Posted on May 18, 2020
Cancer imaging is complex and a lot of myths get passed around. Whether it's from something read on the internet or advice from a well-meaning acquaintance, misinformation can be harmful.
To debunk the most common myths about cancer imaging, we asked some of the nation’s top oncological radiologists to share the truth about popular misconceptions. Here are 9 cancer imaging myths, debunked.
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Myth: PET-CT is always the best test to determine whether an abnormality seen on another imaging exam (CT, MRI, Ultrasound) is malignant.
Truth: PET-CT is an excellent exam for staging (seeing the extent) of a newly diagnosed cancer. But it is less effective at deciding whether something is malignant or not.
For example, let’s say a lung nodule is found on a CT scan. If you do a PET-CT and the nodule is hot it could be a malignancy or a granuloma (infection). If the nodule is cold on PET-CT it could be a slow-growing malignancy or an inactive granuloma. Not much help! If the nodule is smaller than 1 cm it probably won’t be seen on PET-CT whether it is malignant or benign. Often the best course of action is to get a follow-up CT to see if the nodule grows rather than a PET-CT.
Myth: If I have any cancer in my breast tissue, a screening mammogram is guaranteed to find it.
Truth: Currently, mammograms are widely accepted as the best tool for early detection of breast cancer. However, for women with dense breast tissue the accuracy of mammography can drop to as low as 50 percent.
This is because there may be cancers hidden within the dense tissue that appear obscured on mammogram images. Fortunately, other imaging tests can be performed in addition to an annual mammogram and clinical breast exam to help prevent abnormalities from being missed. Breast ultrasound, for instance, can significantly increase the detection of node-negative (earlier stage) breast cancers. Among the newest technology being used to find small cancers that mammography may miss is a method of breast ultrasound screening called automated whole breast ultrasound (AWBUS ). Breast MRI is another exam that can be used to improve diagnostic accuracy.
NEXT UP: Patient Story Feature - Mammogram and Breast Ultrasound Second Opinion Help Diagnose Tumor
by, Dr. Arif Sheikh
Myth: Expensive scans, such as PET scans, should be avoided whenever possible unless they are absolutely necessary.
Truth: While these scans have a great initial cost, they often pay off in the long run. By getting a detailed study, your doctors can accurately stage the disease, as well as determine the probability of response to therapy. This can help better stratify the correct course of treatment and save you money.
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by, Dr. Michael Rozenfeld & Dr. Sunil Kini
Myth: Standard closed MRI machines and open MRI machines are equally effective and produce the same quality images.
Truth: [Dr. Kini] A closed MRI often produces better and more accurate results.
Many patients opt for an open MRI due to concerns over claustrophobia. But buyer beware! Standard closed MRIs with a field strength of 1.5T or greater produce a much higher image quality and are usually far more accurate than low-field (less than 1.5T) open MRIs.
[Dr. Rozenfeld] Open MRIs produce lower quality images. They serve an invaluable purpose in patients with claustrophobia who otherwise wouldn’t be able to tolerate an MRI, but if a patient can tolerate one, a standard MRI scanner is almost always superior.
Dr. Shereef Ramadan
Myth: An endorectal coil (ERC) has to be placed in the rectum during a prostate MRI exam for optimum accuracy.
Truth: An endorectal coil is not necessary for high-quality prostate MRI images given the presence of modern well-optimized MRI scanners.
Think of an ERC as an antenna that can be placed into the rectum with the goal of obtaining high-quality MRI images of the prostate. While researchers have traditionally favored the use of ERC, multiple fairly recent studies demonstrate that it is not a must. In a 2017 Scientific Reports study, it was concluded that the addition of ERC was not superior in diagnostic performance when compared to examination without ERC performed on an optimized 3T magnet. A 2014 study published in the Journal of Urology concluded that without ERC, 3T prostate MRI has a high probability of detecting significant prostate cancer.
Placement of ERC commonly produces patient anxiety and discomfort, which can actually lead to motion and, thus, reduction of exam quality.
Myth: All MRIs are the same - it doesn’t matter where I get mine performed.
Truth: MRI scanners can vary significantly in quality.
In addition, it takes a substantial amount of time and expertise to make a scanner perform at its peak potential. The exact same scanner at two different centers can produce very different images and exams. Finally, there can be large differences in quality and accuracy of the final report produced depending on whether it was interpreted by a board-certified fellowship-trained sub-specialized radiologist vs a general radiologist, a non-radiologist, or even a non-physician such as a chiropractor or a nurse.
by, Dr. Arif Sheikh
Myth: Medical imaging is only used to help diagnose disease.
Truth: Imaging can help patients well beyond the diagnosis stage.
Even after a disease has already been staged, medical scans are frequently used to assist in patient management. For example, in lymphoma imaging, PET-CT scans are often done at baseline, before chemotherapy, and again in the interim before completion to see whether the therapy is on the right track, or needs to be switched.
by, Dr. Sunil Kini
Myth: CT scans cause cancer.
Truth: A single CT scan does not cause cancer. Repeated CTs, however, can increase your risk over time.
A CT scan can deliver anywhere between 2-10 millisieverts of radiation, depending on the type of scan. This may seem high, but to put it in perspective, the average American is exposed to 3 millisieverts of radiation each year simply from background environmental radiation, and if you live in higher elevations like Colorado, then it can be as high as 10 millisieverts per year.
by, Dr. Arif Sheikh
Myth: On a PET scan, anything with FDG uptake is abnormal.
Truth: While this is a common perception among patients, it is not always true and can cause unnecessary alarm and concern.
When determining what FDG uptake is indicative of, the interpreting radiologist should also take into consideration any findings on a CT, MRI, or other imaging tests. Given the complexity - one really has to specialize in PET and have read a lot of FDG PET scans to understand all the variables and intricacies.