technetium-tc-99m-sulfur-colloid and Pulmonary-Embolism

To compare the thrombolytic effects of the two dosing regimes with urokinase (UK) in a canine model of pulmonary thromboembolism induced by radioactive blood clots.. Seventeen dogs were randomly assigned into three groups: the control group, the UK(2h) group (UK infused over 2 hours) and the UK(12h) group (UK given over 12 hours). The thrombolytic differences was investigated among the three groups. Thrombolysis was assessed by continuously counting over both lung fields with single photon emission computed tomography (SPECT) and calculated by regions of interest (ROI) technology and by counting radioactivity in the lung in vitro. The extent of thrombolysis was calculated as the difference between the radioactivity originally incorporated in the clot (decay-corrected) and the radioactivity in the lung in vitro.. In three groups, the lysis rates measured by ROI technology were (6.2 +/- 4.0)%, (39.5 +/- 13.9)%, and (16.9 +/- 8.9)% respectively, and (6.0 +/- 2.7)%, (42.8 +/- 12.4)%, and (17.7 +/- 9.3)% by the method in vivo. The thrombolytic ratio of the UK(2h) group was significantly higher than that of the other two groups (P < 0.01), and there was no marked difference between the control group and the UK(12h) group. There was a thrombolytic peak in the UK(2h) group at the first four hours after infusion of agent.. For the fresh thrombi, the UK(2h) regime is superior to the UK(12h) due to its higher thrombolytic ratio and prompt thrombolytic property. The model and methods are highly reliable.

Topics: Animals; Disease Models, Animal; Dogs; Female; Male; Pulmonary Embolism; Technetium Tc 99m Sulfur Colloid; Thrombolytic Therapy; Urokinase-Type Plasminogen Activator

To establish a canine model of pulmonary thromboembolism (PTE) for evaluating the effects of thrombolytic therapy.. The preparations of radioactive blood clots in vitro were made from fresh whole blood (from 6 donors) mixed with (99m)Tc-SC. After eluting the clots with saline solution, the stability and evenness of (99m)Tc-SC in the clots were determined. Then a canine model of PTE induced by these clots was established and the rates of spontaneous lysis were measured by the regions of interest (ROI) technique and the in vitro method.. (99m)Tc-SC was stable in the radioactive blood clots after elution, and the radioactivities in the thrombi were well-distributed. The rates of thrombolysis were (6.2 +/- 4.0)% as measured by ROI and (6.0 +/- 2.7)% by the in vitro method.. (99m)Tc-SC is stable and well-distributed in blood clots. A canine model of PTE can be induced by autologous radioactive blood clots.

Topics: Animals; Disease Models, Animal; Dogs; Evaluation Studies as Topic; Female; Humans; Male; Pulmonary Embolism; Radionuclide Imaging; Technetium Tc 99m Sulfur Colloid; Thrombolytic Therapy; Urokinase-Type Plasminogen Activator

Topics: Diagnosis, Differential; Female; Humans; Middle Aged; Pulmonary Embolism; Radiopharmaceuticals; Spleen; Splenic Infarction; Technetium Tc 99m Sulfur Colloid; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

We employed a canine model of pulmonary embolism induced by injection of radioactive blood clots to investigate effects of changes in cardiac output (CO) on recombinant tissue plasminogen activator- (rtPA) induced pulmonary thrombolysis. Rate and extent of thrombolysis were assessed with a gamma camera. Eighteen dogs were studied. Emboli increased mean pulmonary arterial pressure and decreased CO from 2.6 to 1.9 l/min (P less than 0.001). Subsequently, dogs were randomly divided into three groups: group 1 received 0.5 mg/kg of rtPA over 30 min; 30 min before the same dose regimen of rtPA, in the six group 2 dogs, mean CO was increased to approximately 3.25 l/min by opening one systemic arteriovenous fistula; in the six group 3 dogs, before rtPA, mean CO was increased to approximately 4.5 l/min by opening two or three fistulas. After embolization, CO remained low in group 1; the mean 2-h time-averaged CO was 1.8 l/min. CO was much higher in groups 2 and 3 (3.3 and 4.6 l/min, respectively; both P less than 0.001 compared with group 1; and P less than 0.001, group 2 vs. group 3). Compared with group 1, corresponding to the increased flow in groups 2 and 3, rate and extent of pulmonary thrombolysis significantly increased. These results indicate that an increase in flow per se augments rtPA-induced pulmonary thrombolysis. Also, because thrombolysis was similar between groups 2 and 3, these results define an upper limit to the flow-thrombolytic relationship with rtPA.

