Evaluation of radiation induced myocardial damage by FDG PET

Objectives This study is aimed to evaluate the changes of myocardial FDG uptake in patients with thoracic malignancies who underwent radiation therapy (RT).

Methods Among patients who underwent RT for thoracic malignancies, a total of 38 patients whose myocardium was partly included in RT fields were retrospectively enrolled. FDG PETs were performed before and after RT, respectively. Interval between pre-RT PET and RT was 37±30 days and interval between RT and post-RT PET was 67±32 days. RT field myocardium and non-RT field myocardium were defined by RT map on CT. Myocardial FDG uptake ratio was defined as myocardium to blood pool uptake ratio.

Results Of 38 patients, 12 patients showed increased myocardial FDG uptake after RT and the others showed unchanged myocardial FDG uptake. For patients with increased myocardial FDG uptake, uptake ratios of RT field myocardium were significantly increased after RT (1.21±0.34, 2.69±1.55, p<0.001). In contrast, uptake ratios of non-RT field myocardium were not changed after RT (1.39±0.63, 1.49±0.52, p=0.52). During follow up (489±370 days), cardiac events were detected in 4 patients who had increased myocardial FDG uptake after RT. The incidence of cardiac events in increased myocardial FDG uptake group (4/12, 33%) was significantly higher than no increased myocardial FDG uptake group (0/26, 0%; p<0.05).

Conclusions Increased myocardial FDG uptake after RT may be correlated with myocardial damage and FDG PET can predict cardiac events in patients who undergo RT