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At least 199 records · Page 11Linked to original sources

PubMed1992

Pulmonary artery pressure measurement in patients with elevated pressures: effect of backrest elevation and method of measurement.

OBJECTIVE: To determine whether pulmonary artery pressure measurement is accurate if the head of the bed is elevated; to compare the end-expiratory graphic recording and digital monitor methods for pulmonary artery pressure measurement; to determine whether either mean arterial pressure or mixed venous oxygen saturation changes during backrest elevation. DESIGN: Nonrandomized clinical trial. SETTING: A six-bed cardiac surgical intensive care unit of a 540-bed federal facility. POPULATION: Twenty-five postoperative cardiac surgical patients with elevated pulmonary artery pressures (systolic higher than 35 mm Hg). INTERVENTIONS: In supine patients pulmonary artery pressures were measured at each of the following backrest elevations: 0, 20, 30, 45 and again at 0 degrees. Measurements were obtained once during mechanical ventilation and once during normal breathing after extubation. MAIN OUTCOME MEASURES: End-expiratory graphic recording of pulmonary artery pressures; digital monitor values of pulmonary artery pressures; mean arterial pressure; and mixed venous oxygen saturation. RESULTS: No statistical difference was found in pulmonary artery pressures measured at each of the backrest elevations during mechanical ventilation or normal breathing after extubation. Pulmonary artery diastolic and pulmonary capillary wedge pressures obtained with the digital monitor method were significantly lower than the end expiratory graphic recording method during normal breathing after extubation but not during mechanical ventilation. No changes in mean arterial pressure or mixed venous oxygen saturation occurred during backrest elevation. CONCLUSIONS: These results show that pulmonary artery pressures can be measured accurately with the head of the bed in an elevated position. The data indicate that obtaining pulmonary artery pressure measurements from the digital display of the bedside monitor is accurate when respiratory wave form fluctuations are minimal but may lead to inaccurate values with prominent respiratory fluctuations. Further research is needed to validate this finding in different patient populations and with other models of monitoring equipment.

Adult↗

PubMed2004

Assessment of the 3-dimensional Fastrak measurement system in measuring range of motion in ankylosing spondylitis.

OBJECTIVE: To assess the repeatability and validity of the electromagnetic 3-dimensional tracking system, Fastrak, in measuring cervical spine and shoulder movement in patients with ankylosing spondylitis (AS). METHODS: Fifty patients with AS had their cervical spine and shoulder movements measured on up to 3 occasions with the Fastrak. Patients also completed disease-specific and generic patient assessed health instruments, and their spinal mobility was assessed by tape measure methods. Repeatability over 2 weeks was assessed using intraclass correlation coefficients (ICC). Fastrak measurements were compared between patients with different self-ratings of AS related health. Comparisons between the Fastrak measurements and patient assessed health instruments and tape measurements were made using Spearman correlations and multilevel modeling. RESULTS: Patients with AS tended to be limited in both cervical spine and shoulder movements. ICC were all > 0.80 (except shoulder extension, 0.75), indicating substantial reliability. Fastrak was able to differentiate between patients with a high self-rating of AS related health and those with a poorer rating. Cervical spine flexion and shoulder flexion and abduction were most strongly related to the patient assessed health instruments, although the shoulder movements had limited relationships with the tape measurements of spinal mobility. CONCLUSION: The Fastrak appears to be reliable and valid in an AS population. Shoulder movements tended to have a stronger relationship with the patient assessed health instruments than cervical spine movements. Shoulder movement may be more related to everyday function measured by these instruments, which indicates the importance of this joint in assessment of AS.

Adult↗

PubMed2005

The development of a race and gender-specific stress measure for African-American women: Jackson, Hogue, Phillips contextualized stress measure.

