HN CT Sim: with or w/o iv contrast?

[Radonc90]

HN CT Sim: with or w/o iv contrast?

So, this tweet came up with a good question: HN radonc Sim CT: with or w/o iv contrast...

If you scroll down the tweet, you will see ppl were making respectful/polite
comments until "our friend Drew" makes a stupid comment, but anyway...

- All HN pts come to me with CT Neck with and w/o iv contrast already done, as well as a PET-CT.

- So, I see no need to inject iv contrast in my dept for 4 reasons:

1. I don't see the need bc I fuse the diagnostic CT with iv contrast into my sim CT (no contrast).

2. It is a hassle to set up iv contrast in a radonc dept (following hosp guidelines and getting an iv injector).

3. I hate to stick my pt with a needle that I don't have to, not to mention risks of further contrast issues
(kidney issues however small it is in the setting of concurrent CDDP).

4. I have done hundreds of HN pts over the years and am very confident to draw GTV/CTV etc.
even w/o contrast. I know my way around the HN regions. Plus I have reviewed the diagnostic CT anyway.

Anyway, this is my practice: diagnostic CT w/ and w/o, PET-CT already done and radonc sim CT (w/o).

I wonder what you guys/gals think...

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[medgator]

Contrast when possible. Sometimes it can't happen if pt has bad veins, really poor gfr etc so in that case i just use the pet and deal with it. Sometimes I'm the one obtaining the pet which i use for simulation and that can be handy.

P.S. drew's comment was absurd, as usual

 

[Ray D. Ayshun]

HN CT Sim: with or w/o iv contrast?

So, this tweet came up with a good question: HN radonc Sim CT: with or w/o iv contrast...

If you scroll down the tweet, you will see ppl were making respectful/polite
comments until "our friend Drew" makes a stupid comment, but anyway...

- All HN pts come to me with CT Neck with and w/o iv contrast already done, as well as a PET-CT.

- So, I see no need to inject iv contrast in my dept for 4 reasons:

1. I don't see the need bc I fuse the diagnostic CT with iv contrast into my sim CT (no contrast).

2. It is a hassle to set up iv contrast in a radonc dept (following hosp guidelines and getting an iv injector).

3. I hate to stick my pt with a needle that I don't have to, not to mention risks of further contrast issues
(kidney issues however small it is in the setting of concurrent CCDP).

4. I have done hundreds of HN pts over the years and am very confident to draw GTV/CTV etc.
even w/o contrast. I know my way around the HN regions. Plus I have reviewed the diagnostic CT anyway.

Anyway, this is my practice: diagnostic CT w/ and w/o, PET-CT already done and radonc sim CT (w/o).

I wonder what you guys/gals think...

I agree with you. Won't repeat if already done relatively closely to sim date. OTOH, the question asked had to do with contrast enhanced PETs, which would be nice if available.

 

[seper]

In postop cases, you absolutely need IV to draw reasonably confident IMRT vols

 

[fiji128]

In residency our head and neck attending never got it, but I can say in retrospect he basically didn't know what he was doing as he trained in the pre IMRT era.

Now I will almost always get it unless there is some patient specific reason not to. I agree it is absolutely necessary in post op cases if you want to generate the most accurate possible volumes.

 

[Radonc90]

Ray Ayshun,

Agree.

My radiologists always do the PET-CT with the CT portion w/o iv contrast, it is their dept and their protocols.
Independent of sites (HN, abd etc.), most pts get both:
- Let's say CT abdomen with and w/o iv contrast and a PET-CT (where the CT portion is without contrast).
- So when the pt comes to me, it is all ready with these studies that had contrast, all I have to do is fuse it.

Even in HN post-op IMRT, I always obtain a post-op Diagnostic CT with and w/o iv contrast anyway as a baseline for future F/U months and years later. This is a very important concept (post-op baseline studies for future comparison).
So if a post-op CT with iv contrast is already done, I don't inject contrast in my dept.

 

[thecarbonionangle]

am i the only one who thought the spongebob monster looking slime was funny?

 

[elementaryschooleconomics]

I argue for IV contrast for most complex H&N sims. There are some faculty at my institution who like to spit out the line "I learned to do this without IV contrast, we don't need it", like it's some sort of badge of honor. The difference is night and day. If you have a contrasted CT sim with a deformable PET merge, it's basically a "paint by numbers" situation, better for you, better for the patient.

The one caveat being if the patient, for some reason, underwent a diagnostic CT with IV contrast in the same week as the sim. In that case, yeah, no need to punch the kidneys, merging the diagnostic scan is usually great.

Sure, I've contoured a lot of cases without contrast, and I can understand why some people don't think it's necessary (especially if you come from the era of drawing on radiographs with crayons using bony anatomy), but...why? I want to use every tool I have in my arsenal if I'm about to blast someone's face with Beams of Healing.

 

[Radonc90]

Just to clarify a few things...

