Deconvolution
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A new approach to 2-D blind deconvolution of ultrasonic images in a Bayesian framework is presented. The radio-frequency image data are modeled as a convolution of the point-spread function and the tissue function, with additive white noise. The deconvolution algorithm is derived from statistical assumptions about the tissue function, the point-spread function, and the noise. It is solved as an iterative optimization problem. In each iteration, additional constraints are applied as a projection operator to further stabilize the process. The proposed method is an extension of the homomorphic deconvolution, which is used here only to compute the initial estimate of the point-spread function. Homomorphic deconvolution is based on the assumption that the point-spread function and the tissue function lie in different bands of the cepstrum domain, which is not completely true. This limiting constraint is relaxed in the subsequent iterative deconvolution. The deconvolution is applied globally to the complete radiofrequency image data. Thus, only the global part of the point-spread function is considered. This approach, together with the need for only a few iterations, makes the deconvolution potentially useful for real-time applications. Tests on phantom and clinical images have shown that the deconvolution gives stable results of clearly higher spatial resolution and better defined tissue structures than in the input images and than the results of the homomorphic deconvolution alone.
- MeSH
- algoritmy MeSH
- Bayesova věta MeSH
- interpretace obrazu počítačem metody MeSH
- reprodukovatelnost výsledků MeSH
- rozpoznávání automatizované metody MeSH
- senzitivita a specificita MeSH
- ultrasonografie metody MeSH
- umělá inteligence MeSH
- vylepšení obrazu metody MeSH
- Publikační typ
- práce podpořená grantem MeSH
Blind deconvolution, which comprises simultaneous blur and image estimations, is a strongly ill-posed problem. It is by now well known that if multiple images of the same scene are acquired, this multichannel (MC) blind deconvolution problem is better posed and allows blur estimation directly from the degraded images. We improve the MC idea by adding robustness to noise and stability in the case of large blurs or if the blur size is vastly overestimated. We formulate blind deconvolution as an l(1) -regularized optimization problem and seek a solution by alternately optimizing with respect to the image and with respect to blurs. Each optimization step is converted to a constrained problem by variable splitting and then is addressed with an augmented Lagrangian method, which permits simple and fast implementation in the Fourier domain. The rapid convergence of the proposed method is illustrated on synthetically blurred data. Applicability is also demonstrated on the deconvolution of real photos taken by a digital camera.
- MeSH
- algoritmy MeSH
- artefakty MeSH
- interpretace obrazu počítačem metody MeSH
- reprodukovatelnost výsledků MeSH
- rozpoznávání automatizované metody MeSH
- senzitivita a specificita MeSH
- vylepšení obrazu metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Unobtrusive sensing is a growing aspect in the field of biomedical engineering. While many modalities exist, a large fraction of methods ultimately relies on the analysis of thoracic movement. To quantify cardiorespiratory induced thorax movement with spatial resolution, an approach using high-performance motion capture, electrocardiography and deconvolution is presented. In three healthy adults, motion amplitudes are estimated that correspond to values reported in the literature. Moreover, two-dimensional mappings are created that exhibit physiological meaningful relationships. Finally, the analysis of waveform data obtained via deconvolution shows plausible pulse transit behavior.
- MeSH
- ambulantní monitorování přístrojové vybavení MeSH
- biomedicínské inženýrství * přístrojové vybavení MeSH
- diagnostické techniky dýchacího ústrojí MeSH
- diagnostické techniky kardiovaskulární * MeSH
- lidé MeSH
- počítačové zpracování signálu * MeSH
- technologie dálkového snímání přístrojové vybavení MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
PURPOSE: One of the main obstacles for reliable quantitative dynamic contrast-enhanced (DCE) MRI is the need for accurate knowledge of the arterial input function (AIF). This is a special challenge for preclinical small animal applications where it is very difficult to measure the AIF without partial volume and flow artifacts. Furthermore, using advanced pharmacokinetic models (allowing estimation of blood flow and permeability-surface area product in addition to the classical perfusion parameters) poses stricter requirements on the accuracy and precision of AIF estimation. This paper addresses small animal DCE-MRI with advanced pharmacokinetic models and presents a method for estimation of the AIF based on blind deconvolution. METHODS: A parametric AIF model designed for small animal physiology and use of advanced pharmacokinetic models is proposed. The parameters of the AIF are estimated using multichannel blind deconvolution. RESULTS: Evaluation on simulated data show that for realistic signal to noise ratios blind deconvolution AIF estimation leads to comparable results as the use of the true AIF. Evaluation on real data based on DCE-MRI with two contrast agents of different molecular weights showed a consistence with the known effects of the molecular weight. CONCLUSION: Multi-channel blind deconvolution using the proposed AIF model specific for small animal DCE-MRI provides reliable perfusion parameter estimates under realistic signal to noise conditions.
