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PubMed2006

Deglutitive upper esophageal sphincter relaxation: a study of 75 volunteer subjects using solid-state high-resolution manometry.

This study aimed to use a novel high-resolution manometry (HRM) system to establish normative values for deglutitive upper esophageal sphincter (UES) relaxation. Seventy-five asymptomatic controls were studied. A solid-state HRM assembly with 36 circumferential sensors spaced 1 cm apart was positioned to record from the hypopharynx to the stomach. Subjects performed ten 5-ml water swallows and one each of 1-, 10-, and 20-ml volume swallows. Pressure profiles across the UES were analyzed using customized computational algorithms that measured 1) the relaxation interval (RI), 2) the median intrabolus pressure (mIBP) during the RI, and 3) the deglutitive sphincter resistance (DSR) defined as mIBP/RI. The automated analysis succeeded in confirming bolus volume modulation of both the RI and the mIBP with the mean RI ranging from 0.32 to 0.50 s and mIBP ranging from 5.93 to 13.80 mmHg for 1- and 20-ml swallows, respectively. DSR was relatively independent of bolus volume. Peak pharyngeal contraction during the return to the resting state postswallow was almost 300 mmHg, again independent of bolus volume. We performed a detailed analysis of deglutitive UES relaxation with a novel HRM system and customized software. The enhanced spatial resolution of HRM allows for the accurate, automated assessment of UES relaxation and intrabolus pressure characteristics, in both cases confirming the volume-dependent effects and absolute values of these parameters previously demonstrated by detailed analysis of concurrent manometry/fluoroscopy data. Normative values were established to aid in future clinical and investigative studies.

Adult↗
PubMed2006

A probabilistic functional atlas of the VIM nucleus constructed from pre-, intra- and postoperative electrophysiological and neuroimaging data acquired during the surgical treatment of Parkinson's disease patients.

We have previously introduced a concept of a probabilistic functional atlas (PFA) to overcome limitations of the current electronic stereotactic brain atlases: anatomical nature, spatial sparseness, inconsistency and lack of population information. The PFA for the STN has already been developed. This work addresses construction of the PFA for the ventrointermediate nucleus (PFA-VIM). The PFA-VIM is constructed from pre-, intra- and postoperative electrophysiological and neuroimaging data acquired during the surgical treatment of Parkinson's disease patients. The data contain the positions of the chronically implanted electrodes and their best contacts. For each patient, the intercommissural distance, height of the thalamus and width of the third ventricle were measured. An algorithm was developed to convert these data into the PFA-VIM, and to present them on axial, coronal and sagittal planes and in 3-D. The PFA-VIM gives a spatial distribution of the best contacts, and its probability is proportional to best contact concentration in a given location. The region with the highest probability corresponds to the best target. The PFA-VIM is calculated with 0.25-mm3 resolution from 107 best contacts in two situations: with and without lateral compensation against the width of the third ventricle. For the PFA-VIM compensated laterally, the anterior, lateral and dorsal coordinates of the mean value are (in mm) 6.24, 13.83, 1.68 for the left VIM and 6.54, -13.84, 2.10 for the right VIM. The coordinates of the mean value of the highest probability region along with the highest number of the best contacts (P) are: 6.25, 14.25, 1.75, P = 16, for the left VIM, and 6.0, -14.0, 1.00, P = 18, for the right VIM. The coordinate system origin is at the posterior commissure. For the PFA-VIM not compensated laterally, the coordinates of the mean value are 6.24, 13.99, 1.68 for the left VIM and 6.53, -14.13, 2.10 for the right VIM. The coordinates of the mean value of the highest probability region along with the highest number of the best contacts are 5.58, 13.67, 1.33, P = 14, for the left VIM, and 6.36, -14.03, 1.11, P = 17, for the right VIM. The PFA-VIM atlas overcomes several limitations of the current anatomical atlases and can improve targeting of thalamotomies and thalamic stimulations. It is dynamic and can easily be extended with new cases.

Algorithms↗
PubMed1995

Fractal clustering of ventricular ectopy correlates with sympathetic tone preceding ectopic beats.

