Combined modality PET/MR for the detection of severe large vessel vasculitis

John W Cerne; Sophia Liu; Muhammad Umair; Ashitha Pathrose; Jackson E Moore; Bradley D Allen; Michael Markl; James C Carr; Hatice Savas; Lisa Wilsbacher; Ryan Avery

doi:10.1186/s41824-022-00136-3

Combined modality PET/MR for the detection of severe large vessel vasculitis

Eur J Hybrid Imaging. 2022 Aug 15;6(1):16. doi: 10.1186/s41824-022-00136-3.

Authors

John W Cerne¹, Sophia Liu², Muhammad Umair¹, Ashitha Pathrose¹, Jackson E Moore^{1

3}, Bradley D Allen¹, Michael Markl^{1

3}, James C Carr¹, Hatice Savas¹, Lisa Wilsbacher⁴, Ryan Avery¹

Affiliations

¹ Department of Radiology, Northwestern University Feinberg School of Medicine, 420 East Superior St, Chicago, IL, 60611, USA.
² Department of Radiology, Northwestern University Feinberg School of Medicine, 420 East Superior St, Chicago, IL, 60611, USA. sophia.liu1@northwestern.edu.
³ Biomedical Engineering, Northwestern University McCormick School of Engineering and Applied Science, Evanston, USA.
⁴ Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, USA.

Abstract

Background: Large vessel vasculitis (LVV) can be characterized based on symptom severity, and this characterization helps clinicians decide upon treatment approach. Our aim was to compare the imaging findings of combined modality positron emission tomography/magnetic resonance (PET/MR) and inflammatory markers between severe and non-severe LVV. A retrospective query was performed to identify all patients with LVV who underwent PET/MR at our institution between January 2015 and January 2021.

Results: Eleven patients (nine females; age 62.2 ± 16.4 years) underwent 15 PET/MR scans. Positivity was defined by findings indicative of active LVV on each modality: PET positive if vessel metabolic activity > liver metabolic activity; MR positive if wall thickening or contrast enhancement. When positive PET or positive MR findings were considered a positive scan, LVV patients with severe disease (n = 9 scans) showed a higher number of positive scans (n = 9) compared to the number of positive scans in non-severe patients (n = 3) (p < 0.05). The sensitivity and specificity for the detection of severe LVV were 1.00 and 0.50, respectively. When only the presence of both positive PET and positive MR findings were considered a positive scan, inflammatory marker levels were not significantly different between severe and non-severe LVV groups (severe: erythrocyte sedimentation rate (ESR) = 9.8 ± 10.6 mm/h; C-reactive protein (CRP) = 0.6 ± 0.4 mg/dL) (non-severe: ESR = 14.3 ± 22.4 mm/h; CRP = 0.5 ± 0.6 mg/dL). Blood- and liver-normalized maximum standardized uptake values were not significantly different between severe and non-severe patients (1.4 ± 0.3 vs 1.5 ± 0.4; 1.1 ± 0.4 vs 1.0 ± 0.3, respectively).

Conclusions: Because of the differences observed, PET/MR appears to be better suited to facilitate the characterization of LVV as severe or non-severe compared to inflammatory marker measurements and quantitative measurements of metabolic activity. Qualitative assessment of PET and MR positivity by ¹⁸F-fluorodeoxyglucose PET/MR may be able to supplement clinical symptoms-based LVV classification decisions and may be helpful when clinical symptoms overlap with other disease processes.

Keywords: Giant cell arteritis; Inflammation; MRI; PET; Takayasu arteritis; Vasculitis.