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Results for “Measuring algorithm”

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PubMed1998

Consensus on microembolus detection by TCD. International Consensus Group on Microembolus Detection.

Transcranial Doppler ultrasound is capable of detecting microembolic material, both gaseous and solid, within the intracranial cerebral arteries. To avoid discrediting this promising and exciting new technique, experts in this field met in January 1997 in Frankfurt, Germany, to discuss the limitations and problems of embolus detection and to determine guidelines for its proper use in clinical practice, as well as in scientific investigations. In particular, the authors suggest that studies report the following parameters: (1) ultrasound device, (2) transducer type and size, (3) insonated artery, (4) insonation depth, (5) algorithms for signal intensity measurement, (6) scale settings, (7) detection threshold, (8) axial extension of sample volume, (9) fast Fourier transform (FFT) size (number of points used), (10) FFT length (time), (11) FFT overlap, (12) transmitted ultrasound frequency, (13) high-pass filter settings, and (14) recording time. There was agreement that no current system of automatic embolus detection has the required sensitivity and specificity for clinical use.

Humans↗

PubMed2004

Minimax mutual information approach for independent component analysis.

Minimum output mutual information is regarded as a natural criterion for independent component analysis (ICA) and is used as the performance measure in many ICA algorithms. Two common approaches in information-theoretic ICA algorithms are minimum mutual information and maximum output entropy approaches. In the former approach, we substitute some form of probability density function (pdf) estimate into the mutual information expression, and in the latter we incorporate the source pdf assumption in the algorithm through the use of nonlinearities matched to the corresponding cumulative density functions (cdf). Alternative solutions to ICA use higher-order cumulant-based optimization criteria, which are related to either one of these approaches through truncated series approximations for densities. In this article, we propose a new ICA algorithm motivated by the maximum entropy principle (for estimating signal distributions). The optimality criterion is the minimum output mutual information, where the estimated pdfs are from the exponential family and are approximate solutions to a constrained entropy maximization problem. This approach yields an upper bound for the actual mutual information of the output signals - hence, the name minimax mutual information ICA algorithm. In addition, we demonstrate that for a specific selection of the constraint functions in the maximum entropy density estimation procedure, the algorithm relates strongly to ICA methods using higher-order cumulants.

Algorithms↗

PubMed2006

Atherosclerosis, C-reactive protein, and risk for open-angle glaucoma: the Rotterdam study.

PURPOSE: To test the hypotheses that atherosclerosis and elevated serum C-reactive protein (CRP) levels are risk factors for open-angle glaucoma (OAG). METHODS: In a prospective, population-based cohort study, all participants 55 years and older and at risk for incident OAG underwent, at baseline (1990-1993) and at follow-up (1997-1999), the same ophthalmic examination, including visual field testing and optic disc photography. Baseline atherosclerosis was assessed by means of echography of the carotid arteries, abdominal x-ray examination, and ankle-arm index; baseline serum CRP levels were used in the analyses. The diagnosis of OAG was based on an algorithm using optic disc measures and visual field loss. Odds ratios of OAG were computed with logistic regression analyses. Risk factors were categorized in tertiles and according to standard deviation. RESULTS: After a mean follow-up of 6.5 years, incident OAG was diagnosed in 87 of 3842 (2.3%) participants at risk for OAG. Carotid artery plaques, carotid intima-media thickness, aortic calcifications, ankle-arm index, and CRP levels were not significant risk factors for OAG. The odds ratio, given for the highest and lowest tertiles, for carotid plaques was 1.43 (95% confidence interval [CI], 0.68-2.99), for carotid intima-media thickness 0.86 (95% CI, 0.47-1.57), for aortic calcifications 1.02 (95% CI, 0.60-1.75), for ankle-arm index 0.69 (95% CI, 0.38-1.25), and for CRP 1.19 (95% CI, 0.68-2.07). CONCLUSIONS: In this prospective, population-based study, neither atherosclerosis nor serum CRP level was an important risk factor for OAG.

Aged↗

PubMed2005

Predictors of adequacy of depression management in the primary care setting.