BACKGROUND: Fractal geometric analysis of ventricular ectopy yields a fractal dimension, which can range from zero to one and is inversely related to clustering of ventricular premature contractions (VPCs). Low values of this fractal dimension, which reflect significantly nonuniform distributions of ventricular ectopy, are found in patients with life-threatening ventricular arrhythmias and predict adverse outcomes in selected patients with congestive heart failure and with mitral regurgitation. However, the physiological mechanism and correlates of the fractal dimension are unknown. METHODS AND RESULTS: To explore the physiological correlates of clustered ventricular ectopy, we studied 30 patients with a history of sustained ventricular tachycardia or ventricular fibrillation who had inducible sustained monomorphic ventricular tachycardia during electrophysiological study and also underwent drug-free 24-hour ambulatory ECG. In addition to fractal dimension (determined by use of our previously described algorithm), we measured the mean RR interval (+/- SD) for all sinus beats preceding a sinus beat and for all sinus beats preceding a single VPC and the mean root-mean-square difference (RMSSD) of all windows of 15 successive RR intervals (excluding ectopic beats) preceding a sinus beat and preceding a single VPC. Based on the directional changes of mean RR (a measure of both sympathetic and parasympathetic tone) and of RMSSD (a measure of parasympathetic tone), each patient's inferred relative sympathetic tone preceding ventricular ectopy was classified as increased, unchanged, or decreased. If these values changed concordantly, relative sympathetic tone was indeterminate. Fractal dimension did not correlate with the mean RR interval, SD of the RR interval, or RMSSD preceding sinus beats or preceding VPCs (all P > .10). In 20 patients, fractal dimension was significantly lower among those with increased relative sympathetic tone (n = 14) than those with unchanged or decreased sympathetic tone (n = 6, P = .008). Ten patients had indeterminate relative sympathetic tone. CONCLUSIONS: Clustering of ventricular ectopy, as measured by the fractal dimension, is observed in patients at increased risk of sudden cardiac death. A low fractal dimension (clustered ventricular ectopy) is related to changes in heart rate and heart rate variability that are consistent with transient increases in cardiac sympathetic tone.

Aged↗
PubMed1997

ECG-gated three-dimensional intravascular ultrasound: feasibility and reproducibility of the automated analysis of coronary lumen and atherosclerotic plaque dimensions in humans.

BACKGROUND: Automated systems for the quantitative analysis of three-dimensional (3D) sets of intravascular ultrasound (IVUS) images have been developed to reduce the time required to perform volumetric analyses; however, 3D image reconstruction by these nongated systems is frequently hampered by cyclic artifacts. METHODS AND RESULTS: We used an ECG-gated 3D IVUS image acquisition workstation and a dedicated pullback device in atherosclerotic coronary segments of 30 patients to evaluate (1) the feasibility of this approach of image acquisition, (2) the reproducibility of an automated contour detection algorithm in measuring lumen, external elastic membrane, and plaque+media cross-sectional areas (CSAs) and volumes and the cross-sectional and volumetric plaque+media burden, and (3) the agreement between the automated area measurements and the results of manual tracing. The gated image acquisition took 3.9+/-1.5 minutes. The length of the segments analyzed was 9.6 to 40.0 mm, with 2.3+/-1.5 side branches per segment. The minimum lumen CSA measured 6.4+/-1.7 mm2, and the maximum and average CSA plaque+media burden measured 60.5+/-10.2% and 46.5+/-9.9%, respectively. The automated contour-detection required 34.3+/-7.3 minutes per segment. The differences between these measurements and manual tracing did not exceed 1.6% (SD<6.8%). Intraobserver and interobserver differences in area measurements (n=3421; r=.97 to.99) were <1.6% (SD<7.2%); intraobserver and interobserver differences in volumetric measurements (n=30; r=.99) were <0.4% (SD<3.2%). CONCLUSIONS: ECG-gated acquisition of 3D IVUS image sets is feasible and permits the application of automated contour detection to provide reproducible measurements of the lumen and atherosclerotic plaque CSA and volume in a relatively short analysis time.

