Comparison of In-111-MERC leukocytes with In-111-Oxine leukocytes for abscess detection

This study was done to compare the clinical results of generally accepted Indium-111-oxine (oxine) labeled leukocytes with a relatively newer Indium-111-2-Mercaptopyridine-N-oxide (Merc) labeled leukocytes for the detection of occult abscesses. Of the 74 patients suspected of harboring an occult abscess, autologous leukocytes of 34 patients were labeled with oxine while in 40 patients Merc labeled leukocytes were used. Whole body imaging was performed at 24 hours. Interpretation of the scans was done without the knowledge of the leukocyte label (i.e. oxine vs Merc). The diagnosis was confirmed in each case by either subsequent clinical course, radiographic correlation (CT, US, etc.), surgery pathology, or autopsy. The results presented in this paper indicate that there is no significant difference between the Merc and oxine labeled leukocytes for abscess detection. The ease of labeling and potential availability of Merc as a kit is an advantage.