T1 T2 Mapping Research Articles

An integrated geochemical, spectroscopic, and petrographic approach to examining the producibility of hydrocarbons from liquids-rich unconventional formations

The geochemical and petrophysical complexity of source-rock reservoirs in liquids-rich unconventional (LRU) plays necessitates the implementation of a more expansive analytical protocol for initial play assessment. In this study, original samples from selected source-rock reservoirs in the USA and the UK were analyzed by 22 MHz nuclear magnetic resonance (HF-NMR) T1-T2 mapping, followed by hydrous pyrolysis, and a modified Rock-Eval pyrolysis method (multi-heating step method-MHS). The above methods were complemented by organic petrography under reflected white and UV light excitation of the original and pyrolyzed samples. The analytical protocol presented attempts to better qualify and quantify different petroleum fractions (mobile, heavy hydrocarbons, viscous, solid bitumen), thus provide valuable and refined information about producibility of target intervals during appraisal. Results show how the hydrocarbon fractions interpreted from peak locations and intensities on NMR T1-T2 maps are in good agreement with those from MHS pyrolysis in terms of hydrocarbon mobility/producibility. Results from HP (Hydrous Pyrolysis) experiments show that an exception to this general agreement between NMR and MHS estimates occurs for the Kimmeridge Blackstone Clay samples, where MHS shows an increase of >90% in producible hydrocarbon yields vs. minimal to no presence of mobile hydrocarbons in NMR T1-T2 maps. This study clarifies the role of pore structure and networks in these discrepancies of producible oil estimates when comparing programmed pyrolysis to NMR-based techniques. This novel, multi-step and multidisciplinary approach provides a more advanced screening protocol for identifying zones of higher oil-in-place (OIP) and predicting fluid mobility prior to drilling or completions.

T2-mapping increase is the prevalent imaging biomarker of myocardial involvement in active COVID-19: a Cardiovascular Magnetic Resonance study

BackgroundEarly detection of myocardial involvement can be relevant in coronavirus disease 2019 (COVID-19) patients to timely target symptomatic treatment and decrease the occurrence of the cardiac sequelae of the infection.The aim of the present study was to assess the clinical value of cardiovascular magnetic resonance (CMR) in characterizing myocardial damage in active COVID-19 patients, through the correlation between qualitative and quantitative imaging biomarkers with clinical and laboratory evidence of myocardial injury.MethodsIn this retrospective observational cohort study, we enrolled 27 patients with diagnosis of active COVID-19 and suspected cardiac involvement, referred to our institution for CMR between March 2020 and January 2021.Clinical and laboratory characteristics, including high sensitivity troponin T (hs-cTnT), and CMR imaging data were obtained. Relationships between CMR parameters, clinical and laboratory findings were explored.Comparisons were made with age-, sex- and risk factor–matched control group of 27 individuals, including healthy controls and patients without other signs or history of myocardial disease, who underwent CMR examination between January 2020 and January 2021.ResultsThe median (IQR) time interval between COVID-19 diagnosis and CMR examination was 20 (13.5–31.5) days. Hs-cTnT values were collected within 24 h prior to CMR and resulted abnormally increased in 18 patients (66.6%). A total of 20 cases (74%) presented tissue signal abnormalities, including increased myocardial native T1 (n = 11), myocardial T2 (n = 14) and extracellular volume fraction (ECV) (n = 10), late gadolinium enhancement (LGE) (n = 12) or pericardial enhancement (n = 2). A CMR diagnosis of myocarditis was established in 9 (33.3%), pericarditis in 2 (7.4%) and myocardial infarction with non-obstructive coronary arteries in 3 (11.11%) patients. T2 mapping values showed a moderate positive linear correlation with Hs-cTnT (r = 0.58; p = 0.002). A high degree positive linear correlation between ECV and Hs-cTnT was also found (r 0.77; p < 0.001).ConclusionsCMR allows in vivo recognition and characterization of myocardial damage in a cohort of selected COVID-19 individuals by means of a multiparametric scanning protocol including conventional imaging and T1–T2 mapping sequences. Abnormal T2 mapping was the most commonly abnormality observed in our cohort and positively correlated with hs-cTnT values, reflecting the predominant edematous changes characterizing the active phase of disease.

Early myocardial damage and microvascular dysfunction in asymptomatic patients with systemic sclerosis: A cardiovascular magnetic resonance study with cold pressor test.

