The NeuWave Microwave Ablation System: A Guide for IRs

[Dr. Christopher Beck]:
Will you unpack it a little bit? What does it look like from a user perspective?

[Dr. Josh Kuban]:
Yes. The normal NeuWave ablation device has one screen. Their newer versions have two. It just looks like a second ablation screen. Your normal one on the left is going to be your power and wattage. On the right, it's just going to be a very similar user interface where you go through five steps to bring in scans, and then you do all the tools, use all your tools on that screen.

The first thing you do is you upload your base scan. I usually get a CT scan with contrast, pre-arterial venous, but usually upload the venous phase for everyone I bring it into the system. I use that first tool to define my tumor, and that's pretty fast. I do that while I'm marking with the text. I'm going to do a CT guide or whatever. While they're prepping, I go over there, and I think, initially, that took a couple of minutes, and now it's like 30 seconds. It's very fast. I use a sphere tool or create tool to really define my tumor.

The cool part about that versus, sometimes, when that wasn't available, I was using Siemens software just to make my own segmentation, but you can't add margins to that one. With the NeuWave microwave ablation device, you can set what margins you want. For certain things like, "Hey, I want to get a centimeter margin, or I only want a five-millimeter margin." It shows you the tumor and then it gives you what your margin is.

Then I set it aside at that point, and I start placing my NeuWave ablation probes. I don't know, there's two different flavors here. There's the cases that you can't see the lesion. I'm sure you've had this before. You see it for arterial phase or venous phase. Then you start getting your probe anywhere near it, and you have no idea where you are, like a 1-centimeter lesion. Those, I actually go back to the AC, like halfway through, and I upload a scan midway through, and the upload is super easy. You just drag it over.

[Dr. Christopher Beck]:
Nice.

[Dr. Josh Kuban]:
That is going to show you where your probe is. It's going to fuse your probe image for your pre-image. It'll fuse those two images and show you your probe over where that you segmented that tumor, so you can see, "Oh, perfect, I'm right on trajectory." or "I got it." A lot of times you'll see, like, "Oh, wow, I'm there, but I'm a little bit on the top left. I'll burn here, pull back, and do a redirect." or "On my next probe, I went a little bit anterior here, so I'll go a little bit posterior on the next one," but it helps to know, "Okay, that lesion didn't disappear. I know where it is. I can target it, I can adjust, and you can continue to see it.

If you have a lesion you can see really well, or using ultrasound, at that point, I don't really use it on the way. I place my probes in my normal way, and then I'll confirm it if I'm not sure. If I place it with ultrasound, then I'll do another one of those fusions. "Okay, it is where I thought it was," but if you can really see it, sometimes, I don't even do the probe placement step. I just skip that, do my ablation, and then go to the ablation confirmation. [crosstalk] The third big bun-- oh, go ahead.

[Dr. Christopher Beck]:
I wanted to ask you about the prescan. Does the prescan have to be the same day of the procedure or the prescan is just like any CT that happens within the last day?

[Dr. Josh Kuban]:
I've only done it with the same day. [crosstalk] I think you can upload them. There's a method for bringing in PET scans and MRIs, but I don't know if you ever tried to use any of these 3D loops and registrations from different days.

[Dr. Christopher Beck]:
Mixed results.

[Dr. Josh Kuban]:
It's mixed results, and even if you're off by just a few millimeters, it's a huge difference. I always do it the same day, and if I can see really well, no contrast, great, I can skip that step, but, otherwise, I almost always get a pre-CT scan now. I think it's just much more accurate when you're doing the fusion, to not have that uncertainty.

[Dr. Christopher Beck]:
Plus, I think that how often are your patients perfectly supine, arms up? A lot of times you'll have them in a different position to drop down on the lesion or open up something. All right, so you were staying-- I think you were on step three of ablation or one other is the way you use ablation confirmation.

[Dr. Josh Kuban]:
Yes. Step three is-- The first one, obviously, define tumor, place your NeuWave ablation probes, third one is actually confirm you got the ablation. That's the meat and potatoes of it. I usually do attract ablation for my cases, take my probes all the way out if I'm in the plane, but, sometimes, if I'm doing a really steep out of plane, I had to come from really low to get up to a dome lesion, you can actually keep some of your probe in the liver, and it won't distort your ablation confirmation software too much-- or not your software but your images.

I'll either take the probe all the way out or get it out of my field of view so I can have a clean CT of my tumor bed. Then I'll do another scan, and that's arterial venous. Pre-arteriovenous, you're looking for bleeding arterial, very rare. Then the venous phase, that's when you're going to upload that to AC. You go back to step three, which is bring that scan over, you drag it over, and now the computer is going to merge those two.

It's going to take your scan and the prescan and merge them. What you do right before that is you just define your ablation zone. It has a really cool feature. It's called "The create tool." It kind of uses Hounsfield units and a little computer algorithm to figure out what your ablation zone is, and it's very accurate. Where it's not perfect and, sometimes, if you have multiple probes or redirects, and it's not a great shape, you can just use one of those ROI functions to carve it a little bit, but I don't know. Perfect is the enemy of good here. I want to have a nice ablation zone, but I don't want to add 20 minutes to my case either.

The create function does really good job, just giving you what you need. Then you ask computer to fuse it, and that's the magic of it. It fuses those two, and then you get a scan overlaying your segment to tumor with your margin and your ablation zone. You get to see, "Did I get it? Did I get my tumor? Did I get my ablation zone? Did I get my margin?" That's it. You can then know, for sure, that you got what you came to get. If you do not, then you can make a mark there and use that to target and do a re-ablation, but most of the time, having used it for a while, I had pretty good results of getting it the first time, but if not, I go back in, no problem.

[Dr. Christopher Beck]:
That was my question. If you have something, say, you left over a little bit of tumor on the inferior margin, things are distorted now, like, the ablation zone is contracted, but you can use the ablation confirmation software to say, "Okay, this is where the bottom part of the lesion is." Do you then use the ablation confirmation software to get back at that spot, or do you just use the CT landmarks that you already have formed from the ablation zone?

[Dr. Josh Kuban]:
This version of AC, you don't use them to target but what I do is I'll go to the same slice, "Okay, at this slice, which you can correlate over to your image acquisition machine, whatever it is, and say, "Okay, the lesion was here. This is where I left margin. Now put an ROI at that spot on that slice," and I go back in. That's something that's different, but if you were a family member getting ablation and you knew you still had margin left, you'd obviously want them to go back in.

They're already in procedure. They already made the trip there. They're already getting it on the table. It's like a surgeon doing a procedure, checking the margin with pathology, be like, "Oh, there's a little bit like a couple of cells here. I think we'll be okay. We'll keep an eye on it." No, you go back in, you clean that part out. I think that's an established thing to do in surgery. It's not really in IR. It's just quick, quick, get done, but I think the times where you do have to go back in, it's worth it. You just don't have the recurrences. You're able to prove that you got what you came to get for and have that A0 ablation, that get-everything-the-first-time kind of approach.