- MeSH
- algoritmy MeSH
- arterie diagnostické zobrazování MeSH
- farmakokinetika MeSH
- kontrastní látky farmakokinetika MeSH
- lidé MeSH
- magnetická rezonanční tomografie * MeSH
- myši inbrední BALB C MeSH
- myši MeSH
- nekróza patologie MeSH
- perfuze MeSH
- počítačová simulace MeSH
- počítačové zpracování obrazu metody MeSH
- poměr signál - šum MeSH
- regresní analýza MeSH
- reprodukovatelnost výsledků MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
PURPOSE: Dynamic Contrast-Enhanced (DCE) MRI with 2nd generation pharmacokinetic models provides estimates of plasma flow and permeability surface-area product in contrast to the broadly used 1st generation models (e.g. the Tofts models). However, the use of 2nd generation models requires higher frequency with which the dynamic images are acquired (around 1.5 s per image). Blind deconvolution can decrease the demands on temporal resolution as shown previously for one of the 1st generation models. Here, the temporal-resolution requirements achievable for blind deconvolution with a 2nd generation model are studied. METHODS: The 2nd generation model is formulated as the distributed-capillary adiabatic-tissue-homogeneity (DCATH) model. Blind deconvolution is based on Parker's model of the arterial input function. The accuracy and precision of the estimated arterial input functions and the perfusion parameters is evaluated on synthetic and real clinical datasets with different levels of the temporal resolution. RESULTS: The estimated arterial input functions remained unchanged from their reference high-temporal-resolution estimates (obtained with the sampling interval around 1 s) when increasing the sampling interval up to about 5 s for synthetic data and up to 3.6-4.8 s for real data. Further increasing of the sampling intervals led to systematic distortions, such as lowering and broadening of the 1st pass peak. The resulting perfusion-parameter estimation error was below 10% for the sampling intervals up to 3 s (synthetic data), in line with the real data perfusion-parameter boxplots which remained unchanged up to the sampling interval 3.6 s. CONCLUSION: We show that use of blind deconvolution decreases the demands on temporal resolution in DCE-MRI from about 1.5 s (in case of measured arterial input functions) to 3-4 s. This can be exploited in increased spatial resolution or larger organ coverage.
The aim of this study was to estimate the lowest concentration of pesticide residues in non-fatty food matrix at which the residues can be successfully identified by automatic spectral deconvolution software AMDIS. For GC-MS measurements fast GC with narrow capillary column was utilized. For a mixture of 18 pesticides, the identification was successful at concentration levels 4–0.4 mg kg-1 in real matrix samples (apples). With decreasing concentration, the number of identified pesticides and the quality of deconvoluted spectra decreased. The calculated limits of full-scan detection ranged from 0.20 ng for chlorpyrifos to 1.10 ng for captan. Software AMDIS with the used experimental set-up is not sufficiently sensitive for reliable identification of pesticide residues in non-fatty food matrices with low maximal residual limits (e.g. baby food 0.01 mg kg-1).
Neurological complications of AIDS (NeuroAIDS) include primary HIV-associated neurocognitive disorder (HAND). OAS3 is an enzyme belonging to the 2', 5' oligoadenylate synthase family induced by type I interferons and involved in the degradation of both viral and endogenous RNA. Here, we used microarray datasets from NCBI of brain samples of non-demented HIV-negative controls (NDC), HIV, deceased patients with HAND and encephalitis (HIVE) (treated and untreated with antiretroviral therapy, ART), and with HAND without HIVE. The HAND/HIVE patients were stratified according to the OAS3 gene expression. The genes positively and negatively correlated to the OAS3 gene expression were used to perform a genomic deconvolution analysis using neuroimmune signatures (NIS) belonging to sixteen signatures. Expression analysis revealed significantly higher OAS3 expression in HAND/HIVE and HAND/HIVE/ART compared with NDC. OAS3 expressed an excellent diagnostic ability to discriminate NDC from HAND/HIVE, HAND from HAND/HIVE, HAND from HAND/HIVE/ART, and HIV from HAND/HIVE. Noteworthy, OAS3 expression levels in the brains of HAND/HIVE patients were positively correlated with viral load in both peripheral blood and cerebrospinal fluid (CSF). Furthermore, deconvolution analysis revealed that the genes positively correlated to OAS3 expression were associated with inflammatory signatures. Neuronal activation profiles were significantly activated by the genes negatively correlated to OAS3 expression levels. Moreover, gene ontology analysis performed on genes characterizing the microglia signature highlighted an immune response as a main biological process. According to our results, genes positively correlated to OAS3 gene expression in the brains of HAND/HIVE patients are associated with inflammatory transcriptomic signatures and likely worse cognitive impairment.
- MeSH
- 2',5'-oligoadenylátsynthetasa genetika metabolismus MeSH
- HIV infekce * komplikace MeSH
- HIV * genetika metabolismus MeSH
- lidé MeSH
- mozek metabolismus MeSH
- neurokognitivní poruchy komplikace metabolismus MeSH
- transkriptom MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Airborne gamma spectrometry is an effective tool for prompt monitoring and mapping of large areas contaminated after NPP accident, radionuclides leakage cases, an impact of uranium ore mining and processing, etc. Airborne spectrometry data analysis using deconvolution technique enables to calculate air kerma rates and/or radionuclides concentrations as well as identification of radionuclides. Application of this technique on the airborne data (from manned as well as an unmanned survey using drones) is rather specific due to the requirements for short time of one scan data acquisition, a relatively long distance from the source and small detector size, due to the limited payload of the usually used drones. Application of deconvolution techniques for analysis of spectra with very poor statistics, methods and possibilities to improve the processing of such spectra are discussed.
- MeSH
- černobylská havárie MeSH
- letadla přístrojové vybavení MeSH
- lidé MeSH
- monitorování radiace MeSH
- radiační expozice analýza MeSH
- radioaktivní látky znečišťující vzduch analýza MeSH
- spektrometrie gama metody MeSH
- technologie dálkového snímání přístrojové vybavení metody MeSH
- uran analýza MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
