Handling of Doubtful WBC Scintigraphies in Patients with Suspected Prosthetic Joint Infections

Chiara Lauri, Giancarlo Lauretti, Filippo Galli, Giuseppe Campagna, Simone Tetti, Donatella Riolo, Alberto Signore*

*Corresponding author for this work

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    Abstract

    Despite the application of EANM recommendations for radiolabelled white-blood-cells (WBC) scintigraphy, some cases still remain doubtful based only on visual analysis. The aim of this study was to investigate the role of semi-quantitative analysis and bone marrow scan (BMS) in solving doubtful cases. We retrospectively evaluated all [Tc-99m]HMPAO-WBC scintigraphies performed, in the last 7 years, for a suspected monolateral prosthetic joint infection (PJI). In doubtful cases, we used five different thresholds of increase of target-to-background (T/B) ratio, between delayed and late images, as criteria of positivity (5%, 10%, 15%, 20% and 30%). BMS were also analysed and sensitivity, specificity and accuracy of different methods were calculated according to final diagnosis. The sensitivity, specificity and accuracy were, respectively, 77.8%, 43.8% and 53.0% for the cut-off at 5%; 72.2%, 66.7% and 68.2% for the cut-off at 10%; 66.7%, 75.0% and 72.7% for the cut-off at 15%; 66.7%, 85.4% and 80.3% for the cut-off at 20%; 33.3%, 93.8% and 77.3% for the cut-off at 30%. BMS provided a significantly higher diagnostic performance than 5%, 10% and 15% thresholds. Conversely, we did not observe any statistically significant difference between BMS and the cut-off of more than 20%. Therefore, doubtful cases should be analysed semi-quantitatively. An increase in T/B ratio of more than 20% between delayed and late images, should be considered as a criterion of positivity, thus avoiding BMS.

    Original languageEnglish
    Article number4031
    Pages (from-to)1-13
    Number of pages13
    JournalJournal of Clinical Medicine
    Volume9
    Issue number12
    DOIs
    Publication statusPublished - Dec-2020

    Keywords

    • WBC scintigraphy
    • qualitative analysis
    • semi-quantitative analysis
    • BMS
    • BLOOD-CELL SCINTIGRAPHY
    • TOTAL-HIP
    • IMAGE ACQUISITION
    • IN-111 LEUKOCYTE
    • INTERPRETATION CRITERIA
    • SYNOVIAL BIOPSY
    • DIAGNOSIS
    • ARTHROPLASTY
    • REPLACEMENT
    • SPECT/CT

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