18F-Axumin
Normal Biodistribution of 18F Axumin
TRACER INFORMATION AND INDICATION
Axumin was approved by the FDA on May 27, 2016, for imaging in men with suspected prostate cancer recurrence based on elevated blood prostate-specific antigen (PSA) levels following prior treatment. This tracer is an analog of the amino acid leucine, that is transported across mammalian cell membranes by amino acid transporters, which are upregulated in prostate cancer cells.
CONTRAINDICATIONS
None.
PATIENT PREPARATION
Patients should avoid any significant exercise for 24 hours prior to their exam. They should not eat or drink anything for four hours prior to injection, except for small amounts of water needed for taking medications.
RADIOPHARMACEUTICAL
The recommended dose is 10mCi (370MBq) administered as an intravenous bolus injection. The tracer should be visually inspected to ensure there is no particulate matter and/or discoloration before administration.
IMAGING PROTOCOL AND ACQUISITION PARAMETERS
-
Correctly identify the patient and begin IV, preferably in the right antecubital area as stasis in the left axillary vein could potentially be misinterpreted as a metastatic lymph node (Virchow’s node).
​
-
Ideally, the patient should use the restroom 30 minutes to 60 minutes prior to injection.
​
-
Change patient if necessary and correctly position patient for the scan. In most cases, the recommended image acquisition should start from the mid-thigh and proceed to the base of the skull, with the patient having their arms raised above their head.
​
-
Injection should be a bolus, followed by a saline flush.
​
-
PET acquisition should begin between 3- and 5-minutes post-injection. Following the administration, tumor-to-normal tissue contrast is highest between 4 and 10 minutes after injection with a 61% reduction in mean tumor uptake at 90 minutes after injection. In some departments, it may be beneficial to complete the CT for anatomic correlation before starting injection to ensure proper timing.
​
-
The scan FOV should include the prostate in the first PET bed. Imaging times are typically between 20- to 30- minutes. Please check with your specific department for proper imaging times.
BIODISTRIBUTION
-
Axumin has a favorable biodistribution for prostate cancer due to its minimal renal excretion and urinary bladder activity. Following administration, 14% distributes to the liver (critical organ), 3% to the pancreas, 7% to the lungs, 12% to the red bone marrow, and 4% to the myocardium. Variable uptake is noted in the salivary glands, bone marrow, and muscles.
​
-
Timing is extremely important with this tracer. Both early and late imaging could result in altered biodistribution (increased blood pool activity in early imaging and increased muscle uptake in late imaging). These alterations should be considered during image interpretation.
IMAGE INTERPRETATION
-
Localization of prostate cancer recurrence is based on the tracer uptake in comparison with tissue background. For small lesions (<1cm), focal uptake greater than the blood pool should be considered suspicious for prostate cancer recurrence. For larger lesions (>1cm), tracer uptake that is equal to or greater than bone marrow is considered suspicious for prostate cancer recurrence. The L3 vertebral body can be used as a bone marrow reference.
​
-
It is important to note that image interpretation errors can occur with Axumin PET imaging. A negative image does not rule out recurrent prostate cancer and a positive image does not confirm its presence. PSA levels determine the performance of Axumin and uptake may occur with other cancers and in benign prostatic hypertrophy in primary prostate cancer.
REIMBURSEMENT
​​
-
To bill Medicare for locally covered PET services use the single most appropriate CPT code 78811 to 78816 based on the imaging area and PET/CT or PET equipment ordered and used for the study. Regarding the Radiopharmaceutical coding, for dates of service January 1, 2017 and beyond, the HCPCS level II code and description is A9588 for Fluciclovine f-18, diagnostic, 1 millicurie. The NDC number, #69932-0001-01, should also be included.
References
AxuminTM (F-18 labeled fluciclovine, Injection) - SNMMI. (n.d.). https://www.snmmi.org/IssuesAdvocacy/QandADetail.aspx?ItemNumber=16039
​
Axumin (Fluciclovine F18 Injection)[package insert]. Oxford, UK. Blue Earth Diagnostics. 2016.
​
Songmen S, Nepal P, Olsavsky T, Sapire J. Axumin positron emission tomography: Novel agent for prostate cancer biochemical recurrence. J Clin Imaging Sci 2019;9:49.