Technetium-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 Tc-99m through the nicotinyl hydrazine derivative (HYNIC) has shown promising results in the detection of experimental infection. in this study, Tc-99m-labeled HYNIC-IgG was directly compared to In-111-labeled diethylenetriaminepentaacetic 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 suspected infectious or inflammatory foci were prospectively studied. After administration 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 microbiological, histological, radiological and clinical methods. Results: Technetium-99m-HYNIC-IgG and In-111-DTPA-IgG scintigraphy showed 100% concordancy. All 17 patients with proven infection or inflammation (19 foci, mainly localized in the locomotor system) had positive scintigraphic findings. No false-negative scintigrams were recorded. In three patients, 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 scintigraphy is equally as effective as In-111-IgG scintigraphy for the detection of infection and inflammation. The apparent physical and logistic advantages of Tc-99m over In-111 make Tc-99m-HYNIC-IgG a promising new radiopharmaceutical for imaging infection and inflammation.