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The paradox image, a functional image of regional dyskinesis derived from the equilibrium (gated) radionuclide ventriculogram, was constructed by subtracting the background-corrected end-diastolic frame from the background-corrected end-systolic frame. In 11 patients showing dyskinesis by contract ventriculography, the percentage of left-ventricular picture elements containing paradox ranged from 3.6 to 55.6% (21.44% +/- 4.45 s.e.m.). In 11 patients with normokinesis and in eight patients with hypokinesis by contract ventriculography, the left-ventricular picture elements demonstrating paradox were less than 1.1% in all cases. In nine patients with akinesis, the percentage of left-ventricular picture elements containing paradox was 2.05% +/- 0.96 s.e.m. and was less tha 2% in seven patients. There was also an excellent agreement between the location of dyskinesis on the paradox image and that by contrast ventriculography. The paradox image is a sensitive indicator of left-ventricular dyskinesis and should be useful in the evaluation of patients with suspected left-ventricular asynergy.
The organ distribution of radiopharmaceuticals in the rat is usually estimated using 7% of body weight (BW) for blood volume (BV). In spite of its important impact on the evaluation of new agents, this value has not been validated adequately. We therefore studied blood volume in 70 awake Wistar rats (100 to 400 g BW) in which red blood cell volume (RBCV) and plasma volume (PV) were measured simultaneously. Red blood cell volume was measured by in vitro RBC-tagging with Tc-99m in Sn-pyrophosphate, 0.05 microgram per ml of blood; plasma volume was measured with I-125 human serum albumin (HSA). Ten minutes after injection of the dose, 0.5 ml of blood was withdrawn from the carotid or femoral artery and duplicate samples of 0.025 ml of blood were counted after separating RBCs from plasma. Total blood volume was calculated by adding RBC volume and plasma volume. The relationship for the entire group was: BV (ml) = 0.06 X BW + 0.77 (r = 0.99, n = 70, p less than 0.001). The difference between male and female rats was not statistically significant. The use of an arbitrary value of 7% for estimation of blood volume can lead to significant errors in calculating radiopharmaceutical distribution. The use of the general formula for the blood-volume calculation described here should improve the accuracy and reliability of estimates of radiopharmaceutical distribution.
Four different Tc-99m labeled phosphorus-based bone-imaging agents were compared by a scan-evaluation technique in which the skeletal uptake was visually assessed at selected sites. A detailed statisticalanalysis of scans, by each of three independent evaluators, on a total of 140 different patients showed that two of the agents (based on pyro- and on trimetaphosphate) were superior. The statistical analysis showed good agreement between the investigators and consistency in thier repeat evaluations.
The use of up-to-date diagnostic methods and the estimation of the extent of myocardial lesion in patients with intermediate coronary conditions (serial assays of CPK and MV-CPK activity with subsequent computation of the weight of affected myocardium, ECTG and myocardial 99mTc-Sn-pyrophosphate scintigraphy using a gamma-counter) demonstrated: the presence of necrotic foci in patients with acute focal myocardial dystrophy; a considerable variation in the weight of affected myocardium; and high diagnostic value of ECTG for the assessment of the extent of myocardial lesion in patients with intermediate coronary conditions. Objective criteria have been worked out for the differential diagnosis of various intermediate coronary conditions.
Myocardial scintigraphy with pyrophosphate-99mTc-Sn was used as a diagnostic test in 23 patients with different disorders of rhythm and intracardia conduction who were admitted to the department of emergency cardiology of the All-Union Cardiological Scientific Center, Academy of Medical Sciences of the USSR with suspected acute myocardial infarction. Scintigrams were positive in 11 of 12 patients with acute myocardial infarction who were examined in periods of 6 hours of 10 days. One patient examined on the 13th day of the disease had negative scintigrams. In 6 of 11 patients with myocardial infarction not confirmed, the scintigrams were also negative, in 3 other patients positive scintigrams were due to a postinfarction aneurysm. The authors conclude that myocardial scintigraphy with pyrophosphate-99mTc-Sn is an adequate test in the diagnosis of acute myocardial infarction, especially in the examination of patients with disorders of intracardiac conduction.
Several stannous pyridoxylideneaminates were evaluated as stannous ion sources for the in vivo labeling of red blood cells (RBCs) with Tc-99m. In spite of a considerable variety of stannous preparations, rapid and efficient RBC labeling was obtained with each stannous chelate. These results suggest that the role of the ligands is merely to stabilize the divalent state of the tin. The optimal time interval between Sn(II) and 99mTcO4- injections, and the best stannous-ion concentration, was found using stannous pyridoxylideneisoleucine (Sn-P.isoL). Maximal in vivo labeling of the RBCs was obtained with an i.v. dose of 10-20 micrograms Sn(II)/kg of Sn-P.isoL followed 15-30 min later by i.v. administration of pertechnetate.
