Pulmonary toxicity in a rabbit model of stereotactic lung radiation therapy: Efficacy of a radioprotector

ABSTRACTThis study aimed to assess the efficacy of the radioprotector amifostine in limiting radiation toxicity in a rabbit model of lung stereotactic body radiation therapy (SBRT) by correlating contrast-enhanced magnetic resonance angiography (ce-MRA), computed tomography (CT), and helium-3 (He-3) magnetic resonance imaging (MRI) with histopathology. Multiple MRI techniques were tested to obtain complementing physiologic information. Thirteen rabbits received SBRT to the right lower lobe of the lung. Specifically, 4 received 3 × 11 Gray (Gy), 6 received 3 × 11 Gy and 50 mg/kg of amifostine pre-SRBT, and 3 received 3 × 7, 3 × 9, or 3 × 13 Gy. Imaging was performed at baseline and 4, 8, 12, and 16 weeks post-SBRT. Ce-MRA perfusion difference between lungs in the irradiated group at 16 weeks post-treatment was statistically significant (P = .04) whereas the difference in the irradiated + amifostine group was not (P = .30). Histologically observed low red blood cell (RBC) count and CT hypodensity suggests c...