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PurposeMagnetization transfer (MT) MRI can be effective for the diagnosis of a broad range of fibrotic diseases, including liver fibrosis. However, respiratory motion, a major source of artifacts in thoracic and abdominal MR imaging, can obscure important anatomic structures, making diagnosis difficult. In this study, we explored the potential to combine free-breathing (FB) respiratory self-gating (RSG) methods with MT saturation for FB MT ratio (MTR) measurements of abdominal organs.MethodsA respiratory self-gated multiple-gradient recalled echo sequence with MT presaturation (RSG-MT GRE) was developed and applied in a series of seven normal volunteers. We compared the MTR values of liver, pancreas, kidney, spleen, and posterior paraspinal muscle measured using our RSG-MT GRE sequence and a conventional MT GRE sequence.ResultsRSG consistently reduced motion artifacts within MT-weighted images acquired during FB, improved the accuracy of FB MTR measurements, and produced comparable MTRs to breath-holding MTR measurements.ConclusionRSG approaches may offer to improve the utility of MT-weighted imaging methods for the assessment of fibrotic diseases and tumor desmoplasia in abdominal organs.

BackgroundWithout the need of contrast media, diffusion-weighted imaging (DWI) has shown great promise for accurate detection of lipid-rich necrotic core (LRNC), a well-known feature of vulnerable plaques. However, limited resolution and poor image quality in vivo with conventional single-shot diffusion-weighted echo planar imaging (SS-DWEPI) has hindered its clinical application. The aim of this work is to develop a diffusion-prepared turbo-spin-echo (DP-TSE) technique for carotid plaque characterization with 3D high resolution and improved image quality.MethodsUnlike SS-DWEPI where the diffusion encoding is integrated in the EPI framework, DP-TSE uses a diffusion encoding module separated from the TSE framework, allowing for segmented acquisition without the sensitivity to phase errors. The interleaved, motion-compensated sequence was designed to enable 3D black-blood DWI of carotid arteries with sub-millimeter resolution. The sequence was tested on 12 healthy subjects and compared with SS-DWEPI for image quality, vessel wall visibility, and vessel wall thickness measurements. A pilot study was performed on 6 patients with carotid plaques using this sequence and compared with conventional contrast-enhanced multi-contrast 2D TSE as the reference.ResultsDP-TSE demonstrated advantages over SS-DWEPI for resolution and image quality. In the healthy subjects, vessel wall visibility was significantly higher with diffusion-prepared TSE (p

BackgroundMulti-contrast weighted imaging is a commonly used cardiovascular magnetic resonance (CMR) protocol for characterization of carotid plaque composition. However, this approach is limited in several aspects including low slice resolution, long scan time, image mis-registration, and complex image interpretation. In this work, a 3D CMR technique, named Multi-contrast Atherosclerosis Characterization (MATCH), was developed to mitigate the above limitations.MethodsMATCH employs a 3D spoiled segmented fast low angle shot readout to acquire data with three different contrast weightings in an interleaved fashion. The inherently co-registered image sets, hyper T1-weighting, gray blood, and T2-weighting, are used to detect intra-plaque hemorrhage (IPH), calcification (CA), lipid-rich necrotic core (LRNC), and loose-matrix (LM). The MATCH sequence was optimized by computer simulations and testing on four healthy volunteers and then evaluated in a pilot study of six patients with carotid plaque, using the conventional multi-contrast protocol as a reference.ResultsOn MATCH images, the major plaque components were easy to identify. Spatial co-registration between the three image sets with MATCH was particularly helpful for the reviewer to discern co-existent components in an image and appreciate their spatial relation. Based on Cohen's kappa tests, moderate to excellent agreement in the image-based or artery-based component detection between the two protocols was obtained for LRNC, IPH, CA, and LM, respectively. Compared with the conventional multi-contrast protocol, the MATCH protocol yield significantly higher signal contrast ratio for IPH (3.1±1.3 vs. 0.4±0.3, p

The process of bridge construction is accompanied by many uncertainties. These uncertainties can have an impact on the quality of bridge construction and are thus directly related to the safe operation of the bridge. Therefore, it is very important to conduct bridge construction quality control evaluations for safe bridge construction and operation. In this paper, a three-tier bridge construction quality control evaluation system is established. This study uses a combination of subjective and objective assignment methods and TOPSIS theory to carry out an evaluation calculation of bridge construction quality. The CWM-TOPSIS theory was applied to the actual engineering calculation by taking the construction process of a mega bridge across the Yellow River as an example. After a series of calculations, the bridge construction quality evaluation results were obtained as level IV. This showed that a construction quality control method was needed for this bridge as soon as possible, and inspection and protection of the bridge should be started to avoid the emergence of bigger quality problems. Finally, the accuracy and applicability of the method proposed in this paper were proved by comparing and analyzing the evaluation results with the standard element theory. [ABSTRACT FROM AUTHOR]

