for high HFpEF risk vs. low HFpEF risk classification, Kaplan-Meier analysis, intraclass correlation (ICC), and Uno C statistic test. During a median follow-up of 27 (interquartile range, 19-37) months, 31 SLE patients developed HFpEF. Patients with elevated ECV (≥31%) and a higher output (≥42.7) from the radiomic feature "S_33_sum average" of the precontrast T1 map had a significantly higher risk of developing HFpEF than those who had lower ECV (<31%) and an output <42.7. Patients with a higher "S_33_sum average" value on precontrast T1 map had a significantly increased risk for HFpEF (hazard ratio, 1.363, 95% CI, 1.130-1.645), after adjusting for covariates including ECV and LVEF. Finally, "S_33_sum average" from precontrast T1 mapping had modest but significantly incremental prognostic value over the mean ECV value (Uno C statistic comparing models, 0.860 vs. 0.835). The precontrast T1 map-based radiomic nomogram, as a measure of diffuse myocardial fibrosis was associated with HFpEF and provided modest prognostic value for predicting HFpEF in SLE patients. 1 TECHNICAL EFFICACY: Stage 2.

Water Occurrence Characteristics of Gas Shale Based on 2D NMR Technology

Determination of water occurrence in gas shale reservoirs is vital for understanding the gas storage and migration behavior. Clay, kerogen, and shale samples with different water contents were analyzed based on the 2D NMR technology to decipher the characteristic of water occurrence in different shale compositions. By establishing a new classification method of water in shale, the water absorption characteristics of shale during hydraulic fracturing and the law of water mobilization in shale reservoirs during development are quantitatively analyzed. The results suggest that the water in shale can be classified as mobile water and immobile water, with the boundary T1 = 0.1 ms. The mobile water can be further divided into clay bound water, capillary bound water, and free water by the T1–T2 map. Most of the water in shale is clay bound water, which is also the most important object in the study of fracturing fluid retention. The influence of free water and clay bound water on the gas–water two-phase flow of shale is greater. Accurate analysis of different types of water in shale can clarify their different effects on methane occurrence and migration. This study overcomes the shortcomings of inaccurate quantitative analysis of water in shale by traditional methods and provides help for the analysis of fracturing fluid retention law and the development effect of gas wells.

OD131 - Implementation of T1-T2 mapping quality assurance in cardiovascular magnetic resonance

OD131 - Implementation of T1-T2 mapping quality assurance in cardiovascular magnetic resonance

Multiparametric Cardiovascular Magnetic Resonance in Acute Myocarditis: Comparison of 2009 and 2018 Lake Louise Criteria With Endomyocardial Biopsy Confirmation.

Background: Cardiac magnetic resonance (CMR) has been shown to improve the diagnosis of myocarditis, but no systematic comparison of this technique is currently available. The purpose of this study was to compare the 2009 and 2018 Lake Louise Criteria (LLC) for the diagnosis of acute myocarditis using 3.0 T MRI with endomyocardial biopsy (EMB) as a reference and to provide the cutoff values for multiparametric CMR techniques.Methods: A total of 73 patients (32 ± 14 years, 71.2% men) with clinically suspected myocarditis undergoing EMB and CMR with 3.0 T were enrolled in the study. Patients were divided into two groups according to EMB results (EMB-positive and -negative groups). The CMR protocol consisted of cine-SSFP, T2 STIR, T2 mapping, early and late gadolinium enhancement (EGE, LGE), and pre- and post-contrast T1 mapping. Their potential diagnostic ability was assessed with receiver operating characteristic curves.Results: The myocardial T1 and T2 relaxation times were significantly higher in the EMB-positive group than in the EMB-negative group. Optimal cutoff values were 1,228 ms for T1 relaxation times and 58.5 ms for T2 relaxation times with sensitivities of 86.0 and 83.7% and specificities of 93.3 and 93.3%, respectively. The 2018 LLC had a better diagnostic performance than the 2009 LLC in terms of sensitivity, specificity, positive predictive value, and negative predictive value. T1 mapping + T2 mapping had the largest area under the curve (0.95) compared to other single or combined parameters (2018 LLC: 0.91; 2009 LLC: 0.76; T2 ratio: 0.71; EGEr: 0.67; LGE: 0.73; ). The diagnostic accuracy for the 2018 LLC was the highest (91.8%), followed by T1 mapping (89.0%) and T2 mapping (87.7%).Conclusion: Emerging technologies such as T1/ T2 mapping have significantly improved the diagnostic performance of CMR for the diagnosis of acute myocarditis. The 2018 LLC provided the overall best diagnostic performance in acute myocarditis compared to other single standard CMR parameters or combined parameters. There was no significant gain when 2018LLC is combined with the EGE sequence.