OBJECTIVE: Community-based research was conducted to develop an identity stress measure for African-American women. The aim of the investigation was to capture the voices of African-American women telling their experiences of stress and support and to have their voices inform the development of an identity stress measure representing the realities of being Black and female. In this paper, we describe the components of a race and gender-specific stress measure emerging from a multidisciplinary iterative process that employed qualitative and quantitative methods. METHOD: The research was initiated by focus groups and interviews where women were asked to share their experiences of stress and support. Four hundred seventy-four (474) African-American women from the metropolitan Atlanta area collaborated in the study by participating in one or more phases of the research. Content analysis of the qualitative data informed the development of a 71-item race and gender-specific stress measure for African-American women. The scale and a battery of validity measures (Spielburger Anger and Anxiety, John Henryism, and NHIS-depression) were administered twice over a 30-day period followed by group discussions and interviews. RESULTS: Content and factor analysis resulted in the development of six subscales: racism, burden, personal history, work, support/coping, and stress states. The measure has been validated with established measures of anger, anxiety, depression. Significant correlations were established for all of the stress subscales and measures of anger (trait anger, anger-in, anger-out, and anger expression). Findings indicate significant correlations for the burden subscale and anger-in (r=.33, <.01) and stress states and trait anxiety (r=.57, <.01).

Adaptation, Psychological↗

PubMed2005

Effects of total plasma protein concentration on plasma sodium, potassium and chloride measurements by an indirect ion selective electrode measuring system.

OBJECTIVE: Ion selective electrodes (ISE) measure electrolytes by two different technologies, direct and indirect. We wished to investigate the effect of total plasma protein concentration on the plasma sodium, potassium and chloride measurements by indirect ISE compared with measurements by direct ISE. METHODS: The evaluation of the objective was performed in a tertiary care hospital on patient blood samples sent to the pathology laboratory for general chemistry analysis. To determine the degree of difference between the two ISE measurements, 195 lithium heparin plasma samples were measured and the results were separated into three groups (65 samples in each group) depending on the protein concentration (e.g. total plasma protein concentration less than, greater than and within the reference range between 62-83 g/L). The samples were analysed over a 40 day period on a Hitachi Modular ISE system - indirect ISE (Roche Australia) and Bayer Rapidlab 865 Blood Gas Analyser - direct ISE (Bayer Diagnostics, Australia). RESULTS: Using indirect ISE, low plasma protein concentrations caused a 'pseudohyper' effect in all 3 analytes and a 'pseudohypo' effect with high plasma protein concentrations. The variation in total protein concentration had the greatest effect on plasma sodium measurement. The relationship was non-linear and no accurate predictive value could be calculated for the plasma electrolytes with changes in plasma protein concentrations. CONCLUSIONS: The plasma sodium, potassium and chloride measurements are effected by changes in plasma protein concentration when measured by indirect ISE systems. Clinicians must be aware that differences exist between the ISE technologies and in border-line clinical situations, the direct ISE systems provide a more accurate estimate of plasma sodium, potassium, chloride, anion gap, osmolality and strong ion difference calculations, and should be used for clinical decision-making.

Journal Article↗

PubMed1990

[Three-dimensional shape measurement of teeth. (6) Measurement of tooth model by tilting method by means of the double sensor laser displacement meter, and the simulation of occlusion].

To measure the three-dimensional shape of the undercut portion of a molar model tooth, the tilting method was used. The measuring system was composed of a laser displacement meter with double sensor and a computer controlled tooth model scanning machine (CAMM-3). A model tooth was tilted on the gonio stage with +/- 20 degrees and measured divisionally, and a couple of data were connected by the TILCOMPO program. The undercut portions from the survey line to the tooth neck were measured and drawn by CG. By this tilting method, the whole shape of tooth including the undercut portion could be measured, and these data will be available for the production of the data base for CAD of prosthesis. The marginal line on the crown abutment measured previously was searched. Initially, the difference in the inclination dz/dx between the data before and behind was calculated, and the gingival line was extracted by limiting its value. Then, also by limiting the difference value, the margin located above the gingival line was determined. Thus the marginal line in contact with the inner and outer crown and a significantly important point for the production of crown by the CAD/CAM technique could be determined around the crown abutment. Another elementary attempt to simulate the occlusion by using the data of teeth models measured on the articulator was carried out. The maxillary and mandibular teeth were set on the articulator and the maxillary teeth turned over. The shapes of the 5-7 upper and lower molar were measured. The two data were connected and occluded by the "OCCLUS" program.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Simulation↗

