Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Linear Regression”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
PubMed1995

[Temporal trends in myocardial infarct morbidity, mortality and 28-day fatalities and medical management. Results of the Augsburg Myocardial Infarct Register 1985 to 1992].

Between 1985 and 1992 a significant decrease in rates of acute myocardial infarction (AMI; fatal and non fatal, including prehospital cardiac death) from 533 cases per 100,000 population of 455 cases was observed in the 25- to 74-year-old male study population (linear regression model: -13%, p < 0.01). In the corresponding female study population the AMI rate increased from 153 cases per 100,000 population in 1985 to 153 cases in 1992 (linear regression model: +18%, p < 0.05). The decrease was only in 50- to 59-year-old male AMI patients without changes in risk factors (smoking, diabetes, hypertension, recurrent AMI) but with a decrease in patients with a history of angina pectoris, which may have been caused by intensified medical treatment of AMI endangered patients. Over time 34% of the patients died before hospitalization and another 19% died within the first 24 h after hospitalization. The register results show an underestimation of the coronary mortality by the official cause of death statistics. In contrast, the significant increase in treatment with thrombolytics (men from 16% to 38%, women from 8% to 42%), beta-blockers (men from 48% to 69%, women from 45% to 71%), and antiplatelets (men from 55% to 94%, women from 52% to 91%) was not related to any significant changes in 28-day case fatality of the 24-h survivors (men and women 13% to 14%). Without media campaigns, for the increased number of cases hospitalized within 4 h after the event (1985-1987 men 50%, women 42%; 1990-1992 58% and 60%; p < 0.01) thrombolytic treatment shows an increase from 25% in men and 17% in women (1985-1987) to 54% in men and 47% in women (1990-1992; p < 0.01).

Adult↗
PubMed2002

Net protein oxidation is adapted to dietary protein intake in domestic cats (Felis silvestris catus).

Cats have a requirement for dietary protein two to three times that of omnivores and herbivores. This was reported to be due to the hepatic catabolic enzymes of this species being set to a permanently high level and, therefore, showing little adaptation to low dietary protein. A major mechanism for adapting to dietary protein in other species is amino acid oxidation (hereafter referred to as protein oxidation), and the objective of this study was to determine whether protein oxidation in cats was correlated with protein intake. Net protein and net fat oxidation in six adult cats were studied directly from gas exchanges using indirect calorimetry, after feeding moderate protein (MP; 35% energy) and high protein (HP; 52% energy) diets. Protein oxidation was significantly higher (P < 0.05) when cats were fed the HP diet (28.4 plus minus 0.7 mg/min) rather than the MP diet (20.4 plus minus 0.8 mg/min). Fat oxidation was significantly higher (P < 0.05) when cats consumed the MP diet (9.0 plus minus 0.7 mg/min) rather than the HP diet (4.7 plus minus 0.5 mg/min). Protein oxidation was significantly correlated (linear regression, R(2) = 46.0, P < 0.05) with protein intake such that the mean ratio of 18-h oxidation: 18-h intake was 1.2 on both diets. Fat oxidation was significantly correlated (linear regression, R(2) = 18.9, P < 0.05) with fat intake such that the mean ratio of 18-h fat oxidation: 18-h fat intake was 1.1 (MP) and 0.9 (HP). This study demonstrated that cats adapt net protein oxidation at these levels of protein intake, and the reason for the high dietary protein requirement of this species is, therefore, unclear.

Animal Nutritional Physiological Phenomena↗
PubMed1989

Estimation and comparison of changes in the presence of informative right censoring: conditional linear model.

A general linear regression model for the usual least squares estimated rate of change (slope) on censoring time is described as an approximation to account for informative right censoring in estimating and comparing changes of a continuous variable in two groups. Two noniterative estimators for the group slope means, the linear minimum variance unbiased (LMVUB) estimator and the linear minimum mean squared error (LMMSE) estimator, are proposed under this conditional model. In realistic situations, we illustrate that the LMVUB and LMMSE estimators, derived under a simple linear regression model, are quite competitive compared to the pseudo maximum likelihood estimator (PMLE) derived by modeling the censoring probabilities. Generalizations to polynomial response curves and general linear models are also described.

Analysis of Variance↗
PubMed1996

Jugular venous bulb oxyhemoglobin saturation during cardiac surgery: accuracy and reliability using a continuous monitor.

