Abstract: Fifteen dogs were studied by perfusion scan, angioscopy and autopsy. In 10, emboli were formed in leg veins and released before study; five dogs were not embolized and served as controls. In controls, angioscopy disclosed no emboli, perfusion scans were normal after angioscopy and autopsy disclosed no emboli. Among the embolized dogs, 23 emboli were identified at autopsy. Perfusion scans disclosed 23 defects, but in three dogs there was a disparity between scan and autopsy localization. Angioscopy identified 21 of the 23 autopsy-defined emboli and localized them correctly; two emboli in vessels less than 1 mm in diameter were not visualized. Angioscopy may provide a useful new approach in animal investigations of pulmonary embolism and perhaps, after additional study, in selected patients.

Abstract: It is generally agreed that at least one-third of Strokes arise from atherosclerotic lesions developing on the extracranial arterial channels. The bifurcation of the common carotid artery in the neck is a site particularly prone to develop plaques. The adverse effects of carotid atherosclerotic plaques are manifest through two effects on brain perfusion: 1), embolism to the brain and eye from intimai ulcerations, and 2), a reduction in hemispheric flow. The purpose of this chapter is to understand the local Doppler velocity signals and the local pressure-flow relationships associated with stenosis of the carotid arteries in order to quantitate the degree of carotid narrowing and its effect on brain perfusion.

Abstract: Twenty-seven patients were studied for cerebral blood perfusion abnormalities using krypton 81m. A solution of 81mKr was continuously infused into an internal carotid artery, and single-photon emission computed tomograms were recorded. The transverse section images using 81mKr represented the three-dimensional regional cerebral blood perfusion, and this technique seemed to be useful for evaluating the regional cerebral blood perfusion in the deep brain.

Abstract: The serious causes of morbidity and mortality after cardiac surgery are still: (1) low cardiac output (2) surgical haemorrhage (3) dysrhythmias (4) brain damage.

Abstract: Sixty-five patients with suspected pulmonary embolism were studied prospectively with both Kr-81 m and Xe-133 ventilation imaging and Tc-99m MAA perfusion imaging. The krypton images, perfusion scintigrams and chest radiographs were read independently of the xenon images, perfusion scintigrams and chest radiographs by three observers. The studies of 53 patients were interpreted as normal or as indicative of a low or intermediate probability for pulmonary embolism with both gases. One study indicated intermediate probability with Xe-133 due to diffuse, severe xenon retention but low probability with Kr-81 m because of close ventilation-perfusion correspondence. The studies of 9 patients indicated a high probability of embolism with both gases, while those of two additional patients (one with emboli at angiography) indicated a high probability only with Kr-81m. While essential agreement between Xe-133 and Kr-81m ventilation imaging was found in most patients, the significant difference in interpretation in 2 of 11 patients with probable pulmonary embolism suggests that a controlled, prospective trial with pulmonary angiography is warranted before Kr-81m is employed for routine clinical use.

Abstract: A whole body single photon emission computed tomographic system (SPECT) has been used to investigate canine pulmonary perfusion utilizing 99mTc-microspheres and has been compared to conventional radionuclide pulmonary perfusion studies. The SPECT data were reconstructed and displayed in 32 transverse, 16 sagittal, and 16 coronal plane sections, producing additional anatomical information on the pattern of pulmonary perfusion compared to that available with the conventional perfusion scan. The major bronchi, the major blood vessels, and the pulmonary hila are readily seen on the SPECT examination (confirmed anatomically) but are not easily identified on a conventional lung scan. Qualitative assessment of serial SPECT scans established that the distribution and relative concentration of infected radiopharmaceutical was consistent provided the studies had been performed with the animal in the same anatomical position. Changes in the dog's position resulted in a redistribution of radiopharmaceutical such that the most dependent lung contained the greatest concentration.

Abstract: Radionuclide lung perfusion imaging was performed on 27 patients with valvular disease of the left heart. The ratio of upper to total counts for the lungs, determined by computer, was correlated against pulmonary vascular mean pressures. A close correlation (r = 0.91) was obtained against pulmonary wedge pressure. After corrective cardiac surgery upper/total ratios fell towards normal in four patients in whom pulmonary vascular pressures were measured and the correlation persisted. This simple non-invasive index can be used to follow changes in pulmonary venous hypertension.