Adult↗
PubMed2006

Noninvasive volumetric imaging and morphometry of the rodent retina with high-speed, ultrahigh-resolution optical coherence tomography.

PURPOSE: To demonstrate high-speed, ultrahigh-resolution optical coherence tomography (OCT) for noninvasive, in vivo, three-dimensional imaging of the retina in rat and mouse models. METHODS: A high-speed, ultrahigh-resolution OCT system using spectral, or Fourier domain, detection has been developed for small animal retinal imaging. Imaging is performed with a contact lens and postobjective scanning. An axial image resolution of 2.8 mum is achieved with a spectrally broadband superluminescent diode light source with a bandwidth of approximately 150 nm at approximately 900-nm center wavelength. Imaging can be performed at 24,000 axial scans per second, which is approximately 100 times faster than previous ultrahigh-resolution OCT systems. High-definition and three-dimensional retinal imaging is performed in vivo in mouse and rat models. RESULTS: High-speed, ultrahigh-resolution OCT enabled high-definition, high transverse pixel density imaging of the murine retina and visualization of all major intraretinal layers. Raster scan protocols enabled three-dimensional volumetric imagingand comprehensive retinal segmentation algorithms allowed measurement of retinal layers. An OCT fundus image, akin to a fundus photograph was generated by axial summation of three-dimensional OCT data, thus enabling precise registration of OCT measurements to retinal fundus features. CONCLUSIONS: High-speed, ultrahigh-resolution OCT enables imaging of retinal architectural morphology in small animal models. OCT fundus images allow precise registration of OCT images and repeated measurements with respect to retinal fundus features. Three-dimensional OCT imaging enables visualization and quantification of retinal structure, which promises to allow repeated, noninvasive measurements to track disease progression, thereby reducing the need for killing the animal for histology. This capability can accelerate basic research studies in rats and mice and their translation into clinical patient care.

Animals↗
PubMedDate not supplied

The clinical algorithm nosology: a method for comparing algorithmic guidelines.

Concern regarding the cost and quality of medical care has led to a proliferation of competing clinical practice guidelines. No technique has been described for determining objectively the degree of similarity between alternative guidelines for the same clinical problem. The authors describe the development of the Clinical Algorithm Nosology (CAN), a new method to compare one form of guideline: the clinical algorithm. The CAN measures overall design complexity independent of algorithm content, qualitatively describes the clinical differences between two alternative algorithms, and then scores the degree of similarity between them. CAN algorithm design-complexity scores correlated highly with clinicians' estimates of complexity on an ordinal scale (r = 0.86). Five pairs of clinical algorithms addressing three topics (gallstone lithotripsy, thyroid nodule, and sinusitis) were selected for interrater reliability testing of the CAN clinical-similarity scoring system. Raters categorized the similarity of algorithm pathways in alternative algorithms as "identical," "similar," or "different." Interrater agreement was achieved on 85/109 scores (80%), weighted kappa statistic, k = 0.73. It is concluded that the CAN is a valid method for determining the structural complexity of clinical algorithms, and a reliable method for describing differences and scoring the similarity between algorithms for the same clinical problem. In the future, the CAN may serve to evaluate the reliability of algorithm development programs, and to support providers and purchasers in choosing among alternative clinical guidelines.

Algorithms↗
PubMed2004

Detection of evolutionarily stable fragments of cellular pathways by hierarchical clustering of phyletic patterns.

