In-111 labeled leukocytes: a review of problems in image interpretation

Leukocyte suspensions labeled with In-111 oxine or tropolone were administered intravenously to 150 patients for the detection of suspected foci of bacterial infection by gamma camera imaging. The results were correlated with other imaging modalities, and clinical, laboratory, and surgical findings after a minimum follow-up period of six months. Twenty-five of 29 foci of bacterial infection were demonstrated on the leukocyte-labeled images (sensitivity of detection = 86%). Three of the four missed lesions were chronic active osteomyelitis. The specificity of detection proved difficult to define, varying with different criteria for a false positive diagnosis. In every region of the body, a variety of lesions other than foci of bacterial infection produced positive uptake of the labeled leukocytes. An intense focal uptake was uncommon in lesions other than abscesses and hematomas. It was concluded that imaging with labeled leukocytes is valuable for demonstrating sites of infection in conjunction with other diagnostic methods. Detectable leukocytic infiltration, however, may occur in inflammatory lesions of any cause and in some noninflammatory states as well.