T1 T2 Mapping Research Articles

Cardiac magnetic resonance including parametric mapping in acute Takotsubo syndrome: Preliminary findings

IntroductionT1 and T2 mapping have been shown to be reliable markers of interstitial myocardial fibrosis, edema, and inflammation. The aim of this study was to evaluate myocardial involvement in acute phase Takotsubo syndrome using native and post-contrast T1 mapping, ECV fraction, and T2 mapping. Material and methodsWe investigated 14 patients with acute Takotsubo syndrome and 14 healthy controls. CMR included cine imaging, black-blood STIR imaging, early and late gadolinium enhancement imaging, native and post-contrast T1 mapping, and T2 mapping. Wall motion, T2 ratio, early gadolinium enhancement ratio, extracellular volume fraction, T1 and T2 relaxation times were analyzed. ResultsPatients had significantly impaired left ventricular function (46 ± 10%) and acute wall motion abnormalities compared with controls (62 ± 2%). Native T1 and T2 values, T2 ratio, and ECV fraction were significantly higher in patients compared with controls. In patients, native T1 and T2 values as well as T2 ratio were significantly higher in segments with abnormal wall motion compared with normokinetic segments. Native T1 values, T2 relaxation times, T2 ratio, and ECV fraction were significantly higher, post-contrast T1 relaxation times significantly lower in segments with abnormal wall motion compared with segments of controls; except for T2 ratio and post-contrast T1 relaxation times this also held true for patients’ segments with normal wall motion. ConclusionsNative T1 and T2 mapping, as well as ECV fraction, discriminate between visually affected vs. unaffected segments in patients with acute Takotsubo syndrome and reveal significant T1 and T2 tissue changes even in visually unaffected segments. Thus, mapping may allow for better detection in convalescent stages of disease and additionally may have the potential to serve as a marker of disease progress. These preliminary findings warrant further investigation in a larger patient cohort.

A comparison of clustering algorithms applied to fluid characterization using NMR T1-T2 maps of shale

Nuclear magnetic resonance T1-T2 maps are popular for characterizing fluids in shale. The characterization, however, is often done manually, which is difficult for shale due to its complicated nature. This work investigates the clustering approach for fluid characterization on T1-T2 maps by comparing 6 different algorithms: k-means, Gaussian mixture model, spectral clustering, and 3 hierarchical methods. T1-T2 maps are collected on shale samples at as-received and dried conditions. We propose two cluster validity indices to select the optimal cluster number and best algorithm. Our results validate the capability of the two indices. Gaussian mixture model is found to be the best algorithm in most of the cases, as its fluid partitioning shows the highest consistency with theoretical fluid boundaries. In addition, 5 fluid components are identified from Gaussian mixture model, and their values are qualitatively validated by comparing with those in literature. Results also indicate that clustering is sensitive to the fluid distribution. Drying the sample producing better clustering by revealing the footprint of organic matter. This work provides a practical guide for applying cluster analysis in fluid characterization in Nuclear magnetic resonance T1-T2 maps.

Frequency and Temperature Dependence of 2D NMR T1-T2 Maps of Shale

Frequency and Temperature Dependence of 2D NMR T1-T2 Maps of Shale

Setting Characteristics, Mechanical Properties and Microstructure of Cement Pastes Containing Accelerators Mixed with Superabsorbent Polymers (SAPs): An NMR Study Combined with Additional Methods.

In this study, the setting property and mechanical strength of cement pastes containing accelerators (CPCA) with or without superabsorbent polymers (SAPs) were first studied. The early microstructure evolution and water distribution at 7 and 28 days were probed by 1D (T2) and 2D (T1-T2 maps) H1 nuclear magnetic resonance (NMR) relaxometry, and the microstructure was systematically investigated by using mercury intrusion porosimetry (MIP), back-scattered electron (BSE) image and energy-dispersive X-ray spectroscopy (EDX) analysis. Results showed that the SAPs in the cement paste containing accelerators had various influences on setting time and compressive strength depending on the type of accelerators. The presence of SAPs in the cement paste containing alkaline free accelerators could alleviate the decrease of internal relative humidity, promote hydration and help to modify the pore structure. Moreover, it was observed that the SAP cavities could be nicely filled with calcium hydroxide (CH) in the cement paste with alkaline free accelerators.

