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Biomedical subjects

M J Lipton

Publications and source records attributed to M J Lipton.

At least 127 records · Page 7Linked to original sources
PubMed1983

Canine left ventricular mass estimation by two-dimensional echocardiography.

This study was designed to develop a two-dimensional echocardiographic method of measuring the mass of the left ventricle. The general formula for an ellipse was used to derive an algorithm that described the shell volume of concentric truncated ellipsoids. In 10 canine left ventricular two-dimensional echocardiograms, this algorithm accurately predicted postmortem left ventricular mass (r = .98, SEE +/- 6 g) and was independent of cardiac cycle phase (systole vs diastole, r = .92).

Animals↗
PubMed1983

CT attenuation ratio of myocardium and blood pool in the normal and infarcted canine heart.

The CT attenuation of the myocardium varies with the contrast medium concentration of the blood at steady state. The demonstration of myocardial infarcts depends on the differences of CT numbers within the myocardium. In order to make possible objective estimation and measurement of myocardial ischemia the normal regression between CT attenuation of the blood pool and the myocardium has been determined in 13 dogs. The relationship has been applied to 15 dogs with experimental infarcts examined with contrast enhanced CT. The results indicate that this method may be of value in identifying and sizing myocardial infarcts of different ages in patients.

Animals↗
PubMed1983

Measurement of regional changes in myocardial perfusion using dynamic computed tomography and contrast medium.

Changes in regional myocardial perfusion were measured using rapid sequence dynamic transmission tomography to detect differences in the initial distribution of contrast medium injected as an intravenous bolus. The experiments were carried out on 8 mongrel dogs instrumented with flow probes and vascular occluders around the coronary arteries. Flow reductions of 50 per cent or more were detected as regions of myocardium with less contrast enhancement than those with normal perfusion. Reactive hyperemia induced by transient ischemia was detected as areas of relatively increased contrast enhancement. These changes could be demonstrated on the images and quantitated using data depicting changes in HU (Hounsfield units) with time to develop an index of perfusion. The images obtained were of satisfactory quality and differences between the underperfused and normal myocardium were made more prominent by using dipyridamole infusions.

Animals↗
PubMed1983

What is the role of CT scanning of the heart?

Computed tomography of the heart and great vessels is a promising new imaging technique whose full potential is as yet undefined. The clinical conditions in which it has been used, as outlined in this report, indicate it offers great promise. The ability of the computer to rearrange transverse scan data into parasagittal, coronal, and oblique planes gives a new (third) dimension to cardiac imaging. This display format should greatly enhance the clinician's understanding of the spatial configuration of normal and diseased hearts. Dynamic scanning with contrast enhancement by bolus injection permits, in addition to anatomic definition of pathology, further information about cardiac dynamics. Faster CT scanners are already under development. Scanning speeds of 20 to 25 msec. are a realistic possibility. Also, future scanners will have multiple simultaneous slice capability. These technical advances will certainly enhance the clinical utility of CT for evaluating cardiovascular disease. The future of cardiac imaging is, indeed, bright and exciting.

Aortic Dissection↗
PubMed1983

CT scanning of the heart.

It is generally agreed that all present diagnostic cardiac methods including echocardiography, nuclear medicine, and coronary arteriography have significant limitations. Nuclear cardiology provides excellent diagnostic sensitivity using small amounts of radioactive tracers, but it currently lacks the spatial fidelity needed to differentiate many anatomic structures in the heart. CT complements the capabilities of these alternative imaging modalities. Computed tomography offers accurate reconstruction of the whole myocardium with far greater spatial and density resolution in three dimensions. CT may eventually find its most important and clinically useful application in the diagnosis and management of heart disease.

Animals↗
PubMed1983

Computed tomography. The technique and its use for the evaluation of cardiocirculatory anatomy and function.

Computed tomography, a promising new imaging technique, has not yet been widely applied to cardiac disease. There is, furthermore, very little experience with CT scanning for patients with congenital cardiovascular malformations. Nevertheless, early studies with this remarkable modality indicate great promise for future application at low levels of radiation--approximately 10 to 15 per cent that of a conventional angiogram. The feasibility studies so far performed should be considered in that context. Nevertheless, relatively slow, whole body CT scanners can contribute useful clinical diagnostic information in patients with heart disease. Cardiac CT scanning is presently limited, as were all other conventional x-ray techniques at first, by relatively long exposure times. CT scan technology has made dramatic strides during its short existence of one decade, and there is strong evidence that this trend will continue in conjunction with rapid advances in high technology.

Calcinosis↗
PubMed1983

Cardiovascular imaging with nuclear magnetic resonance.

