technetium-tc-99m-exametazime and Thrombophlebitis

Thirty-three patients with symptoms and signs of a deep venous thrombosis (DVT) were examined by contrast venography and radionuclide imaging with 99Tcm-hexamethylpropyleneamineoxime (99Tcm-HMPAO)-labelled autologous platelets. There were 13 patients on heparin therapy and 20 without anticoagulation during the scintigraphy. Scintigraphy consisted of blood pool imaging at 5 to 20 min and accumulation imaging at 2, 4-6 and 18-24 h. In scintigraphy a positive finding was either a defect of radioactivity in the immediate blood pool phase or a hot spot indicative of accumulation of platelets in later phases. Fifteen out of 23 patients positive by venography were also positive by scintigraphy. Five of the eight false negative patients were on heparin treatment, two probably had DVT which were not quite fresh. The venography negative patients were also negative on scintigraphy. Nine out of 12 patients without anticoagulation had positive platelet accumulation compared with two out of 11 patients on heparin therapy. This difference was statistically significant (P less than 0.025). The sensitivity and specificity of platelet scintigraphy were 65 and 100%, respectively, in all patients and 83 and 100% in patients without anticoagulation. Our results suggest that scintigraphy with 99Tcm-HMPAO-labelled platelets is a useful alternative in diagnosing DVT in patients in whom a standard contrast X-ray venograph is contraindicated or otherwise unsuccessful.

Topics: Adult; Aged; Aged, 80 and over; Blood Platelets; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Phlebography; Radionuclide Imaging; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Thrombophlebitis

Topics: Cerebral Veins; Humans; Jugular Veins; Leukocytes; Radionuclide Imaging; Technetium Tc 99m Exametazime; Thrombophlebitis

Disintegrins are peptides found in viper venoms which bind to platelets through the glycoprotein IIb-IIIa receptor. The purpose of this work was to evaluate the ability of disintegrins to image thrombi and emboli in vivo.. Eight disintegrins (bitistatin, albolabrin, echistatin, eristostatin, kistrin, mambin, halysin and barbourin) were purified from snake venom. After radiolabeling with 123I, disintegrins were tested for their ability to image 24-hr-old experimental deep vein thrombi (DVT) and pulmonary emboli in a canine model. Labeled fibrinogen and platelets were used as controls. Gamma camera imaging was performed during the first 4 hr, after which tissue samples were collected for counting.. Of the disintegrins tested, 123I-bitistatin had higher uptake in DVT (0.21 +/- .06% ID/g) than any other disintegrin (0.009-0.036%/g, p < 0.05). Bitistatin had higher DVT-to-blood ratios (9.8 +/- 2.5) than all other disintegrins, 125I-fibrinogen or 99mTc-HMPAO-platelets (p < 0.05). Images of DVT obtained with 123I-bitistatin were focally positive within 1 hr and improved by 4 hr. In pulmonary emboli, the absolute uptake of 123I-bitistatin (0.64 +/- 0.17% ID/g) was higher than all other compounds (p < 0.05), although barbourin had moderate uptake (0.23 +/- 0.11% ID/g) and may also be useful for imaging pulmonary embolism (PE). The uptake of bitistatin in PE was superior to both 125I-fibrinogen (0.18 +/- 0.02% ID/g) (p < 0.05) and 99mTc-HMPAO-platelets (0.14 +/- 0.02% ID/g, p < 0.05). Iodine-123-bitistatin had embolus-to-blood ratios averaging 27 +/- 7, which was higher than platelets, fibrinogen, echistatin, mambin or halysin (p < 0.05). Iodine-123-bitistatin background in lungs, liver and heart were low, which permitted visualization of all pulmonary emboli by 2-4 hr after injection.. Labeled bitistatin should be investigated further as an agent which may permit rapid imaging of both thrombi and emboli.

Topics: Amino Acid Sequence; Animals; Blood Platelets; Disintegrins; Dogs; Evaluation Studies as Topic; Fibrinogen; Humans; Iodine Radioisotopes; Male; Molecular Sequence Data; Organotechnetium Compounds; Oximes; Peptides; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Pulmonary Embolism; Radionuclide Imaging; Snake Venoms; Technetium Tc 99m Exametazime; Thrombophlebitis; Time Factors; Tissue Distribution; Venoms

Eighteen patients with suspicion of deep venous thrombosis (DVT) in the lower extremities were imaged both with autologous 99mTc-HMPAO-labeled platelets (Tc-PLT) and 111In-labeled monoclonal antifibrin antibodies (In-MoAbs) on the same day. Presence or absence of thrombosis was verified by venography. Tc-PLT was given i.v. followed after 30 min by In-MoAbs. Anterior and posterior projections of the lower extremities were obtained with a large field-of-view gamma camera at 5 to 25 min, 2 h, 4 to 6 h, and 20 h after administration of the marker. Both Tc-PLT and In-MoAbs detected DVT well but less frequently than venography. Thrombi were visualized at 2 to 4 h after injection. The quality of images was better with Tc-PLT than with In-MoAbs. In the patients treated during the study, heparin significantly (p < 0.01) inhibited the uptake of Tc-PLT but not of In-MoAbs. We conclude that both Tc-PLT and In-MoAbs are suitable agents for the detection of DVT especially in patients without anticoagulation.

Topics: Adult; Aged; Antibodies, Monoclonal; Blood Platelets; Female; Fibrin; Humans; Indium Radioisotopes; Male; Middle Aged; Organotechnetium Compounds; Oximes; Phlebography; Radionuclide Imaging; Technetium Tc 99m Exametazime; Thrombophlebitis

The optimum conditions for labelling platelets with lipophilic 99mTc-hexamethyl propylene amine oxime (99mTc-HMPAO) were evaluated. An aseptic closed system was used throughout the procedure in patient studies. 48 ml blood were withdrawn into 12 ml ACD using sterile 60 ml plastic syringes. After mixing, the blood was transferred to sterile 10 ml vacuum tubes and platelets were isolated according to standard centrifugation procedures. The labelling efficiency was not dependent upon incubation temperature (22 degrees C, 37 degrees C) but was greater in saline than in the presence of plasma. The labelling efficiency increased with time up to 60 min in saline. The elution of 99mTc from platelets was about 25% in plasma milieu in vitro but did not increase with time during 160 min. 5 patients with verified fresh deep vein thrombosis in the lower leg were imaged after injection of labelled autologous platelets. All 4 of the patients without anticoagulant therapy showed positive uptake of 99mTc-HMPAO-labelled platelets, but the 5th patient--under heparin therapy--was negative in scintigraphy. Our results are encouraging and 99mTc-HMPAO-labelled platelets offer a promising tool for evaluating various clinical situations.

Topics: Blood Platelets; Female; Humans; Male; Middle Aged; Organometallic Compounds; Oximes; Radionuclide Imaging; Technetium; Technetium Tc 99m Exametazime; Thrombophlebitis