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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Anterior Uveitis with Negative Work-up: Giant Cell Arteritis Remains the Pet Peeve.

BACKGROUND: Giant Cell Arteritis (GCA), is the most common primary vasculitis. It affects large vessels such as the aorta and its branches. According to Chapel Hill Consensus, GCA is one of the larger vessel vasculitis. The underlying mechanism involves inflammation of the large arteries. The most frequent presentation consists of headache, polymyalgia, and jaw claudication. GCA can put the visual prognosis at risk, and rapid diagnosis is compulsory. Cotton wool spots, due to focal inner retinal ischemia, are an early diagnostic ophthalmological sign. The most frequent presentation is a rapid, partial or complete blindness. However, atypical presentations, such as uveitis, especially in the anterior chamber, can delay diagnosis. CASE REPORT: We report a 75-year-old woman with GCA who initially presented with anterior uveitis and without any other clinical sign. At the beginning, there was the only ophthalmic sign and systemic inflammation, the all exhaustive work-up including positron emission tomography (PET) scan was negative. The biology was fully normal without auto-immune profile (Angiotensin converting enzyme level, Interferon Gamma Release Assay, Syphilis serology, antinuclear antibody titer, Rheumatoid factor, CCP antibodies, and chest x-ray were normal. HLA B27 was negative). In the following weeks, she subsequently developed large vessel vasculitis with headache and more typical sign. She developed cotton wool spots linked to retinal arteriolar hypoperfusion. Anterior uveitis has been reported rarely in GCA and moreover, it is very uncommon at the early stages of GCA. Our case stresses that uveitis onset can precede large vessels vasculitis and typical symptoms of GCA. PET-scan is a useful tool for atypical GCA, but its sensitivity is not perfect, and its repetition can be helpful in selected cases such as that of this patient.