Added Value of ^99mTc-HMPAO–Labeled Leukocyte SPECT/CT in the Characterization and Management of Patients with Infectious Endocarditis

^99mTc-HMPAO-WBC SPECT/CT images for patient with positive blood cultures and fever that arose a few months after substitution of mitral valve with mechanical prosthesis (coronal views [top], transaxial views [bottom]; CT [left], fused SPECT/CT [center], and SPECT [right]). SPECT images demonstrate clear focus of uptake in right heart, identified as endocarditis of native tricuspid valve by superimposed SPECT/CT images. Endocarditis of mechanical prosthesis, expected site of infection before ^99mTc-HMPAO-WBC was performed, was therefore excluded.

^99mTc-HMPAO-WBC scintigraphy demonstrating value of SPECT/CT for precisely localizing site of infection. (A) Planar anterior (left) and posterior (right) views, where focal uptake of radiolabeled WBC mimics sternal osteomyelitis. (B) Coronal, sagittal, and transaxial CT (left); fused SPECT/CT (middle); and SPECT (right). Tomographic images correctly localize uptake of ^99mTc-HMPAO-WBC at mitral valve prosthesis.

Examples of septic embolism at different sites as detected by ^99mTc-HMPAO-WBC SPECT/CT. (A) Patient with septic embolism in left lung (coronal, sagittal, and transaxial CT [left]; fused SPECT/CT [middle]; and SPECT [right]). (B) Patient with septic embolism in spleen, where infection shows as photopenic area in splenic parenchyma (transaxial CT [left], fused SPECT/CT [center], and SPECT [right]). (C) Patient with septic embolism in spine (coronal, sagittal, and transaxial CT [left]; fused SPECT/CT [middle]; and SPECT [right]). Similarly, as in case of spleen, infection shows as photopenic area, which in this patient involves 2 vertebral bodies.