Experimental Investigation of Solid Organic Matter with a 2D NMR T1–T2 Map

Experimental Investigation of Solid Organic Matter with a 2D NMR <i>T</i>₁–<i>T</i>₂ Map

Technology Focus: Formation Evaluation (August 2021)

Leading into the third quarter of this year, I am honored to be able to highlight and share three impactful SPE papers that demonstrate integration at its best. In reviewing the papers, five main technical themes emerged. These include * Machine learning and artificial intelligence as applied to formation evaluation * Production analysis methodologies and their effect on understanding rock characterization and behavior * Subsurface characterization primarily focused on rock typing and permeability * Tool advancements (openhole, cased-hole, or laboratory-based tools) * Subsurface-to-production integration across subdisciplines (e.g., geology, geochemistry, petrophysics, and engineering) The latter is the common thread between the three papers recommended and discussed here. In this new decade, the prevalence of integration is at the forefront of the scientific community. Every discipline, scientist, or company has a way in which they define the term “integration.” Regardless of how you define the effort that links disciplines quantitatively, the importance of constraining subsurface characterization to link it to production results and drive toward a predictive model is a critical accomplishment for our industry. As such, I’d like to highlight three papers in this feature (OTC 30644, SPE 201417, and SPE 202683) and the knowledge and workflow applications they define and demonstrate. Sharing these integrated work flows with the community aids in teaching and leads to best-practice components of integrative studies. These efforts also share and demonstrate how to bridge the gap between in-situ characterization and wellhead performance prediction and results—in other words, the static-to-dynamic link between rock and fluid properties as quantified and how they will inevitably produce hydrocarbon through the rock and fluid interactions. Recommended additional reading at OnePetro: www.onepetro.org. SPE 201334 Combined Experimental and Well-Log Evaluation of Anisotropic Mechanical Properties of Shales: An Application to Wellbore Stability in the Bakken Formation by Saeed Rafieepour, The University of Tulsa, et al. SPE 201486 A New Safe and Cost-Effective Approach to Large-Scale Formation Testing by Fluid Injection on a Wireline Formation Tester by Christopher Michael Jones, Halliburton, et al. SPE 201735 Integrated Reservoir Characterization With Spectroscopy, Dielectric, and Nuclear Magnetic Resonance T1-T2 Maps in a Freshwater Environment: Case Studies From Alaska by ZhanGuo Shi, Schlumberger, et al.

Staging Liver Fibrosis: Comparison of Native T1 Mapping, T2 Mapping, and T1ρ: An Experimental Study in Rats With Bile Duct Ligation and Carbon Tetrachloride at 11.7T MRI.

T1, T2, and T1ρ might be potential biomarkers for assessing liver fibrosis. However, few studies reported the value of them in different animal models. To investigate and compare the performances of T1, T2, and T1ρ for noninvasively staging liver fibrosis in bile duct ligation (BDL) or carbon tetrachloride (CCl4 ) model. Prospective animal model. Liver fibrosis was induced by BDL or injection of CCl4 in 120 rats. 11.7T, T1 mapping with 10 repetition times, T2 mapping with 32 echo times, and T1ρ with 10 spin-lock times. T1, T2, and T1ρ were measured and correlated with liver fibrosis stages, as well as the degree of inflammation, steatosis, iron deposition, and the expression of cytokeratin 19. The discriminative performance of T1, T2, and T1ρ for staging liver fibrosis was compared. One-way analysis of variance (ANOVA), Spearman's correlation analysis, factorial design ANOVA, and receiver operating characteristic curves (P < 0.05 was considered statistically significant). T1, T2, and T1ρ (BDL: rho=0.73, 0.85, 0.68; CCl4 : rho=0.80, 0.29, 0.61) were significantly correlated with liver fibrosis stages, while there was no significant difference in T2 among stage F0-F4 in the CCl4 model (P=0.204). The area under the curves (AUCs) range of T1, T2, and T1ρ for predicting ≥F1, ≥F2, ≥F3, and F4 were 0.76-0.95, 0.89-0.98, and 0.80-0.94 in the CCl4 model. For the CCl4 model, the AUCs range of T1, T2, and T1ρ for predicting ≥F1, ≥F2, ≥F3, and F4 were 0.83-0.95, 0.61-0.74, and 0.73-0.89, respectively. T2 had significantly higher AUC in the BDL model than CCl4 model for diagnosing liver fibrosis. The most sensitive and accurate method for staging liver fibrosis appeared to be T1 in our animal models followed by T1ρ. T2 may not be suitable for evaluating liver fibrosis. 1 TECHNICAL EFFICACY STAGE: 2.