PurposeCardiac involvement in Systemic Sclerosis (SSc) is increasingly recognized as a mayor cause of morbidity and mortality. The aim of present study is to investigate the early stages of cardiac involvement in SSc by Cardiovascular magnetic resonance (CMR), combining the non-invasive detection of myocardial inflammation and fibrosis using T2 and T1 mapping techniques and the assessment of microcirculatory impairment through perfusion response to cold pressor test (CPT).Methods40 SSc patients (30 females, mean age: 42.1 years) without cardiac symptoms and 10 controls underwent CMR at 1.5 T unit. CMR protocol included: native and contrast-enhanced T1 mapping, T2 mapping, T2-weighted, cineMR and late gadolinium enhancement (LGE) imaging. Microvascular function was evaluated by comparing myocardial blood flow (MBF) on perfusion imaging acquired at rest and after CPT. Native myocardial T1 and T2 relaxation times, extracellular volume fraction (ECV), T2 signal intensity ratio, biventricular volumes and LGE were assessed in each patient.ResultsSSc patients had significantly higher mean myocardial T1 (1029±32ms vs. 985±18ms, p<0.01), ECV (30.1±4.3% vs. 26.7±2.4%, p<0.05) and T2 (50.1±2.8ms vs. 47±1.5ms, p<0.01) values compared with controls. No significant differences were found between absolute MBF values at rest and after CPT; whereas lower MBF variation after CPT was observed in SSc patients (+33 ± 14% vs. +44 ± 12%, p<0.01). MBF variation had inverse correlation with native T1 values (r: -0.32, p<0.05), but not with ECV.ConclusionsMyocardial involvement in SSc at preclinical stage increases native T1, T2 and ECV values, reflecting inflammation and fibrosis, and reduces vasodilatory response to CPT, as expression of microvascular dysfunction.

Effect of Thermal Exposure on Oil Shale Saturation and Reservoir Properties

The experimental and numerical modeling of thermal enhanced oil recovery (EOR) requires a detailed laboratory analysis of core properties influenced by thermal exposure. To acquire the robust knowledge on the change in rock saturation and reservoir properties, the fastest way is to examine the rock samples before and after combustion. In the current paper, we studied the shale rock properties, such as core saturation, porosity, and permeability, organic matter content of the rock caused by the combustion front propagation within the experimental modeling of the high-pressure air injection. The study was conducted on Bazhenov shale formation rock samples. We reported the results on porosity and permeability evolution, which was obtained by the gas pressure-decay technique. The measurements revealed a significant increase of porosity (on average, for 9 abs. % of porosity) and permeability (on average, for 1 mD) of core samples after the combustion tube experiment. The scanning electron microscopy showed the changes induced by thermal exposure: the transformation of organic matter with and the formation of new voids and micro and nanofractures in the mineral matrix. Low-field Nuclear Magnetic Resonance (NMR) was chosen as a primary non-disruptive tool for measuring the saturation of core samples in ambient conditions. NMR T1–T2 maps were interpreted to determine the rock fluid categories (bitumen and adsorbed oil, structural and adsorbed water, and mobile oil) before and after the combustion experiment. Changes in the distribution of organic matter within the core sample were examined using 2D Rock-Eval pyrolysis technique. Results demonstrated the relatively uniform distribution of OM inside the core plugs after the combustion.

Insight form cardiovascular magnetic resonance on cardiac sarcoidosis: a single centre experience