This article provides some examples of what the previous article outlined. The sections on Image Display and Myocardial Characterization contain numerous illustrations of gating, cross-sectional images, flow signals, and ischemic injury. The possibility of metabolic imaging with NMR and quantitating blood flow is also considered.

Aorta, Abdominal↗
PubMed1983

Vessel wall and indium-111-labelled platelet response to carotid endarterectomy.

Postendarterectomy platelet deposition and thrombus formation may play an important role not only in vessel wall healing but also in the small incidence of postoperative cerebral ischemia and postoperative stenosis. A study has been performed using a canine model to investigate the healing response to carotid endarterectomy and the validity of an in vivo indium-111 (In-111) radiotracer technique in the assessment of postendarterectomy deposition of autologous labelled platelets. Sixteen endarterectomized carotid arteries showed uptake of autologous In-111 platelets immediately after infusion, reaching a maximum by 1 hour with little increase at 24 or 48 hours. No uptake was seen in ten control vessels following platelet infusion (P less than 0.05). At autopsy, seven vessels were demonstrated to have In-111 platelet deposition immediately prior to sacrifice of the animals. Postmortem scanning confirmed the localization to the vessel lumens, and microscopy revealed thrombus formation with or without partial endothelialization. Complete reendothelialization had occurred in the vessels that failed to show platelet deposition. Delayed healing was associated with continuing platelet deposition, excessive thrombus formation, and luminal stenosis. Arteriotomy closure with a vein patch altered the healing characteristics of the vessel with segmental thrombus formation over the vein patch. A preliminary study of the postendarterectomy in vivo In-111 platelet response in humans demonstrated platelet deposition that was not influenced by the administration of antiplatelet drugs at currently prescribed levels.

Animals↗
PubMed1982

CT demonstration of mediastinal aortic arch anomalies.

Computed tomography (CT) can be helpful in the detection and diagnosis of aortic arch malformations, including anomalous right subclavian artery, left sided aortic arch with right descending aorta, right sided, aorta with anomalous left subclavian artery or mirror image branching, and double aortic arch. This paper reviews the CT findings in 10 such patients. Computed tomography can confirm the presence of an aortic anomaly suspected from plain radiographs or can detect a vascular anomaly when the plain radiograph suggests the presence of a mediastinal mass.

Adolescent↗
PubMed1982

Calculation of left ventricular volume using implanted tantalum markers: a method reproducible despite rotation of the heart.

Endocardial markers implanted by catheter have been used to estimate the left ventricular volume by outlining the ventricle in orthogonal planes. However, if the position of the ventricle with respect to the biplane radiographic system changes, the projected outlines formed by the markers will narrow and the calculated volume will decrease. Therefore, a mathematical technique to correct this error was developed. It was tested by extensively rotating silicone casts of the left ventricle to which markers were glued. Except for one position at which the volume deviated by 4.5 ml, all the calculated volumes of the casts were reproducible to within 2 ml.

Animals↗
PubMed1982

Assessment of saphenous vein graft patency by contrast-enhanced computed tomography.

Early saphenous vein coronary bypass graft patency has been found to range from 82% to 94%. Recent advances in computed tomography have led to the development of a safe, effective, and "relatively noninvasive" means of assessing early graft patency. We designed a prospective study using contrast-enhanced computed tomography (CECT), postulating that selected grafts might be redone prior to the development of pericardial adhesions if early closure was demonstrated. Forty-three random patients undergoing elective coronary artery bypass comprise the study group. All patients underwent CECT study of graft patency an average of 6 days postoperatively (range 1 to 17 days). Ninety of 96 grafts were open, for an early patency rate of 94%. Three of the grafts were closed because of poor run-off or extensive distal coronary atherosclerosis. Two additional grafts were closed, one in a patient with severe atherosclerosis of the ascending aorta and one in a patient having triple vessel bypass using cephalic vein because of limited conduit material. Only one graft was closed without apparent cause and judged potentially suitable for reoperation. CECT was found to be a safe and potentially useful means of assessing early graft patency, particularly in patients sustaining untoward clinical events.

Aged↗
PubMed1981

Utility of computed tomography in the diagnosis of thoracic aneurysm in childhood.

For an unusual case of saccular aneurysm of the thoracic aorta in a child, the computed tomographic demonstration of a totally vascular mass led directly to the definitive diagnosis by angiocardiography and eliminated the need for many additional imaging or chemical tests. This case illustrates how computed tomography can be beneficial in the potentially difficult diagnostic evaluation of pediatric medistinal masses.

Aorta, Thoracic↗