Positron emission tomography-computed tomography for imaging of inflammatory cardiovascular diseases.

Inflammation is a determinant of atherosclerotic plaque rupture, the event usually responsible for myocardial infarction and stroke. Possible causes of inflammatory cardiomyopathy include myocarditis, eosinophilic disease, and sarcoidosis. Although conventional imaging techniques can identify the site and severity of luminal stenosis, they do not provide information regarding inflammatory status. (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for imaging of inflammatory cardiovascular diseases has been rapidly evolving. Integrated PET/computed tomography (CT) is becoming the method of choice for quantification of arterial inflammation across multiple vessels. Moreover, PET/CT provides information about the activation status of inflammatory cells in the vessel wall, thus allowing early diagnosis and risk stratification of patients. The Japanese health insurance system approved reimbursement for FDG-PET use to detect inflammation sites in cardiac sarcoidosis as of April 2012. This approval has necessitated a more detailed assessment of the clinical value of FDG-PET. Standardized preparation, imaging, and image interpretation protocols should be established to sufficiently suppress physiological FDG uptake in the normal myocardium, and thereby facilitate detection of early-stage cardiac inflammatory lesions with more favorable specificity. This review summarizes the background, clinical utility, state-of-the-art advances, and potential future applications of FDG-PET for imaging inflammatory cardiovascular diseases including cardiac sarcoidosis, large-vessel arteritis, and atherosclerosis.

Quantitative analysis of myocardial 18F-fluorodeoxyglucose uptake by PET/CT for detection of cardiac sarcoidosis.

BACKGROUND: Imaging with fluorodeoxyglucose (FDG) PET/CT is used to diagnose patients with cardiac sarcoidosis (CS). However, its specificity is relatively low. We aimed to demonstrate that higher diagnostic specificity for CS can be obtained using quantitative methodology to analyze PET/CT. METHODS: A total of 125 consecutive patients with suspected CS were enrolled in the study. After clinical assessment and cardiac imaging studies, the patients underwent FDG PET/CT imaging after eating a low-carbohydrate diet followed by an overnight fast lasting ≥ 18 h. For visual analysis, fusion and maximum intensity projection images were reviewed. For quantitative analysis, the maximum standardized uptake value (SUV max) within the myocardium was obtained. RESULTS: Of the 92 patients who met study inclusion criteria, 37 were diagnosed with CS. Myocardial SUV max was significantly higher in patients with CS compared with non-CS patients (9.5 ± 4.8 vs. 3.0 ± 1.7, p < 0.0001). The area under the curve by receiver operating characteristic analysis was 0.960 for SUV max. Using a cut-off value of 4.0, the sensitivity was 97.3% and specificity was 83.6% for diagnosing CS, which is more accurate than visual analysis. Moreover, SUV max was the only significant predictor of CS among 10 clinical and imaging variables. In 18 patients who received steroid therapy with a mean follow-up duration of 6.4 ± 5.2 months, SUV max significantly decreased from 9.8 ± 4.2 to 5.5 ± 3.5 (p = 0.003). CONCLUSION: When evaluated by quantification of myocardial SUV max, FDG PET/CT imaging provides high sensitivity and specificity for diagnosing CS.