The How-To of Thyroid Radiofrequency Ablation: Procedure Technique & Post-Procedure Management

[Dr. Aparna Baheti]:
So just walk me through how you would do your standard run of the mill thyroid ablation.

[Dr. Tim Huber]:
Yeah. So we do these all in our outpatient IR suite here at OSHU. So we have a nice big room to put the patients in. They’re laid out on our angio table, which is definitely overkill for this procedure, but it's very nice for us. We get them positioned, and you want the neck pretty extended, so you can really get the nodule into a good position to visualize the whole nodule. And then I always scan the patient to make sure we're in a good spot. Then we prep everything out. We numb the neck, numbing the skin, numbing down to the thyroid capsule and that's with 1% lidocaine. And I find that really lidocaine is sufficient for most patients to get them a completely numb and more or less pain-free during the procedure. You don't need to do moderate sedation or anything more heavy. Then we go in with the electrode, trans-isthmic approach kind of medial to lateral in a transverse plane. And you really want to work basically ablating deep to superficial because as you start ablating the nodule, you're going to create this echogenic cloud of microbubbles around the tip of your electrode, and it's going to gas out everything posterior. So if you work deep to superficial, you'll be able to kind of see what you're doing the whole time. And basically you just fan your electrode up, ablating that whole segment of the nodule, and then work on another segment kind of go up down with your ultrasound unit and find another place to start ablating and keep it going until the whole thing is covered.

[Dr. Aparna Baheti]:
Okay. How big are these electrodes?

[Dr. Tim Huber]:
Good question. So most people are familiar with the really long electrodes that we use for kidney ablations or liver ablations. These are much shorter. They're specially designed to be a little bit more friendly for the head and neck and a little more user-friendly so they have a nice grippy handle that's a little bit shorter than the standard RFA electrode, and then the shaft is shorter as well. So it's more like a pencil size, a little bit longer than a pencil. So much more maneuverability allows for a lot more fine control.

[Dr. Aparna Baheti]:
Okay. So then in terms of equipment purchases, your capital equipment purchases, the RFA generator, and then a probe for each patient, right?

[Dr. Tim Huber]:
That's negotiable as it always is with these kinds of ablation systems. So the newer model that most practices are going with now is essentially rolling the cost of the generator into the volume purchase with your electrodes, and see that's the most common thing that I've heard about across the country. So you can choose to buy the generator upfront and kind of reduce your probe costs that way, or kind of roll that in on a per probe cost. Pay a little bit more per electrode, but then if you're not using them, you can basically give everything back and not have purchased that piece of equipment.

[Dr. Aparna Baheti]:
Oh, that's great. Gives people a chance to try it before they buy it, right?

[Dr. Tim Huber]:
Absolutely.

[Dr. Aparna Baheti]:
One other thing you've mentioned to me before about the trans-isthmic approach with these probes is just that going trans-isthmic allows the probe to really have a place to stay. And it prevents it from moving around a bunch in the thyroid. Have you found that that's another benefit of going trans-isthmic as opposed to lateral to medial?

[Dr. Tim Huber]:
Yeah. So a lot of patients and even providers kind of worry that the thyroid, being so superficial in the neck and not having much tissue to kind of anchor it, what's going to happen when the patient breathes or coughs or swallows? How are we going to secure the probe as you're doing this ablation? And the trans-isthmic approach really gives you more tissue at that oblique angle to kind of hold everything in place. And I found that really, security of the probe is not an issue, it works just fine. And even when patients are talking or swallowing or breathing, that electrode is not going anywhere.

[Dr. Aparna Baheti]:
What's your end point for treating a certain area? Like, do you do 30 seconds at each site or something like that?

[Dr. Tim Huber]:
What I found from doing a little bit of back table experimenting is that the echogenic appearance/echogenic changes that you'll see on ultrasound correspond really well to the ablation zone. So as you're doing your ablation, you really want to see those echogenic changes within the thyroid nodule. And you'll kind of know from that what's been ablated. And so it's this sort of moving shot technique or pullback technique. So you go in, you ablate, and slowly kind of pull back along a track, almost like a track ablation, if you're familiar with that. And as you're doing that, you'll see changes in the nodule and you want to see basically those same changes throughout the entire nodule.

[Dr. Aparna Baheti]:
Okay. How long does the whole procedure take?

[Dr. Tim Huber]:
It varies a lot on the size of the nodule for a two to three centimeter nodule, you're looking at probably 15 to 20/25 minutes. For a bigger nodule, that's say six centimeters, you're looking at probably 45 minutes, maybe an hour.

[Dr. Aparna Baheti]:
I see. Yeah, you get faster the more you do it, right?

[Dr. Tim Huber]:
Yeah. Yeah, definitely. There's a learning curve with this, that the first couple you do are going to be much slower. And I find that with myself too. The first few that I did definitely took a lot longer, trying to be very meticulous and get the whole thing ablated very carefully. As you go on, you can kind of use a little bit higher wattage, move a little bit faster to the nodule and a little faster with your times.

[Dr. Aparna Baheti]:
So, is it a big deal if you ablate some normal thyroid tissue too?

[Dr. Tim Huber]:
In general, no. There's usually not a huge impact to the thyroid function with this procedure. It's very difficult to really ablate too much into the normal thyroid tissue. There's usually enough peritumoral vascularity that'll kind of buffer a little bit of the heat and the ablation zone kind of outside the nodule. So I've really found very minimal impact on the normal thyroid tissue in my follow-ups.