Previous studies have demonstrated the feasibility of continuously monitoring jugular venous oxygen saturation (SjO2) with a fiberoptic catheter during hypothermic cardiopulmonary bypass (CPB). In the present study, with patients maintained at either moderate (28 degrees C) or mild (32-34 degrees C) hypothermia during CPB, SjO2 values obtained from a fiberoptic catheter were compared to intermittent samples analyzed by a co-oximeter. Twenty patients scheduled for elective coronary artery or valvular surgery had a 5.5 Fr Opticath catheter inserted into the left internal jugular bulb after induction of general anesthesia. The catheter was calibrated in vitro and in vivo according to the manufacturer's specifications. Catheter and co-oximetry SjO2 values obtained at four time points--1) pre-CPB, 2) target CPB temperature, 3) mid-rewarming, and 4) post-CPB--were compared using linear regression, Bland-Altman analysis, and Shrout-Fleiss interclass correlation coefficient analysis. These statistical methods revealed poor correlation between the catheter and co-oximetry SjO2 values: r = 0.44 by linear regression and 0.32 by interclass correlation coefficient analysis, and was unacceptably discrepant by Bland-Altman analysis. Oxyhemoglobin saturation values obtained continuously from a jugular venous bulb fiberoptic catheter during CPB may not accurately reflect true oxyhemoglobin saturation, and caution is warranted when interpreting SjO2 values obtained from a fiberoptic catheter during CPB.

Aged↗
PubMed1996

Factors influencing the postoperative use of analgesics in dogs and cats by Canadian veterinarians.

Four hundred and seventeen Canadian veterinarians were surveyed to determine their postoperative use of analgesics in dogs and cats following 6 categories of surgeries, and their opinion toward pain perception and perceived complications associated with the postoperative use of potent opioid analgesics. Three hundred and seventeen (76%) returned the questionnaire. An analgesic user was defined as a veterinarian who administers analgesics to at least 50% of dogs or 50% of cats following abdominal surgery, excluding ovariohysterectomy. The veterinarians responding exhibited a bimodal distribution of analgesic use, with 49.5% being defined as analgesic users. These veterinarians tended to use analgesics in 100% of animals following abdominal surgery. Veterinarians defined as analgesic nonusers rarely used postoperative analgesics following any abdominal surgery. Pain perception was defined as the average of pain rankings (on a scale of 1 to 10) following abdominal surgery, or the value for dogs or cats if the veterinarian worked with only 1 of the 2 species. Maximum concern about the risks associated with the postoperative use of potent opioid agonists was defined as the highest ranking assigned to any of the 7 risks evaluated in either dogs or cats. Logistic regression analysis identified the pain perception score and the maximum concern regarding the use of potent opioid agonists in the postoperative period as the 2 factors that distinguished analgesic users from analgesic nonusers. This model correctly classified 68% of veterinarians as analgesic users or nonusers. Linear regression analysis identified gender and the presence of an animal health technologist in the practice as the 2 factors that influenced pain perception by veterinarians. Linear regression analysis identified working with an animal health technologist, graduation within the past 10 years, and attendance at continuing education as factors that influenced maximum concern about the postoperative use of opioid agonists.

Abdomen↗
PubMed1989

Myocardial salvage after regional beta-adrenergic blockade.

UNLABELLED: The aim of the study was to determine whether regional beta-adrenergic blockade via the coronary sinus limited myocardial damage after coronary artery occlusion in the canine model. Accordingly, open-chest anesthetized dogs were randomly allocated to one of three groups: a control group and groups treated with propranolol (in doses of 0.02, 0.2, and 2.0 mg/kg) given either intravenously or via the coronary sinus. The hypoperfused zone (i.e., risk area) and the extent of myocardial damage were assessed by autoradiography and triphenyltetrazolium chloride staining, respectively. Myocardial damage expressed as a percent of the hypoperfused zone was 84 +/- 5% in the control group (n = 9) and 78 +/- 7% (0.02 mg/kg, n = 7, NS), 63 +/- 6% (0.2 mg/kg, n = 7, p less than 0.05), and 62 +/- 7% (2.0 mg/kg, n = 9, p less than 0.02) in the groups receiving intravenous propranolol and 73 +/- 6% (0.02 mg/kg, n = 7, NS), 58 +/- 7% (0.2 mg/kg, n = 7, p less than 0.01), and 44 +/- 9% (2.0 mg/kg, n = 9, p less than 0.001) in groups receiving propranolol via the cardiac veins. There was a significant enhancement of myocardial salvage with increasing doses of propranolol delivered via the cardiac veins (linear regression trend, p less than 0.05). In contrast, myocardial damage expressed as a percent of the hypoperfused zone remained comparable with propranolol doses of 0.2 and 2.0 mg/kg administered intravenously (linear regression trend, NS). IN CONCLUSION: (1) regional beta-adrenergic blockade via the cardiac veins afforded significant myocardial salvage and (2) the regional administration of propranolol resulted in significant reduction of myocardial damage in a dose-dependent fashion.

