BETA - What is a PET/CT scan? How can a PET/CT scan help monitor myeloma?

If you're living with multiple myeloma, you've probably heard of PET CT scans. But what exactly are they? And how do they help track the disease? In this video, we'll break down what a PET CT scan is, how it's used to monitor myeloma, and when it might be time to repeat one. Whether you're newly diagnosed or well into treatment, understanding this powerful imaging tool can help you stay informed and empowered throughout your care journey. What is a PET CT scan? So a PET CT is actually a two-part scan, an anatomy scan for the CT, and a functional scan which is the PET, and I'll explain. Sometimes you can kill cancer and it can die, but it can still be there. Think about a lesion that you have that turns into a scar. So that will still show up on a CT scan, but the PET scan gives you a radioactive sugar. And all cells in the body use sugar to survive. And the more sugar it takes up, the more active the cell is, and the more sugar it takes up, the brighter it glows. So if we give anybody a PET CT, the brain will glow brighter than your chin. And areas of activity, of myeloma will glow bright. And I like to jokingly say, you know, if my nurse practitioner got fed up with me and killed me and put me in a CT scan, you're still going to see brain, lungs, liver, kidney. It doesn't tell you alive or dead. But the benefit of doing PET CT is sometimes you can have lesions in the bone that are now dead. You've killed the cancer, but you still have the lesion or the hole in the bone. And the benefit of a PET CT is it doesn't just show the hole, it says active or not. Now we give sugar with this. We don't give the classical contrast dye, which is an iodine based contrast that's given with CAT scans. Iodine contrast, the intravenous contrast that's given with CAT scans can be harmful to the kidneys. And we like to try to avoid that. Oral contrast or the sugar that's given with the PET, neither of those are harmful to patients with myeloma and can be given without concern. PET CT, as I mentioned, combination of PET and CT. It's only mentioning PET, but usually we do it with a CT. The PET part, positron emission tomography, is you infuse radioactive tracer, which is very short half-life, so it's not dangerous for you. You give a tracer in the vein and then it distributes in the body. And this tracer is a nucleotide that is emitting radiation and it's attached to a sugar. The cells in our body that use a lot of sugar are, for example, the brain cells. Actually it's not shown here, but usually the brain lights up very well. The brain cells, cancer cells, inflammatory cells. So there is where you see the tracer. We know where the inflammation usually is, like in the teeth, oftentimes there's something lighting up. Or in the lymph nodes if you have a cold. But we know that the brain has a lot of sugar uptake. But other than that, if something appears on the PET, then we know, okay, there might be malignant cells. And this is pretty sensitive and pretty well established. It shows us the metabolism. So high metabolism is a very strong signal for cancer cells. It is of prognostic significance. If you have a lot of those cancer cells in your body, it's worse, of course. It shows disease activity together, this combination of tumor mass and proliferative metabolism activity. The disadvantages are that you can have false positive results. As I mentioned, you can have an inflammation somewhere and you don't know if this now is an inflammation or is a tumor. But as I mentioned, since we know where the inflammations usually are, most of the time we can differentiate. In the worst case, we have to stick a needle in there to see if it's really myeloma or if it's just an inflammation. The radiation dose is of course a bit higher because you add the nucleotracer, which still dose, but it's not zero, to the actual CT that also has some radiation exposure. So this combination has a bit higher radiation. But again, the information we gain from that is so valuable that I think it's really worth taking this very, very, very tiny risk of getting a cancer from radiation exposure. Is a PET CT scan different from a PET scan? If you use the regular PET CT, yes, it's different because the CT part, PET is showing you where there's activity, where it's metabolism, where sugar is taken up and cancer cells do that, myeloma cells do that. So that's the PET part. But the CT part shows you the actually, if you only do a PET, you have kind of clouds of tracer uptake and you can kind of estimate where the body is. But the CT gives you kind of the background. It shows you, okay, there's the skeleton, there's the brain, there's the organs, there's the limbs. So the CT is in the PET CT is mostly just to allocate where the uptake is. What we recommend also in the new guidelines that we say we want to, and a CT we can do, a CT has a much higher sensitivity. It's not just showing the background of the body. It really shows the bones. It really shows the areas where the myeloma is taking place. So we recommend that if you do a PET CT in myeloma that you use this good quality CT and use it as the allocation part of the PET CT. So it's not only that you kind of can guess where things are, but you really have the full information from the CT plus the full information from the PET. So a standard PET usually has a very low resolution CT, a little bit higher resolution CT gives us best of both worlds basically. So PET CT should have a good CT in it if it's used for multiple myeloma. What should patients expect on the day of a PET CT scan and how long does the visit usually take? It depends on the tracer with FDG. It's rather short. You give an infusion with this tracer, which is a radioactive sugar. You give this as an infusion and then it distributes through the blood in the body. And then the cells that have a high metabolism need a lot of sugar, are very active like cancer cells, but also like inflammatory cells, also like brain cells. So the brain and the heart, they always light up because they need a lot of sugar. But we know that, so we ignore that more or less. And then you give this infusion, the sugar goes into those cells and then you take a picture a few hours later and then combine that with the CT. So you see where those sugar accumulations are basically and that's what we do. So it takes a few hours, but you're not a few hours in the machine. You're just getting the infusion, then you wait until it's distributed and taken up, and then you get the CT. Do all PET tracers take the same amount of time to be absorbed by the body? This new CD38 for example, this tracer that's used there, it takes about six days to distribute in the body. So you have to wait six days to get the infusion and then six days later or seven days later, you do the imaging. So these are different tracers have different kinetics in this regard. How often should PET CT scans be repeated? How often to do the test is individualized. For me in my practice, anyone with a diagnosis of myeloma, meaning smoldering or symptomatic disease should get a PET scan or some type of whole body imaging at least once a year. Sometimes people can have what we call non-secretory myeloma where the myeloma doesn't make an M-spike or a light chain and the only way to evaluate it is by doing some type of body imaging. Those patients may need scanning every three to six months and again, individual by individual, but at a bare minimum, I believe anyone with a diagnosis of myeloma should be scanned at least once a year. PET CT scans are a powerful tool in the fight against myeloma, helping doctors see what's happening inside the body and make more informed treatment decisions. Knowing when and how often to use them can be just as important. By understanding this process, you're taking an active role in your care. As always, talk to your health care team to find out what's right for you. Remember you can keep track of all your testing results in Health Tree Cure Hub. Once you sign up for a Cure Hub account and connect your medical records, your test results from all the centers you listed will be found in one report in the Track My Disease tab. If you found this video helpful, don't forget to like, subscribe, and share it with others who might benefit. Thanks for watching and take care on your myeloma journey.