Mark R. Goldman

Quantification of experimental myocardial infarction using nuclear magnetic resonance imaging and paramagnetic ion contrast enhancement in excised canine hearts.

Determination of myocardial infarct size is important for clinical management of patients with ischemic heart disease and for research on limiting infarct size. Nuclear magnetic resonance (NMR) imaging permits tomographic depiction of the distribution of mobile tissue protons. NMR imageshave demonstrated high spatial resolution and contrast. To evaluate the potential of this technique in measuring myocardial infarct size, NMR imaging was performed in six canine hearts excised 24 hours after circumflex coronary artery ligation. Before sacrifice, the dogs received i.v. manganous chloride (0.05 mmol/kg). After NMR imaging, the hearts were sectioned and the myocardial slices were stained with triphenyl tetrazolium chloride. The pathologically determined infarct size was compared with the infarct size measured by NMR imaging. The correlation was good (regression line slope 1.06; r= 0.94). We conclude that NMR imaging with paramagnetic contrast agents canbe used to determine infarct size in excised hearts.

Computed Tomography in Crohn Disease

Twelve patients with Crohn disease were studied by computed tomography. Characteristic findings of small intestinal involvement include symmetrical bowel wall thickening, a “double halo” appearance on cross section of the diseased bowel segment, and an associated mesenteric fat mass. Computed tomography provided crucial diagnostic information in the management of some of the intestinal and extraintestinal complications of the disease.

Proton NMR imaging in experimental ischemic infarction.

Proton nuclear magnetic resonance (NMR) images depict the distribution and concentration of mobile protons modified by the relaxation times T1 and T2. Using the steady-state-free-precession (SSFP) technique, serial coronal images were obtained sequentially over time in laboratory animals with experimental ischemic infarction. Image changes were evident as early as 2 hours after carotid artery ligation, and corresponded to areas of ischemic infarction noted pathologically. Resulting SSFP images in experimental stroke are contrasted to inversion-recovery NMR images in an illustrative patient with established cerebral infarction. Bulk T1 and T2 measurements were made in vitro in three groups of gerbils: normal, those with clinical evidence of infarction, and those clinically normal after carotid ligature. Infarcted hemispheres had significantly prolonged T1 and T2 (1.47 +/− .12 sec, 76.0 +/− 9.0 msec, respectively) when compared to the contralateral hemisphere (T1 = 1.28 +/− .05 sec, T2 = 58.7 +/− 3.9 msec) or to the other two groups. These data suggest that changes in NMR parameters occur and can be detected by NMR imaging as early as two hours after carotid artery ligation.

Clinical relevance of two different nuclear magnetic resonance (NMR) approaches to imaging of a low grade astrocytoma.

A young patient with progressive neurological deficit of uncertain cause underwent true three-dimensional nuclear magnetic resonance (NMR) imaging by the inversion-recovery and by the saturation-recovery techniques. Differences between the results of the two methods helped clarify the nature of the underlying disorder and revealed an extent of neoplasia greatly exceeding that suggested by X-ray computed tomography. The NMR imaging results were instrumental in selecting the site for brain biopsy, which demonstrated a Grade II astrocytoma.

Nuclear magnetic resonance imaging: potential cardiac applications.

During the past several years, the production of high resolution images of organs in intact animals and human beings using nuclear magnetic resonance (nmr) has generated much interest and raised the possibility that the technique could be usefully applied to clinical problems. Because the images are derived from biochemical as well as structural information, valuable data relating to the metabolic status of the tissues and organs may be obtained. Furthermore, nuclear magnetic resonance imaging involves no potentially hazardous ionizing radiation. The technology of the technique is complex and much work remains to be done defining the biochemical and physiologic basis of such images, but the potential rewards of defining the metabolic state of organs such as heart and brain in the intact animal and human justify continued research.

Value of radionuclide imaging techniques in assessing cardiomyopathy

Radionuclide imaging techniques add an important dimension to the diagnosis, classification and management of myocardial disease. The gated blood pool scan provides information allowing determination of the functional type of cardiomyopathy (congestive, restrictive or hypertrophic) as well as evaluation of ventricular performance. Myocardial perfusion imaging with thallium-201 is useful in distinguishing congestive cardiomyopathy from severe coronary artery disease and also in depicting septal abnormalities in hypertrophic cardiomyopathy. Radionuclide techniques also prove useful in following progression of disease and in evaluating the efficacy of therapeutic interventions.

Spectrum of congestive heart failure late after aortic valve or mitral replacement: Differentiation of valvular versus myocardial cause by radionuclide ventriculogram-ejection fraction

Heart failure (CHF) appearing late after aortic (AV) or mitral valve (MV) replacement (R) may be due to mechanical factors such as prosthetic or native dysfunction, or due to myocardial disease. We studied 41 patients who developed CHF late (6 weeks to 11 years) after AVR or MVR with gated blood pool scan (RNV) to analyze the spectrum of ejection fraction (EF) and its clinical correlates. Of the 17 patients who developed CHF after AVR, 10 had RNV EF greater than 0.5 (all of whom had severe valve or prosthetic dysfunction as the primary cause of CHF) and seven had EF less than 0.5 (five with severe myocardial disease and two with prosthetic dysfunction). Of the 24 with CHF after MVR, 13 had RNV EF greater than 0.5. In contrast to post-AVR patients, only 8 of the 13 patients had mechanical causes of CHF (seven prosthetic dysfunction and one constrictive pericarditis). Of the 11 patients after MVR with EF less than 0.5, nine had severe myocardial disease and two had prosthetic dysfunction. Thus (1) reduced EF in patients and CHF-after AVR or MVR suggests myocardial disease as the basis for CHF, and (2) normal EF implies a mechanical cause of CHF after AVR but may be associated with either myocardial or mechanical factors after MVR.