Administration, Topical↗
PubMed1993

Evaluation of a single-stage isoproterenol-tilt table test in patients with syncope.

OBJECTIVES: The purpose of this study was to compare clinical outcomes and tilt test variables between a single-stage tilt test with an infusion of 5 micrograms/min of isoproterenol and a conventional multistage test with infusions of 0, 2 and 5 micrograms/min of isoproterenol in three successive stages. BACKGROUND: The diagnosis of neuromediated syncope is often established with isoproterenol--head-up tilt table testing. Previous work has suggested that a single infusion of 5 micrograms/min of isoproterenol during 80 degrees head-up tilt for < or = 10 min should be sufficient to establish the diagnosis. METHODS: Forty patients with recurrent syncope underwent both tests in a randomized crossover fashion. RESULTS: Of 24 patients with positive findings on a multistage test, 19 (79%) had positive findings on a single-stage test, whereas 13 (81%) of 16 patients with negative results on a multistage test had negative results on a single-stage test (p < 0.001, chi-square analysis). Presyncope developed monoexponentially with time at similar rates in both tests, with half-times to presyncope of 1.3 and 2 min for the single-stage and multistage test, respectively. Intertest intrapatient times to presyncope correlated well (r = 0.74, p = 0.001). Finally, peak and trough heart rates each were similar and correlated well between tests. The mean peak heart rate was 136 +/- 25 and 133 +/- 18 beats/min for the single-stage and multistage test, respectively (p = NS, t test; r = 0.50, p = 0.002, linear regression). The mean trough heart rate was 76 +/- 31 and 78 +/- 36 beats/min for the single-stage and multistage test, respectively (p = NS, t test; r = 0.86, p < 0.001, linear regression analysis). CONCLUSIONS: The single-stage and multistage tilt tests are equivalent with regard to clinical outcome and tilt test variables, although the single-stage test is considerably less time-consuming.

Adult↗
PubMed2005

The rate at which residents learn to use hand-held echocardiography at the bedside.

PURPOSE: Because there is little information about the training that general internists require to perform hand-carried cardiac ultrasonography (HCU), we studied the rate of learning of a group of medical residents performing HCU after minimal formal training. METHODS: Medical residents on the inpatient services at Johns Hopkins Bayview Medical Center received formal training in HCU consisting of 15-30 minutes of didactic instruction about the principles of echocardiography, followed by ongoing one-on-one instruction in performing HCU and subsequent ongoing one-on-one training from a certified echocardiography technician as they were doing scans. The residents were shown how to position the patient to obtain 2-dimensional echo images from the parasternal short and long axes and apical 4-chamber views, and how to obtain color-flow Doppler images across the mitral and aortic valves. Residents were asked to determine whether pericardial effusion was present and to assess left ventricular size, left ventricular function, and the mitral and aortic valves. The residents performed cardiac physical examination and HCU independently on patients who had a conventional transthoracic echocardiogram (CTTE) performed within 24 hours of the HCU. The residents' HCU results were compared with the CTTE results by a cardiologist specializing in echocardiography. The rates at which residents gained technical proficiency and skills in interpreting their studies were measured by linear regression to fit various outcome variables against their experience at scanning as gauged by the number of scans performed. RESULTS: Thirty medical residents performed a total of 231 HCU studies. Linear regression models showed that the residents' overall technical proficiency skills improved at the rate of 0.79 (95% confidence interval [CI] 0.53-1.04) points on an overall assessment index (0-3 scale) per 10 scans completed. Interpretation accuracy improved at a rate of 1.01 (95% CI 0.69-1.39) points per 10 scans as measured by an interpretation accuracy index (0-3 scale). Because scanning efforts and instruction in HCU occurred during residents' usual rotation duties, some residents gathered experience in HCU slowly and sporadically. CONCLUSION: This study, the first prospective, experimental effort of its kind, shows that residents as a group learned important aspects of HCU scanning and interpretation at a reasonably rapid rate.

