Terminology

Preprocedure

Procedure

Post Procedure

Outcomes

Definitions

• Lung cancer
  • Epidemiology
    • 2nd most common cancer type in USA; leading cause of cancer-related death
    • Estimated 228,820 new cases of lung cancer diagnosed in 2020 in USA
    • Non-small cell lung cancer (NSCLC) is most common cancer subtype (80-85% of primary lung cancer)
    • Lungs are 2nd most frequent site of metastatic disease [colorectal, renal cell carcinoma (RCC), breast, sarcomas, germ cell tumors]
  • TNM staging system
    • Stage IA
      • T1: 3 cm surrounded by lung/visceral pleura, not involving main bronchus, no nodal (N0) or metastatic spread (M0)
      • T1a: ≤ 1 cm; T1b: > 1 cm to ≤ 2 cm; T1c: > 2 cm to ≤ 3 cm
• Liver cancer
  • Epidemiology
    • Hepatocellular carcinoma (HCC) is most common primary liver malignancy
    • 6th most common newly diagnosed primary malignancy worldwide
    • Colorectal cancer (CRC)
      • 3rd most common newly diagnosed solid cancer worldwide
      • Liver is most common site of metastasis
      • Incidence: 38.9 new diagnoses/100,000 people in North America
  • Barcelona clinic liver cancer staging system (BCLC)
    • Used to stratify patients to decide best treatment plan
    • Consider following
      • Number and size of hepatic tumors
      • Patient performance status (PS) using Eastern Cooperative Oncology Group (ECOG) scale
      • Child-Pugh system
    • BCLC stages 0, A, B, C, D
  • Milan criteria
    • Determines eligibility for liver transplantation
• Kidney cancer
  • Epidemiology
    • RCC is most common renal malignancy
    • 12th most newly diagnosed primary malignancy worldwide
    • Incidence: 15.9 new diagnoses/100,000 people in North America
  • TNM staging system
    • T1: < 7 cm in greatest dimension, confined to kidney
      • T1a: < 4 cm, T1b: > 4 cm and < 7 cm
• Bone/soft tissue tumors
  • Epidemiology
    • Osteoid osteomas are benign tumors that account for 10-12% of benign bone tumors
      • Symptom onset between 5-24 years of age; male predominance
    • Bone is 3rd most common site of metastasis

Ablation Modalities

• Radiofrequency ablation (RFA)
  • Physics
    • Transforms radiofrequency (RF) energy into heat
    • RF generator ranging from 60-250 W produces alternating current, resulting in agitation of ions surrounding probe tip
    • Ionic agitation leads to frictional heat, which is deposited within surrounding tissue/tumor
    • Tissue temperature parameters
      • Goal of 60-100 °C: Irreversible cellular damage occurs instantly at this temperature; goal temperature should be maintained for ~ 8-16 minutes, depending on RFA system used
      • 50-60 °C: May induce coagulation necrosis in minutes
      • < 50 °C does not reliably induce necrosis
      • > 100 °C should be avoided as high temperatures lead to tissue char/vaporization resulting in gas production, which acts as insulator, impeding further heat diffusion within surrounding tumor
    • Applicator design
      • Probe diameter range: 14-17.5 Fr
      • 3 types of RF applicators: Single straight needle, cluster straight needles, and multitoned expandable electrodes
      • Main difference among applicators is size of ablation zones possible in one treatment
      • Monopolar vs. bipolar RFA: Bipolar RFA allows for use of multiple probes simultaneously, creating larger ablation zones and making it less susceptible to heat sink
    • Ablation zone
      • Shape and size of ablation zone depends on both type and number of applicators placed within tumor
      • Goal is 5- to 10-mm treatment margin beyond suspected tumor border
  • Advantages
    • Intrinsic cautery effect may decrease bleeding complications
  • Disadvantages
    • Associated with higher procedural pain than microwave ablation (MWA) or Cryo
    • Variable tissue thermal conductivity may lead to irregular ablation margins
    • Lung tissue has high impedance and low conduction, thus increasing procedure time
    • Heat sink effect
      • Flowing blood in nearby vessels cools tissue, limiting heating of tumor tissue
      • Presence of vessels or bronchi > 3 mm in diameter within ablation zone may be predictor of incomplete local treatment due to "heat sink" effect
    • May require slow and lengthy treatment to effectively kill tumor
• MWA
  • Physics
    • Relies on dielectric heating
      • Applied electromagnetic field causes water molecules in surrounding tissues to rotate at microwave's frequency
      • Rapidly oscillating water molecules results in frictional heating, raising tissue temperature surrounding probe tip
      • Higher water content = better heat absorption and conductivity = larger ablation zone
    • As with RFA, goal of treatment is to sustain temperatures > 50 °C and ideally > 60 °C
    • Advantages
      • More rapid generation of high temperatures
      • Not limited by increased impedance seen with tissue boiling/charring in RFA: This allows for much higher intratumoral temperatures, leading to larger ablation zones with relatively shorter treatment durations
      • Less susceptible to heat sink
      • Does not require grounding pads
• Cryoablation
  • Physics
    • Causes tumor necrosis through rapid cell freezing
      • Multifaceted cellular death: Protein denaturation, cell membrane rupture, vessel thrombosis/ischemia
    • Joules-Thomson effect
      • Rapid expansion of argon gas at applicator tip leads to rapid drop in temperature (Joules-Thomson effect), cooling surrounding tissue: Temperatures can range from -80 to -150 °C
      • To induce thaw cycle, compressed helium is circulated within applicator; expansion of helium at tip leads to rapid increase in temperature
    • Process consists of alternating freezing and thawing cycles
      • Triple cycle is typically used in lung (3-minute freeze, 3-minute passive thaw, 7-minute freeze, 3-minute passive thaw, 10-minute freeze followed by variable active/passive thaw to raise temp to 22 °C
      • Nonlung ablation typically consists of 2 freeze cycles of variable length, depending on "ice ball" growth (10-minute freeze followed by 8-minute thaw cycle common)
    • Multiple probes can be used to treat large tumors
  • Advantages
    • Decreased procedure associated pain
    • Real-time visualization of treatment area
      • "Ice ball" readily visible with CT/US/MR guidance
    • Ablation zone can be modulated by probe placement and modulating freeze power and time of each probe to create shapes that ensure tumor and margin coverage
    • Data suggests increased efficacy of cryoablation compared to RFA/MWA in treating renal tumors
    • Prospective data suggests efficacy comparable to partial nephrectomy, which is standard of care
  • Disadvantages
    • Longer ablation time than thermal-based techniques
    • More expensive, as multiple probes may be required
    • System requires gas availability and storage

Indications

Contraindications

Preprocedure Imaging

Getting Started

Patient Position/Location

Alternative Procedures/Therapies

Baseline Imaging and Planning

Probe Insertion/Positioning

Ancillary Procedures

Intraprocedural Monitoring of Patient and Treatment

Completion Imaging and Recovery

Follow-Up

Complications

Expected Outcomes