PubMed1989

Three dimensional shape measurement of teeth by the system of laser displacement meter and computer controlled scanning machine. 2. The improvement of accuracy by means of the divisional measurement method.

The accuracy of the three dimensional shape measurement of teeth was improved. The system was composed of a laser displacement meter and a computer controlled scanning machine. The compensation of errors which were observed when the reflected beam was shaded by the model teeth itself was attempted by connecting the data which were measured by rotating the model tooth at 180 degrees on the going stage. The accuracy of measurement was examined at the slope of 7 crown abutment tooth. When the model tooth were measured without tilting, the difference between the true value and the measured data was -240 microns (-2.8%). However, by tilting the model tooth at +/- 20 degrees on the going stage and connecting the two couples of data obtained, the difference considerably decreased into +/- 10 microns (+0.1%). In order to measure a complete crown abutment tooth with high accuracy and without error at the shaded portion, the model tooth was tilted +/- 30 degrees and rotated 180 degrees on the going stage and measured divisionally at four regions. The four partial data thus obtained were combined by using the software program. By the present procedure, the margin of the abutment tooth was recognized and the error data were eliminated. The overlapped data upon divisional measurements were excluded and the complete data of the single abutment tooth were saved into a file. They are possible to be the basic data for the future production of prostheses by means of CAM technique.

Computer Graphics↗

PubMedDate not supplied

[Self-measurement and automatic measurement in ambulatory blood pressure monitoring].

INTRODUCTION: There are strictly determined conditions under which blood pressure measurement should be done and diagnosis of hypertension made. The first BP measurement should be performed on both arms. If there is a difference, controls should be made on the side on which the pressure is higher. In older persons the Osler manoeuvre should be made in order to exclude pseudohypertension. One should be aware that in hospitalized patients the BP is lower due to the bed rest itself. SELF-MEASUREMENT OF BLOOD PRESSURE: It seems that erroneous interpretation of blood pressure fluctuation and the tendency for self-medication by patients are the most important shortcomings of blood pressure self-monitoring. According to the World Hypertension League instructions, the BP self-measurement is not recommended for patients obsessed by the disease, neurotic and anxious persons, old subjects and in those who are physically handicapped. Since the diagnosis of hypertension should be made by the physician in office conditions, in our opinion the evolution of the disease and effects of treatment should be estimated under the same conditions. BLOOD PRESSURE AMBULATORY MONITORING: Ambulatory 24-hour monitoring is of a considerable diagnostic, therapeutic and prognostic importance over the casual or self-measurement, but one should be familiar with some peculiarrities of this method. Due to the adaptation to the device, the values of BP on the first measurement, particularly during the first 5 hours are significantly higher than during the subsequent measurements. In some subjects the values during the night may be higher due to the sleeping disturbances caused by the procedure. Differentiation between dippers and non-dippers has some prognostic and therapeutic implications. White coat hypertension may be successfully established by the ambulatory measurement. There is also a correlation between the BP variations and the myocardial mass. The trough:peak ratio may contribute to the estimation of efficiency of a certain drug. There are particular indications for ambulatory BP monitoring: the differences between the office and home values of BP are considerable; borderline hypertension; hypertension without signs of the target-organ damage; transitory hypertension of hypotension; syncopal attacks; vague symptoms in hypertensive patients; atypical or nocturnal angina; evaluation of the efficiency and duration of drug action; for research purposes.

