Background Inflammatory disorders of the large vessel walls (aortitis-A) or such arising around large vessels (periaortitis-P) are rare and generally difficult to diagnose. Acute phase inflammatory markers are used for monitoring these entities, but they knowingly fail in up to 20% of cases, in particular in patients with periaortitis. Moreover, these follow-up markers rapidly turn normal after onset of some novel therapeutic agents like biologicals (e.g. anti-IL6)[1]. Therefore, functional imaging techniques have advanced to the methods of choice in A/PA diagnosis, and even therapy monitoring [2].

Objectives To evaluate the role of perfusion-based CT for monitoring inflammatory activity in patients with aortitis and chronic periaortitis (A/PA) undergoing immunosuppressive therapy (IST).

Methods A retrospective database search at our institution between January 2010 and March 2015 identified 17 patients (8 female; median age 68.5 years) with A/PA that underwent combined anatomical and functional CT, including CT perfusion-based monitoring for assessment of disease activity. Institutional review board approval was obtained for data analysis. All patients were symptomatic at the time of 1st CT-imaging. Patients first underwent segmental volume perfusion-CT (VPCT) for assessment of the degree of vascularization of A/PA as a surrogate marker for inflammatory activity. Blood flow (BF) and blood volume (BV) were determined. The thickness of the increased perivascular connective tissue formation was measured. Perfusion data was correlated with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR).

Results In all patients, perfusion parameters dropped at FU under IST, this reduction was significant for BF and BV (p<0.05). 15 patients had elevated ESR and CRP at the time of the 1st perfusion-CT; 2 patients had normal values. In aortitis patients, CRP dropped from 3.86±5.31 to 0.9±1.37 and in periaortitis patients from 1.78±2.25 to 0.79 ±1.55, whereas ESR dropped from 45.71±37.59 to 8.57 ±3.1 and 36.78±34.67 to 17.22±21.82, in aortitis and in periaortitis, respectively. Correlation between serologic data and perfusion parameters was very good. Clinical symptoms were resolved in 12 patients at FU. At follow-up, the mean thickness of aortic or perivascular tissue formation decreased by 41.7±25.63% (range, 0–87.5%). The response was more vigorous in PA-patients (47.7±27.0%; range: 9–87.5%) than in A-patients (35.4±23.88%; range: 0–62.5%). The difference between baseline and follow-up imaging was significant for both disease entities (p<0.001).

Conclusions The course of perfusion-CT parameters in A/PA undergoing IST correlated well with that of serological markers with respect to disease activity assessment. In cases with bland serological data, perfusion-CT was the sole reliable monitoring parameter.

1. Loricera J, Blanco R, Castaneda S, et al. Tocilizumab in refractory aortitis: study on 16 patients and literature review. Clinical and experimental rheumatology 2014; 32:S79–89

2. Bier G, Henes J, Eulenbruch C, Xenitidis T, Nikolaou K, Horger M. Perfusion-based assessment of disease activity in untreated and treated patients with aortitis and chronic periaortitis: correlation with CT morphological, clinical and serological data. The British journal of radiology 2015; 88:20150526

Disclosure of Interest None declared