Abstract: The technical feasibility of selectively changing internal organ temperatures using balloon catheter perfusion was investigated. The liver or kidney temperatures were measured during the perfusion of cold or heated saline or preheated blood into the afferent vessels. Hyperthermic perfusion of the renal artery distal to an occlusion balloon catheter raised the kidney temperature to 43 degrees C. The hepatic arterial perfusion caused small changes in the liver temperature, whereas, with portal venous perfusion, the liver could be heated to 43 degrees C. Selective heating of the left hepatic lobe could be achieved by selective perfusion of the left portal vein. The potential therapeutic application of this technique is described.

Abstract: . The increase in mortality from cardiovascular disease in the presence of electrocardiographic signs of left ventricular hypertrophy (LVH) has been ascribed to ischaemic changes in the hypertrophied left ventricle even in the absence of overt coronary artery disease. To test this hypothesis and to investigate the usefulness in the detection of LVH myocardial perfusion scintigraphy with thallium-201 and echocardiography was performed in thirty-three hypertensive patients. Sixteen had had electrocardiographic signs of left ventricular hypertrophy. Twelve patients had symptoms of cardiovascular disease. In twenty-six subjects the scintigraphic procedure consisted of a combined restexercise study, in the other seven only resting images were obtained. Measurement of septa1 wall thickness on the scintiscans correlated fairly well with echographic dimensions and allowed separation of a group of patients with LVH from a group without. In individual patients, however, the perfusion scan was not a reliable tool to affirm the presence of LVH. A total of eight patients, six with LVH on the echocardiogram, had an abnormal rest-exercise perfusion scan, either with a new perfusion defect after exercise and/or with a resting defect alone. In nine other patients with echocardiographic LVH, on the other hand, no abnormal perfusion was found. Thus, perfusion abnormalities did not correlate with the presence of LVH. The presence of such abnormalities in relation to increasing age and symptomatic cardiovascular disease could well be the expression of anatomic coronary artery disease and cannot be differentiated from the possible ischaemia of the hypertrophied left ventricle.

Abstract: Significant progress in the clinical assessment of peripheral vascular disease has resulted from the use of radionuclide scans to evaluate alterations of blood flow through small vessels. Two patients with Type II muscle atrophy and normal vessels on muscle biopsy were examined; abnormal lower extremity perfusion scans were obtained after the administration of 99mTc-labeled human albumin microspheres directly into the femoral arteries. These case studies illustrate the use of this technique for delineating muscle groups affected by a myopathic process. Muscle perfusion scans can be used as an aid in selecting biopsy sites and may provide a means of following the response to therapy.

Abstract: The cerebral hemodynamic evaluation is the embodiment of a system approach to the hemodynamic factors that affect brain blood flow. The stresses employed are those encountered in everyday living. The instruments are simple and the method is basic. The importance of the cardiovascular response to the upright position and of brain perfusion to head motion deserves close attention in the clinical setting. The CHE complements the angiogram, the CT scan, and CT-rBBC studies by addressing the system and arterial hemodynamic factors affecting brain circulation. The CT-rBBC studies have given greater validity and direction to noninvasive and electrophysiologic testing because the ultimate concern is brain perfusion and function and not the angiogram. This combination of techniques has defined the role of the dynamic arterial obstruction and the vertebral artery in the hemodynamics of the brain. The cerebral hemodynamic evaluation is an integral part of the physiologic approach to the diagnosis and treatment of brain ischemia.

Abstract: Scintiphotographic studies as a method for analyzing the brain perfusion in carotid cavernous sinus fistulae before and after surgical treatment with different techniques are presented. Twelve patients have been reexamined long after their operation to prove the sufficient crossover circulation through the circle of Willis while the homolateral carotid artery is impatent. Sufficient perfusion of both hemispheres could be well-documented by this radionuclide method. No neurological deficit was found in clinical examination either.

Abstract: In the first of these 2 chapters on the subject of nuclear imaging, the techniques that have been described for infarct scanning and perfusion scanning produce images that are static. In other words, an image produced over a few minutes shows no appreciable change in tracer distribution over the imaging period. The dynamic imaging techniques to be described in this chapter differ, in that tracer distribution changes rapidly with time within a region of interest.