Proton density

Background and purpose: The aim of this prospective study is to investigate and evaluate in clinical practice the diagnostic impact of 3DFLAIR in regards to 2DT2/PD in terms of infratentorial lesions detection in multiple sclerosis (MS). Material and methods: 164 MS patients from the OFSEP database were reviewed retrospectively. MR examinations were performed on 1.5T or 3T systems from four different centers. Infratentorial lesions were counted and allocated to different regions of the posterior fossa by three raters independently (junior resident, resident with an expertise in neuroradiology, and senior neuro-radiologist) on the 3DFLAIR and 2DT2/PD. Both sequences do not have the same spatial resolution but reflect what is recommended by most of the consensus and done in clinical practice. Results: With an overall number of 528 for Rater-1 and 798 for Rater-2 infratentorial lesions, 3DFLAIR had a significantly higher number of lesions detected than 2DT2/PD (303 for Rater-1 and 370 for Rater-2). The prevalence of trigeminal lesions detected by using 3DFLAIR was also significantly higher than 2DT2/PD. ROC analysis showed 3DFLAIR to be more specific and sensitive than 2DT2/PD. An overall difference between all three Raters has been observed. The more the Rater is experienced the more lesions he detects. Conclusion: Along with the radiologist ability to detect lesions based on his level of experience, the OFSEP optimized 3DFLAIR can significantly improve infratentorial lesion detection in MS compared to 2DT2/PD. This is important in MS follow-up that takes into account new lesions number to adapt patients' treatment.

BACKGROUND AND PURPOSE Besides the severity of carotid artery stenosis, atherosclerotic plaque composition is an important determinant of cerebral symptoms. We analyzed the relationship between the composition of the atherosclerotic plaque at the carotid artery bifurcation and ipsilateral ischemic cerebral lesions on MR imaging. METHODS Forty-one patients with symptomatic carotid artery stenosis (>70%) underwent black-blood, fast spin-echo imaging of the carotid artery and turbo fluid-attenuated inversion recovery (t-FLAIR) imaging of the brain. Plaque regions with a relative decrease in signal intensity in the plaque from proton density-weighted (TE = 14 ms) to T2-weighted (TE = 50 ms) imaging were considered to be lipid cores. We assessed the number and location of infarcts in the ipsilateral cortex, basal ganglia, and centrum semiovale, and hyperintense white matter lesions on t-FLAIR images. RESULTS Lipid in the atherosclerotic plaque at the carotid bifurcation was seen in 25...

In this work, we propose the use of the concepts of Fractal Dimension and Digital Image Processing, as a possible methodology to characterize the degree of malignancy of neoplastic structures located in the Central Nervous System. The images were detected by Magnetic Resonance Imaging (MRI) techniques including Proton Density, T1, and T2 images. Malignant lesions (Gliomas) were compared with benign ones (Cysts). The Correlation Dimension, Lyapunov Exponents and Information Dimension were used as the relevant geometrical properties to characterize the irregular edge present in a particular structure. The edge was obtained by means of an edge detector operator and afterwards a codification procedure based on Fourier Descriptors was used to generate a numerical array or Time Series. The analysis of the processed images revealed that the relevant geometrical properties exhibit a different behavior in the case of gliomas compared to cystic lesions, a fact that can be used by the physicia...

Page 1. DRYING TECHNOLOGY. 14(7&8). 1595-1623 (1996) EVALUATION OF SOYBEAN SEEDCOAT CRACKING DURING DRYING: PART 11. USING MRI' X. Suzy Zeng'. R. Roger Rum". RG;uy Fulcher'. Paul Chen' ' Depanment of Food Science & Nuuition ...

The use of two powerful classification techniques (boosting and SVM) is explored for the segmentation of white-matter lesions in the MRI scans of human brain. Simple features are generated from proton density (PD) scans. Radial basis function (RBF) based Adaboost technique and support vector machines (SVM) are employed for this task. The classifiers are trained on severe, moderate and mild cases. The segmentation is performed in T1 acquisition space rather than standard space (with more slices).

The purpose of this project is to study the behaviour of the solar wind parameters during the 23rd solar cycle and the possible correlation between them. The presented parameters are Alfven Mach number, plasma beta, flow speed, proton density and temperature, dynamic pressure, average magnetic field, Bx and By, and all data has been taken from OMNI 2. The first

T1-, T2-, and proton density (PD)-weighted sequences are used to characterize the content of cystic intracranial lesions. Fluid-attenuated inversion recovery (FLAIR) MR sequences produce T2-weighted images with water signal saturation. Therefore, we attempted to verify whether FLAIR, as compared with conventional techniques, improves the distinction between intracranial cysts with a free water-like content versus those filled with a non-free water-like substance and, consequently, aids in the identification of these lesions as either neoplastic/inflammatory or maldevelopmental/porencephalic. Forty-five cystic intracranial lesions were studied using T1-weighted, T2-weighted, FLAIR, and PD-weighted sequences. By means of clustering analysis of the ratio in signal intensity between the cystic intracranial lesions and CSF, the intracranial lesions were classified as filled with a free water-like content or with a non-free water-like substance. The results were compared with their true c...

