[18F]Fluorodeoxyglucose (FDG)-PET/CT and US are both well established for diagnosing GCA. The present study investigates their accuracy and whether they provide overlapping or complementary information in a cohort of patients presenting with suspicion of GCA. We selected consecutive patients from our cohort of suspected GCA cases that underwent both extended vascular US and PET/CT for diagnostic work-up between December 2006 and August 2012. A total of 102 patients were included. Diagnosis of GCA was confirmed in 68 patients and excluded in 34 patients (controls). Vasculitic changes in US were most often found in the temporal artery with 32 positive findings on each side, followed by the popliteal artery (10 right, 9 left) and the subclavian/axillary artery (7 right, 8 left). By contrast, PET/CT showed vasculitis most frequently in the vertebral (23 right, 33 left) and common carotid arteries (32 right, 24 left), followed by the subclavian arteries (16 right, 18 left), and the thoracic (17) and abdominal aorta (23). In 37/68 GCA patients PET/CT and US both revealed vasculitic findings, 11/68 had positive findings in US only and 14/68 in PET/CT only. Specificity of US was higher (one false-positive vs five false-positive in PET/CT). On a single segment level, only 20 of 136 positive segments were positive in both imaging modalities. PET/CT measuring vessel wall metabolism and US vessel wall morphology showed a comparable diagnostic accuracy for GCA. However PET/CT and US were often discrepant within single vascular regions. Thus PET/CT and US should be considered as complementary methods, with a second imaging modality increasing the diagnostic yield by 16–20%.

Tocilizumab (TCZ) has been approved for giant cell arteritis (GCA). Interleukin-6 (IL-6) receptor blockade suppresses clinical disease and is steroid sparing.1 2 Since IL-6 induces the acute-phase response, the clinically used inflammation markers (C reactive protein (CRP), erythrocyte sedimentation rate (ESR)) are suppressed during TCZ treatment. Whether serum IL-6 is useful in monitoring disease activity and detecting infections in TCZ-treated GCA is unknown. We longitudinally measured IL-6 in 23 patients with intravenous TCZ–treated GCA, two patients with polymyalgia rheumatica and one patient with Takayasu arteritis of our GCA cohort (EKBB-239/09), and in 13/26 patients additionally before TCZ treatment. Patient characteristics are shown in table 1. At each visit, clinical and laboratory parameters (white blood cell (WBC), CRP, ESR) were assessed. Relapse was defined as the need for treatment intensification following new or increasing symptoms, or rising CRP/ESR not otherwise explained.2 View this table: Table 1 Patient characteristics of ‘relapser’ and ‘non-relapser’ During TCZ therapy, CRP, ESR and WBC rapidly declined and were sustainably suppressed. IL-6 levels rose and remained elevated throughout TCZ treatment (figure 1). Daily prednisone doses were successfully tapered after TCZ was initiated (figure 1C). During 23.8 patient-years of TCZ therapy, eight infections were documented with available IL-6 levels (online supplementary table S1). IL-6, but not CRP, ESR …

The usefulness of [¹⁸F] fluorodeoxyglucose-positron emission tomography/computed tomography ([¹⁸F]FDG-PET/CT) for diagnosing giant cell arteritis (GCA) has been previously reported. Yet, the interpretation of PET scans is not clear-cut. The present study aimed at determining the best method to analyse PET/CT in a large, real-life cohort of patients presenting with suspicion of GCA. One hundred and three patients with clinical suspicion of GCA undergoing PET/CT between 2006 and 2012 were included. Clinical data were retrieved from patients’ charts. PET/CT was categorized by visual scoring of the uptake and by the artery/liver standardized uptake values (SUV) ratios. Diagnosis of GCA was confirmed in 68 patients and excluded in 35 patients, which served as the controls. GCA patients were older (median age 75 vs. 68 years), and presented more often with ischaemic symptoms. The best discrimination between GCA patients and controls was achieved for PET/CT findings within the supra-aortic arteries (sensitivity 0.71, specificity 0.91 for a SUV_/LE cut-off value of 1.0). Specificity of PET/CT for the aorta and the iliofemoral arteries was lower (<0.34). Visual scoring correlated poorly to SUV measurements (Kendall Tau-b 0.13–0.55) and had a lower diagnostic accuracy (sensitivity 0.77, specificity 0.75). Prednisone treatment for ≥10 days significantly reduced PET/CT sensitivity (P = 0.009). SUV based analysis of PET/CT enhances diagnostic accuracy with best discrimination in the supra-aortic region, particularly in steroid naïve patients. For discrimination based on the aorta and the iliofemoral region, higher cut-off values have to be applied, resulting in lower sensitivities for diagnosing GCA.

Objectives To characterise factors associated with permanent vision loss (PVL) and potential reasons for the therapeutic delay contributing to PVL in giant cell arteritis (GCA). Methods Retrospective analysis of GCA patients diagnosed at the University Hospital Basel between December 2006 and May 2021. Results Of 282 patients with GCA (64% females), 49 (17.4%) experienced PVL. In 43/49 (87.8%) PVL occurred before treatment. Of these, 24 (55.8%) patients had first non-ocular symptoms and eventually sought consultation when PVL occurred in a median of 21 (IQR 14.75–31.0) days after the first symptoms. Only five of the 24 patients had consulted a physician before PVL, but GCA diagnosis was missed. Treatment was initiated rapidly after diagnosis (median 1 day (IQR 0.0–7.0)). PVL on therapy occurred in six patients in a median of 40 (IQR 20.5–67.3) days after treatment started. In two of those, glucocorticoids were tapered too quickly. In multivariable analysis, patients with PVL were older (OR 1.17, 95% CI 1.07 to 1.29, p=0.001) and reported more frequently jaw claudication (OR 3.52, 95% CI 1.02 to 13.16, p=0.051). PVL was present in 18 (42.9%) of the 42 patients with vasculitic ultrasound findings in all six temporal artery segments. The incidence of PVL over 15 years did not decline (Spearman rank=0.3, p=0.68). Conclusion The prevalence of GCA-associated PVL remains high. Associated factors were advanced age, jaw claudication and ultrasound findings consistent with vasculitis in all six temporal artery segments. Despite preceding non-ocular GCA symptoms weeks before the onset of PVL, most patients were not seen by a rheumatologist before PVL occurred.