PET with FDG-labeled leukocytes versus scintigraphy with 111In-oxine-labeled leukocytes for detection of infection.

PURPOSE: To compare prospectively the accuracy of positron emission tomography (PET) with leukocytes labeled in vitro with (18)F fluorodeoxyglucose (FDG) versus that of conventional scintigraphy with leukocytes labeled in vitro with (111)In oxine in patients suspected of having infection. MATERIALS AND METHODS: This HIPAA-compliant study had institutional review board approval; informed consent was obtained from all patients. Patients were 25 men and 26 women aged 32-86 years. In vitro labeling of autologous human leukocytes with FDG and (111)In-oxine was performed according to published methods. Labeling efficiencies and cell viability were determined. Imaging was performed 2.5-5.8 hours after injection of 196-315 MBq of FDG-labeled leukocytes and approximately 24 hours after injection of 17-25 MBq of (111)In-oxine-labeled leukocytes. Forty-three (20 men, 23 women; mean age, 59 years; range, 32-86 years) patients could be successfully imaged with both tracers. Six patients were not injected with FDG-labeled leukocytes because of low labeling efficiency (<35%). Two patients were injected with FDG-labeled leukocytes but were not imaged. One reader interpreted all results as positive or negative for infection. Imaging results were compared with final diagnoses. Labeling efficiencies and cell viabilities were compared by using the paired t test. Differences between PET and scintigraphy were determined by using the McNemar test. RESULTS: For the 43 patients who were imaged with both tracers, labeling efficiency of FDG was lower than that of (111)In oxine (72% +/- 8 [standard deviation] vs 90% +/- 5, P < .001). Viability of FDG-labeled leukocytes was not different from that of (111)In-oxine-labeled leukocytes (98% +/- 1 vs 97% +/- 3). There were no differences between FDG PET and (111)In scintigraphy in terms of sensitivity (87% vs 73%), specificity (82% vs 86%), or accuracy (84% vs 81%). CONCLUSION: PET with FDG-labeled leukocytes was comparable to scintigraphy with (111)In-oxine-labeled leukocytes. Further investigation in a larger population with dedicated PET or PET/computed tomography seems warranted.

Rapid diagnosis of pedal osteomyelitis in diabetics with a technetium-99m-labeled monoclonal antigranulocyte antibody.

An in vivo method of labeling white cells that diagnoses diabetic pedal osteomyelitis safely, rapidly, and accurately is desirable. The objectives of this investigation were to evaluate a technetium-99m-labeled monoclonal antigranulocyte antibody for diagnosing diabetic pedal osteomyelitis, compared with indium-111-labeled leukocyte and 3-phase bone imaging for this purpose. Twenty-five diabetic patients with pedal ulcers, 22 in the forefoot and 3 in the midfoot, underwent antibody, indium-111-labeled leukocyte, and technetium-99m methylene diphosphonate 3-phase bone imaging. The 1-hour antibody, 24-hour labeled leukocyte, and 3-phase bone images were interpreted separately for the presence of osteomyelitis. The antibody and labeled leukocyte images also were interpreted together with the bone images to determine if the combined study was more accurate than each individual study. There were 10 cases of osteomyelitis among the 25 patients. The sensitivity, specificity, and accuracy of the antibody were.90,.67, and.76, respectively. These results were not significantly different from those obtained with labeled leukocyte imaging:.80,.67, and.72, respectively. The antibody was significantly more specific (P =.004) than 3-phase bone imaging (.27). Interpreting the antibody together with the bone scan did not alter the results. When interpreted with the bone images, the accuracy of labeled leukocyte imaging improved from.72 to.80. This was not significantly more accurate than either the antibody or labeled leukocyte imaging alone. The data suggest that the monoclonal antigranulocyte antibody is comparable with in vitro labeled leukocyte imaging for diagnosing pedal osteomyelitis in diabetic patients, and warrants further investigation in a larger population.