A new method for measuring shale porosity with low-field nuclear magnetic resonance considering non-fluid signals

Abstract Porosity is a key parameter for the evaluation of potential shale oil and gas resources. Low-field nuclear magnetic resonance (NMR) is a rapid technique for measuring shale porosity without causing damage to the testing samples. Previous NMR methods for porosity characterization are mainly based on the NMR T2 distribution of saturated oil shale, but for shales with high total organic carbon (TOC) and clay mineral contents, not all signals of NMR detection originate from the pore fluid. Nine continental shales in Damintun Sag were selected and subjected to pyrolysis, X-ray diffraction (XRD), mercury injection capillary pressure (MICP), weighing before and after fluid saturation, and NMR tests to improve the accuracy of NMR porosity measurements. According to the NMR T2 distribution and T1–T2 map of shale with different oil contents (original, extracted, and saturated oil states), we revealed that the non-fluid signals (kerogen and structural water) accounted for 15.77%–43.10% (with a mean of 28.87%) of saturated oil shale. A stronger NMR signal intensity was observed for the extracted shale with higher TOC and clay mineral contents. A ΔT2 distribution of oil present in the pores of oil-saturated shale was constructed based on the difference between the oil-saturated shale and extracted shale and was combined with the calibration equation of oil (the relationship between oil volume and its NMR signal intensity) to directly evaluate the porosity. The porosity that was calculated based on the ΔT2 distribution versus the weighing method had an absolute error of ≤0.7%, and the relative error was

Integration of critical care echo with other noninvasive cardiac imaging techniques

The gradual integration of echocardiography with other noninvasive imaging techniques continues to progress, giving the practicing critical care clinician increasing diagnostic capability. Such capability can be divided into four main areas – coronary artery disease, myocardial pathology, valvular disease, and cardiac function. Coronary artery disease The presence of segmental wall defects on echocardiography alerts the clinician as to a high likelihood of underlying epicardial coronary artery disease (CAD). At the bedside the use of echocardiographic myocardial perfusion techniques can often further differentiate between ischaemic and nonischaemic aetiologies. Coronary computerized Tomographic Angiography (CCTA) over the last decade has moved from being a guide to the presence of CAD, to now offering accurate anatomical assessment, often being used as a first line diagnostic tool.The addition of Fractional Flow Reserve (FFR-CT) now adds a functional assessment of perfusion, reaching an accuracy of that obtained with invasive coronary angiography FFR studies.A noninvasive nuclear medicine alternative is SPECT or Single Photon Emission Computed Tomography which also has high diagnostic capability. Myocardial Pathology When abnormal myocardial appearances are found with echocardiography, it is difficult to be certain of the underlying pathology and historically a myocardial biopsy is considered when seeking to identify presumed inflammatory changes of unknown aetiology. The advent of Cardiac Magnetic Resonance (CMR) assists the physician in the differential diagnosis. The judicious use of T1 mapping, T2 mapping and gadolinium helps differentiate between fibrosis,inflammation and oedema. Valve pathology Although echocardiography remains the major modality is assessing valve function in the critically ill patient, CMR can improve evaluation with prosthetic valves. Myocardial function Echocardiography using Strain have enhance our ability to assess myocardial function. Positron Emission Tomography (PET) using isotopic-labelled substrates offers opportunities to exam metabolic function in the myocardium.It can determine glucose and fatty acid uptake in addition to targeting the mitochondria and angiogenesis. Although challenges arise in the need for a patient to be transferred, information gained may outweigh the risks in some patients. The sophistication of echocardiographic techniques continues to evolve but the wise physician will be cognizant of other noninvasive imaging modalities in an effort to further optimize patient management.

