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그림1 치료반응 환자군의 치료 전 PET/CT로 측정한 심낭의 최대 SUV가 치료무반응 환자군보다 유의하게 높았음.

그림2) 약물 치료 반응군의 치료 전(윗열) 및 후(아랫열)의 PET/CT 사진. 치료 후 심낭의 높은 섭취가 치료 후 많이 감소하였음.​

Abstract​

Constrictive pericarditis (CP) is a condition of limited diastolic ventricular filling caused by inflammation of the pericardium leading to pericardial fibrosis. Surgery is considered treatment for this disease. However, if CP is detected at the early stages of inflammation, the disease process can be reversed without scarring, so-called transient CP (1). Because positron emission tomography/computed tomography (PET/CT) using 18F-labeled fluorodeoxyglucose ([18F]FDG) has a high sensitivity for detecting active inflammatory/infectious diseases, we hypothesized that [18F]FDG PET/CT could predict the reversibility of CP with steroid treatment to identify transient CP.

We prospectively recruited patients diagnosed with CP. The diagnosis was established based on symptoms/signs and transthoracic echocardiography (TTE). Exclusion criteria were pericardial calcification, history of malignancy, radiation therapy, and rapid improvement of CP within 1 week with ibuprofen/colchicine therapy. Our institutional review board approved the protocol and written informed consent was obtained from the participants.

Transthoracic echocardiography, [18F]FDG PET/CT, high-sensitivity C-reactive protein analysis, and erythrocyte sedimentation rate tests were performed at baseline and after 3 months of steroid therapy. The [18F]FDG PET/CT was performed using a PET/CT scanner (Discovery STe, GE Healthcare, Milwaukee, Wisconsin). PET scans were obtained using a 2.5-min acquisition time per frame in 3-dimensional mode. Standardized uptake values (SUV) were derived from the dose of [18F]FDG and body weight.

Steroid therapy was given as follows: oral prednisolone, 0.5 mg/kg/day for 4 weeks; 0.25 mg/kg/day for 4 weeks; 0.125 mg/kg/day for 2 weeks; and 0.0625 mg/kg/day for 2 weeks. The dosage was doubled for tuberculous pericarditis because of the rifampin effect.

Responders were defined as patients who demonstrated improved symptom/signs of CP along with discontinuation of diuresis and resolution of constrictive physiology and findings on TTE. Nonresponders were defined as patients with continuing symptoms and signs of CP who required diuresis and had persistent constrictive physiology findings. Partial responders were defined as steroid-dependent CP patients whose symptom/signs had improved during the early phase of treatment but were aggravated during steroid tapering and were eventually grouped as nonresponders.

Finally, 16 patients were included in our analysis. The majority were male (88%), and the age was 63 ± 12 years. Causes of pericarditis included pericardial tuberculosis (50%), idiopathic pericarditis (31%), and postoperative pericarditis (19%). Dyspnea was common (88%), and the duration of symptoms varied from weeks to 12 months. All patients had elevated jugular venous pressure and Kussmaul sign and features characteristic of constriction on TTE. Small amounts of pericardial effusion were present in 5 patients (31%).

There were 9 responders (56%) and 7 nonresponders (44%), and the rate of tuberculous pericarditis was higher in responders than in nonresponders (77% vs. 14%, respectively). The rates of pericardial effusion and duration of symptoms were not different between the 2 groups. Likewise, high-sensitivity C-reactive protein and erythrocyte sedimentation rate test results were not different between responders and nonresponders (2.27 ± 3.79 mg/dl vs. 1.70 ± 2.38 mg/dl, respectively; 48.9 ± 29.3 mm/h vs. 37.3 ± 25.9 mm/h, respectively; p > 0.05).

After 3 months of steroid therapy, pericardial SUVmax was reduced compared to baseline (2.1 ± 0.8; p <0.001). Specifically, the pericardial SUVmax in study patients at baseline was 5.8 ± 4.0 and was significantly higher in responders than in nonresponders (p = 0.01). Pericardial SUVmax was >3.0 in all responders (Figure 1), whereas no patients with a pericardial SUVmax <3.0 responded to steroid therapy, and 2 nonresponders with a pericardial SUVmax >3.0 were partial responders. Using a pericardial SUVmax of 3.0 as a cutoff value, sensitivity, specificity, positive predictive, and negative predictive values of [18F]FDG PET/CT for predicting responders were 100%, 71%, 82%, and 100%, respectively.

This is the first prospective study of diagnosis of transient CP using [18F]FDG PET/CT. Under clinical circumstances, transient CP tends to be a “follow-up” diagnosis after treatment, as there are currently no specific features or markers that can diagnose this entity. However, our results indicated that [18F]FDG PET/CT can predict the response to steroid therapy in patients with CP with a high accuracy. Importantly, the results of this study may be useful to avoid unnecessary surgery or steroid therapy, although it is small exploratory study.

Although [18F]FDG PET/CT is widely used in oncology, it is also useful for visualizing inflammation with high sensitivity with quantification, because of the high uptake of [18F]FDG by active macrophages at sites of inflammation (2). However, high-sensitivity C-reactive protein and erythrocyte sedimentation rate tests did not predict reversibility of CP in our study. Because transient CP may represent a transitional state between the hyperacute stage of pericarditis to a chronic stage, systemic inflammation can be lower than expected compared with local inflammation of the pericardium.

Author information​

Sung-A Chang, MD, PhD, , Joon Young Choi, MD, PhD, , Eun Kyoung Kim, MD, PhD, Seung Hyup Hyun, MD, Shin Yi Jang, PhD, Jin-Oh Choi, MD, PhD, Sung-Ji Park, MD, PhD, Sang-Chol Lee, MD, PhD, Seung Woo Park, MD, PhD, Jae K. Oh, MD​