Visual estimation of ejection fraction by two-dimensional echocardiography: the learning curve.

Our purpose was to determine the learning curve of visual estimation of ejection fraction (EF) by echocardiography. Sixty consecutive patients, who had clinically indicated echocardiography and radionuclide ventriculography (RVG) within 1 month were selected. Five standard views were reviewed independently by a first-year cardiology fellow, a private cardiologist, and an experienced echocardiographer. Observers were given feedback of the RVG EFs immediately after estimating the EF on each study. To assess the effect of learning, the echocardiographic studies were divided into three groups of 20 and were read successively by each observer. A statistical comparison of the two methods was performed for each group. The correlation between the two techniques for the first group of studies was marginal. There was a significant improvement in the correlation with subsequent groups. The correlation did not change significantly with the last group of studies compared with the second group. In conclusion, visual estimation of EF by two-dimensional echocardiography can be learned, with a learning curve of approximately 20 studies if immediate feed-back is available.

Prognostic value of triple phase bone scanning for reflex sympathetic dystrophy in hemiplegia.

Twenty-two patients with cerebral vascular accident (CVA), clinically confirmed by head computed tomography, were observed for symptoms of the reflex sympathetic dystrophy syndrome (RSDS). All patients received triple phase bone scans; 16 scans were positive for RSDS. Patients with negative scans had no symptoms of RSDS. Five patients with positive scans had RSDS symptoms at the time of bone scanning. Seven of 11 patients with positive scans but no symptoms of RSDS at the time of bone scan developed symptoms of RSDS within six months. We found a significant relationship between positive bone scans and the subsequent development of RSDS (p < 0.01). Considering only those patients who were asymptomatic for RSDS at the time of bone scanning, we found bone scanning to be a good predictor for the future development of clinical RSDS. We found the correlation between positive bone scans and the subsequent development of clinical RSDS in previously asymptomatic individuals to be statistically significant (p < 0.05). We conclude that bone scans may be a good predictor of patients at risk for developing clinical RSDS after CVA.

Gallium-67 renal uptake in Sjogren's syndrome.

This case report describes a 61-year-old male with Sjogren's syndrome. Diffuse Ga-67 uptake in the kidneys was seen due to renal involvement with this disorder. Sjogren's syndrome should be considered in the differential diagnosis of diffuse bilateral Ga-67 accumulation in the kidneys.

An evaluation of methods for sizing radiocolloidal particles.

Technetium-99m-labelled colloids covering the entire spectrum of particle size were prepared from commercial kits (antimony colloid, sulphur colloid, tin colloid) or by chemical (excess aluminium) or thermal modification of sulphur colloid (heating time of 30 min). Particle size measurements were obtained using electron microscopy and/or a laser light scattering technique. The results for antimony colloid agreed reasonably well for both techniques with a range of 3 to 25 nm. However, standard sulphur colloid had a smaller size (220 nm) when measured by electron microscopy in comparison to the larger size (390 nm) obtained with the light scattering method. This discrepancy was felt to be due to artefacts created by electron microscopy. These artefacts (drying and sublimation) were avoided by the laser light scattering techniques which has the advantage of being non-destructive and of quickly sizing particles while still in solution. The larger colloidal particles were sulphur colloid doped with aluminium ions (1000 nm) and the tin colloid (2500 nm) which were sized by electron microscopy and laser light scattering respectively.

Evaluation of radiocolloids as thrombus imaging agents. Effect of particle size on thrombus uptake.

Thrombus uptake values of several 99mTc labeled radiocolloids determined using an experimental rodent model of deep venous thrombosis were correlated with particle size distributions. The thrombus uptake values increased with increasing mean particle size. The 99mTc-tin colloid had the highest thrombus uptake value of any of the colloids used in this study.

Work in progress: detection of deep venous thrombosis with 99mTc-sulfur colloid.

Scintigrams of the leg were obtained following antecubital venous injection of 99mTc-sulfur colloid (SC) in 25 patients with suspected deep venous thrombosis. Contrast venograms were taken following the scan in all cases. Of 14 patients with confirmed deep venous thrombosis, 11 had positive scans. Of 11 patients with normal venograms, 10 had negative scintigrams. The simplicity of 99mTc-SC venography and its high rate of accuracy (84% in this series) suggest that it may be useful as a relatively noninvasive means of identifying deep venous thrombosis of the leg.

The use of technetium-99m sulfur colloid as a marker for experimental venous thrombosis: concise communication.

