Liver lesions that can be thermally ablated are classified into primary liver lesions (hepatocellular carcinoma [HCC]) and secondary liver lesions (metastases).

This is the main indication (utilization) of hepatic radiofrequency ablation in the United States and worldwide.

• Liver cirrhosis with super-added HCC
  
• Nonsurgical patients
  
• Lesions confined to liver (no extrahepatic dissemination)
  
• No evidence of intrahepatic vascular invasion

This is the less common utilization of hepatic thermal ablation.

• Nonsurgical candidates
  
• Postoperative candidates (non-reoperative candidates)
  
  
  
  • Percutaneous thermal ablation increases the possibility of curative treatment in patients with liver recurrence after hepatectomy from 17 to 26% and is preferred over repeat surgery because it is less invasive (lower procedural morbidity).
  
  
• Less than five lesions, with each lesion having a maximum diameter of ≤3 cm (preferable)
  
• Metastasis reported to be ablated:
  
  
  
  • Colorectal metastasis (most common metastasis)
    
    
    
    • 20–25% of colon cancer patients have resectable disease in the liver; surgical resection is the curative modality and not percutaneous thermal ablation.
      
    • Percutaneous thermal ablation increases the possibility of curative treatment in patients with liver recurrence after hepatectomy from 17 to 26% and is preferred over repeat surgery because of its less invasiveness (lower procedural morbidity).
    
    
  • Neuroendocrine metastasis
    
  • Gastric metastasis
    
  • Renal metastasis
    
  • Melanoma metastasis
    
  • Pulmonary (bronchogenic) metastasis
    
  • Uterine metastasis
    
  • Ovarian metastasis
    
  • Breast metastasis

• Ascites (can be drained just prior to biopsy procedure)
  
• Hepatorenal failure
  
• Obstructive jaundice (bilirubin level >3 mg/dL)
  
• Vascular invasion (portal venous tumor thrombus)

• Look for ascites
  
  
  
  • When there is no ascites, bleeding can stop due to the tamponade effect of adjacent organs and particularly the chest wall (rib cage).
    
  • Some operators consider ascites an increased risk for bleeding (controversial).
    
  • Many operators would drain ascites prior to the percutaneous thermal ablation of liver lesions.
    
  • Ascites may act as a heat sump for hepatic lesions at the surface of the liver adjacent to the ascites.
  
  
• Look for adjacent organs that can be inadvertently traversed
  
  
  
  • This helps plan the needle trajectory (ablative approach).
    
  • This can help reduce transgression of adjacent organs with subsequent potential major complications.
    
  • Particular organs that may be traversed include the colon, gallbladder, lung (pleura), stomach, and less likely the small bowel.
  
  
• Look for normal hepatic parenchymal segments for peripherally located subcapsular lesions
  
  
  
  • This helps plan the biopsy needle trajectory so normal hepatic parenchyma is traversed by the needle prior to entering the target lesion.
    
  • Traversing normal hepatic parenchyma may reduce the risk of bleeding.
    
  • Traversing normal hepatic parenchyma may reduce the risk of tumor seeding.
  
  
• Avoid intrahepatic structures: they include
  
  
  
  • Portal triads to avoid injury to their contents (portal veins and main bile ducts) in the hilum
    
  • Nontarget vascular lesions (for example, a large hemangioma), which cause bleeding complications
    
  • Transjugular intrahepatic portosystemic shunts (TIPS)
    
  • Transhepatic biliary drains

• Ultrasound machine with Doppler capability
  
• Multiarray 4–5 MHz ultrasound transducer
  
• Transducer guide bracket
  
• Sterile transducer cover

• Chlorhexidine skin preparation/cleansing fluid
  
• Fenestrated drape

• 21-gauge infiltration needle
  
• 10–20 mL 1% lidocaine syringe

• 11-blade incision scalpel
  
• Coaxial access needle
  
  
  
  • Some thermal probes are introduced through coaxial needles.
    
  • Coaxial needles allow a coaxial biopsy needle placement followed by ablative probe placement without losing access.
    
  • Coaxial needle may reduce the risk of tract seeding (anecdotal).
  
  
• Thermal ablative probes

The following are summaries of types of probes. Details of the probes’ biomedical engineering are beyond the scope of this book.