Morphological And Structural Mapping Of The Oudemans Impact Crater Layered Central Uplift, Mars

Central uplifts in large meteorite impact craters provide valuable information about the subsurface geology of planetary bodies. Compared to impact craters on Earth, Martian central uplifts can be well exposed and can be mapped in detail by using satellite imagery. Central uplifts preserve morphological and structural features formed as result of the combination of emplacement during the impact process, post impact modification, and erosion over time. In this study, the Oudemans Crater central uplift (the largest central uplift with layers on Mars) was investigated. Oudemans (9.89 S, 268.1 E) is 124 km in diameter and is located in the Sinai Planum at the western end of Valles Marineris canyon system; it also is part of the Tharsis province, which is major volcanic region on Mars. The central uplift was structurally and geomorphologically mapped and analyzed using High Resolution Imaging Science Experiment (HIRISE) imagery combined with other data sets tied to topographic data as a base map in Arc-GIS. The Oudemans Crater central uplift was divided into five main geomorphologic units: 1) exposed bedrock; 2) megabreccia; 3) clast-rich impact melt rock; 4) clast-poor and pitted impact melt; and 5) erosional deposits (mass wasting unit and aeolian deposit) units. Faults, folds, dykes, and deformed bedding were also mapped. Through structural mapping, deformed, folded, and fractured layers were mapped as they provide a frame of reference with respect to the structural deformation of the uplift. The preferred orientation of faults appears to be perpendicular to the impact trajectory (obliquity trend to the central uplift) and to be thrust faults. Four obvious folds were mapped towards the centre of the uplift consistent with increased deformation towards the crater centre. Dykes are typically perpendicular to the bedrock and can be seen mostly in the centre of the central uplift

Применение магнитотерапии для лечения заболеваний сердечно-сосудистой системы

Розроблено метод оперативного контролю і кількісної оцінки процесу лікування магнітним полем у динаміці. Пропонується розрахунок нормованого амплітудно-фазового індексу форми (НАФК) для сигналів пульсової хвилі, який дає змогу кількісно порівняти ступінь відмінності пульсових хвиль людини і має чутливість до впливу магнітного поля. Методологія оцінки ефективності застосування магнітотерапії заснована на реєстрації та обробці сигналів пульсових хвиль за допомогою технології нейронних мереж і обчисленні індексу форми для кожного пацієнта. В результаті досліджень визначено динаміку зміни значень НАФК у процесі комплексного лікування, яка дає можливість контролювати функціональне відновлення організму. Запропоновано алгоритм розрахунку НАФК на основі розкладання сигналу пульсової хвилі в ряд Фур’є. Проведені дослідження при лікуванні хворих із захворюваннями серцево-судинної системи дають змогу зробити висновки щодо застосування індексу НАФК для оцінки ефективності комплексного лікування. Чутливість індексу НАФК до зовнішнього впливу на пацієнта дає можливість використовувати індекс для кількісної оцінки функціонального стану і контролю динаміки комплексного лікування.Method for operational control and quantitative analysis of magnetic field treatment process dynamics was developed. The calculation of amplitude and phase index of form is offered for the signals of pulse wave, which allows quantitavely compare the degrees of difference of pulse waves, and has a sensitiveness to influence the magnetic field. Method for evaluating the effectiveness of the use of magnetic therapy based on registration and signal processing of pulse wave using the technology of neural networks and calculating the index form for each patient. As a result of studies determined the dynamics of shape change index that allows to conclude the prospects of using the normalized shape index for the development of a wide variety of medical procedures, including treatment of the magnetic field. The algorithm for calculating normalized shape index based on the decomposition of the signals pulse wave in the Fourier series is proposed. Studies in the treatment of patients with diseases of the cardiovascular system allow drawing conclusions regarding the application of the index — normalized amplitude-phase coefficient (NAPC) for evaluating the effectiveness of integrated treatment. Sensitivity index NAPC was set to external influence on the patient, which allows using an index for quantitative assessment of functional status and control of the dynamics of complex treatment.Разработан метод оперативного контроля и количественной оценки процесса лечения магнитным полем в динамике. Предлагается расчет нормированного амплитудно-фазового индекса формы (НАФК) для сигналов пульсовой волны, который позволяет количественно сравнить степень различия пульсовых волн и имеет чувствительность к воздействию магнитного поля. Методология оценки эффективности применения магнитотерапии основана на регистрации и обработке сигналов пульсовых волн с помощью технологии нейронных сетей и вычислении индекса формы для каждого пациента. В результате исследований определена динамика изменения значений НАФК в процессе комплексного лечения, которая позволяет контролировать функциональное восстановление организма. Предложен алгоритм расчета НАФК на основе разложения сигнала пульсовой волны в ряд Фурье. Проведенные исследования при лечении больных с заболеваниями сердечно-сосудистой системы позволяют сделать выводы относительно применения индекса НАФК для оценки эффективности комплексного лечения. Чувствительность индекса НАФК к внешнему воздействию на пациента позволяет использовать индекс для количественной оценки функционального состояния и контроля динамики комплексного лечения