OBJECTIVES: Depression is most commonly treated in the primary care setting. However, most studies have shown that depression care in this setting is often inadequate. This study examined the adequacy of antidepressant treatment and overall depression management by primary care physicians and identified patient characteristics related to inadequate care. METHODS: Adequacy of depression care among patients with depression who presented to a primary care office was evaluated by using physicians' self-reports and medication prescription data. Adequacy of depression care was measured in two ways: adequacy of the current medication trial was measured by using the Antidepressant Treatment and History Form (ATHF), and adequacy of overall management by the physician was measured by using an algorithm developed for this study. The association was examined between patient characteristics and adequacy of the medication trial or depression management. RESULTS: Data were gathered for 389 patients with depression. Overall, 71 percent of patients had adequate ATHF scores, and 75 percent were judged to receive adequate depression management. No significant differences in adequacy were seen on the basis of race, age, or gender. When depressive symptoms were almost absent or extremely severe, 91 percent of patients were adequately managed; in contrast, when symptoms were mild, mild to moderate, or moderate 69 percent of patients were adequately managed. Additionally, specific medications, such as sertraline and fluoxetine, were associated with a lower likelihood of an adequate ATHF score. CONCLUSIONS: A majority of these primary care patients were adequately treated for depression, with no detectable disparity related to race or age. However, mild to moderate depressive symptoms (as opposed to remitted or severe symptoms) and specific medications were associated with a lower rate of adequacy. These findings have implications for ways that primary care physicians could be trained to more adequately manage the spectrum of severity of depression.

Adult↗

PubMed1997

Longitudinal assessment of diabetic polyneuropathy using a composite score in the Rochester Diabetic Neuropathy Study cohort.

Because there are little satisfactory data on change in severity of diabetic polyneuropathy (DP) over time from study of population-based cohorts of diabetic patients in epidemiologic surveys of DP, it is difficult to predict outcome or morbidity or to identify risk factors; it is also difficult to estimate statistical power for use in controlled clinical trials. In this longitudinal study of almost 200 patients from the Rochester Diabetic Neuropathy Study (RDNS) cohort, we assess which symptoms, clinical examinations, tests, or combinations of examinations and tests (composite scores) are best used as minimal criteria for the diagnosis of DP and as a quantitative measure of severity of DP. An abnormality (> or = 97.5th percentile) of a composite score that included the Neuropathy Impairment Score of the lower limbs plus seven tests (NIS(LL)+7 tests), was a better minimal criteria for DP than clinical judgment alone or previously published minimal criteria. First, it provided a more comprehensive assessment of neuropathic impairment. Second, it avoided the overestimated frequency of DP when the minimal criteria for DP was any one or two abnormalities from multiple measurements. Minimal criteria using nerve conduction and reduced heart beat response to deep breathing identified approximately twice as many patients with DP than did clinical examination and vibration detection threshold using CASE IV. This difference could be used to subclassify state 1 DP. Although various individual measures of DP, for example, vibration detection threshold (as evaluated by CASE IV and the 4, 2, and 1 stepping algorithm [see text]), were good measures of worsening, the composite score NIS(LL)+7 tests (assessing neuropathic impairment) was much better at showing monotone worsening. Using this composite score, the average diabetic patient in the RDNS worsened by 0.34 points per year, whereas patients with diabetic polyneuropathy worsened by 0.85 points per year. On the assumption that a therapeutic agent may prevent worsening of DP but not cause improvement, controlled clinical trials of patients with DP would need to be conducted for a period of 3 years to achieve a meaningful change of 2 NIS points (the level of abnormality considered by a Peripheral Nerve Society consensus group to be clinically meaningful).

Adult↗

PubMed2002

Extended-range temporal electronic speckle pattern interferometry.

In recent years the availability of high-speed digital video cameras has motivated the study of electronic speckle pattern interferometry (ESPI) in the time domain. To this end a properly sampled temporal sequence of N-fringe patterns is used to analyze the temporal experiment. Samples of temporal speckle images must fulfill the Nyquist criteria over the time axis. When the transient phenomena under study are too fast, the required sampling frequency over time may not be fulfilled. In that case one needs to extend the measuring range of the algorithm used to extract the modulating phase. We analyze how to use short laser pulses or short video acquisition times with fairly long temporal separation among them to estimate the modulating phase of a dynamic ESPI experiment. The only requirement is that the modulating phase being estimated be properly sampled in the spatial domain.

Journal Article↗

PubMed2003

Phase-shift extraction and wave-front reconstruction in phase-shifting interferometry with arbitrary phase steps.