Blood Pressure Determination↗

PubMed1998

A series of self-measurements by the patient is a reliable alternative to ambulatory blood pressure measurement.

BACKGROUND: Several studies have reported overdiagnosis and overtreatment of hypertensive patients, especially in borderline hypertensives. AIM: To find a blood pressure measurement procedure that reduces the risk of misclassification to an acceptable level. METHOD: Comparative, prospective study over seven months of primary care patients with elevated initial blood pressures. Blood pressure measurements made by general practitioners (GPs), practice nurses, and patients were compared with ambulatory blood pressure measurements. RESULTS: Ninety-nine patients completed the study. Mean differences (systolic blood pressure) between different measurement procedures and ambulatory measurement ranged from +10 mmHg (doctor) to -1 mmHg (patient), and (diastolic) from +4 mmHg (doctor) to -2 mmHg (patient). Standard deviations of mean differences ranged from 12 mmHg (doctor/systolic) to 10 mmHg (patient/systolic), and from 8 mmHg (doctor/diastolic) to 7 mmHg (patient/diastolic). CONCLUSION: Self-measurements by the patient appear to be a reliable alternative to ambulatory blood pressure measurement. In diagnosing and managing mild hypertension, we recommend the use of a valid self-measuring device.

Adult↗

PubMed1998

The analysis of sex segregation: when is index measurement not index measurement?

In their paper in this issue, Grusky and Charles (1998) make a number of dubious claims about the measurement and interpretation of sex segregation. First, they incorrectly claim that only log-odds measures yield margin-free measures of segregation. Second, the estimation and testing of a limited class of log-linear models does not provide an independent test of the appropriateness of a log-odds ratio index to measure segregation. Their estimation in forms them of the statistically justifiable degree of occupational disaggregation, not whether a log-odds ratio is superior to, say, a linear index in the measurement of segregation. Finally, their index A is beset with problems of interpretation, not withstanding their arguments, and their additional measures, AW and AB, suffer similar problems. Grusky and Charles are, however, correct in arguing that measurement procedures should be margin-free. Further, I concur with the view that the adoption of a single annual summary measure of segregation cannot be justified, because it is premised on the assumption that individual occupations, or groups of occupations, exhibit similar trends in sex segregation.

Female↗

PubMed2003

The relationship between standardized measures of language and measures of spontaneous speech in children with autism.

This study investigated the relationship between scores on standardized tests (Clinical Evaluation of Language Fundamentals [CELF], Peabody Picture Vocabulary Test-Third Edition [PPVT-III], and Expressive Vocabulary Test) and measures of spontaneous speech (mean length of utterance [MLU], Index of Productive Syntax, and number of different word roots [NDWR]) derived from natural language samples obtained from 44 children with autism between the ages of 4 and 14 years old. The children with autism were impaired across both groups of measures. The two groups of measures were significantly correlated, and specific relationships were found between lexical-semantic measures (NDWR, vocabulary tests, and the CELF lexical-semantic subtests) and grammatical measures (MLU, and CELF grammar subtests), suggesting that both standardized and spontaneous speech measures tap the same underlying linguistic abilities in children with autism. These findings have important implications for clinicians and researchers who depend on these types of language measures for diagnostic purposes, assessment, and investigations of language impairments in autism.

Adolescent↗

PubMed2004

Evaluation of SET--a new device for the measurement of pain perception in comparison to standard measures of diabetic neuropathy.

