Over the last 2 decades, 18F-Fluorodeoxyglucose (FDG) has been used as the primary Positron Emission Tomography (PET) imaging tracer for oncologic evaluation of patients. PET/CT imaging with FDG for oncology laid the groundwork for the PETCT modality. Since the inception of FDG in the clinical setting, its utilization has increased covering several types of cancer. As its utilization increased, so did the number of sites who offer PET/CT imaging as a service.
As the PET/CT modality continued to grow and scans increased from year to year, additional radiotracers gained FDA approval and have been implemented into the clinical setting. Starting with the FDA approval of F-18 Axumin in the Spring of 2016, new FDA approved radiotracers emerged for various clinical indications. This article is to serve as a limited guide for departments with interest in using these newly FDA approved radiotracers. The information below was collected via the FDA’s prescribing information labels as well as the manufacturer’s website. Additional information for each of the radiotracers discussed in the following sections can be found via the links at the end of the article as well as from the supplying pharmacies.
When it comes to setting up PET acquisition and reconstruction parameters for new radiotracer protocols, it is always best to use the recommendations provided by the manufacturer of the radiotracer. When a range is given (ex. 2 – 5 minutes) for an acquisition protocol, it is always best to scan on the longer side with list mode enabled for the first few patients. Once the scans have been acquired, the list file can be used to simulate what scans using less acquisition time would look like. A site may determine that it is best to use various acquisition times depending on the patient’s weight or body mass index (BMI).
A similar approach can be used for the reconstruction protocols. Once a few scans have been acquired, retrospective reconstructions can be performed for the purpose of finding the ideal reconstruction parameters that lead to high quality images and approval from the interpreting physician. It is always good practice to run a mock scan on a new protocol prior to patient use. The interpreting physician should approve all acquisition and reconstruction parameters being used in new protocols.
Axumin (18F-Fluciclovine)
Axumin (18F-Fluciclovine) is a PET imaging agent for men with suspected reoccurrence of prostate cancer based on elevated prostate specific antigen (PSA) levels following prior treatment. Blue Earth Diagnostics manufactures Axumin, and it received FDA approval on May 27th, 2016.
The recommended dose of Axumin is 10 mCi (370 MBq) and is administered intravenously as a bolus injection, followed by an intravenous flush of sterile 0.9% Sodium Chloride. The syringe used for the Axumin administration should be assayed pre and post administration for accuracy. Administration via the right arm is preferred as using the left arm for administration may lead to uptake in the subclavian vein. It is also preferred to administer Axumin with the patient’s arms by their side to reduce radiotracer uptake of the injected vein.
Patient preparation includes avoiding significant exercise for 24 hours prior to PET imaging, nothing to eat or drink 4 hours prior to Axumin administration and voiding approximately 30 – 60 minutes prior to Axumin injection. Patients should be instructed to refrain from voiding until the PET/CT scan has been completed.
The patient should be positioned supine with arms up for imaging. The patient is injected on the PET/CT scanning table, which the arms are brought down for, and then the arms are positioned back above the patient’s head once the injection has been completed. The PET acquisition should start 3 – 5 minutes post Axumin injection and start from mid-thigh and end at the base of the skull. The total scan time will vary depending on the PET/CT system being used but will typically be between 20 – 30 minutes. More information on Axumin can be found at the links at the end of this article.
Pylarify (18F-Piflufolastat)
Pylarify (18F-Piflufolastat) is a PET imaging agent for men with prostate cancer and prostate specific membrane antigen (PSMA) positive lesions. Pylarify is indicated for use with prostate cancer patients with suspected metastasis who are candidates for initial definitive therapy and for prostate cancer patients with suspected recurrence based on elevated serum PSA level. Lantheus developed Pylarify and it has received FDA approval on May 27th, 2021.
The recommended dose range of Pylarify is 8 – 10 mCi with a target of 9 mCi which is administered via a single bolus IV injection. After the Pylarify injection, immediately follow with a 0.9% Sodium Chloride flush. The syringe used for the Pylarify administration should be assayed pre and post administration for accuracy.
Patient preparation when using Pylarify is for the patient to drink plenty of water to ensure hydration prior to the injection. Post injection, the patient should continue to drink water for hydration purposes and to promote urinary voiding to decrease radiation exposure.
Prior to placing the patient on the table, they should be instructed to void. The patient should then be positioned supine on the imaging table with their arms above their head. The PET acquisition should start 60 minutes post Pylarify injection starting mid-thigh and finishing at the vertex of the skull. The total scan time will vary depending on the PET/CT system being used but should range between 12 – 40 minutes. The total scan time is based on how many PET beds are needed to scan from mid-thigh to the vertex of the skull and the time/bed used, which is typically 2 – 5 minutes/bed.