A novel method for measuring bowel motility and velocity with dynamic magnetic resonance imaging in two and three dimensions

Increasingly, dynamic magnetic resonance imaging (MRI) has potential as a noninvasive and accessible tool for diagnosing and monitoring gastrointestinal motility in healthy and diseased bowel. However, current MRI methods of measuring bowel motility have limitations: requiring bowel preparation or long acquisition times; providing mainly surrogate measures of motion; and estimating bowel-wall movement in just two dimensions. In this proof-of-concept study we apply a method that provides a quantitative measure of motion within the bowel, in both two and three dimensions, using existing, vendor-implemented MRI pulse sequences with minimal bowel preparation. This method uses a minimised cost function to fit linear vectors in the spatial and temporal domains. It is sensitised to the spatial scale of the bowel and aims to address issues relating to the low signal-to-noise in high-temporal resolution dynamic MRI scans, previously compensated for by performing thick-slice (10-mm) two-dimensional (2D) coronal scans. We applied both 2D and three-dimensional (3D) scanning protocols in two healthy volunteers. For 2D scanning, analysis yielded bi-modal velocity peaks, with a mean antegrade motion of 5.5 mm/s and an additional peak at similar to 9 mm/s corresponding to longitudinal peristalsis, as supported by intraoperative data from the literature. Furthermore, 3D scans indicated a mean forward motion of 4.7 mm/s, and degrees of antegrade and retrograde motion were also established. These measures show promise for the noninvasive assessment of bowel motility, and have the potential to be tuned to particular regions of interest and behaviours within the bowel.Radiolog

Subchondral bone in osteoarthritis: association between MRI texture analysis and histomorphometry.

OBJECTIVE: Magnetic resonance imaging (MRI) texture analysis is a method of analyzing subchondral bone alterations in osteoarthritis (OA). The objective of this study was to evaluate the association between MR texture analysis and ground-truth subchondral bone histomorphometry at the tibial plateau. DESIGN: The local research ethics committee approved the study. All subjects provided written, informed consent. This was a cross-sectional study carried out at our institution between February and August 2014. Ten participants aged 57-84 with knee OA scheduled for total knee arthroplasty (TKA) underwent pre-operative MRI of the symptomatic knee at 3T using a high spatial-resolution coronal T1 weighted sequence. Tibial plateau explants obtained at the time of TKA underwent histological preparation to allow calculation of bone volume fraction (BV.TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp) and trabecular number (Tb.N). Texture analysis was performed on the tibial subchondral bone of MRI images matched to the histological sections. Regression models were created to assess the association of texture analysis features with BV.TV, Tb.Th, Tb.Sp and Tb.N. RESULTS: MRI texture features were significantly associated with BV.TV (R2 = 0.76), Tb.Th (R2 = 0.47), Tb.Sp (R2 = 0.75) and Tb.N (R2 = 0.60, all P < 0.001). Simple gray-value histogram based texture features demonstrated the highest standardized regression coefficients for each model. CONCLUSION: MRI texture analysis features were significantly associated with ground-truth subchondral bone histomorphometry at the tibial plateau.Royal College of Radiologists Pump Priming Gran

Effects of epitaxial strain on the growth mechanism of YBa2Cu3O7-x thin films in [YBa2Cu3O7-x / PrBa2Cu3O7-x] superlattices

We report on the growth mechanism of YBa2Cu3O7-x (YBCO). Our study is based on the analysis of ultrathin, YBa2Cu3O7-x layers in c-axis oriented YBa2Cu3O7-x / PrBa2Cu3O7-x superlattices. We have found that the release of epitaxial strain in very thin YBCO layers triggers a change in the dimensionality of the growth mode. Ultrathin, epitaxially strained, YBCO layers with thickness below 3 unit cells grow in a block by block two dimensional mode coherent over large lateral distances. Meanwhile, when thickness increases, and the strain relaxes, layer growth turns into three dimensional, resulting in rougher layers and interfaces.Comment: 10 pages + 9 figures, accepted in Phys. Rev.