Topics: Animals; Cardiac Output; Dogs; Fibrinolytic Agents; Hematocrit; Hemodynamics; Pulmonary Embolism; Starch; Technetium Tc 99m Sulfur Colloid; Thrombosis; Tissue Plasminogen Activator

We employed a canine model of pulmonary embolism, induced by injection of autologous radiolabelled blood clots, to investigate effects of hydralazine and an increase in cardiac output per se on recombinant tissue plasminogen activator-induced thrombolysis. Emboli increased pulmonary artery pressure (PAP) and decreased CO from 2.7 to 1.8 L/min-1. Following embolization, dogs were randomly divided into three groups. Group 1 received .5 mg/kg of rtPA over 30 minutes. Group 2 received the same dose of rtPA and were pretreated with hydralazine to increase CO approximately 50 percent. In the group 3 dogs, CO was increased by opening a systemic A-V fistula. Following embolization, CO remained low in group 1, the mean 2 h time-averaged CO was 1.9 L/min-1. The CO was 2.9 and 3.1 L/min-1 in groups 2 and 3, respectively. Corresponding to the increased flow in groups 2 and 3, rate and extent of pulmonary thrombolysis significantly increased. These results indicate that an increase in CO augments rtPA-induced pulmonary thrombolysis.

Topics: Animals; Arteriovenous Shunt, Surgical; Blood Pressure; Cardiac Output; Dogs; Fibrinolysis; Hydralazine; Pulmonary Artery; Pulmonary Embolism; Recombinant Proteins; Technetium Tc 99m Sulfur Colloid; Thrombolytic Therapy; Time Factors; Tissue Plasminogen Activator; Vascular Resistance; Ventricular Function, Left

Radiolabeling of Ivalon (polyvinyl alcohol sponge) particles permits localization of injected particles during embolization through the use of a portable gamma camera and provides a means to prevent potentially fatal complications such as pulmonary embolization. A more efficient technique of labeling Ivalon particles with technetium-99m sulfur colloid was developed. An increase in labeling efficiency allowed more accurate determination of the distribution of injected Ivalon particles. Scanning electron microscopy demonstrated the stability of the Ivalon particles during this new labeling process. Two patients with arteriovenous malformations underwent therapeutic embolization with radiolabeled Ivalon particles; gamma camera imaging of the lesion and chest was performed throughout the procedure.

Topics: Adult; Arteriovenous Malformations; Child; Embolization, Therapeutic; Female; Humans; Isotope Labeling; Leg; Male; Microscopy, Electron, Scanning; Polyvinyls; Pulmonary Embolism; Radionuclide Imaging; Technetium Tc 99m Sulfur Colloid

A patient with metastatic gastric carcinoma and malignant ascites developed sudden-onset dyspnea secondary to a new large left pleural effusion. A radionuclide lung scan performed for suspected pulmonary embolism was indeterminate. Scintigraphy performed following intraperitoneal administration of Tc-99m sulfur colloid subsequently demonstrated rapid accumulation of activity in the left pleural space, indicating the presence of a pleuroperitoneal communication. In a patient with known or suspected ascites, a new pleural effusion, and an indeterminate lung scan, peritoneal scintigraphy may identify the origin of the effusion and obviate the need for further invasive evaluation for possible pulmonary embolism.

Topics: Aged; Diagnosis, Differential; Fistula; Humans; Male; Peritoneal Diseases; Pleural Diseases; Pleural Effusion; Pulmonary Embolism; Radionuclide Imaging; Stomach Neoplasms; Technetium Tc 99m Sulfur Colloid

