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61.
Objective
In general, low-field MRI scanners such as the 0.5- and 1-T ones produce images that are poor in quality. The motivation of this study was to lessen the noise and enhance the signal such that the image quality is improved. Here, we propose a new approach using stochastic resonance (SR)-based transform in Fourier space for the enhancement of magnetic resonance images of brain lesions, by utilizing an optimized level of Gaussian fluctuation that maximizes signal-to-noise ratio (SNR).Materials and Methods
We acquired the T1-weighted MR image of the brain in DICOM format. We processed the original MR image using the proposed SR procedure. We then tested our approach on about 60 patients of different age groups with different lesions, such as arteriovenous malformation, benign lesion and malignant tumor, and illustrated the image enhancement by using just-noticeable difference visually as well as by utilizing the relative enhancement factor quantitatively.Results
Our method can restore the original image from noisy image and optimally enhance the edges or boundaries of the tissues, clarify indistinct structural brain lesions without producing ringing artifacts, as well as delineate the edematous area, active tumor zone, lesion heterogeneity or morphology, and vascular abnormality. The proposed technique improves the enhancement factor better than the conventional techniques like the Wiener- and wavelet-based procedures.Conclusions
The proposed method can readily enhance the image fusing a unique constructive interaction of noise and signal, and enables improved diagnosis over conventional methods. The approach well illustrates the novel potential of using a small amount of Gaussian noise to improve the image quality. 相似文献62.
Boron-doped amorphous graphite-like carbon (GLC) films have been prepared with different boron concentrations. Electrical transport measurements in the temperature range 1.3–300?K on the films shows a doping-induced metal–insulator (MI) transition. On the metallic side of the transition, the experimental data are interpreted in terms of weak localization and the effect of electron–electron interactions. Data on the insulator side of transition are analyzed in terms of hopping conduction. Critical behaviour is observed near the transition, with the resistivity obeying a power-law temperature dependence. 相似文献
63.
Ricerche di Matematica - In this paper, we consider a three species plankton–fish system that incorporates external toxicity and nonlinear harvesting. We consider that the growth of species... 相似文献
64.
V. D. Damarupani S. Buddhudu Y. Subramanyam L. R. Moorthy D. C. Hussain Sa 《Czechoslovak Journal of Physics》1991,41(1):85-91
A Taylor-series expansion of the intermediate coupling energy levels for the U4+(5f2) has been developed for the first time by using the mathematical procedures of Racah. The partial derivatives, eigenvalues and eigenfunctions reported in this paper will be of great use in analysing the optical spectral properties of the tetravalent uranium doped crystalline or non-crystalline materials. The usefulness of the Taylor serier expansion has been verified by examining the optical absorption results of the U4+ doped fluoride glasses. The physical properties, namely the refractive index and density, were also determined.Our thanks are due to Prof. S. V. J. Lakshman for his kind cooperation and support in the present work. We are also thankful to the technical staff of the Hull University, Physics Department, UK in the preparation and measurement of various physical properties of the U4+ doped alkali mixed heavy metal based fluoride glass systems. 相似文献
65.
C.J.G. Raw 《Chemical physics letters》1974,28(2):229-230
The maximum thermomolecular pressure differences across a capillary tube whose ends are held at 195 K and 298 K have been measured for CF4, SF6, SiF4 and BF3. These results have been used to predict the collision numbers for rotational relaxation in these gases. 相似文献
66.
A new and straightforward methodology for the construction of complex nitrogen-containing polycycles has been developed. This methodology exploits easily prepared 1,2,4-triazines as substrates for a pericyclic reaction cascade, forming the polycycles in good to excellent yield in a single operation. 相似文献
67.
Ch. Subramanyam Sk. Thaslim Basha G. Madhava Sk. Nayab Rasool Sk. Adam S. Durga Srinivasa Murthy 《Phosphorus, sulfur, and silicon and the related elements》2017,192(3):267-270
A facile synthesis of novel α-aminophosphonates 5a-j was accomplished by condensation of imines (3a-j) with diethyl phosphite (4) in ethanol at 50–60°C using easily recoverable and reusable catalyst, tetramethyl guanidine (TMG) via pudovik reaction in high yields. All the title compounds were characterized by spectral and elemental analysis. They were further screened for their abilities towards in vitro antibacterial, antifungal and antioxidant activities. The compounds 5g, 5d, 5f exhibited good antibacterial and antifungal activities compared to the standard bactericide, Penicillin and fungicide, Griseofulvin, respectively. The compounds 5h, 5i, 5g, and 5c exhibited good antioxidant activity compared to the standard ascorbic acid. 相似文献
68.
Tantry SJ Venkataramanarao R Chennakrishnareddy G Sureshbabu VV 《The Journal of organic chemistry》2007,72(24):9360-9363
An epimerization free and efficient total synthesis of immunosuppressant cyclosporin O (CsO) by step-by-step assembly of amino acids in solution phase is reported. The couplings were performed by employing Fmoc-amino acid chlorides and were mediated by zinc dust under neutral conditions. The yield and purity of the coupling of sterically hindered N-methylamino acids to N-methylamino acids at positions 8, 9, 10, and 11 were enhanced by repeating the coupling thrice at these particular junctures. All the 10 intermediate peptides pertaining to CsO and the final CsO were isolated and completely characterized through IR, 1H NMR, mass spectrometry, and HPLC techniques. 相似文献
69.
M. W. Carey L. W. Green R. E. Schoetzow J. Bougault J. Leboucq H. Schultes Malaprade R. J. W. Le Févre J. Pearson R. Raw L. Palfray S. Sabetay und Denise Sontag 《Fresenius' Journal of Analytical Chemistry》1935,102(3-4):128-132
Ohne Zusammenfassung 相似文献
70.