LAUSR

OBJECTIVE To assess the accuracy of ultrasound (US) versus FDG-PET/CT to identify extracranial involvement in suspected large vessel vasculitis (LVV) patients. METHODS Retrospective observational study of patients referred to our US fast track clinic with suspected LVV. All patients underwent US exam within 24 hours per protocol. FDG-PET/CT was performed according to clinician criteria. The gold standard for LVV diagnosis was clinical confirmation after 6 months. RESULTS Of the 113 patients included (74.3% female, mean age 74 years), 37(32.7%) were diagnosed of LVV after 6 months. Sensitivity and specificity of US was 86.5% and 96.1%, respectively (85.7% and 87.1% for intracranial and 94.1% and 80.2% for extracanial arteries, respectively). Only 12(42.9%) of 28 patients undergoing a FDG-PET/CT per clinician criteria, showed positive findings. Sensitivity and specificity of FDG-PET/CT for LVV was 61.1% and 90%, respectively (55.6% and 63.2% for intracranial and 84.6% and 93.3% for extacranial arteries). Taking FDG-PET/CT as the reference, US showed extracranial inflammation in 10/12(83.3%) and detected 2(12.5%) additional cases of extracranial involvement with negative FDG-PET/CT. Conversely, FDG-PET/CT showed extracranial inflammation in 2 patients with negative US (1 isolated aortitis and 1 aortoiliac involvement). FDG-PET/CT showed cranial artery uptake in none of patients. CONCLUSIONS US and FDG-PET/CT are both valid tools to detect extracranial involvement. Presence of US extracranial artery inflammation is consistent with FDG-PET/CT examination, although a negative US scan does not rule out extracranial involvement. Our data support the use of US as first-line investigation in patients suspected of cranial, but also extracranial LVV.