Estimation of the added value of 99mTc-HMPAO-labelled white blood cell scintigraphy for the diagnosis of infectious foci.

Abstract

Leucocytes scintigraphy (LS) is an in-vivo imaging technique investigating infectious foci, performed in our nuclear medicine department after a 99mTc-bisphophonates bone scintigraphy (BS) or an 18F-FDG-PET, in osteoarticular or vascular localizations, respectively. The aim of this study was to reassert the relevance of LS in the diagnostic of occult infections and its impact in therapeutic management. A 45-month retrospective study (2012-2015), including 34 patients, was conducted. Patients who underwent LS were identified and classified according to the location of the suspected infection and the feature of first-line imaging exploration. The final diagnosis (infected or non-infected lesion) was established regarding patients' follow-up care, including clinical, biological biomarkers and therapeutic interventions. Sensitivity and specificity were calculated for each imaging modality. LS were conducted for exploration of joint prosthesis (N.=14), vascular prosthesis (N.=7), bone infection or osteitis (N.=8), algoneurodystrophia (N.=2), symphisis infection (N.=1), acute infection on chronicle inflammation (N.=1), and cancer (N.=1). All patients underwent a previous imaging exploration: BS (N.=20, 59%), 18FDG-PET (N.=10, 29%), or another exploration (N.=4, 12%). The sensitivity and specificity of BS were 67% and 36%, respectively, and 100% and 50% for 18FDG-PET, evidencing the lack of specificity of these approaches. Fourteen LS were positive (41%), with sensitivity, specificity and diagnostic accuracy of 85%, 86% and 85%, respectively. Despite a long, delicate, and costly radiopharmaceutical and nuclear imaging process, the high specificity of LS supports its qualitative added value in the diagnosis of infectious foci, by improving clinical and therapeutic patient's outcomes.