Scintigraphy using anti-granulocyte
Fab' fragment (
LeukoScan) was performed in a series of 220 consecutive patients with suspected bone
infection referred to our centre between September 1999 and June 2002. Two protocols were compared for interpreting scans: (1) evaluation of early 4 h imaging alone (protocol A), and (2) evaluation both of early and delayed 24 h imaging (protocol B). Protocol A and protocol B showed equal values of sensitivity (91.9% in patients with
diabetic foot and 84.2% in patients with
joint prosthesis/peripheral bone implants). Conversely, specificity was higher adopting protocol B than protocol A: 87.5% vs 75.0% in patients with
diabetic foot, and 85.7% vs 76.2% in patients with
joint prosthesis/peripheral bone implants, respectively. In particular, an improvement in specificity using protocol B was found in those patients with
infection and with only a mild
LeukoScan uptake in the early 4 h imaging: in these patients an increasing uptake intensity pattern observed in the delayed 24 h imaging was indicative of
infection while a decreasing pattern suggested a negative result. Instead, the evidence of a high uptake intensity in the early
LeukoScan imaging was a strong
indicator of
infection and delayed imaging in these cases did not further improve specificity. In conclusion, in our experience,
LeukoScan showed high sensitivity in diagnosing bone
infection in patients with
diabetic foot and
joint prosthesis or other peripheral bone implants. Moreover, in patients with an early high
LeukoScan uptake intensity further delayed images appears unnecessary for the purpose of diagnosing
infection. In contrast in patients with an early mild
LeukoScan uptake intensity only, delayed imaging appears to be recommendable for improving specificity.