Abstract Background Clinically manifest cardiac sarcoidosis (CS) has a prevalence of 5%, but is more frequent in autoptic series (25%). Diagnosis is multiparametric and relies on clinical criteria and imaging findings, although a certain diagnosis, especially in the case of isolated CS (ICS), can only be based on endomyocardial biopsy. Cardiovascular magnetic resonance (CMR) has a comprehensive role in the assessment of CS: left ventricular (LV) dysfunction and extent of late gadolinium enhancement (LGE)are important predictors of prognosis, T2 mapping provides information on disease activity and global longitudinal strain (GLS) analysis can uncover subclinical LV impairment. Purpose To assess the prevalence of CS by CMR in patients with biopsy-proven extracardiacsarcoidosis (ECS); to describe the imaging characteristics of patients with ECS and those with high clinical suspicionof ICS; to investigate the contribution of more recent techniques to the diagnosis of CS alongside traditional LGE assessment. Methods We retrospectively enrolled 84 patients (66% males, mean age 59±13 years) referred to our centreforsuspected CS (biopsy-proven ECS, n=61; clinical presentation suggestive of CS,, n=23). CMR was performed on a 1.5T scanner, with a protocol comprehensive of biventricular functional assessment and post-contrast images; T2-STIR images (n=30), native myocardial T1 mapping (n=24) and T2 mapping (n=19) were also performed in selected patients. Tissue tracking analysis was perfomed in all patients using a dedicated software. Results Based on CMR findings, 35 patients (42%) with ECS did not show cardiac involvement (SS), 26 (31%) showed both cardiac and systemic involvement (CS-SS) and 23 (27%) had evidence of ICS (ICS). 43% of patients had history of arrhythmias, but life-threatening tachyarrhythmiaswere more frequent in patients with CS (p=0.02).Patients with CS had significantly lower LVEF (p&amp;lt;0,01), larger LV volumes (p&amp;lt;0,01) and greater LV mass (p&amp;lt;0,01). GLS values were impaired in all the groups but significantly more in patients with CS (p&amp;lt;0,01). With regards to LGE distribution, ICS patients showed a higher number of segments involved (p=0,011) as compared to CS patients. T2-STIRimages were positive in 3 out of 30 patients; T2 mapping detected myocardial oedema in 1 patient with negative T2- STIR and was positive in 7 who did not undergo traditional oedema evaluation. T1 mapping mainly confirmed the results provided by LGE, but was altered in 1 patient who could not receive gadolinium. Conclusions CMR findings consistent with CS were found in 49 patients referred for suspected CS. Patients with cardiac involvement, particularly if isolated, had significantly lower LVEF, greater LV volumes and more impaired GLS. Patients with SS, despite a normal LV function, showed mildly impaired GLS, subtending subclinical cardiac involvement. Funding Acknowledgement Type of funding source: None

Insights into NMR response characteristics of shales and its application in shale gas reservoir evaluation

To elucidate the NMR response characteristics of gas-bearing shales, NMR T2 and T1–T2 experiments were performed on 38 shale samples selected from the Longmaxi Formation in the southern Sichuan Basin in China. The NMR signals of the totally dried shales were basically distributed in a single left peak and could not be removed completely. The T2 spectra of water-saturated shales presented two- or three-peak distributions. With the increase in depth, the T2 peaks tended to be skewed to the right, indicating that the proportion of meso-macropores of the shale in the L1l1 sublayer is the largest. The T1–T2 signal peaks of the dried shales are dominantly distributed in the region where T1/T2 ratio＜100 and T2 = 0.1 ms, and that of the saturated shales are 1 mainly distributed in the region where 1＜T1/T2 ratio＜100 and 1 ms＜T2＜10 ms, respectively. A preliminary T1–T2 division method was proposed to differentiate hydrogen-bearing components in gas-bearing shales. Combining the T1–T2 maps and correlation analysis confirms that the NMR signal of dry shale is mainly from clay structural water. NMR porosity should be corrected by removing the NMR signal of dry shales. After correction, the error between NMR porosity and WIP (water immersion porosimetry) porosity was considerably reduced, and its mean absolute error was only 0.16%. Moreover, a parameter T2g was proposed to evaluate the Longmaxi shale gas reservoir, which was increased in depth and reached the maximum in the L1l1 sublayer. Moreover, the boundary value of T2g was determined for reservoir evaluation and classification.

Characterization and interpretation of organic matter, clay minerals, and gas shale rocks with low-field NMR

Nuclear magnetic resonance (NMR) has emerged as an essential method for appraising gas-shales, quantifying their petrophysical properties, classifying their fluid types, and discerning their productivity. Comprehensive measurement campaigns, as well as reliable thermal-heating experiments, are required to fully understand the NMR mechanism of shale and to further develop future gas-shale exploitation strategies. NMR signatures from individual matrix components, which comprise shale, are investigated to gather data to better estimate its petrophysical parameters. Subsequently, we perform T1 and T2 measurements of kerogen, solid bitumen, and clay minerals. Next, we analyze the temperature effect on the NMR signal interpretation of different compositions of gas-shale samples in detail, coupled with the position of clay minerals and solid bitumen from the T1-T2 mapping. A shale plug sample was quantified by the NMR T1-T2 relaxation signals under initial conditions and different temperature conditions of 110 °C, 250 °C, 450 °C, and 650 °C. The fluid volume significantly decreased as the temperature increased. The organic matter maturity changed at 450 °C and 650 °C. According to a thermal-heating experiment with powdered clays, we obtained the hydroxyl group and crystal water signals and determined the critical temperature for different dried types of water in clay mineral. It is reasonable to infer that deconvoluting the entire shale sample into different components can further determine the NMR relaxation mechanisms. The ultimate goal of this project was to develop a holistic methodology to understand the NMR mechanisms of isolated components and to assess the positions of kerogen, solid bitumen, illite, kaolinite, smectite, and chlorite from T1-T2 mapping. This work contributes to the fundamental understanding of shale formations by quantifying the NMR relaxation mechanisms of various constituents in shale and provides implications for shale rock evaluations.

