Radiolabeled granulocyte scintigraphy in suspected peripheral osteoarticular infection

Radiolabeled granulocyte scintigraphy is a recently introduced technique for detecting osteoarticular infections. Technetium-99m-labeled hexamethylpropylamineoxime (HMPAO), in use since 1986, provides excellent resolution with less radiation exposure than indium-111. Elimination of lymphocytes provides further improvements in image quality and safety, making the technique suitable for use in children. The authors prospectively studied 30 scintigraphies performed with isolated autologous 99mTc-HMPAO-labeled granulocytes to evaluate suspected osteoarticular infection. Image quality was outstanding. In peripheral sites, infection manifested as a focus of increased uptake visible in all three phases (30 min, 3 hours and 18 hours after the injection). Performance was excellent, with 11 true-positive scans, 14 true negative scans, 4 false-positive scans (including two ascribable to recent surgery), and one false-negative scan. Among the 28 evaluable cases, positive predictive value was 85%, negative predictive value was 90%, and sensitivity, specificity, and accuracy were 92%, 88%, and 89%, respectively. The only limitation to routine use of this technique is the need for in vitro granulocyte separation which is time-consuming and requires special precautions to preserve granulocyte function. Nevertheless, these data demonstrate that 99mTc-HMPAO-labeled granulocyte scintigraphy is of value for the detection of osteoarticular infections in patients without chronic inflammatory joint disease. (authors)