18F-FDG PET/CT in the follow-up of large-vessel vasculitis: A study of 37 consecutive patients

https://doi.org/10.1016/j.semarthrit.2017.08.009Get rights and content

Abstract

Objective

18F-FDG PET/CT has proved to be of potential value for early diagnosis of large-vessel vasculitis (LVV), which frequently involves the aorta. However, its role in the follow-up of these patients has not been well established. Our aim was to evaluate the contribution of 18F-FDG PET/CT in this clinical situation.

Methods

This study included 37 consecutive patients (28 women, 66.5 ± 9.9 years) with an initial 18F-FDG PET/CT positive for LVV and a mean ± standard deviation follow-up PET/CT of 7.5 ± 2.9 months after the initial scan. A semiquantitative analysis of aortic wall uptake was performed calculating the target-to-background ratio (TBR: aortic wall uptake divided by blood pool uptake). The initial and follow-up TBR as well as the clinical and laboratory outcome were compared.

Results

Overall, the mean TBR decreased from 1.7 ± 0.5 at the initial scan to 1.5 ± 0.3 at the time of follow-up (p = 0.0001). In the 21 patients who experienced clinical improvement following therapy the TBR also decreased from 1.8 ± 0.6 to 1.5 ± 0.3 (p = 0.0002). However, in the other 16 patients, in whom the treating physician considered that there was no clinical improvement following therapy, no statistically significant differences in TBR were found when data from the first and the follow-up PET/CT scans were compared (1.6 ± 0.3 versus 1.5 ± 0.3, p = 0.1416). Patients who experienced clinical improvement following therapy showed a nonstatistically significant higher TBR at the time of disease diagnosis (1.8 ± 0.6 versus 1.6 ± 0.3; p = 0.12).

Conclusions

The results obtained in the present study highlight the impact of 18F-FDG PET/CT on the management of patients with LVV.

Introduction

Large-vessel vasculitis (LVV) typically involves the aorta and its major branches [1]. Giant cell arteritis (GCA) and Takayasu arteritis are the most common types of LVV [2], [3]. Nevertheless, noninfectious LVV may occur in the context of autoimmune and inflammatory diseases such as systemic lupus erythematosus, Sjögren’s syndrome, rheumatoid arthritis, spondyloarthropaties, ulcerative colitis, sarcoidosis, other systemic vasculitis, and polymyalgia rheumatica (PMR) [4], [5], [6].

Patients with LVV often show nonspecific clinical manifestations, including back or chest pain, malaise, weakness, weight loss, fever, and increased levels of laboratory inflammatory parameters [erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)]. In some cases, structural imaging techniques may yield negative results in patients with early stages of the disease. In this context, a tool that may help us to make an early diagnosis of LVV could be of great relevance for clinicians.

18F-FDG PET/CT was found to be of potential value to make an early diagnosis of large and medium vessels inflammation, even before the development of vascular structural changes [6], [7], [8], [9], [10]. It was also useful to establish the presence and extend of extracranial vasculitis in patients with GCA [7], [8], [9], [10], [11]. In this context, aortic involvement has been described in more than 50% of 18F-FDG PET/CT scans performed in patients with GCA [7], [8], [12], [13] and a positive PET/CT has been associated with a significantly higher risk of complications such as aneurysms, stenosis, and aortic dissection [14]. In these patients an early and adequate therapy (including glucocorticoids with/without immunosuppressive drugs) and close follow-up is important to prevent these severe complications [2], [3].

Besides limitations for the early diagnosis of LVV, the structural imaging techniques have in some cases limitations in monitoring the vascular inflammatory activity. This fact highlights the need of a non-invasive sensitive tool for the follow-up of these patients in the clinical setting. In this context, the role of 18F-FDG PET/CT has not been well established and, up to now, only a few studies involving a limited number of patients have been published with promising preliminary results [8], [15], [16], [17], [18]. A recent guideline recommended the use of 18F-FDG PET/CT for the diagnosis of LVV. However, the authors of this guideline recognized that the utility of PET/CT in monitoring anti-inflammatory therapy response is still unknown and requires further clarification [19].

Taking all these considerations into account, the purpose of the present study was to evaluate the contribution of 18F-FDG PET/CT in the follow-up of patients with LVV.

Section snippets

Patients

This study included 38 consecutive patients with LVV who were evaluated by 18F-FDG PET/CT scan and showed abnormal 18F-FDG uptake involving mainly the aorta. One patient was excluded due to technical problems and poor quality of PET/CT images. Therefore, we assessed 37 patients [28 women and 9 men, mean ± standard deviation (SD) age: 66.5 ± 9.9 years]. Table 1 summarizes the main characteristics of the patients, including the features that led to perform PET/CT scan to determine the presence of

Results

Overall, the mean ± SD TBR decreased significantly from 1.7 ± 0.5 in the initial PET/CT scan to 1.5 ± 0.3 in the PET/CT scan follow-up (p = 0.0001). In all, 21 of the 37 patients evaluated (56.8%) experienced clinical improvement after the initial PET/CT scan and 16 patients (43.2%) had no clinical improvement. In the 21 patients with clinical improvement the mean TBR decreased significantly from 1.8 ± 0.6 to 1.5 ± 0.3 (p = 0.0002). However, in the other 16 patients, in whom the treating

Discussion

The role of 18F-FDG PET/CT scan in early diagnosis of LVV, including cases presenting as an isolated PMR [23], [24], evaluation of the extent of the disease [7], [8], [13] and also in the management of these patients [10], [25] has previously been established. In this regard, in a former report we emphasized the potential value of the semiquantitative analysis of 18F-FDG PET/CT images for the diagnosis of aortitis [11].

In the present study, we assessed the results obtained of the

Conclusions

In conclusion, the results obtained in the present study highlight the impact of 18F-FDG PET/CT on the management of patients with suspected LVV. Our data support the use of 18F-FDG PET/CT in the follow-up of these patients. 18F-FDG PET/CT was found especially useful in the assessment of LVV patients with poor clinical treatment response or suspicion of relapse after the reduction or the withdrawal of the therapy.

Acknowledgments

Professor Gonzalez-Gay’s research was supported by “Fondo de Investigación Sanitaria” (grants PI12/00060 and PI15/00525) from “Instituto de Salud Carlos III” (ISCIII, Health Ministry, Spain). His work is also partially supported by RETICS Programs RD12/0009 (RIER) from ISCIII (Spain) (RD16/0012/0009).

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