Utility of 18F-FDG PET/CT in early detection of radiation-induced heart disease in Beagle dogs

Objective To establish radiation-induced heart disease (RIHD) Beagle models, investigate the efficacy of 18F-FDG PET/CT in the detection of RIHD and observe the pathological changes. Methods The ventricular anterior wall of 12 Beagle dogs were X-ray irradiated locally with a single dose of 20 Gy. 18F-FDG PET/CT and echocardiography were performed at baseline and 3 months after radiation. ROI was drawn on the irradiation field and the non-irradiation field (the posterior wall of left ventricle) to obtain the SUVmax. Then the SUVmax ratio of the irradiation field to the non-irradiation field (INR) was calculated. The left ventricular function parameters before and after radiation were obtained by echocardiography. Within 1 week after the imaging examinations were finished, the dogs were sacrificed, and hearts were taken out to perform pathological observation. Paired t test was used to analyze the data. Results High 18F-FDG uptake in the irradiation field was shown 3 months after radiation. The average INRs before and after radiation were 0.99±0.15 and 2.54±0.43 respectively (t=7.021, P=0.001). No significant difference was observed on cardiac function parameters between baseline and 3 months after radiation(t values: from -1.253 to -0.786, all P>0.05). The pathological results showed a few degenerated myocytes, increased thickness of myocardial vascular walls in irradiated myocardium. Conclusions 18F-FDG PET/CT can detect early RIHD before abnormal cardiac function. Increased 18F-FDG uptake in irradiated field may be related to myocardial ischemia which results from microvascular damage by radiation. Key words: Radiation injuries, experimental; Heart; Positron-emission tomography; Tomography, X-ray computed; Deoxyglucose