A pilot study of magnetic resonance fingerprinting in Parkinson's disease.

Parkinson's disease (PD) affects more than six million people, but reliable MRI biomarkers with which to diagnose patients have not been established. Magnetic resonance fingerprinting (MRF) is a recent quantitative technique that can provide relaxometric maps from a single sequence. The purpose of this study is to assess the potential of MRF to identify PD in patients and their disease severity, as well as to evaluate comfort during MRF. Twenty-five PD patients and 25 matching controls underwent 3 T MRI, including an axial 2D spoiled gradient echo MRF sequence. T1 and T2 maps were generated by voxel-wise matching the measured MRF signal to a precomputed dictionary. All participants also received standard inversion recovery T1 and multi-echo T2 mapping. An ROI-based analysis of relaxation times was performed. Differences between patients and controls as well as techniques were determined by logistic regression, Spearman correlation and t-test. Patients were asked to estimate the subjective comfort of the MRF sequence. Both MRF-based T1 and T2 mapping discriminated patients from controls: T1 relaxation times differed most in cortical grey matter (PD 1337 ± 38 vs. control 1386 ± 37 ms; mean ± SD; P = .0001) and, in combination with normal-appearing white matter, enabled correct discrimination in 85.7% of cases (sensitivity 83.3%; specificity 88.0%; receiver-operating characteristic [ROC]) area under the curve [AUC] 0.87), while for T2 mapping the left putamen was the strongest classifier (40.54 ± 6.28 vs. 34.17 ± 4.96 ms; P = .0001), enabling differentiation of groups in 84.0% of all cases (sensitivity 80.0%; specificity 88.0%; ROC AUC 0.87). Relaxation time differences were not associated with disease severity. Standard mapping techniques generated significantly different relaxation time values and identified other structures as different between groups other than MRF. Twenty-three out of 25 PD patients preferred the MRF examination instead of a standard MRI. MRF-based mapping can identify PD patients with good comfort but needs further assessment regarding disease severity identification and its potential for comparability with standard mapping technique results.

Cardiac MRI Myocardial Functional and Tissue Characterization Detects Early Cardiac Dysfunction in a Mouse Model of Chemotherapy-Induced Cardiotoxicity.

Doxorubicin and doxorubicin-trastuzumab combination chemotherapy have been associated with cardiotoxicity that eventually leads to heart failure and may limit dose-effective cancer treatment. Current diagnostic strategies rely on decreased ejection fraction (EF) to diagnose cardiotoxicity. The aim of this study is to explore the potential of cardiac MR (CMR) imaging to identify imaging biomarkers in a mouse model of chemotherapy-induced cardiotoxicity. A cumulative dose of 25 mg/kg doxorubicin was administered over three weeks using subcutaneous pellets (n = 9, Dox). Another group (n = 9) received same dose of Dox and a total of 10 mg/kg trastuzumab (DT). Mice were imaged at baseline, 5/6 weeks and 10 weeks post-treatment on a 7T MRI system. The protocol included short-axis cine MRI covering the left ventricle (LV) and mid-ventricular short-axis tissue phase mapping (TPM), pre- and post-contrast T1 mapping, T2 mapping and Displacement Encoding with Stimulated Echoes (DENSE) strain encoded MRI. EF, peak myocardial velocities, native T1, T2, extracellular volume (ECV), and myocardial strain were quantified. N = 7 mice were sacrificed for histopathologic assessment of apoptosis at 5/6 weeks. Global peak systolic longitudinal velocity was reduced at 5/6 weeks in Dox (0.6 ± 0.3 vs 0.9 ± 0.3, p = 0.02). In the Dox group, native T1 was reduced at 5/6 weeks (1.3 ± 0.2 ms vs 1.6 ± 0.2 ms, p = 0.02), and relatively normalized at week 10 (1.4 ± 0.1 ms vs 1.6 ± 0.2 ms, p > 0.99). There was no change in EF and other MRI parameters and histopathologic results demonstrated minimal apoptosis in all mice (~1-2 apoptotic cell/high power field), suggesting early-stage cardiotoxicity. In a mouse model of chemotherapy-induced cardiotoxicity using doxorubicin and trastuzumab, advanced CMR shows promise in identifying treatment-related decrease in myocardial velocity and native T1 prior to the onset of cardiomyocyte apoptosis and reduction of EF.