BACKGROUND: Phyletic patterns denote the presence and absence of orthologous genes in completely sequenced genomes and are used to infer functional links between genes, on the assumption that genes involved in the same pathway or functional system are co-inherited by the same set of genomes. However, this basic premise has not been quantitatively tested, and the limits of applicability of the phyletic-pattern method remain unknown. RESULTS: We characterized a hierarchy of 3,688 phyletic patterns encompassing more than 5,000 known protein-coding genes from 66 complete microbial genomes, using different distances, clustering algorithms, and measures of cluster quality. The most sensitive set of parameters recovered 223 clusters, each consisting of genes that belong to the same metabolic pathway or functional system. Fifty-six clusters included unexpected genes with plausible functional links to the rest of the cluster. Only a small percentage of known pathways and multiprotein complexes are co-inherited as one cluster; most are split into many clusters, indicating that gene loss and displacement has occurred in the evolution of most pathways. CONCLUSIONS: Phyletic patterns of functionally linked genes are perturbed by differential gains, losses and displacements of orthologous genes in different species, reflecting the high plasticity of microbial genomes. Groups of genes that are co-inherited can, however, be recovered by hierarchical clustering, and may represent elementary functional modules of cellular metabolism. The phyletic patterns approach alone can confidently predict the functional linkages for about 24% of the entire data set.

Cluster Analysis↗
PubMed2005

Computer-assisted kinematic evaluation of induced compensatory movements resembling lameness in horses trotting on a treadmill.

OBJECTIVE: To characterize compensatory movements of the head and pelvis that resemble lameness in horses. ANIMALS: 17 adult horses. PROCEDURE: Kinematic evaluations were performed while horses trotted on a treadmill before and after shoe-induced lameness. Lameness was quantified and the affected limb determined by algorithms that measured asymmetry in vertical movement of the head and pelvis. Induced primary lameness and compensatory movements resembling lameness were assessed by the Friedman test. Association between induced lameness and compensatory movements was examined by regression analysis. RESULTS: Compensatory movements resembling lameness in the ipsilateral forelimb were seen with induced lameness of a hind limb. There was less downward and less upward head movement during and after the stance phase of the ipsilateral forelimb. Doubling the severity of lameness in the hind limb increased severity of the compensatory movements in the ipsilateral forelimb by 50%. Compensatory movements resembling lameness of the hind limb were seen after induced lameness in a forelimb. There was less upward movement of the pelvis after the stance phase of the contralateral hind limb and, to a lesser extent, less downward movement of the pelvis during the stance phase of the ipsilateral hind limb. Doubling the severity of lameness in the forelimb increased compensatory movements of the contralateral hind limb by 5%. CONCLUSIONS AND CLINICAL RELEVANCE: Induced lameness in a hind limb causes prominent compensatory movements resembling lameness in the ipsilateral forelimb. Induced lameness in a forelimb causes slight compensatory movements resembling lameness in the ipsilateral and contralateral hind limbs.

Animals↗
PubMedDate not supplied

Outcomes, clinical models and the redesign of behavioral healthcare.

Outcomes measurement and data-triggered improvements in treatment delivery are formidable challenges, in part because of their inherent interdependence. Outcomes systems need to provide reliable, valid and comparable data that can also guide transitions in care delivery. While there is much empirical support for the efficacy of psychiatric and behavioral healthcare interventions, it is incumbent upon those who know both the literature and clinical practice to participate in setting the future course of behavioral healthcare by stirring together the seemingly immiscible aims of good business and good care. This paper briefly reviews the importance of outcomes measurement systems and their use in redesigning treatment delivery in behavioral healthcare. It then describes a clinical care model now being implemented at Park Nicollet Medical Center, incorporating clinical and operational considerations, clinical outcomes measures and algorithms or decision trees into a framework for redesigning treatment and improving the delivery of appropriate clinical care.

Hospital Restructuring↗
PubMed2002

[Blunt isolated pancreatic trauma. Diagnostic problems--a clinical and radiological challenge].

INTRODUCTION: Blunt isolated pancreas trauma is rare, but it is a very serious condition. Diagnosis and treatment are often delayed, which considerably increases morbidity. The delay is caused by uncharacteristic symptomatology and the application of paraclinical and radiological diagnostic methods of low initial sensitivity and specificity. The aim of this study was to describe the diagnostic difficulties and the applicability of the various radiological modalities. MATERIAL AND METHODS: During the period 1995-2000, three patients with blunt isolated pancreas trauma were treated, and the case reports were examined retrospectively. RESULTS: All three showed classical mechanisms of injury, and a characteristic delay in diagnosis and treatment of 24 to 48 hours was seen. DISCUSSION: The frequent delay in diagnosis and subsequent treatment of the blunt pancreas trauma requires a more optimal strategy for handling such traumas. We recommend the following diagnostic algorithm: Repeated measurements of serum amylase initially. Image diagnostics with a dynamic spiral CT-scan with both oral and intravenous contrast. The CT scan is to be repeated or supplemented by MRCP on continued suspicion of pancreas injury, even when the initial CT scan shows normal findings.

