99mTC-labelled antigranulocyte monoclonal antibody FAB' fragments versus echocardiography in the diagnosis of subacute infective endocarditis

Abstract

Objective: We performed this pilot study to gain first clinical data of immunoscintigraphy with 99mTc-labelled anti-NCA-90 antigranulocyte antibody Fab' fragments (99mTc-Fab' (LeukoScan((R)))) in endocarditis.

Patients and methods: 99mTc-Fab' and echocardiography were used in 24 consecutive patients with suspected endocarditis. Nuclear medicine imaging was performed after i.v. injection of 925 MBq 99mTc-Fab' fragments and evaluation was done by region of interest (ROI) technique and visually.

Results: Seven patients were found to have endocarditis on the basis of the revised Duke criteria, which served as gold standard. Initial scintigraphy was true positive in five patients and false positive in one. In the five true positives, T/B ratios in projection to the heart valve plane (with T/B>/=1.3+/-0.072) were highly suspicious for florid endocarditis. TTE and TEE were true positive in two and in six patients, whereas false positives were seen in two and in four patients. Scintigraphy was positive in four of the five patients with the false negative TTE and negative in the three false positive TEE. Vice versa, TEE was positive in the two patients with false negative scintigraphy.

Conclusions: Immunoscintigraphy with 99mTc-Fab' fragments in combination with TEE improves diagnostic accuracy compared with TTE/TEE in patients with subacute infective endocarditis.