Case of the week Details

• Figure 1 (a, b): sagittal and axial images of the chest CT obtained 20 months after metastasectomy demonstrates a new oval soft tissue lesion with spiculated margins adjacent to the post-surgical changes.
• Figure 2 (a): Pre-ablation planning CT
• Figure 2 (b): Intra-procedural CT demonstrating RFA electrode within the lesion
• Figure 3: Axial CT image immediately after ablation shows cavitation of the lesion with perilesional ground-glass opacification.

Diagnosis:
Radiofrequency ablation of lung metastasis

Discussion:

Treatment options for lung metastasis

• Surgical resection
• Laser-Induced Thermotherapy
• Radiofrequency Ablation
• Microwave Ablation

• Radiofrequency ablation offers a similar median survival range as of surgical metastasectomy
• Advantages of thermal ablation
  • Minimal effect on pulmonary function/quality of life
  • Can be repeated
  • Short hospital stay
  • Does not require interruption of chemotherapy

Mechanism of action:

• Thermal energy  damage to cellular proteins, enzymes, & nucleic acids  creates tissue necrosis and coagulation
• RFA is indicated in small (<3 cm) solitary lung lesions located peripherally.
• The lesion should not be contiguous with major vessels as it can lead to heat sink effect.
• Relative contraindications for the procedure include underlying interstitial disease, coagulopathies and immediate proximity to sensitive structures such as central airways, major vascular structures or esophagus.
• Rarely, the procedure is complicated by bronchopleural fistula, tumor seeding, neural or diaphragmatic injury.

Complications:

• Most frequent complications include
  • Pleuritis
  • Pneumonia
  • Abscess
  • Hemorrhage
  • Refractory pneumothorax requiring pleurodesis
• Major complications are rare and include
  • Bronchopleural fistula
  • Tumor seeding
  • Nerve or diaphragmatic injury.

References:

1. Vogl TJ, Eckert R, Naguib NN, Beeres M, Gruber-Rouh T, Nour-Eldin NE. Thermal ablation of colorectal lung metastases: retrospective comparison among laser-induced thermotherapy, radiofrequency ablation, and microwave ablation. American Journal of Roentgenology. 2016 Dec;207(6):1340-9.
2. Ridge CA, Solomon SB. Percutaneous ablation of colorectal lung metastases. Journal of gastrointestinal oncology. 2015 Dec;6(6):685.
3. Bhatia S, Pereira K, Mohan P, Narayanan G, Wangpaichitr M, Savaraj N. Radiofrequency ablation in primary non-small cell lung cancer: What a radiologist needs to know. The Indian Journal of Radiology & Imaging. 2016 Jan;26(1):81.

Dr Rajesh Helavar
MD, PDCC
Consultant Interventional Radiology
Columbia Asia Radiology Group

Dr Renu Jadiya
DNB Resident
Columbia Asia Radiology Group