The Zhangjiatan shale of the Southeastern Ordos Basin, which deposits in deep lake facies, has strong lithologic heterogeneity; it represents as shale, sandy laminae shale and thin sandstone. Shale with mm- to cm-scale sandy laminae is defined as Sandy Laminae Shale (SLS). However, the relationship between lithologic heterogeneity and hydrocarbon accumulation has never been studied. This study shows that lithologic heterogeneity, especially the occurrence of SLS will influence the accumulation of hydrocarbons within the shale system. SLS commonly has a larger pore size, higher porosity and better connectivity than thick and homogeneous shale. SLS commonly contains fewer residual hydrocarbons than homogeneous thick shale, indicating comparative ease in hydrocarbon expulsion. SLS commonly generates more bedding fractures. More fractures can be incurred when fracture extending into SLS. The occurrence of SLS can provide more storage spaces for fluids and gases, including oil, water, adsorbed gas, dissolved gas and free gas. SLS has been the pilot exploration and development target for shale hydrocarbon in the southeastern Ordos Basin. Homogeneous and thick shales, which have a large content of residual hydrocarbons, would be the targets for future exploration.

Although neutral in situ leaching through CO2 + O2 is employed to extract uranium (U) in sandstone by in situ leaching (ISL), mechanisms of U mobilization and O2 consumption remained unclear. To address this gap, 18 groundwater samples were taken from the Qianjiadian sandstone U ore field, including seven samples from production wells in mining area M1 (mining for 5 years), six samples from production wells in mining area M2 (mining for 4 years), and five samples from monitoring wells (GC), to quantify U‐mobilizing processes in the mining aquifer by employing hydrogeochemical compositions and multi‐isotopes. The introduction of O2 and CO2 efficiently stimulated U mobilization in the mining aquifer. The injected CO2 critically promoted the dissolution of carbonate minerals, which enhanced the formation of uranyl carbonate (predominantly CaUO2(CO3)22− and Ca2UO2(CO3)3(aq)) and thus facilitated U mobility. Generally, δ34SSO4 and δ18OSO4 in M2 and M1 were significantly lower than those in GC (p < 0.01). A Bayesian isotope mixing model of δ34SSO4 and δ18OSO4 showed that the contribution of pyrite oxidation to SO42− concentration increased from 1.7% in GC to 13.6% in M2 and to 15.0% in M1. During ISL, pyrite, ammonium, and dissolved organic carbon were major compounds competing with U(IV) for introduced O2 in the ore‐bearing aquifer. Most of the consumed O2 was used for pyrite oxidation (56.2%) and U(IV) oxidation (39.3%), following the thermodynamic sequence of those redox reactions. The current results highlighted the significance of increasing O2 utilization efficiency in improving the performance of ISL operations. [ABSTRACT FROM AUTHOR]

Background: MRI‐targeted biopsy (MRTB) improves the clinically significant prostate cancer (csPCa) detection rate with fewer biopsy cores in men with suspected PCa. However, whether concurrent systematic biopsy (SB) can be avoided in patients undergoing MRTB remains unclear. Purpose: To evaluate the potential value of MRI‐based radiomics models in avoiding unnecessary SB in biopsy‐naïve patients. Study type: Retrospective. Population: A total of 226 patients (mean age 66.6 ± 9.02 years) with suspicion of PCa (PI‐RADS score ≥ 3) and received combined cognitive MRTB with SB were retrospectively recruited and randomly divided into training (N = 180) and test (N = 46) cohorts at an 8:2 ratio. Field Strength/Sequence: A 3.0 T, biparametric MRI (bpMRI) including T2‐weighted imaging (T2WI) and apparent diffusion coefficient (ADC) map. Assessment: The whole prostate gland (PG) and the index lesion (IL) were delineated. Three radiomics models of bpMRIPG, bpMRIIL, and bpMRIPG+IL were constructed, respectively, and the performance of each radiomics model was compared with that of PI‐RADS assessment. Statistical Tests: The least absolute shrinkage and selection operator (LASSO) regression method was used to select texture features. The area under the curve (AUC) and decision curve analysis were used to estimate the models. Results: The bpMRIPG+IL radiomics model exhibited good discrimination, calibration, and net benefits, which would reduce the SB biopsy in 71.2% and 71.4% of men with PI‐RADS ≥ 5 lesions in the training and test cohorts, respectively. Data Conclusion: A bpMRIPG+IL radiomics model may outperform PI‐RADS category in help reducing unnecessary SB in biopsy‐naïve patients. Evidence Level: 3 Technical Efficacy: Stage 6 [ABSTRACT FROM AUTHOR]