A critical weapon in the fight against cancer is having a detailed and accurate diagnosis. Therefore, it’s not surprising that hybrid PET/CT (positron emission tomography/computerized tomography) scan technology is now essential to detecting and diagnosing different types of cancer. Radiologists can see things on a PET/CT scan that typically cannot be found using traditional CT scan or MRI imaging alone. While CT shows the location, size and shape of a potentially cancerous growth, PET scan can actually show if a tumor or growth is malignant. This is credited to the use of radioactive imaging agents, such as fluorodeoxyglucose F 18, or FDG, which can detect metabolic activity indicative of cancer.
FDG – The Workhorse of PET Scan Technology
Known as the workhorse of PET imaging, FDG was the first imaging tracer to receive approval from the U.S. Food & Drug Administration (FDA) and is widely used for oncology imaging. FDG is a radioactive molecule that is similar to glucose. It is injected into the body and travels to areas of highest metabolism, helping radiologists discern metabolic abnormalities when the body is scanned. This is important because cancerous growths and tumors have a very high metabolic rate. FDG accumulates in the body’s neoplasm (new or abnormal tissue growth) and then provides a map to where a primary tumor is located as well as areas of metastatic disease.
“It’s a tremendously exciting time to be part of a new PET/CT practice,” shared Dr. Andrew Moran, chair of Nuclear Medicine and a nuclear medicine/PET imaging radiologist at Raleigh Radiology. He and his team have worked tirelessly to bring hybrid PET/CT to the practice. “Combined PET/CT scanning is an incredible tool to support oncologists in making sound treatment decisions for their patients. Playing a role in helping cancer patients get the best care possible is very rewarding.”
New Radiopharmaceuticals Emerge to Image Specific Cancers
PET/CT can be used to help diagnose many different types of cancers, including neuroendocrine cancers, prostate cancer, lung cancer, breast cancer, gastric cancer, and cancers of the head and neck. According to the American Cancer Society, a PET/CT scan with FDG, most often used for diagnosing lung cancer and detecting if the cancer has spread. However, over the past six-plus years, radiopharmaceutical scientists have also been working to develop new PET imaging agents that are specifically targeted for detecting certain types and sub-types of cancer.
“PET imaging is really just in its infancy stage now,” explained Dr. Moran. “In 20 to 30 years, the field is on target for a revolution that will introduce many new, more specific radiotracers – we will be able to track tumors and metastatic disease better than we ever have in the past.”
For example, gallium-68 DOTATATE is being used to diagnose neuroendocrine cancers with great sensitivity and specificity. Meanwhile, Axumin® (fluciclovine F 18) has already received FDA approval in the United States for metastatic prostate cancer by tracking rising prostate-specific antigen (PSA) levels. Additionally, gallium-68 PMSA (prostate-specific membrane antigen) just recently received FDA approval, although it isn’t yet commercially available. It’s an even more specific tracing agent for metastatic prostate cancer.
“Urologists are really excited about these new tracers and the opportunity to order these scans when they become available,” explained Dr. Moran. “Historically, no good imaging method for metastatic prostate cancer has ever been available, we’ve been relying on bone and CT scans.”
For breast cancer imaging, the radiopharmaceutical Cerianna™ (fluoroestradiol F 18) just recently received FDA approval and can be used specifically for patients with estrogen receptor positive cancer; looking for the metastatic or recurring disease in these patients.
“It’s amazing that a radiotracer can be targeted for this specific sub-type of breast cancer. It will have an immense impact on detection and treatment decisions for breast cancer patients,” added Dr. Moran. “Additionally, new tracers will be developed in the next several years for specific sub-types of lung cancer and GI tract cancers, making the process to track these diseases even more sophisticated as well.”
Theranostics – Using Radiotracers to Treat Cancer
Meanwhile, to peek further into the future, a new field has developed within PET imaging called theranostics. In addition to being able to image tumors with PET imaging agents, radiologists will soon be able to use those tracers to treat cancer as well. This will be done by attaching a radioactive particle to the imaging agent. For example, a radiologist will use gallium-68 DOTATATE to image a patient and detect metastatic disease, then will follow up with an IV injection of lutetium (radioactive element) DOTATATE and actually ablate the tumor. Currently, scientists are developing approximately 25 different theranostics agents to pair with PET imaging agents for cancer treatment.
“Actually being able to treat cancer based on the imaging agent is a real gamechanger,” said Dr. Moran. “It’s a fascinating time in the field of PET because of the future and where all of this is headed for patient care.”
Raleigh Radiology and WakeMed Health & Hospitals introduced a new hybrid PET/CT scanner in February 2021.
References
Stanford Health Care: Advantages of a PET/CT Scan
National Cancer Institute: Radiopharmaceuticals – Radiation Therapy Enters the Molecular Age
Physics World: New PET tracers show immense promise in cancer imaging
American Cancer Society: Tests for Lung Cancer