1. If the pt had ONLY a PET-CT and nothing else, I always order a Diagnostic CT with and w/o contrast.
Sometimes the radiologists (especially the ones fellowship-trained in HN) pick up stuff that the PET-CT does not.
So, from a diagnostic standpoint, this is good for pt care bc the radiologists are trained for that.
The "danger" of obtaining our own CT sim with iv contrast for dual purposes (for diagnostic purpose + for radonc dosimetry): most radiologists that I know do NOT want to read our stuff bc of liability issues. Also, from a economic standpoint, they cannot bill for prof reading of our radonc sim CT with iv contrast.

2. I use MIM software, my radonc sim CT (w/o contrast) is fused with the diagnostic CT (with iv contrast), so on my screen, I clearly see the blood vessels.
To me, I think this is win-win:
- The DR reads the CT with contrast, get paid, and we have a diagnostic studies for future F/U.
- My CT sim is very quick, without iv contrast, my CT sim takes only 5 min (once the plastic mask has hardened).

Plus as a reply in that Tweet said "setting up for iv contrast in radonc dept takes time" and I agree.

 

[gmsquid]

I always do contrast (if medically able). The better you visualize the tighter you can draw your high dose ctv and the more you can spare oars. I think it may improve tumor control and reduce toxicity.

 

[gmsquid]

I always do contrast (if medically able). The better you visualize the tighter you can draw your high dose ctv and the more you can spare oars. I think it may improve tumor control and reduce toxicity.

I also do MRI sim for pharyngeal and oral cavity tumors. Helps with normal tissue and tumor delineation as well. But I’m in academics so feasible for me.

 

[Ray D. Ayshun]

I also do MRI sim for pharyngeal and oral cavity tumors. Helps with normal tissue and tumor delineation as well. But I’m in academics so feasible for me.

Oral cavity? Post-op MRI?

 

[gmsquid]

Oral cavity? Post-op MRI?

Yep, helps me delineate surgical changes and violated tissue planes. Also helps me better draw parotids and other oars. And minimizes effects of any dental artifact

 

[deleted969641]

IV contrast whenever treating nodes at any site, including head and neck. It's annoying when people don't use all the tools they can to deliver the best treatments. My opinion.

Also, does Drew Moghanaki have a brain tumor? Seriously, what is wrong with this guy? I'm concerned. His Twitter account suggests he is treating SCLC with 60/40 BID based off the results of a phase 2 study numerous limitations. I'm really concerned. Speaking of hard to cure cancers, I wish we could cure the cancer that is social media and the hive mindset and virtue signaling it engenders. Ugh.

 

[Ray D. Ayshun]

IV contrast whenever treating nodes at any site, including head and neck. It's annoying when people don't use all the tools they can to deliver the best treatments. My opinion.

Also, does Drew Moghanaki have a brain tumor? Seriously, what is wrong with this guy? I'm concerned. His Twitter account suggests he is treating SCLC with 60/40 BID based off the results of a phase 2 study numerous limitations. I'm really concerned. Speaking of hard to cure cancers, I wish we could cure the cancer that is social media and the hive mindset and virtue signaling it engenders. Ugh.

I gotta say, contrast is rarely helpful when treating the pelvis.

 

[deleted969641]

I gotta say, contrast is rarely helpful when treating the pelvis.

Knew I would raise some eyebrows with that. But I can't tell you how many times I've seen the external iliacs morph into a mess of bowel or else have some other weird anatomic variant and been very thankful I always use contrast. (disclaimer: I use IMRT for treating virtually everything in the pelvis).

 

[elementaryschooleconomics]

Knew I would raise some eyebrows with that. But I can't tell you how many times I've seen the external iliacs morph into a mess of bowel or else have some other weird anatomic variant and been very thankful I always use contrast. (disclaimer: I use IMRT for treating virtually everything in the pelvis).

*clutches pearls* "But what about vascular distension? What about the need for heterogeneity corrections in the contrasted scan? I do declare!"

 

[Radonc90]

I have a $1M question for you guys/gals...

- If the HN pt had a diagnostic CT of the HN region with iv contrast last week, and you sim
the pt today, would you inject iv contrast in a radonc dept? I don't bc I simply fuse the diagnostic
CT with my non-contrast CT. I clearly see the vessels by sliding the "fusion sliding bar" up and down
in the MIM software.

 

[beamseyeview]

*clutches pearls* "But what about vascular distension? What about the need for heterogeneity corrections in the contrasted scan? I do declare!"

But there is data for that!!

Prospective study evaluating the use of IV contrast on IMRT treatment planning for lung cancer - PubMed

PTV and OARs dose differences between noncontrast and contrast scans appear to be minimal for lung cancer patients undergoing IMRT. Using IV contrast scans as the primary simulation dataset could increase treatment planning efficiency and accuracy by avoiding unnecessary scans, manually region...

pubmed.ncbi.nlm.nih.gov

 

[beamseyeview]

I have a $1M question for you guys/gals...

