Comparison of early and delayed scintigraphy with Tc-99m-apcitide and correlation with contrast-enhanced venography in detection of acute deep vein thrombosis

Preliminary studies with Tc-99m-apcitide ((TC)-T-99m-P280), a synthetic pep tide that binds to glycoprotein IIb/IIIa receptors expressed on activated p latelets, have shown promising results in the detection of acute deep vein thrombosis (ADVT). The purpose of this study was to compare the diagnostic value of early and delayed imaging with Tc-99m-apcitide in patients with su spected ADVT, using contrast-enhanced venography as the gold standard. Meth ods: Thirty-nine patients (17 women, 22 men; mean age 59 y) with signs or s ymptoms suggestive of ADVT (within 10 d of onset) and scheduled for contras t-enhanced venography were prospectively studied. The patients were injecte d with approximately 740 MBq (20 mCl) Tc-99m-apcitide within 36 h of contra st-enhanced venography. Both anterior and posterior planar images (8-10 min /view) of the lower extremities using a dual-head gamma camera were obtaine d at 10, 60 and 120 min after the injection of Tc-99m-apcitide. The three s ets of images initially were interpreted randomly and separately by three e xperienced observers unaware of the clinical history, the site of ADVT and results of contrast-enhanced venography. All images from the three sets for a given patient were then analyzed together during a second session. Conve ntional contrast-enhanced venography was performed on 31 patients before Tc -99m-apcitide scintigraphy and in the remaining 8 patients after Tc-99m-apc itide scintigraphy. Tc-99m apcitide findings were considered positive for A DVT when a focus of increased uptake was found to correspond to the locatio n of a deep vein. Disagreements were resolved by consensus. Results: Twenty -two patients had ADVT observed on contrast-enhanced venography, whereas 17 had normal findings. Six cases of ADVT were infrapopliteal. One patient di d not complete the third set of images with Tc-99m-apcitide. The sensitivit y of Tc-99m-apcitide in detecting ADVT was 63.6% (14/22), 68.2% (15/22), 76 .2% (16/21) and 86.4% (19/22) for images obtained at 10, 60 and 120 min and for the three sets analyzed together, respectively. The specificity was 82 .4% (14/17), 76.5% (13/17), 88.2% (15/17) and 88.2% (15/17) for images obta ined at 10, 60 and 120 min and for the three sets of images together, respe ctively. Conclusion: Although the set of Tc-99m-apcitide images obtained 12 0 min after injection showed good overall diagnostic accuracy, the combinat ion of at least two sets of images provided the highest accuracy in detecti ng ADVT.