Role of FDG PET/CT in prediction of post-radiation therapy chest wall toxicity

Objectives Radiation therapy (RT) is used to treat many intrathoracic malignancies. A variety of changes may occur after RT to the thorax. In patients with lung cancer, radiation-induced chest wall injuries are a common and potentially serious complication of RT. Such complications range from skin inflammation to rib fracture. The purpose of this study is to evaluate whether PET/CT images can predict the development of such abnormalities.

Methods Patients with early stage non small cell lung cancer who underwent RT and subsequent PET/CT were retrospectively reviewed and assigned to two select groups. Group one was defined as patients with chest wall abnormalities secondary to RT and group two consisted of patients without chest wall abnormalities or abnormalities not related to RT. Both groups had comparable lung lesions as well as RT doses/techniques. Distinction between both groups was made by the treating RT physician. PET/CT images of these patients were retrospectively reviewed to measure SUV mean and SUV max from a region of interest placed at the most FDG avid area of the chest wall of the affected lung lesion treated with RT.

Results Group one consisted of 5 patients, 2 male and 3 female and signs of radiation induced chest wall complications ranging from skin inflammation to rib fracture. The average mean SUV for these patients was 1.311 and the average SUV maximum was 2.344. Group 2 consisted of 3 males and 2 females. The average mean SUV for this group was .933 and the average SUV maximum was 1.967.

Conclusions PET/CT images revealed a 29 % higher SUV mean and a 16 % higher SUV max in patients who subsequently developed RT induced chest wall injuries. Larger prospective studies are needed to elucidate the utilization of FDG PET/CT in the prediction of higher risk for developing chest wall injuries. In so doing, progression of such injuries could be avoided