BACKGROUND: Early detection of sensory impairment and loss of protective pain sensation is of major importance for the prevention of neuropathic foot ulceration. The aim of our study was to evaluate a new handheld device (SET, a prototype developed by Dr. W. Henniges, Zülpich, Germany) for measurement of pain perception, in comparison with established methods for diagnosis of diabetic neuropathy. METHODS: Sixty-one patients with diabetes mellitus (13 type 1, 48 type 2; 42 men, 19 women; mean +/- SD age 61.6 +/- 11.6 years) received measurement of pain perception threshold using the new SET device and a measurement of light touch sensation, temperature sensation, and vibration sensation by the use of standard clinical devices. In addition, warm, cold, heat pain and vibration perception thresholds were determined by the use of a computer-based peltier thermode and a vibration stimulator (TSA 2001, Medoc, Ramat Yishai, Israel). RESULTS: Using the new SET device, patients with sensory impairment showed significantly elevated pain perception thresholds at the dorsum of the foot (P < 0.001), while only a trend towards higher measurements could be observed at the plantar aspect of the foot. A significant correlation could be observed between plantar and dorsal measuring sites (r = 0.78, P < 0.0001) and between both feet (r = 0.85, P < 0.0001). Compared with other qualities of sensory dysfunction, pain perception measurement with the SET device provided the highest sensitivity (pain = 0.82; vibration = 0.61; temperature = 0.42; light touch = 0.11). CONCLUSIONS: Measurement of pain perception threshold using the SET device is an easy and reliable method for identifying patients with impaired small nerve fiber function.

Cold Temperature↗

PubMed1986

Accuracy of measured and predicted residual lung volume on body density measurement.

The effects of measured and predicted residual lung volume on the accuracy of body density and percent fat (%Fat) were investigated. Adult fitness subjects (N = 46) had residual lung volume measured with the oxygen dilution method while those from an athlete sample (N = 134) utilized the nitrogen washout technique. Residual lung volume was also predicted with gender-specific regression equations using height and age and from 24% of vital capacity (%FVC). Residual lung volume alpha reliability for the average of four residual lung volume trials exceeded 0.90 (SEM less than = 161 ml) for the oxygen dilution method and 0.99 (SEM = 30 ml) for the average of two nitrogen washout measures. The standard errors for predicted residual lung volume were 579 and 355 ml, respectively, for the men and women in the adult sample and 288 ml for the trained athlete sample. Estimating residual lung volume from %FVC yielded a SEE of 318 ml for the trained athlete sample. Measured residual lung volume errors resulted in errors of 1.04%Fat, 0.87%Fat, and 0.21%Fat for the men, women, and trained athlete samples, respectively. In contrast, predicted residual lung volume measurement errors resulted in errors of 3.70%Fat, 2.85%Fat, and 1.98%Fat for the respective samples and 2.18%Fat when using %FVC with the trained athletes. Measured residual lung volume introduces little %Fat error while predicted residual lung volume introduces a substantial source of measurement error.

Adipose Tissue↗

PubMedDate not supplied

On summary measures analysis of the linear mixed effects model for repeated measures when data are not missing completely at random.

Subjects often drop out of longitudinal studies prematurely, yielding unbalanced data with unequal numbers of measures for each subject. A simple and convenient approach to analysis is to develop summary measures for each individual and then regress the summary measures on between-subject covariates. We examine properties of this approach in the context of the linear mixed effects model when the data are not missing completely at random, in the sense that drop-out depends on the values of the repeated measures after conditioning on fixed covariates. The approach is compared with likelihood-based approaches that model the vector of repeated measures for each individual. Methods are compared by simulation for the case where repeated measures over time are linear and can be summarized by a slope and intercept for each individual. Our simulations suggest that summary measures analysis based on the slopes alone is comparable to full maximum likelihood when the data are missing completely at random but is markedly inferior when the data are not missing completely at random. Analysis discarding the incomplete cases is even worse, with large biases and very poor confidence coverage.

Computer Simulation↗

PubMed1996

Measurement of lung function in awake 2-4-year-old asthmatic children during methacholine challenge and acute asthma: a comparison of the impulse oscillation technique, the interrupter technique, and transcutaneous measurement of oxygen versus whole-body plethysmography.