The application of Nuclear Magnetic Resonance T1-T2 maps in the research of sedimentary organic matter: A case study of early mature shale with type Ⅰ kerogen

The Nuclear Magnetic Resonance (NMR) 2D T1-T2 map was widely used in shale resources for separation of the different proton contributions, and the obtained data provided lots of information for shale resources evaluation. However, the further work of its application in organic matter quantification and hydrocarbon generation research was quite limited. In this article, we used a low field NMR instrument working at a high frequency (15 MHz) to test isolated organic matter, raw oil shales and shale samples processed by pyrolysis respectively. The results indicated that the kerogen and bitumen could be distinguished by positions located in NMR 2D T1-T2 maps. The standard equations (the relationship between the signal intensity and the mass of isolated organic matter) with excellent linear relationship were established for firstly calculating the content of organic matter in oil shales. The results of NMR were almost identical with that tested by traditional methods. In addition, the NMR relaxometry measurements correlated well with geochemical properties of pyrolyzed oil shales obtained from Rock-Eval pyrolysis (S1 and S2).

DI-5-Cuffs: Lumbar Intervertebral Disc Proteoglycan and Water Content Changes in Humans after Five Days of Dry Immersion to Simulate Microgravity.

Most astronauts experience back pain after spaceflight, primarily located in the lumbar region. Intervertebral disc herniations have been observed after real and simulated microgravity. Spinal deconditioning after exposure to microgravity has been described, but the underlying mechanisms are not well understood. The dry immersion (DI) model of microgravity was used with eighteen male volunteers. Half of the participants wore thigh cuffs as a potential countermeasure. The spinal changes and intervertebral disc (IVD) content changes were investigated using magnetic resonance imaging (MRI) analyses with T1-T2 mapping sequences. IVD water content was estimated by the apparent diffusion coefficient (ADC), with proteoglycan content measured using MRI T1-mapping sequences centered in the nucleus pulposus. The use of thigh cuffs had no effect on any of the spinal variables measured. There was significant spinal lengthening for all of the subjects. The ADC and IVD proteoglycan content both increased significantly with DI (7.34 ± 2.23% and 10.09 ± 1.39%, respectively; mean ± standard deviation), p < 0.05). The ADC changes suggest dynamic and rapid water diffusion inside IVDs, linked to gravitational unloading. Further investigation is needed to determine whether similar changes occur in the cervical IVDs. A better understanding of the mechanisms involved in spinal deconditioning with spaceflight would assist in the development of alternative countermeasures to prevent IVD herniation.

Adsorbed and free hydrocarbons in unconventional shale reservoir: A new insight from NMR T1-T2 maps

Abstract Characterizing free and adsorbed hydrocarbon is crucial for the resources assessment and mobility evaluation of shale oil plays. The complex feature of hydrogen-bearing components in shale reservoirs requires new analytical methods to study the occurrences of different states of hydrocarbons. In this study, forty core samples from five shale oil research wells in the Jiyang Depression of China were analyzed using various analytical tools including nuclear magnetic resonance (NMR) T1-T2 mapping, Leco total organic carbon (TOC) analysis, routine and special programmed Rock-Eval pyrolysis, solvent extraction and fractionation, as well as mercury injection capillary pressure (MICP) experiments. Additional experiments were conducted on a powdered shale for NMR T1-T2 maps under four states: as-received, after being dried at 110 °C, after special programmed pyrolysis to 350 °C, and after solvent extraction. The results showed that residual water signals in the NMR T1-T2 map disappeared after being dried at 110 °C. Free oil signals decreased dramatically when the sample was thermally treated to 350 °C, while adsorbed oil signals decreased sharply after solvent extraction. A good accordance was observed between the organic hydrogen T2 spectra and three modes of Rock-Eval pyrograms, representing free hydrocarbons, adsorbed hydrocarbons, and hydrocarbons from kerogen/bitumen decomposition. A positive correlation was also found between the intensity of NMR T1-T2 map signals and the free and adsorbed hydrocarbon contents from geochemical analysis. T2 cut-off values of adsorbed hydrocarbons and free hydrocarbons were determined to be 0.2 ms and 1 ms, respectively. Core samples with a high oil saturation index, porosity, and relative content of hydrocarbons display a low T1/T2 ratio indicative of a high shale oil mobility. As a complementary method to the Rock-Eval analysis, NMR T1-T2 mapping is a non-destructive technique for the characterization of adsorbed and free hydrocarbons at the core scale with limited sample preparation. The results of this study are helpful for NMR characterization of shale reservoirs.