Adult↗
PubMed2000

Abdominal adiposity and clustering of multiple metabolic syndrome in White, Black and Hispanic americans.

PURPOSE: The aim of this study was to evaluate the association of abdominal adiposity assessed by waist circumference (WC) with clustering of multiple metabolic syndromes (MMS) in White, Black and Hispanic Americans. MMS was defined as the occurrence of two or more of either hypertension, type 2 diabetes mellitus, dyslipidemia, hypertriglyceridemia or hyperinsulinemia. METHODS: The number of MMS and fasting insulin (a surrogate measure of MMS) were each used as dependent variables in gender-specific multiple linear regression models, adjusting for age, smoking and alcohol intake. The contribution of WC to interethnic differences in clustering of MMS and fasting insulin concentration was assessed in gender-specific linear regression models. The risk of MMS due to large waist was estimated by comparing odds ratio for men with WC >/= 102 cm with those with WC < 102, and women with WC >/= 88 cm with women with WC < 88 cm in the logistic regression model adjusting for age, smoking and alcohol intake. RESULTS: WC was positively and independently associated with clustering of MMS and increased fasting insulin concentration adjusting for age, smoking and alcohol intake in the three ethnic groups (p < 0.01). Black ethnicity was associated with clustering of MMS and fasting insulin concentration (p < 0.01). Hispanic ethnicity was also associated with clustering of MMS in men and associated with fasting insulin concentration in both men and women (p < 0.01). In both men and women, the risk of MMS clustering was strongly associated with increased WC in all ethnic groups independent of BMI. CONCLUSION: WC appears to be a marker for multiple metabolic syndromes in these ethnic groups. The results of this investigation lend support to the view that waist measurement should be considered as a clinical variable for assessing the risk of cardiovascular diseases.

Abdomen↗
PubMedDate not supplied

[Evaluation of the reproducibility of Doppler ultrasonographic measurements in obstetrics].

BACKGROUND: Are obstetric doppler ultrasonographic measurements of the fetal and maternal flow parameters reproducible? PATIENTS AND METHODS: For internal quality management, doppler ultrasonographic measurements were performed on 81 patients (random screening sample) with an Acuson Sequoia Ultrasound at the Universitätsfrauenklinik Marburg. Successively two experienced investigators measured the umbilical artery, medial cerebral artery, and the uterine arteries. The correlation between the measurements of the two investigators was presented in a spread chart. In order to exclude systematic differences between the measurements, linear regression was analyzed and the distance to the abscissa was calculated. A relative divergence of more than 20% was determined as a non corresponding measurement. RESULTS: The distance of the linear regression to the abscissa was calculated for the four vessels: umbilical artery 0.4 (95% CI; 0.124 - 0.486), medial cerebral artery 0.9 (95% CI; 0.534 - 1.264), right uterine artery 0.2 (95% CI; 0.124 - 0.305), and left uterine artery 0.2 (95% CI; 0.121 - 0.317). Concerning the four arteries, a divergence of more than 20% between the two investigators was found: umbilical artery 16%, medial cerebral artery 42%, right uterine artery 28%, and left uterine artery 37%. CONCLUSIONS: Because the interobserver variability was surprisingly high and acceptable correlation could be stated only for the umbilical artery, internal quality standards are essential. Routine use of different devices should be made after careful consideration only, especially if clinical decisions are to be based on them.

Blood Flow Velocity↗
PubMed2003

Estimating mechanisms and equilibria for offspring begging and parental provisioning.

Evolutionary models for the resolution of family conflicts are sensitive to assumptions regarding the behavioural mechanisms regulating parental resource provisioning and offspring begging. Thus, quantitative empirical estimates of the mechanisms are critical to validate current evolutionary models, but a standardized method is lacking. I present a formalization of Hussell's (1988 Am. Nat. 131, 175-202) original graphical model of mechanisms regulating the effect of begging on provisioning, and of provisioning on begging, based on linear regression equations. The model makes it possible to estimate quantitatively the behavioural mechanisms and the resulting proximate equilibria for begging and provisioning by the use of appropriate experiments and standard linear regression analysis.