This study evaluated three techniques for testing of lung function in young awake children. We compared measurements by the forced or impulse oscillation technique (IOS), the interrupter technique (IT), and transcutaneous measurements of oxygen (tcPo2) with concomitant measurements of specific airway resistance (sRaw) during methacholine challenge in 20 stable asthmatic children, 2-4 years old. Measurements were performed with all techniques after each dose of methacholine and after inhalation of a bronchodilator. Measurements were carried out during tidal breathing using a face-mask with a built-in mouthpiece. The ranking of sensitivity was as follows: sRaw > IOS, respiratory reactance at 5 Hz (Xrs5) > tcPo2 > interrupter resistance (Rint) > IOS, respiratory resistance at 5 Hz (Rrs5). The sensitivity of sRaw and Xrs5 was not significantly different, but both were significantly more sensitive than Rint and Rrs5; the sensitivity of tcPo2, Rint, and Rrs5 was not significantly different. Measurements in eight of the subjects performed during an episode of acute asthma yielded comparable results in regard to the sensitivity of the techniques. Measurements improved significantly after bronchodilator administration; however, the response to bronchodilator tended to be less during acute asthma and was best demonstrated by a deterioration of tcPo2. All the evaluated techniques reliably reflect short-term changes in respiratory function and can provide clinically useful estimates of airway function. The techniques are non-invasive, are not dependent on the active co-operation or sedation of the subjects, and therefore are well suited for routine use in young children.

Acute Disease↗

PubMed2003

Computerized measurement of magnetic resonance imaging erosion volumes in patients with rheumatoid arthritis: a comparison with existing magnetic resonance imaging scoring systems and standard clinical outcome measures.

OBJECTIVE: One of the major aims of therapy in rheumatoid arthritis (RA) is to prevent erosive disease and subsequent disability. One of the important goals of therapy assessment must therefore be the accurate measurement of damage progression. We undertook this study to assess the feasibility, reliability, and validity of measuring magnetic resonance imaging (MRI) erosion volumes and synovial volumes in the wrists of RA patients with the use of a semiautomated computerized method. METHODS: Twelve subjects with seropositive RA were chosen to reflect a spectrum of RA severity as determined by the clinical Joint Alignment and Motion (JAM) Scale. MRI of the dominant wrist was performed at the same time of day at baseline and at 48 hours. Images were transferred to a workstation. Erosion volumes and synovial volumes were measured on the coronal images using OSIRIS imaging software. All images were reread in random order at 72 hours by 1 observer. The results were compared with erosion scores and global synovitis scores obtained by the same observer using the Outcome Measures in Rheumatology Clinical Trials MRI RA scoring system. Radiographs were performed at baseline and were read on 2 occasions by 1 observer using the Scott modification of the Larsen method. RESULTS: Total erosion volume per subject ranged from 0 cm(3) to 4.7 cm(3). The total synovial membrane volume per subject ranged from 0.1 mm(3) to 12.1 cm(3). Intraclass correlation coefficients for erosion volumes and synovial volumes demonstrated excellent intraobserver reliability and interoccasion reliability. There was a strong positive correlation between the total erosion volume and the total erosion score. The correlation between the synovial volumes and synovitis score was less favorable (r = 0.53-0.86). Positive correlations were demonstrated between the erosion volumes, the JAM score, and the modified Larsen scores. No significant correlation was demonstrated between the erythrocyte sedimentation rate, C-reactive protein level, swollen joint count, tender joint count, or the Disease Activity Score in 28 swollen and 28 tender joints and the synovial volumes or synovitis scores. CONCLUSION: This study is the first to demonstrate the feasibility, reliability, and validity of computerized MRI erosion volume measurements in the wrists of RA patients. The method will require further evaluation in terms of interobserver reliability, with examination of responsiveness in longitudinal studies, but the method demonstrates excellent interoccasion and intraobserver reliability and compares favorably with existing RA clinical outcome measures. Synovial volume measurements demonstrated good intraobserver reliability and appeared to be more responsive to synovial change over a 48-hour period in this group of patients.