1D and 2D Nuclear magnetic resonance (NMR) relaxation behaviors of protons in clay, kerogen and oil-bearing shale rocks

Abstract Few 1D T2 and 2D T1-T2 Nuclear magnetic resonance (NMR) studies have focused on oil-bearing shales with complex constituents and a deeper understanding of the NMR relaxation behaviors of oil confined in shale is needed. In this paper, a series of T2 and T1-T2 NMR experiments were performed on oil-bearing shale and its components (clay minerals and kerogen) to obtain the T1-T2 fluid typing chart and analyze the adsorbed and free oil in shale. The results were as follows: five types of water (bound, adsorbed, free, crystal and structural water) in clay minerals were qualitatively identified and described by the specific T2 to T1/T2 ratio values, and T1-T2 maps were used to qualitatively indicate the clay type. The T1-T2 fluid typing chart containing the signatures of 8 proton populations in oil-bearing shale was defined and included bulk liquid, macropore (>1000 nm) oil, nanopore (

Using T1 as a direct detection dimension in two-dimensional time-domain NMR experiments using CWFP regime

The transverse relaxation time (T2), measured with Carr-Purcell-Meiboom-Gill (CPMG) sequence, has been widely used to obtain the direct dimension data in two-dimension time domain NMR (2D TD-NMR). In this paper we are demonstrating that Continuous Wave Free Precession sequence, with low flip angle (CWFP-T1), can be an alternative to CPMG as direct detection dimension. CWFP-T1 is a fast single shot sequence, like CPMG, and yields an exponential signal governed predominantly by the longitudinal (T1) relaxation time. To obtain the correlations between T1 and T2 (T1-T2 maps) we are proposing the use of CPMG-CWFP-T1 pulse sequence. In this sequence CPMG encodes T2 information (indirect dimension) that modulates the CWFP-T1 (direct dimension) signal amplitudes. CPMG-CWFP-T1 experiments were compared with classical 2D sequences such as Saturation-Recovery-CPMG (SR-CPMG) and Inversion-Recovery-CPMG (IR-CPMG) sequence and yields similar results in phantom sample. The experimental time for the 2D sequences, using single scan, shows that SR-CPMG ≤ CPMG-CWFP-T1 < IR-CPMG. Experimental and simulated results demonstrated that 2D-CPMG-CWFP-T1 maps have higher resolution in T1 dimension than the techniques that uses CPMG as direct dimension. CPMG-CWFP-T1 sequence was also applied to study beef samples, and 2D maps showed higher resolution in the two fat signals than the classical IR-CPMG method.

MRI monitoring of sea spray freezing.

Sea spray icing is a common hazard for vessels and offshore structures in cold climates. In this paper, quantitative 3D MRI and T1-T2 mapping of the formation of sea spray ice were performed. Three different freezing regimes were employed. During freezing, changes in both relaxation times and signal intensity were greater than an order of magnitude. Results show strong differences in brine intensity and distribution for the three freezing regimes. The observed ranges of spin densities and relaxation times during freezing are well suited to measurements with portable NMR devices. There is a considerable potential for the use of MRI in studies of sea spray ice.

Reservoir characteristics and evaluation of fluid mobility in organic-rich mixed siliciclastic-carbonate sediments: A case study of the lacustrine Qiketai Formation in Shengbei Sag, Turpan-Hami Basin, Northwest China

Organic matter-rich mixed siliciclastic-carbonate sediments is a special type of tight oil reservoir in the Turpan-Hami basin, which is characterized by complex fluid type, mineral composition and pore structure. By using casting thin sections, scanning electron microscopy (SEM) and whole rock X diffraction (XRD), pore types and petrological characterization of reservoirs are analyzed. Combined with the result of the physical property, nuclear magnetic resonance (NMR) experiments, the effects of the porosity, permeability, and pore size distribution on the movable fluid distribution in the tight reservoir were evaluated. The results showed that there are four types of mixed siliciclastic-carbonate sediments reservoir, which have high TOC. The reservoirs are characterized by low porosity range from 2% to 10% and extra low permeability mainly less than 0.1 × 10−3 μm2. Nanometer scale intergranular pores and micro-fractures were the main reservoir pore types, we further divided the pore sizes distribution into two categories based on their water-saturated NMR T2 spectra: Type I (bimodal pattern) and Type II (left unimodal, micropores with a diameter less than 100 nm). The fluid components in the reservoir including water in nano-pores, movable light oil, non-movable heavy oil and bound water were analyzed using advanced NMR T1-T2 maps. The mobile light oil content in the silt-bearing argillaceous arenaceous limestone and silt-bearing lime micritic dolomite is higher than that of other lithological reservoirs. The movable light oil content exhibited a strong correlation with permeability, and the proportion of large pores, indicating that the large pores, which are mainly supplied by the intergranular pores in dolomite, substantially contributed to mobility of the hydrocarbon fluid. The non-movable heavy oil fluid component is impacted the small pores ratio and solid organic matter, while water the in nano-pores is greatly affected by clay minerals.