A new approach to reconstructing the object wave front in phase-shifting interferometry with arbitrary unknown phase steps is proposed. With this method the actual phase steps are first determined from measured intensities with an algorithm based on the statistic property of the object phase distribution in the recording plane. Then the original object field is calculated digitally with a derived formula. This method is simple, accurate, and capable of retrieving the original object field, including its amplitude and phase distributions simultaneously, with arbitrary and unequal phase steps in a three- or four-frame method. The effectiveness and correctness of this approach are verified by a series of computer simulations for both smooth and diffusing surfaces.

Journal Article↗

PubMed1999

[Intensive care in surgical sepsis].

The experience in treatment of 740 patients with surgical sepsis is presented. The problems of the diagnosis, pathogenesis of sepsis, clinical and laboratory features of its course, and disturbances of homeostasis are discussed. Score systems for evaluation of the severity of patients' conditions are analysed. The problems of intensive care of surgical sepsis are considered, absolute and relative components are singled out. The principles for application of antibacterial and immune therapy, restoration of protein and energy losses, infusional and transfusional therapy are discussed. The algorithm for intensive care measures is suggested.

Adjuvants, Immunologic↗

PubMedDate not supplied

Collaborative partnership for optimizing heart failure outcomes in the long-term care environment: a clinical experience.

RATIONALE: Heart failure (HF) is a devastating cardiovascular syndrome affecting more than 4.6 million Americans and resulting in a substantial economic burden. It is the number one cause of hospitalization in the older population. Because there is no cure for this costly disease, goals of therapy include; slowing progression, increasing patient survival, minimizing symptoms, improving patient functional capacity, and decreasing ER visits, hospital admissions, and readmissions. Studies have shown ACE inhibitors (ACEIs) to be extremely beneficial in reaching these goals. However, data nationwide indicate that less than half of HF patients are prescribed an ACEI. Therefore, a national long-term care pharmaceutical provider has committed to the development of a HF disease management program, which has been implemented through a collaborative partnership between medicine, nursing, and pharmacy. This report describes the experience and results of implementing this program in a large group of nursing homes. METHODS: With help from an independent health outcomes consulting firm and an expert panel, a multifaceted program was developed. The AMDA heart failure guidelines were used as a foundation to design program interventions, which included educational programs for the long-term care facility staff, implementation of a HF treatment algorithm, and an outcomes measurement program. The primary goals of this program were to increase awareness of HF and treatment options available and to decrease morbidity and mortality associated with HF through the optimization of pharmacologic management in a long-term care setting. OUTCOMES: A retrospective evaluation was conducted to assess changes in ACEI utilization, ACEI targeted dosing and HF-related hospitalizations 1 year after program implementation. A total of 510 patients followed by 23 consultants, representing 152 facilities met the inclusion criteria for the analysis. Data indicated an increase of 36% in newly enrolled HF patients utilizing ACEI after 1 year. A decreasing trend in HF hospitalizations was also noted from the first quarter, (2.2/100 patients) to the fourth (1.0/100 patients). The results of the Heart Failure-Health Outcomes Management Program (HF-HOMP) program demonstrate the opportunity existing for long-term care providers to improve patient health while minimizing expenditures. It also provides additional evidence that such programs should be implemented more broadly within this population.

Journal Article↗

PubMed2000

[The noise-filtering of chemiluminescence spectra with wavelet multiresolution analysis].

In this paper, the wavelet multiresolution signal decomposition was successfully applied to the filtering of high-frequency noise in chemiluminescence spectra. The spectra signal-to-noise ratio was greatly improved while the noise was suppressed effectively. The effect of wavelet basis and time of decomposition are also discussed. It is shown that the wavelet analyses have many advantages in processing of discrete signals.

Algorithms↗

PubMed2005

Comparison of different methods for delineation of 18F-FDG PET-positive tissue for target volume definition in radiotherapy of patients with non-Small cell lung cancer.

