The Koreans are Leading the Way in RF Ablation Devices for Thyroid Nodules
Thyroid Radiofrequency Ablation: Updates on Innovative Devices and Techniques
HS Park, JW Baek et al
Article in Korean Journal of Radiology 18(4):615 · January 2017
DOI: 10.3348/kjr.2017.18.4.615 · License: CC BY-NC 4.0
Review article of advances in RF treatment of thyroid nodules and recurrent thyroid cancer.
1. The basic RF technique is still the trans-isthmic approach.
2. The other unchanged method is the moving of the probe in what is called a”moving shot” method.
3. Modified thyroid dedicated probes are a must for the neck area.The 7 cm 18 -gauge is shorter and thinner than standard probes used for other organs ( 17,30,31)
4. Also varies size active probe tips are available from 5,7 and 10 mm.
5. For small thyroid cancer recurrences there is a new 3.8 mm probe tip.
6. A thinner 19-gauge probe tip is useful to puncture small recurrent thyroid cancers.
7. New bipolar RF does not need grounding pads like uni-polar RF.
and they do not send the electric current through the entire body.This makes its use safer for pregnant women and patients with implanted
electrical devices as pacemakers. Bipolar RF probes limit the current to the probe and can do ablations faster. Also no skin burns occur.
8.A new system to track the probe is a virtual needle tracking system
Beginners at first will have some difficulties constant monitoring the tip location. A small sensor on the shaft of the probe constantly tracks the position. There is a V on screen where the tip is located. Decreased complications with tracking system. Shortens the procedure and learning curve for beginners. Hard nodules may bend the needle tip and cause inaccurate location information.
Courtesy from J.W.Baek Guidebook of RFA for thyroid nodules and Tumors
9.Another new device is the unidirectional probe. It causes a half moon zone to decrease exposure of the vital structures near the nodule.Best use is for small recurrent cancers or secondary hyperparathyroidism abutting vitals structures. No studies on it’s use for thyroid nodules so far.
10. Lidocaine injections in puncture site and the thyroid capsule to reduce pain.There are no sensory nerves inside the thyroid. RF can be done with just local. Monitoring the pain during the procedure is essential to avoid major complications. Since they are awake you can tell if there is pain voice changes or ptosis. Sedation or general will limit awareness of possible complications.
Image from the article quoted.
11.Ablation of arteries and veins is another new method. Vascular nodules with big feeder artery can be ablated. Most useful is marginal venous ablation is for most thyroid nodules.
12. Vascular nodules are harder to ablate due to heat sink effect. Ablating the feeder artery first then the nodule also decreases hemorrhage inside the nodule.
13. Draining veins are near the margin of the nodule. Monitor the perithyroidal structures when doing venous ablations vagus middle cervical ganglia.
14. Relative narrow neck with many vital structures makes complete
destruction of nodules difficult. Another new method is the separate the nodule from vital structures. Called Hydro-dissection”. Prior to inserting the probe 5% dextrose is injected into the nodule and adjacent vital structures. Continuous drip of Dextrose during the procedure keeps the vital structure away from the nodule. No Saline as it conducts electricity. Dextrose puts a thermal barrier around the nodule. Transient voice change due to mild irritation of the nerve from cold fluid.Last 30 minutes after the procedure only.
Image from article Dextrose barrier before RF.
15. Finally use lidocaine injection as a provocative test into to soft tissue around the tumor. This will expose any nerves not seen on ultrasound.
Comments: This is a great article. The team has produced a critical article in the use of RF for thyroid nodules and small recurrent thyroid cancer.
Bravo to Dr.Baek and all the physicians in Korea and Virgina who took part in this review.
Richard Guttler MD,FACE,ECNU