A novel method for measuring bowel motility and velocity with dynamic magnetic resonance imaging in two and three dimensions

Increasingly, dynamic MRI has potential as a non-invasive and accessible tool for diagnosing and monitoring gastrointestinal motility in healthy and diseased bowel. However, current MRI methods of measuring bowel motility have limitations: requiring bowel preparation or long acquisition times; providing mainly surrogate measures of motion; and estimating bowel-wall movement in just two dimensions. In this proof-of-concept study we apply a method that provides a quantitative measure of motion within the bowel, in both 2D and 3D, using existing, vendor-implemented MRI pulse sequences with minimal bowel-preparation. This method uses a minimised cost function to fit linear vectors in the spatial and temporal domains. It is sensitised to the spatial scale of the bowel and aims to address issues relating to the low signal-to-noise in high-temporal resolution dynamic MRI scans, previously compensated for by performing thick-slice (10 mm) 2D coronal scans. We applied both 2D and 3D scanning protocols in two healthy volunteers. For 2D scanning, analysis yielded bi-modal velocity peaks, with a mean antegrade motion of 5.5 mm/s and an additional peak at ~9 mm/s corresponding to longitudinal peristalsis, as supported by intra-operative data from the literature. Furthermore, 3D scans indicated a mean forward motion of 4.7 mm/s, and degrees of ante- and retrograde motion were also established. These measures show promise for the non-invasive assessment of bowel motility, and have the potential to be tuned to particular regions of interest and behaviours within the bowel

Validation of left atrial volume correction for single plane method on four-chamber cine cardiac MRI

Background: Left atrial (LA) assessment is an important marker of adverse cardiovascular outcomes. Cardiovascular magnetic resonance (CMR) accurately quantifies LA volume and function based on biplane long-axis imaging. We aimed to validate single-plane-derived LA indices against the biplane method to simplify the post-processing of cine CMR. Methods: In this study, 100 patients from Leeds Teaching Hospitals were used as the derivation cohort. Bias correction for the single plane method was applied and subsequently validated in 79 subjects. Results: There were significant differences between the biplane and single plane mean LA maximum and minimum volumes and LA ejection fraction (EF) (all p < 0.01). After correcting for biases in the validation cohort, significant correlations in all LA indices were observed (0.89 to 0.98). The area under the curve (AUC) for the single plane to predict biplane cutoffs of LA maximum volume ≥ 112 mL was 0.97, LA minimum volume ≥ 44 mL was 0.99, LA stroke volume (SV) ≤ 21 mL was 1, and LA EF ≤ 46% was 1, (all p < 0.001). Conclusions: LA volumetric and functional assessment by the single plane method has a systematic bias compared to the biplane method. After bias correction, single plane LA volume and function are comparable to the biplane method

MRI texture analysis of subchondral bone at the tibial plateau

OBJECTIVES: To determine the feasibility of MRI texture analysis as a method of quantifying subchondral bone architecture in knee osteoarthritis (OA).   METHODS: Asymptomatic subjects aged 20-30 (group 1, n = 10), symptomatic patients aged 40-50 (group 2, n = 10) and patients scheduled for knee replacement aged 55-85 (group 3, n = 10) underwent high spatial resolution T1-weighted coronal 3T knee MRI. Regions of interest were created in the medial (MT) and lateral (LT) tibial subchondral bone from which 20 texture parameters were calculated. T2 mapping of the tibial cartilage was performed in groups 1 and 2. Mean parameter values were compared between groups using ANOVA. Linear discriminant analysis (LDA) was used to evaluate the ability of texture analysis to classify subjects correctly.   RESULTS: Significant differences in 18/20 and 12/20 subchondral bone texture parameters were demonstrated between groups at the MT and LT respectively. There was no significant difference in mean MT or LT cartilage T2 values between group 1 and group 2. LDA demonstrated subject classification accuracy of 97 % (95 % CI 91-100 %).   CONCLUSION: MRI texture analysis of tibial subchondral bone may allow detection of alteration in subchondral bone architecture in OA. This has potential applications in understanding OA pathogenesis and assessing response to treatment.   KEY POINTS: • Improved techniques to monitor OA disease progression and treatment response are desirable • Subchondral bone (SB) may play significant role in the development of OA • MRI texture analysis is a method of quantifying changes in SB architecture • Pilot study showed that this technique is feasible and reliable • Significant differences in SB texture were demonstrated between individuals with/without OA

