Objective.: Large vessel uptake on positron emission tomography/computerized tomography (PET/CT) supports the diagnosis of giant cell arteritis (GCA). Its value, however, in patients without arteritis on temporal artery biopsy and in those receiving glucocorticoids remains unknown. We compared PET/CT results in GCA patients with positive (TAB+) and negative temporal artery biopsies (TAB−), and controls.Methods.: Patients with new clinically diagnosed GCA starting treatment with glucocorticoids underwent temporal artery biopsy and PET/CT. Using a visual semiquantitative approach, 18F-fluorodeoxyglucose (FDG) uptake was scored in 8 vascular territories and summed overall to give a total score in patients and matched controls.Results.: Twenty-eight patients with GCA and 28 controls were enrolled. Eighteen patients with GCA were TAB+. Mean PET/CT scores after an average of 11.9 days of prednisone were higher in patients with GCA compared to controls, for both total uptake (10.34 ± 2.72 vs 7.73 ± 2.56; p = 0.001), and in 6 of 8 specific vascular territories. PET/CT scores were similar between TAB+ and TAB− patients with GCA. The optimal cutoff for distinguishing GCA cases from controls was a total PET/CT score of ≥ 9, with an area under the receiver-operating characteristic curve of 0.75, sensitivity 71.4%, and specificity 64.3%. Among patients with GCA, these measures correlated with greater total PET/CT scores: systemic symptoms (p = 0.015), lower hemoglobin (p = 0.009), and higher platelet count (p = 0.008).Conclusion.: Vascular FDG uptake scores were increased in most patients with GCA despite exposure to prednisone; however, the sensitivity and specificity of PET/CT in this setting were lower than those previously reported.

Takayasu’s arteritis (TAK) is a large-vessel vasculitis that targets the aorta and its major branches. Although extracranial vascular involvement is uniformly present in this disease, the frequency of intracranial involvement in TAK has not been well studied. We retrospectively reviewed the clinical and imaging records of patients diagnosed with TAK at a single Canadian university medical centre to determine the prevalence of intracranial vascular involvement. Intracranial vascular and non-vascular findings were described, and a review of the literature was performed. Of 20 patients with TAK, 12 had vascular neuroimaging completed. Intracranial vascular lesions were identified in 4 patients (33.3% of those with imaging available, 20% of all patients). The frequency of intracranial vessel involvement in TAK may be more common than appreciated. Imaging of both the intra- and extra-cranial vessels should be considered in these young patients.

Giant cell arteritis (GCA) is a large vessel vasculitis that may be associated with significant complications such as blindness, stroke, or aortic aneurysm and dissection in a subset of patients. Given the serious side effects associated with prolonged courses of glucocorticoids and frequent relapses experienced when doses are tapered, increased efforts are being dedicated to the discovery of safer and more effective therapies to control this disease. The purpose of this review is to critically evaluate the role of glucocorticoid-sparing agents in the medical management of GCA with a special focus on the most recent evidence regarding the role of biologic agents, including tocilizumab (TCZ), abatacept and ustekinumab, and other novel therapies.

Purpose of review: To summarize recent evidence regarding the presence and potential role of the microbiome in systemic vasculitides. Recent findings: Microbiomic descriptions are now available in patients with small, medium and large vessel vasculitis. The majority of studies have evaluated gastrointestinal inhabitants, with a smaller number of studies describing the nasal, pulmonary or vascular microbiomes. Most published studies are observational and cross-sectional. Dysbiosis is seen frequently in vasculitis patients with reduced microbial diversity observed in nasal, fecal and vascular samples compared with disease and/or healthy controls. Predominant bacteria vary, but overall, patients with vasculitis tend to have more pathogenic and less commensal bacteria in active disease. In the few longitudinal studies available, improvement or resolution of dysbiosis has been observed following vasculitis treatment and improved disease activity. Summary: Dysbiosis and reduced microbial diversity has been identified in patients with small, medium and large vessel vasculitis. Although limited data suggests microbiomes may ‘normalize’ following immunosuppression, cause or effect cannot be determined. It is hypothesized that microbial disruption in a genetically susceptible individual may trigger excessive host immune activation and vasculitis; however, larger studies with longitudinal and translational design are needed to further our current understanding.