title: [Imaging of thromboembolism by scintigraphy with the 99m-technetium-labelled synthetic peptide P280].
abstract: P280, a synthetic peptide composed of 26 aminoacids, has high affinity (Kd = 100 nM) and specificity for the glycoprotein IIb/IIIa (GPIIb/IIIa) receptor expressed on activated platelets. In this study we investigated the potential usefulness of imaging deep vein thrombosis (DVT) and pulmonary embolism (PE) in humans with 99mTc-P280. In 15 patients (9 men and 6 women; mean age +/- s.d.: 49.2 +/- 14.1) with known DVT and/or PE, serial images were acquired within 24 hours of the injection of approximately 200 micrograms of P280 radiolabelled with 10-23 mCi of 99mTc. P280 was labelled with the ligand exchange method using 99mTc-glucoheptonate. Rapid blood clearance (< or = 5% ID was still circulating in 1 hour) enabled identification of thrombi as early as 60 minutes after the injection, with significant thrombi-to-background ratios (range: 2-4) in 11/15 patients (73%), in 7/9 with DVT, in 2/3 with PE and in 2/3 patients with both DVT and PE. Radiotracer uptake was clearly detectable also in late scans, which confirms that 99mTc-P280 specifically binds to the thrombi through a receptor-mediated mechanism. PE localizations were detectable 3-4 hours after peptide injection, and in 2 cases SPECT enabled the detection of thrombi missed on planar views. Conversely, the test was negative in 4 patients who had the onset of clinical symptoms and the diagnosis of DVT and/or PE more than 40 days before scintigraphy. The lack of 99mTc-P280 uptake in the latter patients suggested that the peptide does not bind to thrombi when thrombogenesis is not active. These preliminary results clearly indicate scintigraphy with 99mTc-P280 to be a suitable, noninvasive and highly specific tool to image fresh clots causing DVT and/or PE. Thus, this technique might overcome the limitations of the imaging procedures currently in use.
authors.affiliation: Medicina Nucleare, Centro per la Medicina Nucleare CNR, Napoli.
authors.forename: S
authors.initials: S
authors.lastname: Lastoria
authors.forename: E
authors.initials: E
authors.lastname: Vergara
authors.forename: P
authors.initials: P
authors.lastname: Varrella
authors.forename: P
authors.initials: P
authors.lastname: Muto
authors.forename: W
authors.initials: W
authors.lastname: Acampa
authors.forename: C
authors.initials: C
authors.lastname: Caracò
authors.forename: M
authors.initials: M
authors.lastname: Salvatore
mesh_terms: D000328:Adult; D000368:Aged; D001682:Biological Availability; D003287:Contrast Media; D004341:Drug Evaluation; D005260:Female; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics; D010456:Peptides, Cyclic / Q000493:pharmacokinetics; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging* / Q000378:metabolism; D011877:Radionuclide Imaging; D013667:Technetium / Q000493:pharmacokinetics; D013924:Thrombophlebitis / Q000000981:diagnostic imaging* / Q000378:metabolism; D013997:Time Factors; D014915:Whole-Body Counting / Q000379:methods
chemical_list: D003287:Contrast Media; D015609:Organotechnetium Compounds; D010456:Peptides, Cyclic; C094919:technetium Tc 99m P280; D013667:Technetium
vernacular_title: Imaging della tromboembolia mediante scintigrafia con peptide sintetico P280 marcato con 99mTecnezio.