Kat-ARC accelerated 4D flow CMR: clinical validation for transvalvular flow and peak velocity assessment

Background: To validate the k-adaptive-t autocalibrating reconstruction for Cartesian sampling (kat-ARC), an exclusive sparse reconstruction technique for four-dimensional (4D) flow cardiac magnetic resonance (CMR) using conservation of mass principle applied to transvalvular flow.   Methods: This observational retrospective study (2020/21-075) was approved by the local ethics committee at the University of East Anglia. Consent was waived. Thirty-five patients who had a clinical CMR scan were included. CMR protocol included cine and 4D flow using Kat-ARC acceleration factor 6. No respiratory navigation was applied. For validation, the agreement between mitral net flow (MNF) and the aortic net flow (ANF) was investigated. Additionally, we checked the agreement between peak aortic valve velocity derived by 4D flow and that derived by continuous-wave Doppler echocardiography in 20 patients.   Results: The median age of our patient population was 63 years (interquartile range [IQR] 54–73), and 18/35 (51%) were male. Seventeen (49%) patients had mitral regurgitation, and seven (20%) patients had aortic regurgitation. Mean acquisition time was 8 ± 4 min. MNF and ANF were comparable: 60 mL (51−78) versus 63 mL (57−77), p = 0.310). There was an association between MNF and ANF (rho = 0.58, p < 0.001). Peak aortic valve velocity by Doppler and 4D flow were comparable (1.40 m/s, [1.30−1.75] versus 1.46 m/s [1.25−2.11], p = 0.602) and also correlated with each other (rho = 0.77, p < 0.001).   Conclusions: Kat-ARC accelerated 4D flow CMR quantified transvalvular flow in accordance with the conservation of mass principle and is primed for clinical translation

Automated 4D flow cardiac MRI pipeline to derive peak mitral inflow diastolic velocities using short-axis cine stack: Two centre validation study against echocardiographic pulse-wave doppler

Background: Measurement of peak velocities is important in the evaluation of heart failure. This study compared the performance of automated 4D flow cardiac MRI (CMR) with traditional transthoracic Doppler echocardiography (TTE) for the measurement of mitral inflow peak diastolic velocities. Methods: Patients with Doppler echocardiography and 4D flow cardiac magnetic resonance data were included retrospectively. An established automated technique was used to segment the left ventricular transvalvular flow using short-axis cine stack of images. Peak mitral E-wave and peak mitral A-wave velocities were automatically derived using in-plane velocity maps of transvalvular flow. Additionally, we checked the agreement between peak mitral E-wave velocity derived by 4D flow CMR and Doppler echocardiography in patients with sinus rhythm and atrial fibrillation (AF) separately. Results: Forty-eight patients were included (median age 69 years, IQR 63 to 76; 46% female). Data were split into three groups according to heart rhythm. The median peak E-wave mitral inflow velocity by automated 4D flow CMR was comparable with Doppler echocardiography in all patients (0.90 ± 0.43 m/s vs 0.94 ± 0.48 m/s, P = 0.132), sinus rhythm-only group (0.88 ± 0.35 m/s vs 0.86 ± 0.38 m/s, P = 0.54) and in AF-only group (1.33 ± 0.56 m/s vs 1.18 ± 0.47 m/s, P = 0.06). Peak A-wave mitral inflow velocity results had no significant difference between Doppler TTE and automated 4D flow CMR (0.81 ± 0.44 m/s vs 0.81 ± 0.53 m/s, P = 0.09) in all patients and sinus rhythm-only groups. Automated 4D flow CMR showed a significant correlation with TTE for measurement of peak E-wave in all patients group (r=0.73, P<0.001) and peak A-wave velocities (r=0.88, P<0.001). Moreover, there was a significant correlation between automated 4D flow CMR and TTE for peak-E wave velocity in sinus rhythm-only patients (r=0.68, P<0.001) and AF-only patients (r=0.81, P=0.014). Excellent intra-and inter-observer variability was demonstrated for both parameters. Conclusion: Automated dynamic peak mitral inflow diastolic velocity tracing using 4D flow CMR is comparable to Doppler echocardiography and has excellent repeatability for clinical use. However, 4D flow CMR can potentially underestimate peak velocity in patients with AF