Animals↗
PubMed2006

A simple way to estimate mean plasma glucose and to identify Type 2 diabetic subjects with poor glycaemic control when a standardized HbA1c assay is not available.

AIMS: To evaluate the relationship between HbA(1c) and fasting plasma glucose (FPG) and postprandial plasma glucose (PPG) levels, and to estimate the mean plasma glucose (mPG) derived from FPG and PPG that would predict Type 2 diabetic subjects with poor glycaemic control. METHODS: FPG, PPG and HbA(1c) values from 565 Type 2 diabetic patients (247 men and 318 women) were recorded. Linear regression analysis and Pearson's correlation was used to determine the relationship between HbA(1c), FPG and PPG. FPG and PPG were included as explanatory variables of HbA(1c) in linear regression analysis. RESULTS: The American Diabetes Association's objective of achieving an HbA(1c) level < 7.0% was obtained in 26.2% of the patients. The coefficients of FPG and PPG which determined HbA(1c) were similar. Therefore, mPG was calculated using the equation (FPG + PPG)/2. Pearson's correlation coefficient for HbA(1c) and FPG, PPG and mPG were 0.723 (P < 0.0001), 0.734 and 0.761 (P < 0.0001), respectively. A mPG cut-off value of 10 mmol/l predicted an HbA(1c) > 7% in the whole population, with a sensitivity of 84.2% and specificity of 80.4%. The area was high (0.90) in receiver-operating characteristic (ROC) curve analysis performed to examine the performance of mPG to predict HbA(1c) > 7%. CONCLUSIONS: The mPG derived from FPG and PPG correlates strongly with HbA(1c). We therefore suggest that using a cut-off of 10 mmol/l for mPG may be appropriate in diabetes management in the primary-care setting, where most management of Type 2 diabetes occurs.

Blood Glucose↗
PubMed1983

A procedure for detecting variability of psychophysical thresholds.

In adaptive psychophysical testing, it is desirable to identify experimental runs during which the subject's threshold changes. This is not easy to do, because the testing level changes during the course of the run. The following screening procedure can assist in detecting threshold variability. At the conclusion of the run, determine for each trial the discrepancy between observed and expected response. Next, determine the linear regression of this discrepancy upon trial number. If the subject's response behavior is stable and well described by the psychometric function, then the expected value of slope of the linear regression is equal to zero. If the observed slope differs greatly from zero, then it is unlikely that the subject's response behavior is stable. Results from computer simulations and psychophysical experiments are presented.

Auditory Threshold↗
PubMed1982

Standard computer programs in statistical analysis of survival in childhood lymphoblastic leukemia.

A material comprising all children in Sweden with acute lymphoblastic leukemia diagnosed in the years 1973-80 was analysed statistically. The total number of children was 505. Studies were made of 38 different variables, using frequency tables, cross tables, life table studies (1) and linear regression analysis according to Cox's method (2,4). Chi-square tests and log rank tests were included in the methods. The combination of life-table studies and linear regression analysis proved to be of value in assessing the significance of different parameters and treatment programs with regard to prognosis. The aim of this paper is to present a method for analysis of a patient material with use of standard computer programs. The results of the total analysis will be published elsewhere (3).

Child↗
PubMed2001

Evaluation of alternative algorithms used to simulate pasture intake in grazing dairy cows.

Four algorithms used to simulate pasture intake in grazing dairy cows in a dairy decision support system were proposed and evaluated with data from the literature. The algorithms proposed were: 1) an algorithm combining the approach used in a published model to determine dry matter intake based on neutral detergent fiber intake as a percentage of the BW, energy requirements, pasture availability and a standard supplementation (PIest), 2) the previous algorithm modified to consider the type and amount of supplementation (PIsup), 3) an algorithm which considers the effect of selection of pasture (PIsel), and 4) the combination of algorithms 2 and 3 (PIsupsel). Pasture intake data of 27 grazing experiments from the literature were used to evaluate those algorithms. Two methods of evaluation were used: 1) simple linear regression between reported and simulated values, and 2) analysis of variance for the difference between reported and simulated values considering pasture availability and type of supplementation. The R2 of the linear regression and average proportional bias between reported values and simulated values were 0.24 and 19% for PIest, 0.42, and 23% for PIsup, 0.45 and 2% for PIsel and 0.41 and 10% for PIsupsel. Those results showed that PIsel had the lower variability and the values closer to pasture intake. The algorithm PIsup had low variability but tended to underpredict pasture intake. The algorithm PIest values were closer to reported values for low pasture availability. The modeling results show the influence of pasture selection in grazing systems.