Diagnosing and sports counselling of athletes with myocarditis

Myocarditis is defined as an inflammation of the heart muscle and its presentation, especially in athletes, is heterogeneous. Underlying causes include in most of the cases viruses, and less often bacteria, toxins, vasculitic diseases or pharmaceutical agents. Cardiac magnetic resonance (CMR) imaging is the primary imaging tool to diagnose myocarditis following laboratory test, electrocardiogram and echocardiography. In certain cases, endomyocardial biopsy is required, especially in unclear cases with reduced systolic left ventricular ejection fraction. Although, athletes and sport physicians face the dilemma of significant performance decline in competitive athletes against the risk of adverse cardiac events, currently abstinence from competitive sports is recommended for at least 3–6 months in myocarditis. Sports recommendations are currently based mainly on autopsy studies and experts’ opinions and better risk stratification tools are imperatively needed. New tissue characterization methods, namely T1 mapping and T2 mapping in CMR continue to improve sensitivity and specificity of diagnosing myocarditis and may further enhance individual risk assessment. In the future, sports physicians may be able to rely more on these novel noninvasive tissue characterisation methods in risk stratification and sports restriction recommendations of athletes with suspected myocarditis.

Two-dimensional nuclear magnetic resonance method for wettability determination of tight sand

The wettability of reservoir rocks is important for oil recovery and reserve calculations. However, current methods for evaluating the wettability of rocks are time-consuming and expensive. Previous work has shown that low-field nuclear magnetic resonance (NMR) is a potentially useful and non-invasive technique for rock wettability determination. However, for rocks with strong internal magnetic field gradients, the current method is less efficient. In this study, the bipolar pulsed field gradient (PFG)-Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence was applied to the study of rock wettability. This method can suppress the effect of the internal magnetic field gradient in rocks and accurately extract wettability information. The diffusion-transverse relaxation time (D-T2) method was employed to quantitatively estimate the wettability of rocks. Results of Amott wettability tests and NMR T1-T2 maps were combined to provide a more complete wettability characterization of tight sand. The results demonstrate the feasibility of the new method for characterizing wettability. The proposed method and workflow is of significance to the development of oil fields.

Numerical Investigations of NMR T1–T2 Map in Two-Phase Fluid-Bearing Tight Sandstone

Study of two-dimensional nuclear magnetic resonance (NMR) longitudinal and transverse relaxation time (T1–T2) responses of tight reservoirs and optimization of T1–T2 acquisition parameter are of significance for exploration and development of tight oil and gas reservoirs. In this paper, a tight sandstone digital model was generated using a micro-CT scanning technique, and the random-walk method was modified to simulate the T1–T2 measurements in a two-phase fluid-bearing tight sandstone. The echo data of the saturation-recovery Carr–Purcell–Meiboom–Gill pulse sequence were acquired and processed to obtain a T1–T2 map. We compared oil–water-bearing tight sandstone T1–T2 maps with gas–water-bearing tight sandstone T1–T2 maps, and analyzed how fluid types, various degrees of fluid saturation, acquisition parameters, and signal-to-noise ratio (SNR) of NMR data affected T1–T2 maps. The research indicated that NMR T1–T2 logging is more suitable for identifying gas-bearing reservoirs, rather than oil-bearing reservoirs. NMR-logging acquisition parameters have different influences on various fluid-bearing tight sandstone T1–T2 maps. Increasing either the magnetic field gradient or echo spacing leads to a leftward shift of the gas signal, but does not affect the water signal and the oil signal in a T1–T2 map; the T1–T2 map with a mixed group of wait time is better than that with a long or short group of wait time in providing fluid relaxation information. The NMR data with lower SNR result in stronger divergence of fluid signal in T1–T2 map, rendering it more difficult to identify the fluid according to the map, and a data SNR more than 21 is recommended.