Adult↗

PubMed2003

Appraising surgeons learning sonography: measuring measurement variability.

PURPOSE: Sonography is increasingly used by various clinicians in several task-specific situations. We present a method of assessing 1 aspect of a nonspecialist's ability in performing sonography, measurement variability. METHODS: An experienced radiologist and a surgeon who had received 4 weeks of sonography training each made triplicate measurements of gallbladder dimensions in 19 adult patients undergoing abdominal sonography. The observers examined the subjects in immediate succession using the same ultrasound equipment and were blinded to each other's measurements until the end of the study. Intraobserver measurement variability rates were calculated for gallbladder length, height, and width by using analysis of variance techniques and were expressed as a within-subject standard deviation and a repeatability coefficient. RESULTS: In terms of intraobserver measurements, the estimated within-subject standard deviations were comparable for the radiologist and the surgeon (length, 0.22 versus 0.17 cm; height, 0.14 versus 0.14 cm; and width, 0.12 versus 0.14 cm, respectively), as were the repeatability coefficients. The interobserver variability showed good agreement as well; the estimated within-subject standard deviations (and 95% limits of agreement) obtained were length, 0.47 cm (-1.08 to 1.48 cm); height, 0.34 cm (-1.08 to 0.49 cm); and width, 0.28 cm (-0.80 to 0.81 cm). CONCLUSIONS: The ability to measure organ dimensions accurately is an essential sonographic skill that can be readily appraised. The findings from this comparison study illustrate that this 1 small aspect of sonography can be learned by various clinicians and that their ability in this task can be appraised. In a clinical setting, the small degree of variability in measurements made by the experienced radiologist and the sonography-trainee surgeon is likely to be satisfactory.

Education, Medical, Continuing↗

PubMed2003

Simple anatomical measurements do not correlate significantly to individual peripheral nerve stimulation thresholds as measured in MRI gradient coils.

PURPOSE: To examine peripheral nerve stimulation (PNS) thresholds for normal human subjects in magnetic resonance imaging (MRI) gradient coils, and determine if observed thresholds could be predicted based on gross physiologic measurements. MATERIALS AND METHODS: PNS thresholds for 21 healthy normal subjects were measured using a whole-body gradient coil. Subjects were exposed to a trapezoidal echo-planar imaging (EPI) gradient waveform and the total change in gradient strength (DeltaG) required to cause PNS as a function of the duration of the gradient switching time (tau) were measured. Correlation coefficients and corresponding P values were calculated for the PNS threshold measurements against simple physiologic measurements taken of the subjects, including weight, height, girth, and average body fat percentage, in order to determine if there were any easily observable dependencies. RESULTS: No convincing correlations between threshold parameters and gross physiologic measurements were observed. CONCLUSION: These results suggest it is unlikely that a simple physiologic measurement of subject anatomy can be used to guide the operation of MRI scanners in a subject-specific manner in order to increase gradient system performance while avoiding PNS.

Echo-Planar Imaging↗

PubMed1980

[Measurement of color-coordinates of the fundus by the color-comparison method with a widened measurement scale (author's transl)].

The method of color measurements by visual comparison was first described in 1974, but the original method was not always adequate in documenting fundal changes in patients being treated with vasodilatators. In these cases the color coordinates reached the threshold of the measuring scale or went beyond it in the livid color area. A few years ago the color measuring instrument was supplied with a new filter system for this purpose and was necessary to move the left cornerpoint of the measuring scale far into the blue range. The instrument and the physical data are described, the standard color values x and y being found by transformational equations. The technical error was measured on a phantom eye. In a defined group of 100 normal eyes (=100 testing persons) the standard color values of the temporal and nasal papillary segments were measured. They are graphically demonstrated in the now widened x; y measuring scale. Clinical use and results will be described later.

Color↗