Twenty consecutive patients with 21 surgically repaired Achilles tendon ruptures were imaged with a 0.1-T magnet at 3 and 6 weeks, and at 3 and 6 months after surgery. Clinical follow-up examinations and functional tests were performed at the time of scanning. An intratendinous area of high-intensity signal was observed in 19 of the 21 surgically repaired Achilles tendons at 3 months after surgery on proton density- and T2-weighted images. The three patients with the largest lesions had clinically poor outcomes at 3 months, whereas those with smaller intratendinous lesions had normal recoveries. Furthermore, patients with an abnormal walk at 3 months (N = 5) had statistically larger intratendinous lesions than patients who could walk normally. In all patients the cross-sectional area of the rejoined Achilles tendon showed the largest increase after cast removal (between 6 weeks and 3 months after surgery). In all cases the largest tendon area was measured at 3 months after surgery. Magnetic resonance imaging provides a precise valuable tool to evaluate the postsurgical internal structure of the surgically repaired Achilles tendon.

The materialist dialectical method is a philosophical investigative method to analyze aspects of reality as complex processes composed by integrating units named poles. Dialectics has experienced considerable progress in the 19th century, with Hegel's dialectics and, in the 20th century, with the works of Marx, Engels, and Gramsci, in philosophy and economics. The movement of poles through their contradictions is

The pruned part of a beech (Fagus sylvatica) branch was imaged by a 3D spin-echo magnetic resonance imaging (MRI) technique to visualize change in structure and water content in the tissues. Proton density-weighted MR images of intact tissues confirmed high moisture content (MC) associated with high MRI signal in the pith, xylem rays and earlywood vessels, as well as in the cambial zone with current annual xylem and phloem increment. MRI images derived from the 3D datasets showed a previously unreported moisture-related structural response of the beech branch to wounding. An extensive wound tissue with a high MRI signal at the wound edge was a conspicuous new structure clearly visualized by 3D MRI. MRI revealed that the xylem at the wound was dehydrated in a cone-shaped pattern extending approximately 4.5 mm deep into the branch. Dehydration was delimited from the underlying sound wood by a layer, corresponding to the reaction zone, of tissue with a high MRI signal and hence high mo...

Nuclear magnetic resonance (NMR) enables an instantaneous determination of the proton density in liquids and is thus convenient for determining the moisture content (MC) of wood. We demonstrated that the MC of a wood sample can be determined instantaneously on the basis of its mass (m) and the amplitude of its NMR free-induction-decay (FID) signal. The measurement is based on the assumption that the only liquid in the wood is water and that the relationship between the amplitude of the FID signal (S) and the mass of the water (m w ) in the sample is linear, i.e., S=k m w +k′ (m-m w ), and can be precisely calibrated for a given NMR probe and NMR spectrometer setup (in our case k=105 AU g-1 and k/k′ =34). With the FID signal converted into the mass of water, the MC is calculated as: MC=(S-m k′)/(m k-S). After the initial calibration of the FID signal with respect to the content of water, the correctness of the method was verified on samples of different wood species with various MCs....

The purpose of this paper is to test the effectiveness of a Support Vector Machine (SVM) classifier, with gaussian kernel function, in the automatic detection of small lesions from Magnetic Resonance Images (MRIs) of a patientt affected by multiple sclerosis. The data set consists of Proton Density, T2 (the spin-spin relaxation time) Spin-Echo images and a three-dimensional T1-weighted gradient echo

The pruned part of a beech (Fagus sylvatica) branch was imaged by a 3D spin-echo magnetic resonance imaging (MRI) technique to visualize change in structure and water content in the tissues. Proton density-weighted MR images of intact tissues confirmed high moisture content (MC) associated with high MRI signal in the pith, xylem rays and earlywood vessels, as well as in the cambial zone with current annual xylem and phloem increment. MRI images derived from the 3D datasets showed a previously unreported moisture-related structural response of the beech branch to wounding. An extensive wound tissue with a high MRI signal at the wound edge was a conspicuous new structure clearly visualized by 3D MRI. MRI revealed that the xylem at the wound was dehydrated in a cone-shaped pattern extending approximately 4.5 mm deep into the branch. Dehydration was delimited from the underlying sound wood by a layer, corresponding to the reaction zone, of tissue with a high MRI signal and hence high mo...

We describe a case of hyperacute subarachnoid and intraventricular hemorrhage from a ruptured aneurysm, which occurred while the patient was undergoing MR imaging. Compared with CSF, the blood in the subarachnoid space had slightly lower signal intensity on T2*-weighted gradient-echo images and increased signal intensity on T2-weighted spin-echo images. This finding differs from the generally accepted MR appearance of intracranial hemorrhage and should be recognized to ensure proper patient care.

A scheme of generation of ultraintense proton beams relevant for proton fast ignition (PFI) which employs multi-ps, circularly polarized laser pulse irradiating a thick (≥ 10 μm) H-rich target is proposed and examined using one-dimensional particle-in cell-simulations. It is shown that a 5-ps laser pulse of intensity∼(2–5)× 1020W/cm2 irradiating the target of the areal proton density∼ 2× 1020cm− 2 can produce–with a high energetic efficiency–a proton beam (plasma block) of parameters (intensity, energy fluence, pulse duration, proton ...

BACKGROUND AND PURPOSE: Ultrasmall superparamagnetic iron oxide particles result in shortening of T1 and T2 relaxation time constants and can be used as MR contrast agents. We tested four hypotheses by evaluating MR images of intracranial tumors after infusion of ...