UNLABELLED: PET with (18)F-FDG ((18)F-FDG PET) is increasingly used in the definition of target volumes for radiotherapy, especially in patients with non-small cell lung cancer (NSCLC). In this context, the delineation of tumor contours is crucial and is currently done by different methods. This investigation compared the gross tumor volumes (GTVs) resulting from 4 methods used for this purpose in a set of clinical cases. METHODS: Data on the primary tumors of 25 patients with NSCLC were analyzed. They had (18)F-FDG PET during initial tumor staging. Thereafter, additional PET of the thorax in treatment position was done, followed by planning CT. CT and PET images were coregistered, and the data were then transferred to the treatment planning system (PS). Sets of 4 GTVs were generated for each case by 4 methods: visually (GTV(vis)), applying a threshold of 40% of the maximum standardized uptake value (SUV(max); GTV(40)), and using an isocontour of SUV = 2.5 around the tumor (GTV(2.5)). By phantom measurements we determined an algorithm, which rendered the best fit comparing PET with CT volumes using tumor and background intensities at the PS. Using this method as the fourth approach, GTV(bg) was defined. A subset of the tumors was clearly delimitable by CT. Here, a GTV(CT) was determined. RESULTS: We found substantial differences between the 4 methods of up to 41% of the GTV(vis). The differences correlated with SUV(max), tumor homogeneity, and lesion size. The volumes increased significantly from GTV(40) (mean 53.6 mL) < GTV(bg) (94.7 mL) < GTV(vis) (157.7 mL) and GTV(2.5) (164.6 mL). In inhomogeneous lesions, GTV(40) led to visually inadequate tumor coverage in 3 of 8 patients, whereas GTV(bg) led to intermediate, more satisfactory volumes. In contrast to all other GTVs, GTV(40) did not correlate with the GTV(CT). CONCLUSION: The different techniques of tumor contour definition by (18)F-FDG PET in radiotherapy planning lead to substantially different volumes, especially in patients with inhomogeneous tumors. Here, the GTV(40) does not appear to be suitable for target volume delineation. More complex methods, such as system-specific contrast-oriented algorithms for contour definition, should be further evaluated with special respect to patient data.

Carcinoma, Non-Small-Cell Lung↗

PubMedDate not supplied

[Complex intensive care for acute gastroduodenal hemorrhages in patients after operations on the heart and vessels].

The purpose of the study was to define the most effective principles of intensive care for acute gastroduodenal hemorrhages in patients undergoing operations on the heart and vessels. The outcomes of 13,345 operations on the heart and vessels, performed at the A. N. Bakulev Research Center of Cardiovascular Surgery, Russian Academy of Medical Sciences, were analyzed. Gastroduodenal hemorrhages were diagnosed in 114 patients, which amounted to 0.8% of the total number of operated patients. In the vast majority (86.8%) patients, gastroduodenal hemorrhages occurred after surgery under extracorporeal circulation. The results of medical and surgical treatment were analyzed. The medical treatment for gastroduodenal hemorrhages included intensive drug therapy and endoscopic hemostasis. The comprehensive and intensive approach to performing antiulcer therapy (concomitant use of the antisecretory agents: proton pump inhibitors, gastric protectors, and reparative agents) could reduce the incidence of recurrent bleeding and the timing of epithelization of gastrointestinal mucosal defects. Analyzing the results of the treatments has indicated that the efficiency of conservative measures significantly exceeds the beneficial effect of the treatment of gastroduodenal bleedings, including urgent abdominal surgical interventions. Emergency surgical interventions for gastroduodenal hemorrhages in cardiosurgical patients deteriorate the postoperative period and lead to an increase in postoperative morbidity, which determines the expediency of their performance only when conservative measures are ineffective. An algorithm of tactical actions has been developed for gastroduodenal hemorrhages occurring after operations on the heart and vessels.

APACHE↗

PubMed1991

Evaluation and treatment of ventricular arrhythmias: an update.

An overall approach to evaluating and treating ventricular arrhythmias based on objective monitoring criteria is described. A clinically useful system classifies patients based on whether their ventricular arrhythmias are benign, potentially lethal, or lethal. Some clinicians believe that antiarrhythmic drug therapy improves survival in patients with potentially lethal arrhythmias. However, disappointing results from the Cardiac Arrhythmia Suppression Trial have led to a greater awareness of the potential adverse effects of antiarrhythmics. Various risk factors for arrhythmia-related death have been identified, such as the presence of frequent and complex ventricular ectopy, abnormal signal-averaged electrocardiography (SAECG) tracings, and poor left ventricular ejection fraction (LVEF). Antiarrhythmic drugs remain the primary mode of therapy for patients with recurrent symptomatic tachycardias. Antiarrhythmic drug efficacy has been evaluated by methods including symptom assessment, continuous ambulatory electrocardiographic monitoring (Holter monitoring), exercise testing, and invasive electrophysiologic testing. There may be an extremely wide range of effective serum concentrations for the class IA agents. Individual target concentrations of antiarrhythmic agents may be determined for individual patients and should assist the clinician in optimizing long-term antiarrhythmic drug therapy. The risk-to-benefit ratio of treatment should be weighed before antiarrhythmic drug therapy is begun, and careful, objective monitoring of drug efficacy should be performed. When pharmacologic treatment of ventricular arrhythmias is considered, treatment algorithms that incorporate LVEF measurements, Holter monitor recordings, and SAECG may aid the clinician.

