fig1

Figure 1. SBRT for HCC in a 59-year-old man who refused surgical resection and RFA. A: Axial arterial phase MRI image showed hyperenhancement of a 1.8-cm liver nodule in the right lobe of the liver; B: the patient received SBRT with a dose of 50 Gy in five fractions; C: axial arterial phase MRI image 2 months after SBRT revealed a stable-size, enhancing lesion (arrowhead). The normal liver parenchyma received 25 Gy and appeared as a low-density area, indicating acute radiation injury; D: axial arterial phase MRI image 4 months after SBRT showed decreased size of the tumor, with atrophy of the perilesional hepatic parenchyma; E: axial arterial phase MRI image 6 months after SBRT showed necrotic changes and a hypovascular target lesion. The perilesional hepatic parenchyma, which received high-dose radiation, also exhibited necrotic changes; F: axial arterial phase MRI image nine months after SBRT demonstrated complete regression of the treated lesion and atrophy of the irradiated hepatic parenchyma; G: axial arterial phase CT image 18 months after SBRT showed a scar in the radiation field. Complete repair of the radiation damage was also observed; H,I: axial arterial phase MRI images 6 years (H) and 7 years (I) after SBRT demonstrated a stable lesion size but the presence of complete necrosis and ring enhancement, indicating a complete radiologic response. Note the SBRT-related changes, which can be differentiated from tumor recurrence. SBRT: stereotactic body radiation therapy; HCC: hepatocellular carcinoma; RFA: radiofrequency ablation; MRI: magnetic resonance imaging; CT: computed tomography