The binding of technetium-99m sulfur colloid to in vivo thrombi was studied in a rat model of deep vein thrombosis. After thrombosis was induced by mechanical traumatization of a right femoral vein segment, technetium-99m sulfur colloid was injected into the peripheral veins of different experimental groups at intervals of 30 min and 1-7 days. Ratios of mean activity in traumatized right femoral vein segment to activity in control segments of left femoral vein (R/L ratios) ranged form 2.97-11.0 for all in situ venous thrombi studied. There was no relation between clot size and R/L ratios. The significant uptake ratios observed by us for venous thrombi up to 1 wk in age suggest that in vivo thrombus detection may be feasible by imaging with a gamma camera after technetium-99m sulfur colloid injection in a peripheral vein.

Sickle cell crisis as evaluated from measurements of hydroxybutyrate dehydrogenase and myoglobin in plasma.

Data on plasma hydroxybutyrate dehydrogenase activity (I) and myoglobin concentration were used to evaluate painful sickle cell crises. I was increased during non-crisis steady state in patients with sickle cell disease as compared to normal values (232, SD 79.7 vs 85, SD 33 Sigma units/mL). During crisis, the mean value for I increased further to 379 (SD 139) Sigma units/mL. For 12 patients evaluated both during steady state and crisis, there was a mean increase in plasma I of 131% (SD 76%). Repeated determinations of I in sickle cell disease patients during several months while they were in steady state showed that baseline I varied by no more than 20% from the mean. Plasma myoglobin in patients with sickle cell disease was not above normal, but during crisis 21 of 39 patients tested had increased plasma myoglobin concentrations. Our data suggest that I may be a useful indicator of sickle cell crisis when the patient's own baseline value is available for comparison. Plasma myoglobin measurements give evidence of muscle damage during crisis with high specificity but low sensitivity.

Differential lung blood flows in experimental unilateral emphysema: nonvalidity of perfusion scans.

As part of an evaluation of the effects of left lung transplantation in dogs with papain emphysema of the right lung, differential lung blood flows were estimated by in vivo scintiscan of 99Mc-macroaggregated albumin (99mTc-MAA) and, after sacrifice, by direct counting of isotopically labeled carbonized microspheres. In six dogs, percentage flow to the right lung was calculated at the following four times: before and after induction of papain emphysema and 2 and 6 weeks after left lung autotransplantation. After the induction of right lung emphysema, the right lung in four of six animals continued to receive more than 50 percent of the total pulmonary blood flow. No correlation could be established between right lung blood flow determined by carbonized microsphere distribution (true right lung blood flow) and the flow determined by anterior and posterior scintiscans (apparent right lung blood flow). This discrepancy was caused by gross distortion of the right, emphysematous lungs, which had herniated into the left hemithoraces. This herniation was demonstrated by coronal slices taken through the thoraces of two additional dogs with right lung emphysema that were given radiolabeled carbonized microspheres and 99Tc-MAA and frozen after sacrifice. These results indicate that external scintiscans for which the particulate distribution technique are used are invalid in circumstances of altered lung geometry.

Scintigraphic diagnosis of ischemic intestine with technetium-99m sulfur colloid-labeled leukocytes.

Positive scintigrams were obtained in 13 of 15 dogs injected with technetium-99m sulfur colloid-labeled leukocytes following the experimental production of intestinal ischemia. The radioactivity of the ischemic intestines averaged 5.9 times that found in normal control segments of intestine from the same animal. Labeled leukocytes may be used as a rapid noninvasive technique for the early identification of ischemic intestine.

A comparison of radionuclide scanning and computed tomography in metastatic lesions of the brain.

Forty-seven patients with a final diagnosis of brain metastases were studied with both computed tomography (CT) and radionuclide (RN) scanning. Fifty-three percent of these patients also underwent contrast enhanced CT. Radionuclide scanning detected 94% of the cases, while CT without contrast enhancement was positive in 89%. The addition of contrast material to the CT examination increased the total sensitivity of CT to 94% and permitted the detection of two cases that were falsely negative on RN scanning and CT without contrast. With both techniques, lesions in the cerebral hemispheres were detected more readily than infratentorial lesions. Radionuclide scanning was less sensitive than CT without contrast in the detection of multiple metastases. Contrast enhanced CT should be used in all cases of suspected cerebral metastases unless contraindicated.

131I-fibrinogen in the detection of pulmonary allograft rejection.

The uptake of 131I-fibrinogen in canine pulmonary allografts was compared to that in lung autografts or lungs with papain-induced unilateral hemorrhagic pneumonia. In addition to serial lung scans and the postmortem measurement of tissue radioactivity, all dogs had serial chest roentgenograms and histologic study of their lungs. All four animals in the allografted group had increased radioactive uptake on the side of the allograft lung at the same time as or slightly before radiographic abnormalities were evident. However, increases in lung radioactivity also occurred in animals with pneumonia or autografts at the time infiltrates were present. Thus the presence of increased lung scan activity, which occurs in rejecting lung allografts after the injection of 131I-fibrinogen, is not a specific index of pulmonary rejection.