Applications of Markov random fields in medical imaging.
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Algorithms↗
Biomedical subjects
R Leahy
Publications and source records attributed to R Leahy.
Three-dimensional maximum-likelihood reconstruction for an electronically collimated single-photon-emission imaging system.
A three-dimensional maximum-likelihood reconstruction method is presented for a prototype electronically collimated single-photon-emission system. The electronically collimated system uses a gamma camera fronted by an array of germanium detectors to detect gamma-ray emissions from a distributed radioisotope source. In this paper we demonstrate that optimal iterative three-dimensional reconstruction approaches can be feasibly applied to emission imaging systems that have highly complex spatial sampling patterns and that generate extremely large numbers of data values. A probabilistic factorization of the system matrix that reduces the computation by several orders of magnitude is derived. We demonstrate a dramatic increase in the convergence speed of the expectation maximization algorithm by sequentially iterating over particular subsets of the data. This result is also applicable to other emission imaging systems.
Image Processing, Computer-Assisted↗
Spoilage of hydrogel contact lenses by lipid deposits. Tear-film potassium depression, fat, protein, and alcohol consumption.
"Jelly-bump" deposits, which are composed mainly of lipids, on high water content, extended-wear hydrogel lenses, are a clinically significant problem of unknown etiology. The authors explored the effect of nutrition on the frequency of deposition of these jelly bumps. Forty-three patients were included in this masked case-control study from five contact lens practices in North America. Thirty patients were lipid-depositor cases and 13 were controls. Tear specimens were drawn and analyzed for potassium by atomic-absorption spectrophotometry. Detailed dietary histories were conducted and diet nutrient composition was computed. Patients with diminished tear-potassium concentrations have an increased risk of jelly-bump deposition. Elevated intake of protein, alcohol, and cholesterol also appeared to be correlated significantly with increased jelly-bump deposition. The authors found that diabetics and the use of diuretics, anticholinergics, sympathomimetics, were associated with tear-film potassium depletion and lipid deposit formation.
Adolescent↗
An evaluation of methods for neuromagnetic image reconstruction.
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Biomedical Engineering↗