NMR relaxometry interpretation of source rock liquid saturation — A holistic approach

Fluid types and saturation are essential factors in assessing oil recovery resources and potential in organic-rich mudstones. One of the methods for analyzing tight rocks' saturation is low-field nuclear magnetic relaxometry (NMR). Interpretation of NMR results, particularly the data of T1-T2 maps, delivers different fluid saturation and estimates hydrogen populations. Although previous research proposed a qualitative interpretation of T1-T2 distributions, there is still no obvious scheme that can be directly applied in routine petrophysical studies. However, current NMR-based workflows and manual interpretation routines are subjective and laborious. We attempt to fill this gap by identifying the best interpretation scheme for three distinct types of organic-rich source rock of the Bazhenov formation and modifying a well-known T1-T2 map interpretation scheme. Experimental results include NMR 2-MHz T1-T2 datasets (original and differential maps for samples in as-received, dried, and saturated states) with the corresponding Rock-Eval pyrolysis parameters and mineral composition from X-ray diffraction. The analytical part compares the existing schemes and modifies the interpretation scheme based on the rock petrophysical background. The paper reviews the features of the manual interpretation and previously established schemes and proposes a modified scheme best fitted to the petrophysical and geochemical data. In addition, we study the impact of mineral composition and geochemical properties on T1-T2 signal interpretation and analyze cross-correlations. The study confirms the presence of a significant amount of clay-bound water from a detailed analysis of the corresponding regions in T1-T2 regular and differential maps. In the paradigm, we propose a semi-automated processing of NMR T1-T2 data using a custom interpretation scheme composed of regions from multiple interpretation schemes and consider their modification for high-quality results.

Increased oxygenation is associated with myocardial inflammation and adverse regional remodeling after acute ST-segment elevation myocardial infarction.

To explore the relationships between oxygenation signal intensity (SI) with myocardial inflammation and regional left ventricular (LV) remodeling in reperfused acute ST-segment elevation myocardial infarction (STEMI) using oxygenation-sensitive cardiovascular magnetic resonance (OS-CMR). Thirty-three STEMI patients and 22 age- and sex-matched healthy volunteers underwent CMR. The protocol included cine function, OS imaging, precontrast T1 mapping, T2 mapping, and late gadolinium enhancement (LGE) imaging. A total of 880 LV segments were included for analysis based on the American Heart Association 16-segment model. For validation, 15 pigs (10 myocardial infarction (MI) model animals and 5 controls) received CMR and were sacrificed for immunohistochemical analysis. In the patient study, the acute oxygenation SI showed a stepwise rise among remote, salvaged, and infarcted segments compared with healthy myocardium. At convalescence, all oxygenation SI values besides those in infarcted segments with microvascular obstruction decreased to similar levels. Acute oxygenation SI was associated with early myocardial injury (T1: r = 0.38; T2: r = 0.41; all p < 0.05). Segments with higher acute oxygenation SI values exhibited thinner diastolic walls and decreased wall thickening during follow-up. Multivariable regression modeling indicated that acute oxygenation SI (β = 2.66; p < 0.05) independently predicted convalescent segment adverse remodeling (LV wall thinning). In the animal study, alterations in oxygenation SI were correlated with histological inflammatory infiltrates (r = 0.59; p < 0.001). Myocardial oxygenation by OS-CMR could be used as a quantitative imaging biomarker to assess myocardial inflammation and predict convalescent segment adverse remodeling after STEMI. • Oxygenation signal intensity (SI) may be an imaging biomarker of inflammatory infiltration that could be used to assess the response to anti-inflammatory therapies in the future. • Oxygenation SI early after myocardial infarction (MI) was associated with left ventricular segment injury at acute phase and could predict regional functional recovery and adverse remodeling late after acute MI. • Oxygenation SI demonstrated a stepwise increase among remote, salvaged, and infarcted segments. Infarcted zones with microvascular obstruction demonstrated a higher oxygenation SI than those without. However, the former showed less pronounced changes over time.

