A comparison study of linear reconstruction techniques for diffuse optical tomographic imaging of absorption coefficient.

We compare, through simulations, the performance of four linear algorithms for diffuse optical tomographic reconstruction of the three-dimensional distribution of absorption coefficient within a highly scattering medium using the diffuse photon density wave approximation. The simulation geometry consisted of a coplanar array of sources and detectors at the boundary of a half-space medium. The forward solution matrix is both underdetermined, because we estimate many more absorption coefficient voxels than we have measurements, and ill-conditioned, due to the ill-posedness of the inverse problem. We compare two algebraic techniques, ART and SIRT, and two subspace techniques, the truncated SVD and CG algorithms. We compare three-dimensional reconstructions with two-dimensional reconstructions which assume all inhomogeneities are confined to a known horizontal slab, and we consider two 'object-based' error metrics in addition to mean square reconstruction error. We include a comparison using simulated data generated using a different FDFD method with the same inversion algorithms to indicate how our conclusions are affected in a somewhat more realistic scenario. Our results show that the subspace techniques are superior to the algebraic techniques in localization of inhomogeneities and estimation of their amplitude, that two-dimensional reconstructions are sensitive to underestimation of the object depth, and that an error measure based on a location parameter can be a useful complement to mean squared error.

Managed care and eye services to diabetic patients: a study of participant behavior.

BACKGROUND: Effective managed care requires the active participation of health professionals and patients alike. The essential elements in management of diabetes involve well-defined professional clinical protocols, adequate patient education, and adherence to these management guidelines by all parties. This study was designed to evaluate how well the involved parties cooperate in this endeavor. METHODS: Health plan records were searched for identified diabetic patients. This information was cross-referenced to vision care claims information. Clinical records of diabetic patients who had an eye examination during the study period were peer-reviewed for evidence of a diabetes notation. RESULTS: Of 2825 diabetic patients identified, we obtained the clinical eye records of 554 for review. Seventy percent of those records noted the presence of diabetes. Ninety-seven percent of the eye examinations included a funds evaluation. Only 56% of records noted any patient education or-- at a minimum--notations about recall advice. CONCLUSION: The nature of diabetes requires that health professionals be more aggressive in the management of individuals at risk or diagnosed with diabetes.

Temporal and spatial analysis of potential maps via multiresolution decompositions.

Cardiac potentials recorded on the epicardium or the body surface by an array of electrodes are usually analyzed either as spatial distributions or temporal waveforms. Thus, the analysis often involves temporal descriptors (eg. max dV/dt) or spatial descriptors (eg. location of local extrema) only. The best known transform technique that has been applied to these data that combines both spatial and temporal characteristics is the Karhunen-Loeve transform, a global transform applied to temporal and/or spatial bases obtained by statistical analysis of a database. As an alternative, multiresolution decompositions and related wavelet-type transforms have recently seen great development in signal processing and related fields. They offer flexibility, employing transformations onto local (rather than global) and fixed (rather than data-dependent) databases, and allow transformation of distributions, waveforms, or both, as desired. The utility of this method as applied to temporal and spatial segmentation and analysis of map data from both epicardial plaques and body surface potentials recorded during percutaneous transluminal coronary angioplasty is illustrated.

Chemotherapy and treatment scheduling: the Johns Hopkins Oncology Center Outpatient Department.

The Chemotherapy and Treatment Scheduling System provides integrated appointment and facility scheduling for very complex procedures. It is fully integrated with other scheduling systems at The Johns Hopkins Oncology Center and is supported by the Oncology Clinical Information System (OCIS). It provides a combined visual and textual environment for the scheduling of events that have multiple dimensions and dependencies on other scheduled events. It is also fully integrated with other clinical decision support and ancillary systems within OCIS. The system has resulted in better patient flow through the ambulatory care areas of the Center. Implementing the system required changes in behavior among physicians, staff, and patients. This system provides a working example of building a sophisticated rule-based scheduling system using a relatively simple paradigm. It also is an example of what can be achieved when there is total integration between the operational and clinical components of patient care automation.

Characterization of the airway smooth muscle muscarinic receptor in vivo.

We examined the bronchodilator activity of eight subtype-selective and non-selective muscarinic antagonists in anesthetized, ventilated guinea pigs bronchoconstricted by carbachol aerosols. Relative bronchodilator potencies were consistent with M3 receptor antagonism and correlated with inhibition of bladder smooth muscle contraction in vivo. We conclude that the airway smooth muscle muscarinic receptor can be functionally characterized in vivo as M3 and that it is of the same subtype as the muscarinic receptor in bladder smooth muscle.

PSRO's and optometry.

Public Law 92-603 is reviewed and reference made to sections where optometry can be involved. A guide to the development of a program for inclusion in the PSRO program is discussed and a challenge to the profession is issued.