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Page 2 of 8 Cho et al. Mini-invasive Surg 2021;5:20 https://dx.doi.org/10.20517/2574-1225.2021.11

treatment that uses heat energy generated by the agitation of ions in cells to induce cell death and
[4]
coagulation necrosis . RFA has been widely used to treat solid tumors in organs such as the liver, lungs,
and kidneys. Recently, EUS-RFA has been described as an effective and safe new therapeutic modality for
treating pancreatic neoplasms. We review EUS-RFA for pancreatic neoplasms and its outcomes.

POTENTIAL INDICATIONS
Currently, there are no established indications of EUS-RFA. However, EUS-RFA can be used for various
[5-7]
tumors, including benign solid pancreatic tumors, such as neuroendocrine tumors and insulinomas ,
[6]
[8,9]
pancreatic cystic tumors , and pancreatic cancers . There is no absolute contraindications of EUS-RFA.
However, as previously reported, there is the possibility that severe adverse events may develop when EUS-
RFA is applied to pancreatic lesions close to the main pancreatic duct [5,10] . Therefore, it may be considered as
a relative contraindication of EUS-RFA.

MATERIALS AND INSTRUMENTS
1. An oblique-viewing therapeutic curvilinear array echoendoscope.

2. Radiofrequency (RF) generator [Figure 1].

3. Radiofrequency ablation (RFA) probes: The currently available RFA probes are EUSRA RF electrodes
(STARmed, Koyang, Korea), Habib EUS-RFA catheters (EMcision Ltd., London, UK), 19-gauge EUS-
TM
FNA needle electrodes (Radionics, Inc., Burlington, MA, USA), and hybrid cryotherm probes (Hybrid-
Therm®; ERBE, Tübingen, Germany). EUS-RFA probes are classified as “through the needle” type and
“EUS-RFA needle” type. Habib EUS-RFA catheter is a “through the needle” type and the remaining three
probes are “EUS-RFA needle” types. Among these probes, the Hybrid cryothermal probe is bipolar and the
rest are monopolar probes. All probes are connected to the RF generator to deliver heat energy to the target
lesions.

4. Ultrasound contrast agents (UCAs): UCAs are useful for identifying remnant tumors, evaluation of early
treatment responses, and an accurate guidance for additional ablation .
[11]
TECHNIQUE
Prophylactic antibiotics are administered intravenously before EUS-RFA. An RFA probe is inserted into the
target lesion under EUS-guidance to avoid major vessels or the pancreatic or bile ducts [Figure 2A].
Ablation is usually started at the far end inside the lesion [Figure 2B]. After the needle tip is identified
within the margin of the tumor on EUS, the RF generator is activated to deliver energy [Figure 2C]. After a
lag period, echogenic bubbles gradually start appearing around the needle, indicating effective ablation at
the site [Figure 2D]. The size of the ablation zone depends on the wattage, RFA needle tip length, and time
duration. For the ablation of large lesions, the electrode may be repositioned under EUS visualization to
ablate another zone along the same trajectory closer to the echoendoscope while staying away from the gut
wall. A fanning technique allows additional needle passes to further ablate different areas within the same
lesion.

RFA-related adverse events are closely related with thermal injury to the pancreatic parenchyma and
surrounding structures, including blood vessels, bile ducts, the stomach, and the duodenum. Technical
precautions are required for preventing thermal injury to adjacent organs, including maintenance of a
5-mm minimum safety margin from the surrounding vessels and a step-up approach for ablation of larger