Algorithms↗
PubMed2006

[High relationship between ciprofloxacin use and prevalence of ESBL Klebsiella pneumoniae].

BACKGROUND: To assess the relationship between ciprofloxacin use and the prevalence of extended spectrum betalactamases (ESBL) Klebsiella pneumoniae. PATIENTS AND METHODS: Semestral mean values regarding use of antibiotic and prevalence of ESBL Kp were compared during 9 semesters using linear regression and coefficient of correlation. RESULTS: The only statistically significant correlation was ciprofloxacin use and ESBL(+) K. pneumoniae prevalence, with a coefficient of correlation of 0.86 and p = 0.0027 using linear regression. CONCLUSIONS: Ciprofloxacin use must be taking into account when considering infection control programs due to high prevalence rates of ESBL(+) K. pneumoniae in the hospital setting.

Anti-Bacterial Agents↗
PubMed2005

Do economic stresses influence child work hours on family farms?

BACKGROUND: Economic stresses are a frequently cited reason for children doing farm work. OBJECTIVE: To explore the relationship between economic indicators and child agricultural work hours between January 2001 and October 2003. METHODS: This ecologic study design compares trends in aggregate child work hours with national and regional economic indicators. Child work hours were obtained from quarterly surveillance data from a randomized field trial of agricultural task guidelines for children. 2,360 children living or working on 845 farms in central New York participated in the original study. The relationship between child work hours and three economic indicators: national all farm index (AFI) ratio, national fuel index, and regional milk prices was analyzed using times series plots, correlation, and multiple linear regression. RESULTS: The AFI ratio was positively correlated with child work hours (r = 0.49, p = 0.008) but there was no significant correlation between child work hours and fuel or milk prices. Multiple linear regression demonstrated that the relationship between AFI and child work hours is independent of a seasonal effect. CONCLUSIONS: Increased child work hours may be associated with periods of higher farm sector productivity, rather than economic stress per se. Findings are limited by the ecologic study design, use of national economic indicators, and the limited number of cycles of child work hours available for time series analysis. Economic conditions may influence decisions about children's farm work.

Accidents, Occupational↗
PubMed2005

Left ventricular myocardial mass determination by contrast enhanced colour Doppler compared with magnetic resonance imaging.

OBJECTIVE: To assess the feasibility of using contrast enhanced colour Doppler echocardiography to determine left ventricular (LV) mass and to compare its accuracy with LV mass obtained by magnetic resonance imaging (MRI). METHODS: Images were acquired in the short axis plane of the heart, derived from coronal and sagittal scout views and double oblique angulation. The LV mass was calculated by two methods: Simpson's rule and the area-length method. Levovist (Schering AG, Berlin, Germany) 2.5 g was given by slow intravenous bolus or infusion over about 45 seconds for contrast imaging. LV images were captured in the apical two chamber, four chamber, and three chamber views. Each contrast harmonic colour Doppler image was converted to a cavity-only image by simple image mathematics. RESULTS: 27 (77.1%) of the patients (mean (SD) age 66.2 (8.9) years) were men. There was a mean (SD) interval of 6.6 (8.6) days (range 0-27 days) between echocardiography and MRI. The mean (SD) LV mass determined by MRI Simpson's rule method was 171.0 (52.4) g (range 105.1-318.7 g). The mean LV mass (SD) determined by the echocardiographic Simpson's rule method was 178.2 (47.0) g (range 112.6-307.6 g). The mean (SD) MRI area-length LV mass was 187.3 (64.5) g (range 109.0-393.6 g). The linear regression correlation between LV mass determined by MRI Simpson's and echocardiographic Simpson's methods was excellent (y = 1.022x, R2 = 0.986) with a mean (SD) difference of 7.20 (20.9) g. The linear regression correlation between the MRI area-length LV mass and MRI Simpson's LV mass was excellent (y = 1.101x, R2 = 0.989) with a mean (SD) difference of 16.3 (22.3) g. CONCLUSIONS: LV mass may be obtained reliably by contrast enhanced colour Doppler and two dimensional echocardiography. The contrast Doppler method accurately determines LV mass with excellent agreement with the MRI technique.

Aged↗