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D Longmore

Publications and source records attributed to D Longmore.

8 recordsLinked to original sources
PubMed1994

The application of breath hold phase velocity mapping techniques to the measurement of coronary artery blood flow velocity: phantom data and initial in vivo results.

A segmented kappa-space breath hold phase velocity mapping technique has been developed for the study of coronary artery blood flow velocity. In vitro validation has been performed using a number of pulsatile flow phantoms and the accuracy of the technique for determining the velocity increase at the site of a stenosis demonstrated in several phantom models. Examples of both in-plane and through-plane velocity maps of the left anterior descending and right coronary arteries of normal subjects in early diastole are presented. In one subject, through-plane velocity maps were obtained in the right and left anterior descending arteries throughout the cardiac cycle in order to generate flow velocity time curves. The problems associated with coronary artery velocity mapping are discussed.

Artifacts↗
PubMed1992

Studies of the heart using magnetic resonance.

Cardiovascular medicine is based on high-technology management of end-stage disease. Preventive medicine is preferable but, before magnetic resonance (MR), there was no noninvasive, safe, repeatable method of detecting occlusive vascular disease, which accounts for more deaths than any other disease at a presymptomatic stage. Demographic and animal studies show that occlusive vascular disease is not a normal aging process and is reversible. There was no method of monitoring the efficacy of preventive and therapeutic measures other than long, expensive, and sometimes inconclusive clinical trials. The rate of precession of atomic nuclei in a magnetic field is related to field strength. Creating a unique magnetic field in each volume of interest allows analysis of emitted radio signals to produce an image containing information about movement and local biochemical environments. MR produces accurate high resolution anatomical images and functional information including blood flow. It is already established as a method of choice in clinical cardiology for congenital heart disease and aortic disease. It is becoming established as a method of evaluating cardiovascular-active drugs, and in the future MR will be used for diagnosis and as a population-screening instrument for all cardiovascular disease including coronary artery disease.

Arteriosclerosis↗
PubMed1988

Comparison of magnetic resonance imaging with echocardiography and radionuclide angiography in assessing cardiac function and anatomy following Mustard's operation for transposition of the great arteries.

The Mustard operation in infancy and childhood has successfully palliated many patients with transposition of the great arteries who have now survived to adulthood. Right ventricular dysfunction and tricuspid regurgitation are important determinants of late morbidity and mortality. The value of noninvasive magnetic resonance imaging (MRI) in the assessment of cardiac function and anatomy 9 to 20 years after this procedure has been investigated, and compared with findings on echocardiography, radionuclide ventriculography and angiography in 17 adult patients. Ejection fractions measured by MRI were higher compared with radionuclide ventriculography. The correlation for the left ventricle was closer (r = 0.75) than for the right ventricle (r = 0.49). Tricuspid regurgitation was assessed by Doppler echocardiography and by MRI using the right/left ventricular stroke volume ratio. The mean stroke volume ratio in those with Doppler evidence of tricuspid regurgitation was 1.6:1 compared to 1.1:1 in those without, and this difference reached significance (p less than 0.01). The anatomy of the great arteries was clearly visible in all patients. Five patients had a residual ventricular septal defect which, with the exception of 1 small defect, was easily visualized. The intraatrial baffle was best seen in transverse slices, and the systemic venous connection showed as a relatively narrow channel lying in the posterior part of the cavity. In general, baffle anatomy was easier to assess on 2-dimensional echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