Abstract: An increased pulmonary thallium-201 concentration has been observed in exercise stress thallium perfusion imaging in patients with coronary artery disease. To understand the cause of this lung uptake, studies were performed in experimental animals and in patients undergoing stress thallium perfusion imaging. The extraction fraction of thallium-201 by the lungs was measured in a group of eight dogs using a dual isotope technique. Basal thallium-201 extraction fraction at rest was 0.09 ± 0.009. After administration of isoproterenol, it decreased to 0.06 ± 0.02 (difference not significant). After balloon obstruction of the left atrium (which increased mean left atrial pressure and pulmonary transit time) and after administration of acetylcholine as a bolus injection (which prolonged pulmonary transit time only) it increased to 0.19 ± 0.02 (p Lung thallium-201 activity was measured in 86 patients who had undergone cardiac catheterization and stress-redistribution myocardial perfusion imaging. The initial/final lung activity ratio was 1.41 ± 0.03 in patients with no significant coronary artery disease, 1.52 ± 0.03 (difference not significant) in patients with single vessel coronary disease, 1.60 ± 0.05 (p

Abstract: An enclosed system is described utilizing an osmotically driven pump to continuously deliver a solution to a variety of intraocular locations. The behavior of this system is illustrated by using it to measure the fluorescein turnover rate in the anterior chamber.

Abstract: This study of 73 patients with the clinical diagnosis of thromboembolism has shown that the pulse rate, respiratory rate, and arterial partial pressure of carbon dioxide have discriminatory value in identifying the group of acutely ill patients who are most likely to have pulmonary embolism. In contrast, the clinical diagnosis of deep venous thrombosis, PaO2 chest radiography and electrocardiography which are all essential to patient management have no such value. In this series, only 29% of the patients had a pulmonary arteriogram positive for thromboembolism, but the mortality rate in this group was 33%. Pulmonary perfusion scanning has been shown to be a useful and accurate screening investigation and should be routinely employed prior to pulmonary angiography if the patient is stable hemodynamically.

Abstract: In a prospective study 169 patients with clinically suspected leg/pelvic-vein thrombosis were tested by 131 I fibrinogen uptake-test and radionuclide venography for confirmation of this diagnosis and also by a nuclearmedical lung investigation In all cases of an abnormal perfusion scan a supplementary ventilation scan was performed The perfusion scan has a sensitivity for pulmonary embolism of near 10 but its specificity is only 057 An additional ventilation study (133 Xenon, 81m Krypton) improves the specificity to 095 A mismatch of regional ventilation and perfusion is the nuclearmedical substrate of pulmonary embolism The diagnosis of thrombosis was confirmed in 105 of 169 cases (62%) Thrombosis was located in the lower legs in 56%, in the thigh veins in 23% and in the external iliac veins in 21% From 105 patients with leg/pelvic-vein thrombosis 60 (571%) had pulmonary emboli, from 64 patients with negative tests concerning thrombosis only 3 (47%) (p < 0001) Pulmonary emboli were present in 46% when thrombosis was located in the lower legs, in 67% when thigh veins and in 77% when pelvic veins were involved The average frequency of 57% emboli found in patients with leg and pelvic vein thrombosis agrees with data from pathologic-anatomical studies An analysis of these patients with embolism showed that 70% of them were over 70 years old, that 52% of the emboli originated from thigh and pelvis and 43% from the lower leg and that 59% had no clinical signs of embolism 804% of the patients had multiple perfusion defects (up to 9) which correlated in size with the severity of the clinical symptoms and which were about equally distributed in both lungs Larger perfusion defects occure more frequently with thromboses of the thigh and pelvis than in thromboses of the lower leg According to the chest x-ray pulmonary emboli were suspected to only 6 of 26 patients with clinical evidence of embolism (23%)

Abstract: Improvement in cardiac perfusion has not been demonstrated in man to explain the increased functional capacity secondary to exercise training. Thallium imaging is a noninvasive method of evaluating myocardial perfusion and scaring. Therefore, using thallium exercise tests, we studied 17 patients with coronary heart disease before and after a mean of 6 months participation in cardiac rehabilitation program emphasizing exercise training. Interobserver variability in imaging interpretation was considered by reading images blinded both individually and in consensus. Agreement with defects called by consensus occurred at least 51% of the time individually and normal readings agreed at least 90% of the time. By consensus reading, seven patients showed improved perfusion, seven showed no change, and three worsened following training. Our study shows that thallium scans may be used to demonstrate central changes in myocardial perfusion after cardiac rehabilitation, but larger controlled studies considering redistribution and utilizing image enhancement are necessary to see if such changes are truly secondary to this intervention.

Abstract: In a series of 23 patients with surgically proven subdural hematoma of durations ranging between two days to seven months, the detection rate of Tc-99m-pertechnetate brain imaging was higher than computerized transaxial tomography (CT). With dynamic perfusion scanning, the detection rate was 71.5%. However, when combined with sequential static images obtained at 10 minutes, 2 hours and 3--4 hours, the detection rate rose to 92% regardless of the duration of the disease. In contrast, CT demonstrated the hematoma in 52% of the cases. In another 28% the diagnosis was suggested through nonconclusive evidence or presence of contralateral shift of midline structures. Lastly, the result of CT scanning was dependent on the size of the subdural hematoma as evaluated at the time of operation.