Netspot (68Ga-Dotatate)
Netspot (68Ga-Dotatate) is a PET imaging agent that is used for the localization of somatostatin receptor positive neuroendocrine tumors (NETs) in adults and pediatric populations. Netspot received FDA approval on June 1st, 2016 and is available through Advanced Accelerator Applications (AAA).
The recommended dose for Netspot is calculated based on the patient’s weight. 0.054 mCi/kg is the recommended weighted dose with 5.4 mCi as the maximum dose. Netspot is administered as an IV bolus injection. The syringe used for the Netspot administration should be assayed pre and post administration for accuracy.
Patient preparation for Netspot PET/CT imaging is for the patient to drink plenty of water for hydration prior to Netspot administration. Post administration, the patient should be instructed to continue drinking water and voiding frequently to reduce radiation exposure.
Prior to Netspot PET/CT imaging, the patient should be instructed to void. After voiding, the patient is positioned supine on the imaging table with their arms above their head. The recommended PET acquisition start time is 40 – 90 minutes post Netspot administration. PET acquisition should include the skull to mid-thighs. The total scan time will vary depending on the PET/CT system being used but typically ranges from 20 – 30 minutes and approximately 3 – 5 minutes/bed.
Detectnet (64Cu-Dotatate)
Detectnet (64Cu-Dotatate) is a PET imaging agent used for localization of somatostatin receptor positive neuroendocrine tumors (NETs) in adult patients. Detectnet is manufactured and distributed by Curium and received FDA approval on September 3rd, 2020.
The recommended dose for Detectnet is 4 mCi and it is administered IV over a period of approximately 1 minute. After Detectnet administration, a 0.9% sodium chloride flush is administered. The syringe used for the Detectnet administration should be assayed pre and post administration for accuracy.
The recommended patient preparation for Detectnet PET/CT imaging varies depending on if the patient is currently prescribed somatostatin analogs and whether the somatostatin analog is short-acting or long-acting. For patients on short-acting somatostatin analogs, a washout period of 2-days is recommended prior to Detectnet administration and imaging. For long-acting somatostatin analogs, a washout period of 28 days is recommended prior to Detectnet administration and imaging. Other than somatostatin analog preparation, the patient should also be instructed to prior to and after Detectnet administration The patient should also be instructed to void frequently to reduce radiation exposure post Detectnet administration.
Prior to Detectnet imaging, the patient should be instructed to void. The patient is then positioned supine on the PET/CT imaging table with their arms raised above their heads. The recommended PET acquisition start time is between 45 – 90 minutes post Detectnet administration. Total PET scan time will vary depending on the PET/CT system being used but typically ranges from 20 – 30 minutes and approximately 3 – 5 minutes/bed.
Cerianna (18F-Fluoroestradiol)
Cerianna (18F-Fluoroestradiol) is a PET imaging agent that is used for detection of estrogen receptor (ER)-positive lesions as an adjunct to biopsy in patients with recurrent or metastatic breast cancer. Cerianna is manufactured by Zionexa and received FDA approval on May 20th, 2020.
The recommended dose of Cerianna is 6 mCi with a range of 3 – 6 mCi. The administration route of Cerianna is IV and should be administered over 1 – 2 minutes as a single injection. A 0.9% Sodium Chloride flush follows the Cerianna administration. The syringe used for the Cerianna administration should be assayed pre and post administration for accuracy.
The patient preparation for Cerianna imaging to have the patient hydrate adequately prior to and post Cerianna administration. The patient should be instructed to void frequently post injection as well to reduce radiation exposure. There are no fasting requirements for Cerianna imaging.
Prior to Cerianna imaging, the patient should be instructed to void. Once the patient has voided, the patient is positioned on the PET/CT imaging table supine with their arms raised above their heads. The recommended PET acquisition start time is 20 – 80 minutes after Cerianna administration. Cerianna imaging should include entire area from the knees to the top of the skull. The total PET acquisition time will vary depending on the PET/CT system being used but typically ranges from 20 – 30 minutes.
Additional information regarding the radiotracers covered in this article can be found using the following links:
Axumin – https://www.axumin.com/
Axumin – https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/208054s000lbl.pdf
Pylarify – https://www.pylarify.com/
Pylarify – https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/214793s000lbl.pdf
Netspot – https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/208547s000lbl.pdf
Detectnet – https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/213227s000lbl.pdf
Detectnet – https://www.curiumpharma.com/products/us-products/
Cerianna – https://www.cerianna.com/
Cerianna – https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/212155s000lbl.pdf