NMR relaxometry a new approach to detect geochemical properties of organic matter in tight shales

Understanding organic matter properties in terms of maturity and production potential are crucial for the initial assessment of unconventional plays. This is important since the amount of hydrocarbon that can be generated is a function of organic matter type and content in the formation and its thermal maturity. The complexity of shale plays in terms of constituent components has demonstrated that new analytical methods should be acquired to better understand hydrocarbon generation processes. In this study, a few samples from the upper and lower members of the Bakken Formation in the USA were selected from different depths and maturity levels. The samples were analyzed by a high frequency (22 MHz) nuclear magnetic resonance (NMR relaxometry) equipment, followed by Rock-Eval pyrolysis (using the Basic/Bulk-Rock method for all samples and a multi-heating rate method, MHR, for the two least mature samples) and bitumen reflectance evaluations. Results showed NMR can detect different hydrogen populations within the samples and distinguish among phases, such as solid organic matter, hydrocarbons (mobile oil), and water by T1-T2 mapping. We were also able to relate different identified areas on NMR T1-T2 maps to geochemical parameters of the organic matter obtained from Rock-Eval pyrolysis (such as S1, S2, and HI) and with thermal maturity (vitrinite reflectance-equivalent).

Magnetic resonance multitasking for motion-resolved quantitative cardiovascular imaging.

Quantitative cardiovascular magnetic resonance (CMR) imaging can be used to characterize fibrosis, oedema, ischaemia, inflammation and other disease conditions. However, the need to reduce artefacts arising from body motion through a combination of electrocardiography (ECG) control, respiration control, and contrast-weighting selection makes CMR exams lengthy. Here, we show that physiological motions and other dynamic processes can be conceptualized as multiple time dimensions that can be resolved via low-rank tensor imaging, allowing for motion-resolved quantitative imaging with up to four time dimensions. This continuous-acquisition approach, which we name cardiovascular MR multitasking, captures — rather than avoids — motion, relaxation and other dynamics to efficiently perform quantitative CMR without the use of ECG triggering or breath holds. We demonstrate that CMR multitasking allows for T1 mapping, T1-T2 mapping and time-resolved T1 mapping of myocardial perfusion without ECG information and/or in free-breathing conditions. CMR multitasking may provide a foundation for the development of setup-free CMR imaging for the quantitative evaluation of cardiovascular health.

The influences of walking, running and stair activity on knee articular cartilage: Quantitative MRI using T1 rho and T2 mapping.

ObjectiveTo explore the different influences of walking, running and stair activity on knee articular cartilage with T1 rho and T2 mapping sequences.Materials and methodsMRI (3.0-T) scans of the right knee were performed in twenty-three young healthy adults immediately after 30 minutes of rest, walking, running and stair activity respectively. Articular cartilage was quantitatively assessed based on T1 rho and T2 relaxation times. Analysis of variance for random block design data, bonferroni test and paired samples t tests were performed to estimate the different influences of physiological activities on articular cartilage.ResultsT1 rho and T2 values had reductions after physiological activities in all regions of articular cartilage. T1 rho and T2 values were decreased more after running than walking. T1 rho and T2 values were decreased more after stair activity than running, except for femoral cartilage. The superficial layer of patella cartilage had higher reduction rates than the deep layer. The T1 rho and T2 values of articular cartilage were reduced in the following order: patellofemoral cartilage> medial tibiofemoral cartilage> lateral tibiofemoral cartilage. Patellofemoral cartilage experienced reductions in the following order: lateral part> middle part> medial part. Tibiofemoral cartilage had reductions in the following order: posterior part> middle part> anterior part.ConclusionsT1 rho and T2 mapping sequences can quantitatively reflect the different influences of physiological activities on knee articular cartilage. Fluid shifts, collagen fiber deformation, spatial heterogeneity, inherent differences in material properties and tissue stiffness have close relationship with cartilage loading characteristics.

