Dr. Stephen Sweriduk is the medical director for Shields MRI. As the medical director, he is responsible for the clinical oversight of the entire network, including quality assurance, protocol development, and direct management of Shields Radiology group. He also works hand-in-hand with radiology groups within Shields' joint-venture partners to ensure consistency in care.
We invited Dr. Sweriduk to participate in a Q&A session about Axumin PET scan. You'll find our questions and his answers below.
Reminder: the information contained in this article is educational in nature, not medical advice. If you have further questions, speak to a urologist.
Before we dive into Axumin PET scan, let's talk about PET scans in general. What's the difference between a PET scan, a CT scan, and an MRI scan?
Dr. Sweriduk: MRI scan images are generated by radio waves and magnetic fields. They don't have ionizing radiation (like an X-Ray), and they provide excellent soft tissue contrast. CT uses X-ray to generate cross sectional images and is great for lung, abdomen and pelvis, bone, and trauma. CT uses ionizing radiation. PET/CT uses a combination of CT and PET (positron emission tomography). PET uses a radioactive tracer to evaluate function of tissues and to detect diseases, such as cancer.
Are there different kinds of PET scans, CT scans, and MRI scans?
Dr. Sweriduk: Yes. PET is used primarily for tumor imaging, but also has applications for neurologic disorders and cardiac diseases. As stated earlier, CT is great for lung, abdomen and pelvis, bone, and trauma. MRI is great in musculoskeletal, neurological, abdomen, and pelvis. MRI is also excellent for detecting and staging prostate cancer.
The most commonly used PET scan for cancer imaging is the FDG PET (a glucose-based tracer). How accurate is it in regards to prostate cancer?
Dr. Sweriduk: Not very good. It’s better in high Gleason score cancer than low Gleason score (Gleason 7 or above) for detecting metastatic disease. Prostate cancer has low glycemic activity. High specificity, but low sensitivity. It has limited value in detecting and staging prostate cancer.
So let's talk about the Axumin PET scan, which was approved by the FDA in May 2016. What is it?
Dr. Sweriduk: Axumin is indicated for Positron Emission Tomography—Computed Tomography (PET/CT) imaging in men with suspected prostate cancer recurrence based on elevated blood prostate specific antigen (PSA) levels following prior treatment. The higher the PSA, the more sensitive the test (>2 is best). Axumin PET CT is a new and valuable tool in managing the treatment of prostate cancer.
How does it compare to bone scans?
Dr. Sweriduk: Equal or better for lytic lesions, but a bone scan is still recommended as a first step. Sclerotic lesions may not uptake. Bone scans are best at demonstrating blastic bone changes where PET is much more sensitive for lytic lesions.
What are the criteria for determining whether a patient qualifies?
Dr. Sweriduk: Patients with suspected prostate cancer recurrence. The patient has been diagnosed and treated but now has a rise in PSA. Axumin is most sensitive in patients with a PSA of 2.0 or higher but still valuable below 2.0. Axumin is also effective in cases with a high doubling rate.
What benefits does the Axumin PET scan provide patients and their doctors?
Dr. Sweriduk: Axumin PET CT can detect tumor recurrence in the treated prostate bed as well as local and distant lymph node and bone involvement. This helps the clinician determine the proper treatment.
Are there any downsides/caveats?
Dr. Sweriduk: Axumin PET CT is less sensitive for recurrent tumor detection in patients with a PSA level below 2ng/ml. If the PSA is above 2ng/ml, the detection rate of tumor recurrence is 91.7%. If the PSA is less than 1, the detection rate is 37.5%. Axumin may not accumulate in densely sclerotic bone metastases, so careful review of the CT images is necessary. In addition, a supplemental radionuclide bone scan may be necessary. Axumin uptake can be detected in benign prostatic hypertrophy nodules in residual prostate tissue.
When undergoing the Axumin PET scan, what happens—what should patients expect?
Dr. Sweriduk: Patients need to fast for four (4) hours. Scans begin 3 to 5 minutes post injection. Scans last 20 to 30 minutes. Patients lie on their back with arms above the head. It is critical that patients are on time for their appointment as Axumin (like FDG) has a short expiration.
Why should a patient consider going to Shields for his Axumin PET scan?
Dr. Sweriduk: The Shields network makes it easily accessible—we have sites that generally cover every region of Massachusetts as well as sites in southern and central Maine. Secondly, our experience. We have unsurpassed experience in performing and interpreting these PET CT scans.
If a patient feels he is a candidate for the Axumin PET scan, what should he do next/whom should he speak to?
Dr. Sweriduk: Patients should talk to their urologist.
Does insurance typically cover this type of PET scan?
Dr. Sweriduk: Yes, most insurance providers cover this type of scan, following Medicare guidelines. Axumin is covered by Medicare for the FDA-approved indication only: Axumin is indicated for positron emission tomography (PET) imaging in men with suspected prostate cancer recurrence based on elevated blood prostate specific antigen (PSA) levels following prior treatment.
Thanks, Dr. Sweriduk! You can read more about Axumin here (check out this patient brochure as well). If you have questions regarding this or any other urological topics, consider making an appointment with one of our physicians.