- If the HN pt had a diagnostic CT of the HN region with iv contrast last week, and you sim
the pt today, would you inject iv contrast in a radonc dept? I don't bc I simply fuse the diagnostic
CT with my non-contrast CT. I clearly see the vessels by sliding the "fusion sliding bar" up and down
in the MIM software.

Probably not necessary in this situation to get the IV contrast, as long as you can ensure a reasonably good fusion in the region of the GTV for tumor delineation. Using vessels as landmarks for contouring is way easier IMHO with contrast but not impossible without.

If no recent diagnostic CT w/ IV contrast though, would absolutely use it for my sim. There are series published of "rapid failures" in the post-op setting with worsening neck nodes on CT sim scan that changes management.

Rapid recurrence in head and neck cancer: Underappreciated problem with poor outcome - PubMed

Rapid recurrence occurs at an underappreciated rate and is associated with poor survival outcomes. Patients with ENE are at highest risk and may benefit from diagnostic imaging evaluations immediately prior to PORT.

pubmed.ncbi.nlm.nih.gov

 

[deleted969641]

I have a $1M question for you guys/gals...

- If the HN pt had a diagnostic CT of the HN region with iv contrast last week, and you sim
the pt today, would you inject iv contrast in a radonc dept? I don't bc I simply fuse the diagnostic
CT with my non-contrast CT. I clearly see the vessels by sliding the "fusion sliding bar" up and down
in the MIM software.

Absolutely. Your fusion capabilities sound like magic to me. I'm not saying you can't, but there's no way I can get anywhere near acceptable fusion when treating neck from skull base to clavicle. Injecting IV contrast is not hard and does not take a lot of extra time. I know some people have fears of contrast to a much higher degree than I do, which is fine. I did have a patient get an AKI from it once that delayed chemo. But IMO benefits outweigh the risks. I usually instruct patients to self hydrate aggressively now (based on nothing but I figure it can't hurt).

 

[thecarbonionangle]

I almost always do contrast. If i am worried about their kidneys, i can call the infusion centre and give them a 2L NS bolus. Make sure you tell them to skip their metformin. Review the med list and be aware of your patients medical issues (you probably dont wanna give a 2L bolus to someone with CHF EF 25%, but you can gently hydrate).

MRI or PET sim when i think it may be helpful.

 

[Radonc90]

Anyone here does fusion from diagnostic CT?

 

[radiation]

Anyone here does fusion from diagnostic CT?

We always fuse diagnostic CT but often times the position is different enough where the fusion is not great, particularly for the neck and c spine due to flexion. We do the classic chin up/shoulders down with the rare bite block at sim, which is almost always different than the diagnostic position. Mim is great, especially if you know how to finesse reg reveal and reg refine, but probably most people arent going that granular

 

[elementaryschooleconomics]

Anyone here does fusion from diagnostic CT?

I will do that often as well. I've spent a lot of time learning how to do my own fusions in MIM over the past few years and will frequently pull in extra diagnostic scans, if for no other reason than to just have a sliver of more information to help guide contouring (for every disease site, not just head and neck).

The deformable fusions can sometimes be too powerful...once, a diagnostic scan for a female patient was mistakenly labeled with a male patient's name, and Dosimetry was still able to fuse the woman's scan into the man's CTSIM and it looked reasonable, at least in the target ROI. It was caught and corrected, obviously, but it was an illustrative mistake to see.

 

[Radonc90]

OTOH,

For those who do sim CT with contrast, no need for fusion with diagnostic CT?

 

[Ray D. Ayshun]

I'll reorient the fusion multiple times before trusting deformation

 

[evilbooyaa]

I have a $1M question for you guys/gals...

- If the HN pt had a diagnostic CT of the HN region with iv contrast last week, and you sim
the pt today, would you inject iv contrast in a radonc dept? I don't bc I simply fuse the diagnostic
CT with my non-contrast CT. I clearly see the vessels by sliding the "fusion sliding bar" up and down
in the MIM software.

I don't routinely do this but as long as you can get it into the same position I'm sure it's fine. The issue for H&N there is frequently a bite block or pulling shoulders more down for mask creation. I'm not at a point where I trust deformable registration yet.

I don't routinely get post-op diagnostic imaging like CT w/ contrast for oral cavity, larynx, etc. At time of CT sim we do both a contrast enhanced and non-con CT so we can make sure it's in the same position, but not make dosimetry have to do overrides on all the contrast. So I end up doing something quite similar to you, except that it's done on the same day because I don't trust positioning.

 

[dieABRdie]

I always had it in residency, but at my new shop the other docs don't do it. I hated to "be the one" but its so much easier to plan and I do think its essential for post op cases. Only time I won't use it is if the patient has intact anatomy and a recent diagnostic contrast CT. I get the physicist to do a deformable fusion and that works great.