On a recent Zoom support group call, there was a discussion about different scans, why they are different, and why different doctors will order different scans under different scenarios. A further part of the discussion was how insurance companies impact the likelihood of a scan or test being covered or the cost of a scan in a different location costing a different amount. These issues are something that many cancer patients face regularly and can feel incomprehensible at times. Fortunately, we had a medical professional in the group, who broke down some of the details from her experience, which was SUPER helpful for the attendees. This blog post is my attempt to gather the information available in one place to help everyone understand the different tests.
As always, if you have a medical question, please ask your doctor. This post is my attempt to explain the medical jargon from my perspective only and I’m not a medical professional of any kind!
“Magnetic resonance imaging (MRI) is a medical imaging technique that uses a magnetic field and computer-generated radio waves to create detailed images of the organs and tissues in your body.” I got this definition from the Mayo Clinic’s page about MRIs, which can be accessed here. Sometimes insurance companies want an MRI to be done prior to paying for a PET scan and it’s important to understand that an MRI does give detailed “slices” in pictorial form of the organ or bone that is looked at. For instance, I’ve had multiple brain MRIs since a PET doesn’t always show a brain lesion clearly — I don’t have any brain lesions, just lots of migraines that cause my doc to want to look at my brain pretty regularly. Additionally, when I’ve had a new lesion show up or something that continues to be active from PET to PET, then an MRI is often scheduled to get a closer, more detailed look at what’s really going on.
A Positron Emission Tomography (PET) is one of the most often ordered scans for Metastatic Breast Cancer (MBC) and my Medical Oncologist calls it the “gold standard” in staging and identifying progression. This Healthline article gives a great overall description of what it is and why it is done. A good thing to remember is if you have Lobular Breast Cancer, differentiated from Invasive Ductal Carcinoma, the PET may not be the best scan for your doctor to determine if there has been progression. For further information, check out the Lobular Breast Cancer Alliance. One other limitation of a PET Scan is that the SUV value (meaning how bright is the metabolic activity in a particular site) is subjective. This can impact how different scans are read and continuity between scans. Just something to consider when discussing the results with your doctor. Further, for those of us with bone mets, it’s important to remember that active cancer and healing bone is nearly indistinguishable on a PET and requires a radiologist who really knows what they are looking at.
Computed tomography (CT) scan is when detailed images of internal organs are obtained by this type of sophisticated X-ray device. I’m not sure anyone has forgotten the taste of the chalky substances that we have to drink before this scan. My cancer center has a few different options with different “tastes,” but all of them are pretty nasty to me. I had a PET/CT at a free standing clinic the other day and they didn’t have the chalky stuff, the tech just mixed iodine in water and said it did the same thing. Since the iodine water was much easier to keep down, I may just schedule further tests there. This article provides more information about CT Scans and why they are used to look at organs because of the limitations of X-rays.
X-rays are a type of radiation called electromagnetic waves and is usually one of the only words beginning with X that my prek kiddo remembers! X-rays are used to look at bones, but are limited in efficacy for looking at soft tissue. An article explaining the details of X-rays and when they are used can be accessed here.
“A bone scan is a nuclear imaging test that helps diagnose and track several types of bone disease. Your doctor may order a bone scan if you have unexplained skeletal pain, a bone infection or a bone injury that can’t be seen on a standard X-ray.” The was the best definition I found and, no surprise, it was from the Mayo Clinic’s website. There are experts that opine for those of us with bone only mets that the PET scans are not the best method of measuring progression or activity since healing bone shows up at metabolically active on a PET and often cannot be differentiated from active cancer. My Medical Oncologist still likes the PET best, but we also do some bone scans as well.
So, the next time your doctor is thinking about which test to use to look at a particular issue or pain or to continue to surveil the efficacy of a particular medication, you will know what to ask and have some framework to understand what the doctor is looking for. I’m a big believer in understanding what and why a doctor is doing even if the doctor doesn’t articulate that right away. This information may help you ask the right questions or just give you peace of mind you understand why your doctor is doing what they are doing.
Again, I’m not a medical professional, so if you have specific questions, please make sure you ask your medical team!