P1813Impact of cardiac MRI imaging on detection rates of myocarditis

Abstract Background The Lake Louise Criteria for the diagnosis of myocarditis by cardiac MRI (CMR) was published in 2009 (JACC April 2009; 53(17): 1475–1487) utilizing T2 STIR, “early” gadolinium enhancement (EGE) and late gadolinium enhancement (LGE). In 2012, our CMR unit adopted a chest pain protocol to enhance detection of inflammatory heart disease, using all 3 pulse sequences. In 2017, T1 relaxing mapping and T2 relaxation mapping were added to the chest pain protocol. Purpose This study was designed to assess the impact of pulse sequence changes in the CMR chest pain protocol on the detection rate of myocarditis. Methods An institutional cardiac imaging database was queried for all patients with chest pain who underwent a CMR study from 2009 thru 2018. The number of newly diagnosed cases of myocarditis per year was computed, based on the prevailing CMR diagnostic criteria at that time. The detection rate of new myocarditis cases per year, was calculated by dividing the number of new cases by the total of CMR studies performed for evaluation of chest pain, during each calendar year. Results Of the 4,946 patients in the cardiac imaging database, 2,126 patients underwent CMR imaging for complaints of chest pain. Detection rates of myocarditis by year are shown in Figure 1. Prior to inclusion of T1 STIR pulse sequences, CMR detection of myocarditis was nearly nil. Use of T2 STIR imaging allowed for an increased rate of myocarditis detection. However, addition of T1 mapping and T2 mapping in 2017 resulted in another increase in myocarditis detection rates from baseline. Figure 1. Detection rate of myocarditis. Conclusions Detection rates of myocarditis using CMR were improved by using T2 STIR pulse sequences, per the initial Lake Louise Criteria. Further enhancement of myocarditis detection rates is achieved by addition of T1 and T2 mapping. These CMR impact data provide additional support for the adoption of the recently modified Lake Louise Criteria (JACC Dec 2018; 72(24): 3158–3176).

Joint T1 and T2 Mapping With Tiny Dictionaries and Subspace-Constrained Reconstruction.

A novel method is developed that adaptively generates tiny dictionaries for joint T1-T2 mapping in magnetic resonance imaging. This work breaks the bond between dictionary size and representation accuracy (i) by approximating the Bloch-response manifold by piece-wise linear functions and (ii) by adaptively refining the sampling grid depending on the locally-linear approximation error. Data acquisition is accomplished with use of an 2D radially sampled Inversion-Recovery Hybrid-State Free Precession sequence. Adaptive dictionaries are generated with different error tolerances and compared to a heuristically designed dictionary. Based on simulation results, tiny dictionaries were used for T1-T2 mapping in phantom and in vivo studies. Reconstruction and parameter mapping were performed entirely in subspace. All experiments demonstrated excellent agreement between the proposed mapping technique and template matching using heuristic dictionaries. Adaptive dictionaries in combination with manifold projection allow to reduce the necessary dictionary sizes by one to two orders of magnitude.

Accurate, precise, simultaneous myocardial T1 and T2 mapping using a radial sequence with inversion recovery and T2 preparation.