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The uptake of technetium-99m stannous pyrophosphate in contused myocardium was measured as a function of time from the insult. The free wall of the dog's left ventricle was surgically exposed and struck with a spring-loaded paddle. Pyrophosphate was injected intravenously from 1 1/2 to 47 1/2 hr after the injury. After 1/2 hr of incubation the hearts were removed and the Tc-99m content of contused and noncontused myocardium was measured. Pyrophosphate was concentrated in contused myocardium at all of the time periods tested. Contused-to-normal ratios for pyrophosphate uptake ranged from 8.1 (8 hr) to 41.9 (48 hr).
The technique of blood pool scanning was used to examine 15 hemophilic subjects. Employing an in vivo method for erythrocyte labeling with Technetium-99 m, a dynamic perfusion sequence is obtained using a scintillation camera positioned over the area to be examined. This demonstrates the vascularity of the tissue. Subsequently, equilibrium blood pool images of the area are obtained and analyzed with a densitometer to assess relative regional blood volume. In patients who were not bleeding but had chronic arthropathy, vascularity was not increased, and the blood volume of comparable joints was similar. By contrast, marked increases in vascularity and image density were observed in studies of acutely bleeding joints. Chronic hemarthroses were associated with persistent, but less marked increases in joint perfusion. Transient increases in joint vascularity were demonstrated after insertion of knee prostheses. In a patient with a thigh hematoma, the dimensions of the hemorrhage were clearly delineated. Since only a tracer dose of nuclide is infused intravenously, there are no allergic reactions or other side effects of the procedure. Blood pool scanning is a safe, non-invasive technique that augments clinical and radiographic evaluations, and provides a new dimension in the assessment of the hemophilic patient.
The rate of incorporation of Tc-99m into red blood cells pretinned in vivo was measured by collecting blood samples in stannous DTPA solution, which served as a competing ligand for Tc-99m. This collection technique permitted a measurement of high-affinity red-cell labeling efficiency at the instant of sampling. At 0.5 min after injection only 62% of technetium is tightly bound to the red cell; this rises to 94.5% at 10 min. Based on the graded labeling of the red cells, the in vivo labeling procedure was modified by isolating pertechnetate and red blood cells tinned in vivo in a syringe during the first 10 min of labeling. The pertechnetate is thus prevented from distributing to extravascular compartments, and 90% of the injected Tc-99m is firmly bound to red blood cells at the time of injection. In a series of 23 patients, seven were tested with the in vivo method and seven with the modified in vivo method, and nine patients were tested with each method on separate occasions. A decrease in gastric activity and improved image quality were found with the modified method compared with the standard method of in vivo red-cell labeling.
Twenty patients with occult gastrointestinal bleeding underwent diagnostic evaluation with autologous TcRBC imaging, which identified a locus of bleeding in 19. Bleeding was demonstrated in the esophagogastroduodenal area in four patients, the cecum in four patients, the ascending colon or hepatic flexure in nine patients and the descending colon in two patients. In the six patients who underwent surgical intervention, the source of bleeding had been correctly located by imaging. The advantages of imaging over those of conventional arteriography included its minimally invasive nature and its ability to detect areas of intermittent minimal bleeding for a period of 30 hours. The major disadvantages of the technique were that localization of the site of bleeding was not as precise as that obtained with arteriography, imaging could not be used as a treatment modality and the nature of the lesion could not be defined. However, we believe that, as an adjunct to conventional angiography and other techniques, autologous TcRBC imaging will improve the localization of obscure foci of gastrointestinal bleeding. Studies are underway to determine the proper place of TcRBC imaging in the gastroenterologic armamentarium. Its noninvasive nature and sensitivity to intermittent hemorrhage suggest that it may become the initial investigative modality of choice in many instances.
Results from 388 patients, examined with quantitative equilibrium radionuclide ventriculography (qERNV) at rest, were stored in a data bank system and evaluated statistically. The value of time and velocity parameters [ejection time (ET), filling time (FT), time ES to peak filling rate (TpFR), mean (mER) and peak (pER) ejection rate, peak filling rate (pFR)] were evaluated in patients with coronary heart disease (CHD, with and without history of earlier myocardial infarction) or with cardiomyopathy (CMP). Significant (p less than 0.025) changes vs. normal in CHD I/II were obtained from pER, pFR, ET, in CHD III from gEF, EDV, mER, pER, pFR, in CHD IV from gEF, EDV, mER, pER, pFR, in patients with infarction or with CMP from gEF, EDV, mER, pER, pFR, ET and TpFR. Resting qERNV revealed a sensitivity in diagnosing a CHD (stages I-III) by mER of 30-59%, by pER of 40-65%, by pFR of 48-60% and by ET of 58-61%, which was higher than the sensitivity of gEF (19-56%).
A case with transient WPW syndrome during silent acute myocardial infarction is presented. Although the clinical picture and laboratory data were non contributory and the surface electrocardiogram showed delta and not Q waves, myocardial perfusion scintigraphy showed typical area of acute necrosis. Abnormal accessory connections probably occur or latent such pathways become functional during acute myocardial ischemia.
Esophageal hemangioma is a benign tumor that may cause dysphagia and upper gastrointestinal bleeding. Invasive measures such as endoscopic biopsy and surgical excision have been required for diagnosis in most reported cases. We have reported a case focusing on the use of two noninvasive techniques, contrast CT and radionuclide angiography, in the diagnosis of esophageal hemangioma.
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