Geochemical and petrophysical source rock characterization of the Vaca Muerta Formation, Argentina: Implications for unconventional petroleum resource estimations

The Vaca Muerta Formation is currently regarded as the most prolific source rock interval for unconventional petroleum exploration in Argentina. In this study, we integrate recent CT-scanner, nuclear magnetic resonance (NMR) T1-T2 and Rock-Eval Shale Play® analytical techniques, combined with classical geochemical, petrological and petrophysical methods to characterize Vaca Muerta source rocks along a vertical profile. The proposed analytical workflow was tested here on 4 samples derived from one core: the LJE-1010 borehole drilled in the lowermost Jurassic Vaca Muerta member (Neuquén Basin – Argentina), to evaluate the unconventional hydrocarbon potential and pore network attributes. First, entire rock samples were analyzed by dual energy CT scanner to evaluate possible heterogeneities; this also helped in the selection of representative samples. Then the organic matter properties were investigated by open-system pyrolysis techniques, organic petrography and biomarker analyses as a function of the core depth. A comparative approach between open-system pyrolysis methods (e.g. Rock-Eval Basic/Bulk-Rock & Shale Play® methods vs. Source Rock Analyzer) is also illustrated in this work. Finally, petrophysical characteristics and pore network attributes in shale were estimated by gas permeability (steady-state method corrected for Klinkenberg effect), porosity and NMR methods. The investigated samples have oil-window maturity and are characterized by a network of solid bitumen. Based on new Rock-Eval Shale Play® data, the potentially producible oil present in the rock samples was estimated using the modified oil saturation index (OSI=Sh0+Sh1 peaks×100/TOC). Results indicate that the oil crossover effect and potential productive oils occur within intervals showing higher TOC values (~3 to 8wt%). We also illustrated here that, for unconventional shale play perspectives, Rock-Eval Shale Play® parameters (Sh0 & Sh1) allow to obtain both a better quantification of free and retained hydrocarbons in source-reservoir rock samples and correct original oil in place (OOIP) estimations in early exploration campaign for shale oil and shale gas assessment. For Vaca Muerta rock samples, OOIP estimations range from 60 to 160bbl oil/acre-ft, approximately. We also demonstrated that the solid bitumen, oil and organic matter are clearly distinguished in the studied samples using advanced NMR T1-T2 maps obtained at different temperatures. The solid bitumen was clearly evidenced as a peak with T1/T2 ratio~14 on NMR T1-T2 maps. Concerning the matrix bulk rock permeability, the obtained results showed that the most deep sample is characterized by a permeability of about 140nanoDarcy (nD) whereas the shallower sample containing also higher amounts of organic matter is more permeable (~213nD), indicating that TOC values play a main control on Vaca Muerta poromechanical characteristics. The maximum total porosity values range between 6.5 and 21.8% and were calculated in this work integrating NMR and helium porosity values. Finally, global interpretations of these obtained results suggest that the Vaca Muerta Formation could be considered as a prolific shale play interval for unconventional petroleum exploration in the near future.

Evaluation of Rabbit VX2 Tumor Model Using Magnetic Resonance T1-Mapping and T2-Mapping Techniques at 1.5T

Most routine magnetic resonance imaging only investigates morphology differences between normal and abnormal tissues. Magnetic resonance T1 and T2 relaxation times are important indices for evaluating pathological changes in tissue. T1-mapping and T2-mapping techniques can be used to perform quantitative analysis as well as qualitative analysis of tissue characteristics. This study aimed to perform long-term monitoring of the VX2 tumor progression and distribution on New Zealand rabbit thigh tissue using three dimensional T1-weighted (T1W) sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE), T2-weighted (T2W) SPACE, T1-mapping and T2-mapping techniques. The signal intensity (SI), T1 and T2 relaxation times of normal muscle and VX2 tumor were measured to evaluate the tumor characteristics. The nonparametric Mann–Whitney U test results showed that there were significant differences in SIs of T1W SPACE images, SIs of T2W SPACE images, T1 relaxation time and T2 relaxation time at the same day after VX2 implantation between normal tissue and VX2 tumor (p values < 0.05). There were also significant differences in time course average values of SIs of T1W SPACE images, SIs of T2W SPACE images, T1 relaxation time and T2 relaxation time between normal tissue and VX2 tumor (p values < 0.05). T2W SPACE, T1 mapping and T2 mapping were superior to T1W SPACE in the early detection of VX2 tumor. T1 mapping and T2 mapping techniques could be used to evaluate tumor growth and metastasis. T1 and T2 maps might be referenced as biomarkers and predictive indices in the evolution of pathologies.