99Tcm-labelled aerosol ventilation and 99Tcm-macroaggregate albumin (99Tcm-MAA) perfusion can be performed in the diagnosis of pulmonary embolism (PE). If both examinations are performed on the same day, the superposition of activity from the first scintigraphic examination might mask defects in the second. In this study, 106 examinations were carried out for suspected PE. Aerosol ventilation was performed first with 20 to 30 mCi 99Tcm-labelled rhenium sulphur (four views, 200,000 counts). Immediately afterwards, with the patient remaining in the same position, 5 to 7 mCi of 99Tcm-MAA were injected (four views, 400,000 counts). After normalization, aerosol activity was subtracted from perfusion images and unprocessed perfusion (UP) and ventilation subtraction perfusion (SP) images were compared. Interobserver diagnostic reproducibility between three readers was calculated both for UP and SP images. Intraobserver reproducibility between UP and SP images was calculated for each reader. Interobserver reproducibility was comparable for SP and UP images. Intraobserver reproducibility was good. Thus, whether ventilation was subtracted or not from perfusion images, there was no appreciable effect on perfusion defect detection. However, some perfusion abnormalities showed up more clearly on SP images. Perfusion can be performed immediately after aerosol ventilation; the images thus obtained are reliable for interpretation, and subtraction of ventilation is not necessary.

Topics: Aerosols; Colloids; Humans; Methods; Pulmonary Embolism; Radionuclide Imaging; Rhenium; Technetium Tc 99m Aggregated Albumin; Technetium Tc 99m Sulfur Colloid

Topics: Aerosols; Humans; Organometallic Compounds; Pentetic Acid; Pulmonary Embolism; Radionuclide Imaging; Technetium Tc 99m Pentetate; Technetium Tc 99m Sulfur Colloid

Two radiopharmaceuticals, 99mTc-DTPA (D) and 99mTc-rhenium sulfur (R), were evaluated with a nebulizer delivering submicronic particles. Seventy-seven patients were examined (42 D, 35 R). For all patients, the examination began with a ventilation study. Immediately after the last ventilation view, 99mTc MAA was injected. Aerosol performance was assessed in 37 D and 17 R. Nebulization yield was 8.98% for D and 9.31% for R. A lung clearance study was performed in 12 patients for D and in 12 different patients for R. The lung clearance was 0.22%/min for R and 2.35%/min for D. The quality of ventilation and the quantification of bronchial and gastric activity were evaluated; the difference between the two groups was not statistically significant. It may be concluded that radioaerosols allow good quality images to be obtained. The yield of the nebulizer is adequate, so that nebulization of 20 mCi delivers approximately 2 mCi of aerosol activity to the lung. When pulmonary embolism is being investigated, R, due to its slower lung clearance, would appear to be preferable to D for patients suspected of increased bronchoalveolar permeability, especially if the time between nebulization and recording is greater than 10 min.

Topics: Adult; Aerosols; Aged; Aged, 80 and over; Bronchi; Female; Humans; Lung Diseases, Obstructive; Male; Middle Aged; Pentetic Acid; Pulmonary Circulation; Pulmonary Embolism; Radionuclide Imaging; Respiration; Rhenium; Technetium; Technetium Tc 99m Pentetate; Technetium Tc 99m Sulfur Colloid

The effect of respiratory motion on pulmonary activity determinations by positron emission tomography (PET) was studied in dogs with experimentally created pulmonary emboli (PE). The location of the PE was evaluated by planar 99mTc lung imaging to determine the appropriate sites for transaxial PET scans. PET scans of the lung then were obtained after i.v. injection of 68Ga-labeled microspheres. PET scans were acquired during slow (15 breaths/min) and fast (30 breaths/min) breathing with the same minute ventilation and then postmortem. Lung perfusion patterns were documented by i.v. injection of India ink before sacrifice. Cross sections of the excised lungs were made at the same levels as the PET scans, and eight sections containing 14 perfusion defects were analyzed. The scans obtained during slow breathing consistently showed edge blurring and demonstrated defects less well than scans obtained during fast breathing or postmortem. The normal-to-defect activity ratios during fast breathing and on the postmortem studies were similar and approximately 17% higher (P less than .01) than in scans obtained in the same animals during slow breathing. The results demonstrate the need for motion correction during quantitative analysis of regional lung activity by positron tomography, and suggest that high-frequency respiration at small tidal volumes may be one means for obtaining this correction.

Topics: Animals; Dogs; Female; Gallium Radioisotopes; Lung; Microspheres; Pulmonary Embolism; Respiration; Technetium Tc 99m Sulfur Colloid; Tomography, Emission-Computed