Differences in native T1 and native T2 mapping between patients on hemodialysis and control subjects

PurposeMyocardial native T1 is a potential measure of myocardial fibrosis, but concerns remain over the potential influence of myocardial edema to increased native T1 signal in subjects prone to fluid overload. This study describes differences in native T2 (typically raised in states of myocardial edema) and native T1 times in patients on hemodialysis by comparing native T1 and native T2 times between subjects on hemodialysis to an asymptomatic control group. Reproducibility of these sequences was tested. MethodsSubjects were recruited prospectively and underwent 3 T-cardiac MRI with acquisition of native T1 and native T2 maps. Between group differences in native T1 and T2 maps were assessed using one-way ANOVAs. 30 subjects underwent test-retest scans within a week of their original scan to define sequence reproducibility. Results261 subjects completed the study (hemodialysis n = 124, control n = 137). Native T1 times were significantly increased in subjects on hemodialysis compared to control subjects (1259 ms ± 51 vs 1212 ms ± 37, p < 0.01). There was no difference in native T2 times between subjects on hemodialysis and control subjects (39.5 ms ± 2.5 vs 39.5 ms ± 2.3, p = 0.9). These differences were unchanged after adjustment for relevant baseline differences (age, sex and hemoglobin). Inter-study reproducibility for native T1 and T2 mapping was excellent (coefficient of variability 0.9 % and 2.6 % respectively). ConclusionsThe increased native T1 signal demonstrated in subjects on hemodialysis occurs independently of differences in native T2 and the two parameters are not orthogonal. Elevated native T1 in patients on hemodialysis may be driven by water related to myocardial fibrosis rather than edema from volume overload.

Preoperative volumetric synthetic magnetic resonance imaging of the primary tumor for a more accurate prediction of lymph node metastasis in rectal cancer.

An accurate assessment of lymph node (LN) status in patients with rectal cancer is important for treatment planning and an essential factor for predicting local recurrence and overall survival. In this study, we explored the potential value of histogram parameters of synthetic magnetic resonance imaging (SyMRI) in predicting LN metastasis in rectal cancer and compared their predictive performance with traditional morphological characteristics and chemical shift effect (CSE). A total of 70 patients with pathologically proven rectal adenocarcinoma who received direct surgical resection were enrolled in this prospective study. Preoperative rectal MRI, including SyMRI, were performed, and morphological characteristics and CSE of LN were assessed. Histogram parameters were extracted on a T1 map, T2 map, and proton density (PD) map, including mean, variance, maximum, minimum, 10th percentile, median, 90th percentile, energy, kurtosis, entropy, and skewness. Receiver operating characteristic (ROC) curves were used to explore their predictive performance for assessing LN status. Significant differences in the energy of the T1, T2, and PD maps were observed between LN-negative and LN-positive groups [all P<0.001; the area under the ROC curve (AUC) was 0.838, 0.858, and 0.823, respectively]. The maximum and kurtosis of the T2 map, maximum, and variance of PD map could also predict LN metastasis with moderate diagnostic power (P=0.032, 0.045, 0.016, and 0.047, respectively). Energy of the T1 map [odds ratio (OR) =1.683, 95% confidence interval (CI): 1.207-2.346, P=0.002] and extramural venous invasion on MRI (mrEMVI) (OR =10.853, 95% CI: 2.339-50.364, P=0.002) were significant predictors of LN metastasis. Moreover, the T1 map energy significantly improved the predictive performance compared to morphological features and CSE (P=0.0002 and 0.0485). The histogram parameters derived from SyMRI of the primary tumor were associated with LN metastasis in rectal cancer and could significantly improve the predictive performance compared with morphological features and CSE.

Distribution Model of Fluid Components and Quantitative Calculation of Movable Oil in Inter-Salt Shale Using 2D NMR

Some inter-salt shale reservoirs have high oil saturations but the soluble salts in their complex lithology pose considerable challenges to their production. Low-field nuclear magnetic resonance (NMR) has been widely used in evaluating physical properties, fluid characteristics, and fluid saturation of conventional oil and gas reservoirs as well as common shale reservoirs. However, the fluid distribution analysis and fluid saturation calculations in inter-salt shale based on NMR results have not been investigated because of existing technical difficulties. Herein, to explore the fluid distribution patterns and movable oil saturation of the inter-salt shale, a specific experimental scheme was designed which is based on the joint adaptation of multi-state saturation, multi-temperature heating, and NMR measurements. This novel approach was applied to the inter-salt shale core samples from the Qianjiang Sag of the Jianghan Basin in China. The experiments were conducted using two sets of inter-salt shale samples, namely cylindrical and powder samples. Additionally, by comparing the one-dimensional (1D) and two-dimensional (2D) NMR results of these samples in oil-saturated and octamethylcyclotetrasiloxane-saturated states, the distributions of free movable oil and water were obtained. Meanwhile, the distributions of the free residual oil, adsorbed oil, and kerogen in the samples were obtained by comparing the 2D NMR T1-T2 maps of the original samples with the sample heated to five different temperatures of 80, 200, 350, 450, and 600 °C. This research puts forward a 2D NMR identification graph for fluid components in the inter-salt shale reservoirs. Our experimental scheme effectively solves the problems of fluid composition distribution and movable oil saturation calculation in the study area, which is of notable importance for subsequent exploration and production practices.