18F-FDG PET/CT for the assessment of myocardial sarcoidosis

Abstract

Cardiac involvement portends a poor prognosis inpatients with sarcoidosis. However, due to the non specific clinical manifestations of the disease, patchy myocardial involvement, and the limited diagnostic yield of diagnostic tests, early diagnosis of cardiac sarcoidosis has been exceedingly difficult. As a result, there is no standardized approach for the early diagnosis of cardiac sarcoidosis. Imaging modalities that can both identify disease and predict response to therapy are paramount to improve management of cardiac sarcoidosis. 18F-FDG PET has many practical advantages in assessing disease activity and monitoring treatment response in patients with cardiac sarcoidosis. Accumulating data support the growing role of 18F-fluorodeoxyglucose (18F-FDG)PET in the diagnosis and risk stratification of patients with cardiac sarcoidosis.

Fig. 1

Perfusion and ¹⁸F-FDG PET imaging protocol. All patients are instructed to take a high-fat low-carbohydrate diet the day prior with or without additional overnight fast. A rest myocardial perfusion imaging study is first performed followed by injection of ¹⁸F-FDG. Some sites use IV (intravenous) unfractionated heparin (50 units/kg) about 15 minutes prior to the IV injection of 10–12 mCi of ¹⁸F-FDG. After a 90-minute uptake period, cardiac and partial whole body PET images (cerebellum to mid-thigh) are acquired

Fig. 2

Perfusion and metabolism patterns in various stages of cardiac sarcoidosis. This figure demonstrates perfusion/metabolism patterns as described in the table

Fig. 3

PET perfusion and ¹⁸F-FDG imaging at baseline and after 6 months of high-dose steroid therapy. These images were obtained in a 51-year-old man being evaluated for heart block and dizziness. A cardiac MRI was suggestive of cardiac sarcoidosis. Invasive coronary angiogram revealed normal epicardial coronary arteries. a, Baseline ⁸²rubidium perfusion and ¹⁸F-FDG images in color in alternate rows displayed as short axis, horizontal long axis, and vertical long axis images along with partial whole body FDG images in grey scale in the coronal, sagittal, and transaxial projections. On the baseline images, there are small and mild, patchy perfusion defects in the basal and mid anteroseptal and inferoseptal walls with a corresponding mismatch on the FDG images. Increased ¹⁸F-FDG uptake is also noted in the right ventricular free wall. Regions of the myocardium with normal perfusion (lateral and inferior walls) show no ¹⁸F-FDG uptake consistent with excellent suppression of myocardial glucose utilization by the normal myocardium. The partial whole body images in grey scale show increased ¹⁸F-FDG uptake in the bilateral upper para-tracheal, anterior mediastinal, right lower para-tracheal, subcarinal, para-esophageal, and bilateral hilar lymph nodes. b, Post-treatment (6 months after high dose steroid therapy) ⁸²rubidium perfusion and ¹⁸F-FDG images in color along with partial whole body FDG images in grey scale as described previously. The small and patchy perfusion defects in the anterior wall and the inferoseptal wall are improved. There was no myocardial ¹⁸F-FDG uptake (only blood pool activity) consistent with excellent suppression of myocardial glucose utilization by the normal myocardium along with no ¹⁸F-FDG uptake in the regions with previously increased ¹⁸F-FDG uptake, suggesting interval improvement with high dose steroid therapy. Improvement/near complete resolution of ¹⁸F-FDG uptake is noted in the heart and lymph nodes on the partial whole body images. The post- treatment images show more pronounced foci of splenic ¹F-FDG uptake compared with baseline

Fig. 3

PET perfusion and ¹⁸F-FDG imaging at baseline and after 6 months of high-dose steroid therapy. These images were obtained in a 51-year-old man being evaluated for heart block and dizziness. A cardiac MRI was suggestive of cardiac sarcoidosis. Invasive coronary angiogram revealed normal epicardial coronary arteries. a, Baseline ⁸²rubidium perfusion and ¹⁸F-FDG images in color in alternate rows displayed as short axis, horizontal long axis, and vertical long axis images along with partial whole body FDG images in grey scale in the coronal, sagittal, and transaxial projections. On the baseline images, there are small and mild, patchy perfusion defects in the basal and mid anteroseptal and inferoseptal walls with a corresponding mismatch on the FDG images. Increased ¹⁸F-FDG uptake is also noted in the right ventricular free wall. Regions of the myocardium with normal perfusion (lateral and inferior walls) show no ¹⁸F-FDG uptake consistent with excellent suppression of myocardial glucose utilization by the normal myocardium. The partial whole body images in grey scale show increased ¹⁸F-FDG uptake in the bilateral upper para-tracheal, anterior mediastinal, right lower para-tracheal, subcarinal, para-esophageal, and bilateral hilar lymph nodes. b, Post-treatment (6 months after high dose steroid therapy) ⁸²rubidium perfusion and ¹⁸F-FDG images in color along with partial whole body FDG images in grey scale as described previously. The small and patchy perfusion defects in the anterior wall and the inferoseptal wall are improved. There was no myocardial ¹⁸F-FDG uptake (only blood pool activity) consistent with excellent suppression of myocardial glucose utilization by the normal myocardium along with no ¹⁸F-FDG uptake in the regions with previously increased ¹⁸F-FDG uptake, suggesting interval improvement with high dose steroid therapy. Improvement/near complete resolution of ¹⁸F-FDG uptake is noted in the heart and lymph nodes on the partial whole body images. The post- treatment images show more pronounced foci of splenic ¹F-FDG uptake compared with baseline