Is 18F-FDG PET/CT useful for diagnosing relapsing polychondritis with airway involvement and monitoring response to steroid-based therapy?

Yunxiang Zeng,Sheng Chen,Lin Lin,Shiyue Li,Minfang Li,Jianxing He,Jinlin Wang

doi:10.1186/s13075-019-2083-8

Abstract

Background18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a promising tool for diagnosing relapsing polychondritis (RP). However, its usefulness in assessing RP with airway involvement is unknown.ObjectiveThis study aimed to further evaluate and confirm the potency of 18F-FDG PET/CT in diagnosing RP with airway involvement and monitoring response to steroid-based therapy.MethodsA total of 30 patients from a dedicated respiratory centre, diagnosed with RP in accordance with McAdam, Damiani or Levine criteria, were included in this study. All patients underwent baseline 18F-FDG PET/CT, and 10 patients underwent second scans after 2.5–15 months of steroid-based therapy. Visual scores (VS) and maximal standard uptake values (SUVmax) were analysed.ResultsIn the initial scan, 83.3% (25/30) of patients were found to have FDG uptake in more than one cartilage. The median VS and SUVmax in the cartilages were 3 (range, 1–3) and 3.8 (range, 1.9–17.9), respectively. Positive rates for PET/CT-guided biopsy in nasal, auricular, and tracheal/bronchial cartilages were 100% (5/5), 88.9% (8/9), and 10.5% (2/19), respectively, but the positive biopsy rate in the auricular cartilage was 92.3% (12/13) even without PET/CT assessment. Based on biopsy-proven sites, the sensitivity of PET/CT was 55.6%, and the specificity was 5.3%. Compared with the baseline scan, the second scan showed much lower median VS (2 vs 3, respectively; p < 0.0001) and SUVmax (2.9 vs 3.8, respectively; p < 0.001). Of 10 patients who underwent second PET/CT, 8 had complete therapeutic response, while 2 had partial response.Conclusion18F-FDG PET/CT assists in identifying multiple cartilage involvement in RP, but it seems neither a sensitive nor specific modality in diagnosing RP with airway involvement. Moreover, PET/CT has limited utility in locating biopsy sites and monitoring therapeutic response to corticosteroids.

Highlights

18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a promising tool for diagnosing relapsing polychondritis (RP)
In 2014, we retrospectively investigated 6 patients with RP and found that PET/CT is a valuable tool in diagnosing RP and monitoring treatment response [20]
Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level were increased in some patients and substantially decreased after regular corticosteroid treatment with a median level of 40 mm/h and 9.78 mg/dL, respectively

Summary

Introduction

18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a promising tool for diagnosing relapsing polychondritis (RP). Objective: This study aimed to further evaluate and confirm the potency of 18F-FDG PET/CT in diagnosing RP with airway involvement and monitoring response to steroid-based therapy. A few case reports or small case series have demonstrated that PET/CT is capable of determining organ involvement and evaluating disease activity and therapeutic response [10,11,12,13,14,15,16,17,18,19]. Yamashita [21] and Lei [22] analysed a series of patients with RP who undergone PET/ CT and concluded that PET/CT is a potentially useful tool for the early diagnosis of RP, especially in patients without biopsied organ involvement or with atypical RP. The value of these investigations was limited by relatively heterogeneous populations and small sample sizes

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