Learning objectives
1. Review the utilization of various techniques to protect adjacent organs from non-target thermal damage during radiofrequency ablation of the liver and kidney. 2. Demonstrate the utilization and applicability of these various techniques with emphasis on our own experience. 3. Demonstrate the potential of novel techniques such as bowel hydro-displacement, balloon interposition and ductal cold fluid infusion.
Background
RFA is a minimally invasive therapeutic modality that continues to gain acceptability in the medical community due to its proven efficacy and safety in the treatment of various primary and metastatic tumors. In the abdomen, its main uses are primary and metastatic non-resectable hepatic and renal tumors, with some cases of adrenal and other retroperitoneal tumors also reported. Appropriate lesion characterization and patient selection continue to represent the main instruments for clinical success. However as experience grows, our center and others have developed new techniques that allow the treatment of lesions previously unsuitable for percutaneous therapy due to their proximity to critical structures. The gallbladder, bile ducts, small bowel and colon are particularly susceptible to non-target thermal damage. Other structures such as the diaphragm, stomach, renal collecting system, ureters and peripheral nerves (genitofemoral nerve) are also at risk for such thermal injuries.
Imaging findings OR Procedure details
We present a comprehensive illustrated review of the various techniques that have been described to protect the non-target adjacent abdominal organs with emphasis on our own center experience, with both pre-clinical and clinical data. The techniques discussed and illustrated will include patient positioning, infusion of fluid (hydrodisplacement) to protect the diaphragm, stomach, colon, and small bowel during liver and renal ablations; the use of intraductal chilled fluid infusion for protection of the biliary tree, and into the ureter and renal pelvis for prevention of hilar and calyceal injury during ablation of central renal lesions. We will also describe the use of alcohol injection as a complementary RFA tool for visceral protection. Other presented techniques include the recently described use of balloon catheter interposition; insufflation with intrabdominal CO2 for diaphragmatic protection and the use of the radiofrequency applicator as a lever to displace the kidney or liver away from non target organs.
Conclusion
The worldwide accumulated experience using RFA as a therapeutic tool shows rare but significant complications related to non target organ thermal injury. In order to maximize the therapeutic benefits of RFA, novel protective techniques can be applied to protect adjacent organs and to allow treatment of lesions previously unsuitable for RFA.