Adult↗
PubMed2003

[Minimally-invasive combined radiosurgical interventions in diagnosis and treatment of pulmonary artery thromboembolism].

Basing on the analysis of results obtained during the investigation and treatment of 38 patients suspected of pulmonary artery thromboembolism (PAT) the algorithm of measures applied in our hospital was developed. Its purpose was to put the PAT diagnosis and treatment in order. In our investigations the leading treatment method was the regional infusion therapy conducted through the transformation of diagnostic catheterization of pulmonary artery trunk into the treatment intervention. With the purpose of embolus hydrodynamic destruction the regional thrombolysis was conducted under conditions of fast high-pressure perfusion. It was preceded by the mechanical recanalization of thrombosis zone by the distal part of probe in order to create more favorable perfusion conditions. To prevent the repeated PAT when the source of thromboembolism was revealed the cava-filter implantation in the infra-renal part of inferior cava was performed.

Combined Modality Therapy↗
PubMed2003

Detection of pediatric respiratory and gastrointestinal outbreaks from free-text chief complaints.

We conducted a retrospective study to ascertain the potential of free-text chief complaints collected in pediatric emergency departments to serve as surveillance data for early detection of outbreaks. We determined that automatically coded chief complaint data provide a signal that reflects outbreaks in a population of children less than five years of age. Using the Exponentially Weighted Moving Average (EWMA) detection algorithm, we measured the timeliness, sensitivity, and specificity of free-text chief complaints for predicting outbreaks of pediatric respiratory and gastrointestinal illness. We found that time series of automatically coded free text-chief complaints in pediatric patients correlate well with hospital admissions and precede them by the mean of 10.3 days (95% CI -15.15, 35.5) for respiratory outbreaks and 29 days (95% CI 4.23, 53.7) for gastrointestinal outbreaks. We conclude that free-text chief complaints may play an important role as an early, sensitive and specific indicator of outbreaks of respiratory and gastrointestinal illness in children less than five years of age.

Child, Preschool↗
PubMed1990

[Image analysis of morphologic features of the corneal endothelium including hexagonality].

We developed an analysis system for the evaluation of corneal endothelial photographs. Morphological parameters including hexagonality were analyzed semiautomatically with this system. The image analyzer used consists of an image processor MC68000 and image memories 512 x 512 x 17bytes in size. The algorithm that measures the number of apices of each cell is as follows. First, all crossing points of cell borders are detected. Then, each cell is enlarged in order by three pixels in eight directions. The number of crossing points which are overlapped with an enlarged cell is detected as the number of apices of the cell. The analysis time was 7.44 +/- 1.48 min. (mean +/- standard deviation) for 40 endothelial photographs which needed no manual trace for contrast enhancement.

Cell Count↗
PubMed1985

Brainstem auditory-evoked potentials.

Brainstem auditory-evoked potentials (BAEPs) are generated in the ear and brainstem nuclei of the ascending auditory pathways following a transient acoustic stimulus. Because they can be recorded noninvasively in humans, BAEPs have a number of clinical and research applications. This paper reviews the properties of BAEPs, with particular emphasis on those characteristics that are relevant to the acquisition and analysis of the responses. Theories of the neural origins of the responses are reviewed. The dependence of the responses on the stimulus waveform and the problem of stimulus artifact are considered. Then, origins of the background noise are discussed, and the use of linear filtering and methods of artifact detection to improve the signal-to-noise ratio are reviewed. Finally, the problem of identifying parameters to quantify the responses is considered. The definition of response components in terms of response peaks and data on intra- and intersubject variability are reviewed, and the use of algorithms to measure parameters is discussed.