[Dr. Aparna Baheti]:
I want to knock on wood here, but it sounds like it doesn't have a ton of complications associated with it. That's great. So then tell me about your clinical follow-up.

[Dr. Tim Huber]:
Yeah, so we're probably a little more aggressive then maybe totally necessary, but we basically see patients back at one month and then every three months for the first year. And at those follow-ups we're checking ultrasound each time to check the nodule size and check for the shrinkage in the volume. We're also checking TSH at the one month visit. And then for non-functional benign nodules, we just check it once, if it's normal, and we kind of hold off until the one-year mark and we check it again there. For the functional nodules, I'll keep checking TSH until it's basically stabilized and normalized, hopefully at a new euthyroid state.

[Dr. Aparna Baheti]:
How long does it usually take for the hyper functioning nodules to get them to euthyroid state?

[Dr. Tim Huber]:
So I've done about three patients so far, and in my practice I've found that it takes about three months, and they're back to euthyroid state. It can take a little bit longer for their symptoms to totally normalize, but in general, I find that it's fairly quick.

[Dr. Aparna Baheti]:
Yeah, I was thinking a year. That's great, and then I know you have the luxury of being able to do the follow-up ultrasounds yourself. But in a lot of practices, the diagnostic folks are going to be reading the follow-up ultrasounds. And I imagine these things look pretty scary, post ablation, like many things post ablation. Can you just talk a little bit about what they look like on the follow-up and how to get them not to say it's like a TI-RADS 5 lesion.

[Dr. Tim Huber]:
Yeah. So that's one of the big things you have to worry about. And that's one of the reasons why I do a lot of the follow-ups in my own clinic. I do get the three month and the one year ultrasounds done in our radiology department here just for some objectivity to make sure I'm not totally making up numbers. But you do want to make sure that whoever's doing the ultrasounds knows what you're doing and what the appearance should be after this procedure. If you lose a patient to follow up and they go off to some other city and get scanned, it's very easy for someone to say, “Hey, this is hypoechoic. This looks scary. There's maybe areas of calcification. This looks like a TI-RADS 5. This is cancer. It needs to come out now.” And if they biopsy it after ablation, it's going to come back with all kinds of weird pathology and necrosis and strange things that are going to look really scary. So it'll get read out as something bad and they're going to get surgery most likely. So you want to make sure they're getting ultrasounds by people who know what's going on and that they're able to basically give you a decent read. So whether that's just informing your local department of, “Hey, I did this ablation, it's going to look a little funky, just FYI,” or doing it yourself. I think either one's acceptable.

[Dr. Aparna Baheti]:
How long does it look all crazy for?

[Dr. Tim Huber]:
So that's a good question. It can look a little bit funky even up to a year. Usually the margin cleans up by about three to six months, and it's looking a little bit more like a normal ablation zone, but it'll look hypoechoic and obviously shrinking down up to a year plus.
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[Dr. Aparna Baheti]:
So Tim, how do you gauge outcomes from this procedure?

[Dr. Tim Huber]:
Yeah. So the papers that have been published on this typically report the volume reduction ratio, so how much the nodule has shrunk by. They also look at the symptomatic score and the cosmetic score. So the symptom score is super subjective. It's basically like a zero to 10 scale of how bothersome the symptoms are for the patient. It's not the most scientific thing in the world, but at least it gives you some sense of how bothered the patient was by symptoms pre-procedure and then kind of where they are afterwards. In general, we're finding that the symptoms improve very quickly, usually by the three-month mark. By the 3-6 month mark, people have a pretty significant reduction in their symptoms. And then the cosmetic grade is basically a one to four scale. Four is a visible neck bulge, three is visible if they swallow, two is palpable, and one is not visible. So those are three different metrics that we're using, just because they've been used in other papers to kind of mirror that.

[Dr. Aparna Baheti]:
How much volume reduction is considered successful?

[Dr. Tim Huber]:
Yes, a lot of the papers talk about 50% as being kind of technical success. But I find that if you want to really reduce the size of the nodule and have it be durable, at least for five plus years, you really want to shoot for something higher than that. More like 70 to 80% at a year. That's kind of what we do here.

[Dr. Aparna Baheti]:
What pushes you to re-treat a patient?

[Dr. Tim Huber]:
So incomplete symptom resolution. If they're getting to sort of the six or nine month mark, and they're still saying, “Yeah, I was at an eight and I'm down to a five, but I'm still kind of feeling this sensation of something in my throat or occasional dysphasia,” and there's still some residual tissue there that's not totally ablated, I'll go back and try to re-ablate and touch that up. Typically patients will have a pretty significant improvement even with a modest reduction in size, like 50%. And there could be some tissue that's viable, but if their symptoms improve, I usually just leave it alone. Kind of let the patient symptoms drive it mostly.

[Dr. Aparna Baheti]:
Have you treated any patients with multinodular goiter?

[Dr. Tim Huber]:
So we have, it's a definitely a little more controversial, especially in the Korean and the Italian literature. They're definitely more challenging patients. And they often have bilateral nodules, which can present some challenges. I don't treat both sides at the same time, just still with that theoretical risk of damaging the laryngeal nerve on both sides and causing bilateral vocal cord paralysis. I just stick to one side at a time, and I'll kind of target the dominant nodule and any adjacent nodules.