Suspected Infection

Background. We sought to characterize the clinical utility of indium 111 (111In)–labeled white blood cell (WBC) scans by indication, to identify patient populations who might benefit most from this imaging modality. Methods. Medical records for all patients who underwent 111In-labeled WBC scans at our tertiary referral center from 2005 to 2011 were reviewed. Scan indication, results, and final diagnosis were assessed independently by 2 in-fectious disease physicians. Reviewers also categorized the clinical utility of each scan as helpful vs not helpful with diagnosis and/or management according to prespecified criteria. Cases for which clinical utility could not be deter-mined were excluded from the utility assessment. Results. One hundred thirty-seven scans were included in this analysis; clinical utility could be determined in 132 (96%) cases. The annual number of scans decreased throughout the study period, from 26 in 2005 to 13 in 2011. Forty-one (30%) scans were positive, and 85 (62%) patients were ultimately determined to have an infection. Of the evaluable scans, 63 (48%) scans were deemed clinically useful. Clinical utility varied by scan indication: 111In-labeled WBC scans were more helpful for indications of osteomyelitis (35/50, 70 % useful) or vascular access infection (10/15, 67 % useful), and less helpful for evaluation of fever of unknown origin (12/35, 34 % useful). Conclusions. 111In-labeled WBC scans were useful for patient care less than half of the time at our center. Tar-geted ordering of these scans for indications in which they have greater utility, such as suspected osteomyelitis and vascular access infections, may optimize test utilization