TC-99M LABELED TO HUMAN-IMMUNOGLOBULIN-G THROUGH THE NICOTINYL HYDRAZINE DERIVATIVE - A CLINICAL-STUDY

A novel method to label polyclonal human immunoglobulin G (IgG) with T c-99m through the nicotinyl hydrazine derivative (HYNIC) has shown pro mising results in the detection of experimental infection. in this stu dy, Tc-99m-labeled HYNIC-IgG was directly compared to In-111-labeled d iethylenetriaminepentaacetic acid (DTPA)-IgG in patients suspected of infectious or inflammatory disease. Methods: Thirty-seven patients (22 women and 15 men; mean age = 54 yr, range = 17-78 yr) with 39 suspect ed infectious or inflammatory foci were prospectively studied. After a dministration of 740 MBq Tc-99m-HYNIC-IgG, imaging was performed at 4 and 24 hr postinjection. To avoid cross-over activity, In-111-DTPA-IgG was injected 24 hr after Tc-99m-HYNIC-IgG and imaged at 4, 24 and 48 hr postinjection. The scintigraphic results were confirmed by microbio logical, histological, radiological and clinical methods. Results: Tec hnetium-99m-HYNIC-IgG and In-111-DTPA-IgG scintigraphy showed 100% con cordancy. All 17 patients with proven infection or inflammation (19 fo ci, mainly localized in the locomotor system) had positive scintigraph ic findings. No false-negative scintigrams were recorded. In three pat ients, the scintigrams were concordantly false-positive. As a result, the sensitivity and specificity of imaging infectious or inflammatory foci with Tc-99m-HyNIC-IgG and In-111-DTPA-IgG in these patients were 100% and 85%, respectively. Conclusion: Technetium-99m-HYNIC-IgG scint igraphy is equally as effective as In-111-IgG scintigraphy for the det ection of infection and inflammation. The apparent physical and logist ic advantages of Tc-99m over In-111 make Tc-99m-HYNIC-IgG a promising new radiopharmaceutical for imaging infection and inflammation.