Anti-Arrhythmia Agents↗

PubMed1990

[A rapid radiotherapy planning program in intracavitary afterloading therapy].

A recently developed program for the irradiation planning of intracavitary afterloading applications in the treatment of gynecological diseases is presented. On the basis of measured data, a rapid algorithm for calculating the dose within the field near to ray emitters is introduced which avoids any uncertainties as to the greatest activity and the dose rate constant. Distance- and direction-dependent corrections of the inverse square law are performed by means of polynomials easy to calculate or by tables. The structure and performance of the program are described. Some examples are given in order to illustrate the possible applications of the irradiation planning program.

Algorithms↗

PubMed1989

[Combination radiodiagnosis of the functional state of the urinary tract in cancer of the kidney].

The results of combined radiodiagnosis of the urinary system in patients with renal tumors before and after nephrectomy were analyzed. Investigations included excretory urography and renography with the processing of the results of measurements by a common algorithm and on the basis of 3 mathematical models of RP body transport. The results were correlated with the findings of biochemical blood and urine tests and pathoanatomical investigation of the removed kidney. Ample potentialities of renography for the detection of latent renal insufficiency in the preoperative period and for accurate and exhaustive assessment of function of the urinary system were shown.

Humans↗

PubMed1987

[Method of determining separate kidney clearance].

The task was to develop a simple and effective method of radionuclide determination of separate clearance of the kidneys (SCK), i.e. separate assessment of secretory-excretory function of each kidney. The other earlier known methods of SCK determination were either methodologically incorrect or very difficult. A method of SCK determination intended both for gamma-chambers and standard radiographic units based on common renographic methods, was proposed. An algorithm for processing of measurement results was based on the generalization of the mathematical apparatus of circulation models usually employed for a study of the central and organ hemodynamics, and on its development for transitory nephrotropic radiopharmaceuticals (RP). An investigation of 21 healthy persons and 51 patients with renal tumors using 131I-hippuran showed that the proposed method possessed sufficient sensitivity for its clinical use. Advantages and shortcomings of the method were analysed. All the allowances were justifiable.

Humans↗

PubMed1983

[Comparison of different methods for the determination of the energy dose distribution of enclosed Cs-137 afterloading sources].

A low-dose afterloading unit of the type "Curitron" with Cs-137 sources is available at the Radiologic Hospital of the Karl-Franzens-Universität of Graz. The available sources are between 4.2 cm and 9.1 cm long. The corresponding activities of the individual sources are at present between 117 mCi and 383 mCi. The energy dose distributions around the sources were measured by means of an automatic dose measuring equipment and an additionally developed water phantom. Based on the measurement results, three rapid algorithms were developed and introduced as program modules into the existing therapy planning system which is running under RSX in a minicomputer of the type PDP 11/34. These algorithms are compared with regard to their precision and calculating speed, and the results are presented in form of energy dose distributions.

Brachytherapy↗

PubMed1994

Comparative DNA analysis of breast cancer by flow cytometry and image analysis.

Measurement of DNA ploidy can be performed either with Flow Cytometry (FCM) and Image-Analysis (IA); both methods provide prognostic information in primary breast cancer. We compared the results of quantitative DNA analysis of formalin fixed, paraffin embedded tissue from 62 invasive ductal breast cancers. For FCM nuclear suspensions from disaggregated tumor were stained with Propidium Iodide and analyzed by means of Ortho Cytoron Absolute. For IA nuclear suspensions were stained by the Feulgen method and analyzed by means of Vidas system. We found a good correlation between flow cytometry DNA Index and Histogram Type, according to Auer classification (rs = 0.65, p < 0.001) and between DNA Index and Grading of Malignancy (MG) which had been measured by Bocking's algorithm (rs = 0.38, p < 0.05). Concerning to disease free survival (DFS), flow cytometric DNA Index showed a better correlation (rs = 0.56, p < 0.001). We concluded that the two methods provide comparable results, but offer individual advantages and are complementary for analyzing DNA ploidy in breast cancer.

Algorithms↗