Infection scintigraphy: added value of single-photon emission computed tomography/computed tomography fusion compared with traditional analysis.

PURPOSE: Positron emission tomography (PET)/computed tomography (CT) imaging is a powerful dual-modality integrating physiology and anatomy. Analogously, fusing separate single-photon emission computed tomography (SPECT) and CT images can overcome interpretive challenges in characterizing and localizing abnormalities. This study explores the value of SPECT/CT image fusion compared with traditional "side-by-side" SPECT-CT image review for infectious /inflammatory processes.

METHODS AND MATERIALS: We identified 17 abnormal infection/inflammation SPECT scans in 16 patients (11 indium 111 WBC and 6 gallium citrate Ga 67) with a contemporary CT scan. The SPECT and CT images were uploaded onto "side-by-side" workstations, one with fusion software. Two nuclear radiologists reviewed "side-by-side" SPECT and CT images and fused SPECT/CT images. They scored 2 parameters (anatomical localization and diagnostic confidence) using a 4-point scale (1 "not helpful" to 4 "very helpful"). Score differences more than 1 indicated "added value" and less than 0, "no added value".

RESULTS: Compared with "side-by-side" SPECT-CT, fused SPECT/CT images yielded "added value" for anatomical localization in 65%, diagnostic confidence in 71%, and altered interpretations in 47% of cases. Greater confidence was achieved in 75% of cases with altered interpretations and 55% of unaltered cases.

CONCLUSIONS: The SPECT/CT image fusion outperformed "side-by-side" SPECT/CT review for anatomical localization and diagnostic confidence of infectious/inflammatory abnormalities. Therefore, SPECT/CT fusion potentially influences clinical decisions and treatment options.