Insight into oil and gas-shales compounds signatures in low field 1H NMR and its application in porosity evaluation

The low field 1H NMR characterization of rock components that are specific for oil- and gas- shales is presented. 1D T2 distributions together with T1-T2 maps and T1/T2 ratios for the samples of smectite, illite, illite-smectite, kaolinite, chlorite and kerogen served to obtain characteristic features. T1-T2 maps measured in three saturation states (native, saturated and dried) allowed the observation of different fractions of water such as water confined in interlayer spaces, filling pore spaces and hydroxyl groups from crystallographic lattice. Differential images are proposed for the evaluation of water distribution in the pore spaces and values of porosity, directly related to the fluid removed after the drying of the sample. Porosity values for exemplary shale samples, calculated for differential results are consistent with the porosity obtained using T2 cut-offs. The relations between cation exchange capacity and T2 log-mean values for the samples at different saturation states are also shown.

Petrophysical characterization of tight oil formations using 1D and 2D NMR

Porosity and fluid types in pores are crucial parameters in evaluating the quality of a tight oil reservoir in both laboratory analyses and log interpretation. As an advanced technique, nuclear magnetic resonance (NMR) has been applied in oilfields to acquire specific petrophysical properties of rocks. In order to interpret NMR data collected from actual oil wells more accurately, it is necessary to perform experiments in the laboratory and then make a well-designed contribution. Due to the complex components of low-permeable rocks, the petrophysical characterization of tight oil formations with both 1D and 2D NMR techniques remains a challenge. In this study, we designed novel NMR experimental procedures to characterize petrophysical properties of tight oil formations. We first investigated optimal parameters for measuring porosities of core samples. In order to explain the porosity differences between NMR porosity and water porosity, we examined contents of hydrogen-bearing matters and studied their total effects on measured porosity. Then, we performed a series of experiments to make core samples in five states, including water saturated state, after-centrifugation state, light oil saturated state, fresh state, and oven drying state. Each state represented a special fluid type, and hydrogen-bearing matters in cores were tried to be identified. Based on experimental results and similarity analyses, identification graphs of hydrogen-bearing phases were made by using 1D T2 spectrums and a 2D T1-T2 map. Our results can not only expand the applications of NMR core analyses, but also help to interpret NMR logging data better.

Associations of three-dimensional T1 rho MR mapping and three-dimensional T2 mapping with macroscopic and histologic grading as a biomarker for early articular degeneration of knee cartilage.

T1 rho and T2 mapping are magnetic resonance imaging (MRI) techniques to detect early degenerative changes in cartilage. Recent advancements have enabled 3D acquisition for both techniques. The objective of the present study was to examine the correlation of 3D T1 rho and 3D T2 mapping with macroscopic and histological characteristics of knee cartilage. Twenty-one patients who underwent total knee arthroplasty due to osteoarthritis with involvement of the medial compartment but with minimum involvement of the lateral compartment were enrolled. Prior to surgery, five series of MRI were acquired with a 3-T scanner. 3D T1 rho/T2 analyses were performed following determination of regions to be assessed using in-house software that incorporated three series of MRI acquisitions data (3D-MERGE, 3D-SPGR, and 3D-CUBE). During surgery, the cartilage of the lateral compartment was macroscopically assessed with the International Cartilage Research Society (ICRS) articular classification system. The extracted specimens were histologically assessed using the OARSI histology score. Three regions of interest (ROI) were assessed for each slice (two slices per knee): the central lateral femoral condyle (cLFC), the posterior portion of the lateral femoral condyle (pLFC), and the lateral tibia plateau (LTP). For each ROI, the mean T1 rho and T2 relaxation time, the ICRS grade, and the OARSI score were compared. Neither the T1 rho nor the T2 reflected the macroscopic grading. The T1 rho could discriminate between histological grades 1 and 2. However, the T2 could not. The T1 rho relaxation time was higher in the pLFC than in the cLFC even in the same grade. Compared to T2 mapping, T1 rho mapping may have an advantage in differentiating grades I and II cartilage degeneration on OARSI histological grading system.

