CEUS guided percutaneous biopsy of peripheral pulmonary lesion with large area of necrosis. (a) Gray-scale ultrasound detected a hypoechoic and heterogeneous lesion in the middle lobe of right lung; no necrotic area was shown with conventional ultrasound. (b) After injection of SonoVue, the lesion showed rapid and heterogeneous enhancement in the peripheral region. A large necrotic area without enhancement was detected in the lesion (arrow). (c) After CEUS, 16-gauge core needle percutaneous biopsies were performed under the real-time guidance of ultrasound in the active area (arrow). (d) Histopathological diagnosis revealed it was a lesion of small-cell lung cancer.