The Effect of Equatorial noise on the Proton Density Structure of the Inner Van Allen Belt

The magnetic resonance images and maps of bovine ovaries acquired at defined phases of follicular development and regression were studied to determine whether magnetic resonance image attributes of the follicular antrum reflect the physiological status of dominant and subordinate ovarian follicles. Ovariectomies were performed at day 3 of wave one, day 6 of wave one, day 1 of wave two and at >/= day 17 after ovulation. The timings of ovariectomies were selected to acquire growing, early static, late static and regressing follicles of the first wave and preovulatory follicles of the ovulatory wave. Pre-selection and subordinate follicles were also available for analysis. Serum samples were taken on the day of ovariectomy and follicular fluid samples were taken after imaging. Numerical pixel value and pixel heterogeneity in a spot representing approximately 95% of the follicular antrum were quantified in T(1)- and T(2)-weighted images. T(1) and T(2) relaxation rates (T(1) and T(2)), proton density, apparent diffusion coefficients and their heterogeneities were determined from the computed magnetic resonance maps. The antra of early atretic dominant follicles showed higher T(2)-weighted mean pixel value (P < 0.008) and heterogeneity (P < 0. 01) and lower T(2) heterogeneity (P < 0.008) than growing follicles. Subordinate follicles in the presence of a preovulatory dominant follicle had higher T(1), T(1) heterogeneity, proton density, proton density heterogeneity, and lower mean pixel value in T(1)-weighted images than subordinate follicles of the anovulatory wave (P < 0.04). T(1) relaxation rate heterogeneity and proton density heterogeneity were positively correlated with follicular fluid oestradiol concentration (r = 0.4 and 0.3; P < 0.04). T(2) relaxation rate heterogeneity was positively correlated with follicular fluid progesterone concentration (r = 0.4; P < 0.008). Quantitative differences in magnetic resonance image attributes of the antrum observed among phases of follicular development and regression coincided with changes in the ability of the dominant follicle to produce steroid hormones and ovulate, and thus were indicative of physiological status and follicular health.

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Calcium-Suppressed Technique in Dual-Layer Detector Computed Tomography to Evaluate Knee Articular Cartilage

Current Medical Imaging Formerly Current Medical Imaging Reviews ◽

10.2174/1573405616666201008150644 ◽

2020 ◽

Vol 16 ◽

Author(s):

Qinglin Meng ◽

Mengqi Liu ◽

Weiwei Deng ◽

Ke Chen ◽

Botao Wang ◽

...

Keyword(s):

Computed Tomography ◽

Bone Marrow ◽

Articular Cartilage ◽

Bone Marrow Edema ◽

Knee Joints ◽

Infrapatellar Fat Pad ◽

Proton Density ◽

Knee Cartilage ◽

Significant Difference ◽

Marrow Edema

Background: Calcium-suppressed (CaSupp) technique involving spectral-based images has been used to observe bone marrow edema by removing calcium components from the image. Objective: This study aimed to evaluate the knee articular cartilage using the CaSupp technique in dual-layer detector computed tomography (DLCT). Methods: Twenty-eight healthy participants and two patients with osteoarthritis were enrolled, who underwent DLCT and magnetic resonance imaging (MRI) examination. CaSupp images were reconstructed from spectral-based images using a calcium suppression algorithm and were overlaid conventional CT images for visual evaluation. The morphology of the knee cartilage was evaluated, and the thickness of the articular cartilage was measured on sagittal proton density– weighted and CaSupp images in the patellofemoral compartment. Results: No abnormal signal or density, cartilage defect, and subjacent bone ulceration were observed in the lateral and medial femorotibial compartments and the patellofemoral compartment on MRI images and CaSupp images for the 48 normal knee joints. CaSupp images could clearly identify cartilage thinning, defect, subjacent bone marrow edema, and edema of the infrapatellar fat pad in the same way as MRI images in the three knee joints with osteoarthritis. A significant difference was found in the mean thickness of the patellar cartilage between MRI images and CaSupp images, while the femoral cartilage presented no significant difference in thickness between MRI images and CaSupp images over all 48 knee joints. Conclusion: The present study demonstrated that CaSupp images could effectively be used to perform the visual and quantitative assessment of knee cartilage.

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DENSITY STRUCTURE OF CRATONIC LITHOSPHERE MANTLE: A TALE OF FOUR CRATONS

10.1130/abs/2019am-335680 ◽

2019 ◽

Author(s):

Irina M. Artemieva ◽

◽

Alexey Shulgin ◽

Bing Xia ◽

Yulia Cherepanova ◽

...

