2D-Cranial T1-black-blood MRI in suspected giant cell arteritis - measurement of vessel wall thickness does not give a diagnostic advantage compared to visual scoring alone

Pascal Seitz^1*Susana Bucher¹Lukas Bütikofer²Britta Maurer¹Harald Marcel Bonel^3,4Fabian Lötscher¹Luca Seitz¹

• ¹Department of Rheumatology and Immunology, Inselspital, Bern University Hospital, University of Bern, Switzerland, Bern, Bern, Switzerland
• ²CTU Bern, Department of Clinical Research, University of Bern, Bern, Bern, Switzerland
• ³Department of Diagnostic, Interventional and Paediatric Radiology, Inselspital, Bern University Hospital, University of Bern, Switzerland, Bern, Switzerland
• ⁴Lindenhof Bern Foundation, Bern, Bern, Switzerland

Objectives: To compare two established scoring schemes for the 2D-T1-weighted “black-blood” MRI sequence (T1-BB) for superficial cranial arteries (SCA) in the diagnosis of giant cell arteritis (GCA).Methods: Ten arterial segments were evaluated in T1-BB images with two different methods: a visual semiquantitative scheme (T1-BB-VISUAL) and a composite scheme that included both the semiquantitative assessment and a quantitative wall thickness measurement (T1-BB-COMP). The expert clinical diagnosis after ≥6 months of follow-up was the diagnostic reference standard. Diagnostic accuracy and agreement on the segment and patient levels were evaluated for the two different rating schemes.Results: Retrospectively, 151 consecutive patients with clinically suspected GCA were included. The study cohort consisted of 82 patients with and 69 without GCA. For the T1-BB-COMP and the T1-BB-VISUAL, the sensitivity was 81.7% versus 87.8% (p=0.025), the specificity was 91.3% versus 88.4% (p=0.16) and the proportion of correct diagnoses was 86.1% versus 88.1% (p=0.26), respectively. The overall agreement between the two methods for 1201 rated arterial segments was very good at 91.6% with a kappa of 0.80. The agreement was higher for segments with a larger calibre than for smaller segments: common superficial temporal arteries 98.0%, occipital arteries 93.2%, frontal branches 89.8% and parietal branches 86.9%. The correlation of wall thickness measurements between readers was strong (Spearman’s rho of 0.68). The time needed to apply the T1-BB-VISUAL was about half as long as for the T1-BB-COMP (4.5 vs. 8.95 minutes). Conclusion: In suspected GCA, the additional measurement of the wall thickness of SCAs in 2D-T1-BB MRI does not lead to a better diagnostic performance compared to visual semiquantitative scoring alone. Visual scoring is preferred due to higher efficiency and reliability.