Advances in Quantitative Tissue Characterization in Myocarditis

Myocarditis is a heterogeneous disease with variable histologic and clinical presentation. Cardiovascular magnetic resonance (CMR) imaging recently emerged as the imaging modality of choice in myocarditis. This review summarizes recent findings and future directions in this field. Advanced quantitative T1 mapping and T2 mapping methods have the technical advantage to detect diffuse myocardial injury in myocarditis, which was not adequately addressed by standard, semiquantitative CMR techniques so far. Recent studies demonstrated that the technical advantages of T1 and T2 mapping techniques improve the diagnostic accuracy and assessment of disease activity in myocarditis compared to standard CMR techniques using the Lake Louise Criteria for a CMR-based diagnosis of myocarditis. Quantitative tissue characterization by T1 and T2 mapping techniques will further enhance the value of CMR in myocarditis.

Evidence for Acute Myocardial and Skeletal Muscle Injury after Serial Transthoracic Shocks in Healthy Swine.

BackgroundPrevious serological studies have shown controversial results whether defibrillation or cardioversion can cause myocardial injury. Cardiovascular Magnetic Resonance (CMR) can be used to detect myocardial edema, hyperemia and capillary leak as features of acute myocardial injury. The aim of this study was to assess for myocardial and skeletal muscle injury in swine following transthoracic shocks.MethodsSeventeen anaesthetized swine were examined, with 11 undergoing five synchronized transthoracic shocks (200J). Myocardial and skeletal muscle injury were assessed at baseline and up to 5h post-shock employing T1 mapping, T2 mapping, early and late gadolinium enhancement. Serologic markers (cFABP, TnI, CK, and CK-MB) and myocardial tissue were assessed by standard histology methods.ResultsIn myocardial regions within the shock path, T1 and T2 were significantly increased compared to remote myocardium in the same animals. The early gadolinium enhancement ratio between the left-ventricular myocardium and the right pectoral muscle was also increased compared to control animals. After the shocks cFABP and CK were significantly elevated. After shock application, the regions identified as abnormal by CMR showed significantly increased interstitial and myocardial cell areas in histological analysis. This increased cell area suggests significant cellular and interstitial edema.ConclusionOur pilot study data indicate that serial defibrillator shocks lead to acute skeletal muscle and myocardial injury. CMR is a useful tool to detect and localize myocardial and skeletal muscle injury early after transthoracic shocks in vivo. In the future the technique could potentially be used as an additional tool for quality control such as verifying insufficient local shock application in non-responders after cardioversion or to develop safer shock forms.

Characterization of shales using T1–T2 NMR maps

Abstract Nuclear Magnetic Resonance (NMR) relaxation methods are key techniques for evaluating shales, from both cores and logging data. First, very small pore sizes, down to nano-meter length scales, can be detected and quantified if the NMR tool has the ability to measure relaxation times in the range [0.1–1 ms], and second the different proton populations (water, oil, gas, and kerogen) can be distinguished using 2D T1–T2 maps. We use a NMR instrument working at a higher frequency (23 MHz) that yields a much higher sensitivity than standard plug-size benchtop apparatus. In this work, we show the position of each proton population in this map: hydroxyls from the clay (T2