Keyword(s):

Density Structure

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Disruption of the Atlantic Meridional Circulation during Deglacial Climates Inferred from Planktonic Foraminiferal Shell Weights

Journal of Marine Science and Engineering ◽

10.3390/jmse9050519 ◽

2021 ◽

Vol 9 (5) ◽

pp. 519

Author(s):

Stergios D. Zarkogiannis

Keyword(s):

Atlantic Ocean ◽

Meridional Circulation ◽

Order Approximation ◽

Planktonic Foraminifera ◽

Sediment Cores ◽

Meridional Overturning Circulation ◽

Density Structure ◽

Last Interglacial ◽

Shell Weight ◽

The North

Changes in the density structure of the upper oceanic water masses are an important forcing of changes in the Atlantic Meridional Overturning Circulation (AMOC), which is believed to widely affect Earth’s climate. However, very little is known about past changes in the density structure of the Atlantic Ocean, despite being extensively studied. The physical controls on planktonic foraminifera calcification are explored here, to obtain a first-order approximation of the horizontal density gradient in the eastern Atlantic during the last 200,000 years. Published records of Globigerina bulloides shells from the North and Tropical eastern Atlantic were complemented by the analysis of a South Atlantic core. The masses of the same species shells from three different dissolution assessed sediment cores along the eastern Atlantic Ocean were converted to seawater density values using a calibration equation. Foraminifera, as planktonic organisms, are subject to the physical properties of the seawater and thus their shells are sensitive to buoyancy forcing through surface temperature and salinity perturbations. By using planktonic foraminifera shell weight as an upper ocean density proxy, two intervals of convergence of the shell masses are identified during cold intervals of the last two deglaciations that may be interpreted as weak ocean density gradients, indicating nearly or completely eliminated meridional circulation, while interhemispheric Atlantic density differences appear to alleviate with the onset of the last interglacial. The results confirm the significance of variations in the density of Atlantic surface waters for meridional circulation changes.

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Free‐breathing multitasking multi‐echo MRI for whole‐liver water‐specific T 1 , proton density fat fraction, and quantification

Magnetic Resonance in Medicine ◽

10.1002/mrm.28970 ◽

2021 ◽

Author(s):

Nan Wang ◽

Tianle Cao ◽

Fei Han ◽

Yibin Xie ◽

Xiaodong Zhong ◽

...

Keyword(s):

Free Breathing ◽

Proton Density ◽

Proton Density Fat Fraction ◽

Fat Fraction

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Comparison of 2D Fat Suppressed Proton Density (FS-PD) and 3D (WATS-c) MRI pulse sequences in evaluation of chondromalacia patellae

Egyptian Journal of Radiology and Nuclear Medicine ◽

10.1186/s43055-019-0102-z ◽

2019 ◽

Vol 50 (1) ◽

Author(s):

Ahmed Ibrahim Tawfik ◽

Wael Hamza Kamr ◽

Saher Ebrahim Taman

Keyword(s):

Diagnostic Performance ◽

False Negative ◽

Pulse Sequences ◽

Proton Density ◽

Grading System ◽

Reference Standard ◽

Mr Images ◽

Arthroscopic Findings ◽

Chondromalacia Patella ◽

Sensitivity Specificity

Abstract Background Comparing the diagnostic performance of widely used 2D FSE technique (fat-suppressed proton density; FS-PD) and the 3D technique (water-selective cartilage scan; WATS-c) in evaluation of the chondromalacia patella by using arthroscopy as reference standard Results Seventy-five adult patients were enrolled in this study. They underwent MRI examinations then arthroscopy done in 2–4 days after it. MRI was done using 2D (FS-PD) and 3D (WATS-c) sequences and MR images were compared by two radiologists separately, then grading of the cartilage lesions was performed according to modified Noyes grading system and comparison between grade 0–1, 2, and 3 lesions was done using arthroscopic findings as a reference. A false-negative result is considered if there was undergrading of chondromalacia and false-positive result if chondromalacia was overgraded. Each sequence sensitivity, specificity, and accuracy was calculated by both readers. For reader 1, the sensitivity is 69% for WATS-c and 80% for FS-PD and the accuracy is 90% for WATS-c and 92% for FS-PD and for reader 2, the sensitivity is 56% for WATS-c and 84% for FS-PD and the accuracy is 88% for WATS-c and 94% for FS-PD. Conclusion 2D FS-PD images showed better diagnostic performance than 3D WATS-c images for evaluating chondromalacia patella.

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