Image acquisition and interpretation criteria for 99mTc-HMPAO-labelled white blood cell scintigraphy: results of a multicentre study

Purpose: There is no consensus yet on the best protocol for planar image acquisition and interpretation of radiolabelled white blood cell (WBC) scintigraphy. This may account for differences in reported diagnostic accuracy amongst different centres. Methods: This was a multicentre retrospective study analysing 235 WBC scans divided into two groups. The first group of scans (105 patients) were acquired with a fixed-time acquisition protocol and the second group (130 patients) were acquired with a decay time-corrected acquisition protocol. Planar images were interpreted both qualitatively and semiquantitatively. Three blinded readers analysed the images. Results: The most accurate imaging acquisition protocol comprised image acquisition at 3 - 4 h and at 20 - 24 h in time mode with acquisition times corrected for isotope decay. Conclusion: Using this protocol, visual analysis had high sensitivity and specificity in the diagnosis of infection. Semiquantitative analysis could be used in doubtful cases, with no cut-off for the percentage increase in radiolabelled WBC over time, as a criterion to define a positive scan.