Acoustic Stimulation↗
PubMed2004

The economic implications of three biochemical screening algorithms for pheochromocytoma.

Pheochromocytoma is a rare, life-threatening condition. Using a modeling technique, we studied the economic implications of detection strategies for pheochromocytoma (third-party payer perspective). The diagnostic efficacy of biochemical tests was based on Mayo Clinic Rochester data. In all hypothetical algorithms, positive biochemical tests were followed by abdominal computerized tomography and, if negative, metaiodobenzylguanidine scintigraphy. In each hypothetical algorithm, imaging would be indicated after positive biochemical testing as follows: algorithm A, fractionated plasma metanephrine measurements above the laboratory reference range; or algorithm B, abnormal measurements of 24-h urinary total metanephrines or catecholamines. In algorithm C, subjects with fractions of plasma metanephrine at or above 0.5 nmol/liter or normetanephrine at or above 1.80 nmol/liter would undergo imaging, whereas those with values between the reference range and these cutoffs would undergo 24-h urinary measurements (total metanephrines and fractionated catecholamines) and be imaged if positive. We determined that, if 100,000 hypertensive patients (including 500 patients with pheochromocytoma) were tested, algorithm A (measurement of fractionated plasma metanephrines alone) would detect 489 pheochromocytoma patients at a cost of 56.6 million dollars, whereas B (24-h urinary measurements) would detect 457 pheochromocytoma patients for 39.5 million dollars, and C (combination of measurements of fractionated plasma metanephrines and urines) would detect 478 patients for 28.6 million dollars. None of the screening strategies for pheochromocytoma described are affordable if implemented on a routine basis in extremely low-risk patients. However, algorithm C may be the least costly, and at a reasonable level of sensitivity, for subjects in whom the suspicion of disease is moderate.

Adrenal Gland Neoplasms↗
PubMed1995

Sub-typing depression, III. Development of a clinical algorithm for melancholia and comparison with other diagnostic measures.

We describe the development of a clinical algorithm to differentiate melancholic from non-melancholic depression, using refined sets of 'endogeneity' symptoms together with clinician-rated CORE scores assessing psychomotor disturbance. Assignment by the empirically developed algorithm is contrasted with assignment by DSM-III-R and with several other melancholia sub-typing indices. Both the numbers of 'melancholics' assigned by the several systems and their capacity to distinguish 'melancholics' on clinical, demographic and a biological index test (the DST) varied across the systems with the algorithm being as 'successful' as several systems that include inter-episode and treatment response variables. Analyses provide information on the criteria set developed for DSM-IV definition of 'melancholia'.

Adult↗
PubMed1995

Comparison of residual stability in thoracolumbar spine fractures using neutral zone measurements.

Because treatment algorithms for spinal injuries depend largely on the clinical assessment of stability after injury, this study both quantified and compared the mechanical stability after three different patterns of injury in the thoracolumbar spine. We created compression fractures, burst fractures, and flexion-distraction injuries in 26 thoracolumbar specimens from human cadavers in order to compare residual stability as a function of type of injury. Spinal stability was evaluated using measurements of the boundaries of the neutral zone, which provide a measure of spinal laxity in various directions of motion. An increase after injury was indicative of greater spinal laxity and hence reduced residual stability. Geometric characteristics (or parameters) of the neutral zone boundaries were used for statistical comparison between the types of injury. Of the three groups, burst fractures retained the least residual stability and compression fractures, the greatest. The angular ranges of motion in the neutral zone for burst fractures demonstrated increases (compared with average values for intact specimens) of 154% in flexion-extension, 134% in lateral bending, and 108% in torsion after injury. The results for flexion-distraction injuries were similar to those for burst fractures in flexion-extension (126%) and torsion (62%); however, more residual stability was retained in lateral bending than was seen for burst fractures (48%). Compression fractures retained the most residual stability, with increases in motion of 40% in flexion-extension, 56% in lateral bending, and 3% in torsion. These findings may be useful in determining the necessity for surgical stabilization of the spine and selection of the appropriate system of fixation.

Biomechanical Phenomena↗