Abstract: From August 1976 through February 1978, 108 suspected cases of pulmonary embolism were studied. In 31 patients, the scintigraphic diagnosis and the findings of pulmonary emboli detected at pulmonary arterial angiography were compared in order to assess the specificity of pulmonary scanning. Of the 108 patients in whom pulmonary embolism had been diagnosed by perfusion lung scan, 77 did not undergo pulmonary angiography: 46 because angiography was not available, 27 because of very severe illness, and four because of the opposition from relatives or from the attending physician. In the remaining 31 patients, a total of 36 pulmonary angiographies were performed, and the results compared with the corresponding perfusion scan findings. In four patients, the contrast media was injected into the main pulmonary artery; the remaining 32 examinations were performed after positioning the injection catheter at different lobar branches, chosen on the basis of the perfusion lung scan findings. In six patients, pulmonary arterial angiography was performed after pulmonary embolism had been treated by continuous heparin infusion, when all of them showed significant improvement in the perfusion lung scan pattern (in five cases pulmonary angiography had also been performed previously, at the time of early diagnosis).

Abstract: This paper reviews 387 patients who had perfusion scintigraphy over a period of two and a half years. Data are presented concerning patients' symptoms and the use of perfusion imaging. Scintigraphy is shown to be subjective and rather unreliable, as practised in this series. Post mortem correlations suggest that used in isolation, perfusion scintigraphy cannot reliably distinguish emboli from other lung diseases. Use of ancillary tests and ventilation scintigraphy is discussed.

Abstract: Myocardial activity was noted on a lung scan performed following the i.v. administration of Tc-99m macroaggregated albumin. The patient had primary pulmonary hypertension with a right-to-left shunt through a functionally patent foramen ovale.

Abstract: Recent progress in diagnostic cardiology has centered around noninvasive methods 1,2 ; among these, echocardiography and myocardial scintigraphy have developed most rapidly. 3-6 Probably most prominent among the diverse scintigraphic methods is relative myocardial perfusion imaging. 1 The method employs an intracellular cation, most commonly thallium (TL) 201, administered in the form of thallous chloride. The TL 201 is rapidly extracted from the blood following a peripheral intravenous injection 7 and is avidly taken up by the viable myocardium in proportion to relative coronary perfusion. " Owing to the rapid extraction of these radionuclides and the transient stability of their localization, injection made during bicycle or treadmill exercise and imaging performed within a brief period following injection permit evaluation of myocardial perfusion present at the time of injection. 9-13 Image abnormalities present on the stress study can be compared with a subsequent image performed at rest or at redistribution, three to four

Abstract: The routine chest X-ray is a standard radiographic procedure which provides a great deal of anatomic information to the physician. Indeed, the chest X-ray will detect increased or reduced density of lung structures, thus providing information on lung anatomy, rather than function.

Abstract: The patterns of pulmonary blood flow have been studied in 21 apparently normal perfusion scans, Two patterns were identified, a predominantly lower lobar distribution and a more even pattern. The predominantly lower lobar distribution is probably the more normal pattern, which suggests that in addition to the relationships between alveolar pressure, pulmonary vascular pressures and gravity, the anatomical structure of the lung also influences the regional distribution of blood flow. West’s zone I was identified in 20 of the patients and occupied, on average, 16% of the vertical height of the lung. It is suggested that recognition of this zone may enable mean pulmonary arterial pressure to be measured from a combination of ventilation-perfusion imaging and the chest radiograph

Abstract: The aims of this paper are (1) to report post-operative angiographic results obtained in a series of 40 patients treated by an extra-intracranial arterial bypass (EIAB) procedure, and (2) to describe the patterns of postoperative regional brain perfusion (rBP), as investigated in a limited series of patients, by a new method.

Abstract: Functional images of brain perfusion can be obtained by a steady-state method which exploits the peculiar physical characteristics of the radioactive gas 81mKr.2 This is a very short half-lived isotope (13 sec half-life), which can be continuously produced either in the gaseous or the solution phase from its parent 81Rb (4.6 hours half-life). It emits 190 keV γ rays, an ideal energy for recording with an Anger γ camera. Because of its short half-life, continuous carotid infusion of 81mKr in solution will never eventually result in the equilibrium of this diffusible tracer within the brain; during continuous infusion continuous recording of the activity over the brain will therefore reflect at any time regional arrival of tracer, which is a linear function of regional perfusion. Thus, when used in conjunction with an ordinary Anger γ camera, it provides images of cerebral perfusion in two dimensions.

Abstract: Several methods for the bulk separation of nerve cells have been developed during the last 20 years. Basically, two procedures are modified in one or another step [5, 6]: First, by mechanical disaggregation of the brain tissue by chopping and then sieving; and secondly, by incubating the brain tissue between the two mechanical steps, with or without exogenous enzymes.