We propose a simultaneous myocardial T1 and T2 mapping technique using a radial sequence with inversion recovery and T2 preparation, which achieves high accuracy and precision, with T1 and T2 reproducibility similar to the Modified Look-Locker Inversion recovery (MOLLI) sequence and the conventional bright blood T2 mapping technique, respectively. The sequence was developed by incorporating gold angle radial fast low angle shot (FLASH) readout combined with an inversion pulse and T2prep pulses. The extended Bloch equation simulation with slice profile correction (BLESSPC) algorithm was proposed to reconstruct T1 and T2 maps at the same time in a few seconds, while maintaining good T1 and T2 estimation accuracy. Accuracy and precision were compared among the proposed technique, MOLLI and conventional T2 mapping techniques using phantom studies, 10 healthy volunteers and three patients. In phantom studies, the proposed technique was more accurate than MOLLI (P<0.05) while achieving similar precision (P=0.3) in T1 estimation, and was more accurate (P<0.05) and precise (P<0.001) than conventional T2 mapping (two-parameter fitting) in T2 estimation. In vivo, the proposed technique achieved significantly higher T1 values (P<0.001) and similar reproducibility (P=0.3) compared with MOLLI, with significantly lower T2 values (P<0.001) and similar reproducibility (P=0.6) compared with the conventional T2 mapping technique. Thus, the proposed radial T1-T2 mapping technique allows for accurate, precise, simultaneous myocardial T1 and T2 mapping in an 11-heartbeat single breath-hold acquisition.

Cardiac Allograft Vasculopathy Post Heart Transplantation: MRI Structural Parameters in Patients Trending towards Restrictive Physiology

BackgroundCardiac allograft vasculopathy (CAV) is a main cause of graft failure beyond the first year post heart transplantation (HTx). Post-HTx restrictive physiology, which is characterized by increased right sided cardiopulmonary pressures (CPP), particularly right atrial pressure (RAP) and pulmonary wedge pressure (PCWP) makes up part of the CAV classification criteria. Cardiovascular magnetic resonance (CMR) allows for the assessment of changes in myocardial tissue structure and function.HypothesisIn HTx patients followed up for CAV, CMR structural parameters are significantly different in subjects with increased RAP and-or PCWP compared to subjects with normal pressures.MethodsFourty-five HTx patients were prospectively recruited. Inclusion criteria included a right heart catheterization (RHC) performed within 2 years post-CMR. Right side CPP measured at the most recent RHC were considered for analysis. Patients were divided in two groups: normal right side pressures (NRSP) and ≥1 right sided pressure increase (RSPI). Thirteen CAV RSPI patients were compared with 32 age and gender matched CAV NRSP patients (Table 1). CAV grade was based on ISHLT criteria. CMR pre and post-contrast T1 maps and T2 maps were acquired at cardiac basal, mid and apical levels. Pre and post-contrast T1, Extracellular volume (ECV), and T2 were calculated after image post-processing on Circle Cardiovascular imaging.ResultsECV was available in 9 patients of the RSPI group and 23 of the NRSP group. Patients in the RSPI groups showed a significantly higher ECV (<0.01) and T2 (<0.05) values. Data are reported in Table 1.ConclusionsCAV patients with increased CPP demonstrated elevated ECV values likely due to increased myocardial fibrosis. The significantly higher T2 also suggest an inflammatory process possibly triggering increased CPP. CMR structural changes may precede the development of restrictive physiology. Cardiac allograft vasculopathy (CAV) is a main cause of graft failure beyond the first year post heart transplantation (HTx). Post-HTx restrictive physiology, which is characterized by increased right sided cardiopulmonary pressures (CPP), particularly right atrial pressure (RAP) and pulmonary wedge pressure (PCWP) makes up part of the CAV classification criteria. Cardiovascular magnetic resonance (CMR) allows for the assessment of changes in myocardial tissue structure and function. In HTx patients followed up for CAV, CMR structural parameters are significantly different in subjects with increased RAP and-or PCWP compared to subjects with normal pressures. Fourty-five HTx patients were prospectively recruited. Inclusion criteria included a right heart catheterization (RHC) performed within 2 years post-CMR. Right side CPP measured at the most recent RHC were considered for analysis. Patients were divided in two groups: normal right side pressures (NRSP) and ≥1 right sided pressure increase (RSPI). Thirteen CAV RSPI patients were compared with 32 age and gender matched CAV NRSP patients (Table 1). CAV grade was based on ISHLT criteria. CMR pre and post-contrast T1 maps and T2 maps were acquired at cardiac basal, mid and apical levels. Pre and post-contrast T1, Extracellular volume (ECV), and T2 were calculated after image post-processing on Circle Cardiovascular imaging. ECV was available in 9 patients of the RSPI group and 23 of the NRSP group. Patients in the RSPI groups showed a significantly higher ECV (<0.01) and T2 (<0.05) values. Data are reported in Table 1. CAV patients with increased CPP demonstrated elevated ECV values likely due to increased myocardial fibrosis. The significantly higher T2 also suggest an inflammatory process possibly triggering increased CPP. CMR structural changes may precede the development of restrictive physiology.