Study of an abnormal accumulation in the cardiac muscle as observed in FDG-PET/CT after radiation therapy targeting thoracic esophageal cancer

Objectives To study abnormal accumulation in the cardiac muscle observed in FDG-PET/CT after radiation therapy targeting thoracic esophageal cancer and to evaluate myocardial damage due to radiation therapy.

Methods The frequency an abnormal accumulation occurring in the cardiac muscle after therapy, the relationship between the irradiated field and the accumulation area in the cardiac muscle, and the patterns of accumulation were retrospectively studied in 37 consecutive cases (male : female = 31:6, aged 67 on average) in which FDG-PET/CT was performed before and after radiation therapy, among the cases in which radiation therapy was performed for thoracic esophageal cancer from October 2007 to September 2010.

Results The occurrence of an abnormal accumulation in the cardiac muscle, which was not present before radiation therapy, was observed after radiation therapy in 19 out of 37 cases (51%). Among these, an abnormal accumulation was observed within the irradiated field in 18 cases and from within the irradiated field to outside the irradiated field in 1 case. With regard to the patterns of abnormal accumulation for the 18 cases in which an abnormal accumulation was observed within the irradiated field, there were 10 cases of an increased accumulation in the left ventricular base, 4 cases of an increased accumulation in the right ventricular cardiac muscle, and others.

Conclusions The pattern of an increased accumulation in the left ventricular base was the most commonly observed; however, the range of the accumulation fell within the irradiated field and did not correspond to the controlled area of the coronary artery. Therefore, myocardial damage due to radiation therapy was suspected. The increased accumulation in the right ventricular cardiac muscle was not observed before radiation therapy either, which thus indicated myocardial damage due to radiation therapy, while it also suggested a possibility of changes accompanied by heart failure which were not directly related to radiation therapy