The Bracco Rubidium Generator, commercially known as CardioGen-82, produces the radioactive diagnostic agent Rubidium-82 (Rb-82) for Positron Emission Tomography (PET) heart scans. This self-contained, portable system allows medical staff to prepare the imaging agent on-site. This capability is necessary because Rb-82 is very short-lived. The generator’s purpose is to help physicians evaluate blood flow to the heart muscle in adults with suspected or known coronary artery disease.
Role in Cardiac PET Scans
The generator facilitates a non-invasive procedure called myocardial perfusion imaging (MPI). This cardiac PET scan visualizes how well blood flows through the coronary arteries to the heart muscle. By observing the agent’s distribution, doctors can identify areas of reduced blood flow that may indicate a blockage or damage from a previous heart attack.
The imaging process involves intravenously injecting the patient with Rubidium-82 chloride. As it travels through the bloodstream to the heart, healthy muscle sections absorb the agent, while areas with poor blood flow show little uptake. A PET scanner then detects the energy emitted by the Rb-82, creating detailed images that map these differences in blood flow.
The generator integrates into the workflow of a nuclear medicine department and connects to an infusion system that delivers a precise dose to the patient. This on-demand production makes Rb-82 a practical option for cardiac imaging. It allows clinics to perform these scans without needing to be near a specialized production facility.
How the Generator Produces the Imaging Agent
The CardioGen-82 generator uses the natural process of radioactive decay. Inside the unit, a parent radioisotope, Strontium-82 (Sr-82), is held on a specialized column. As the unstable Sr-82 decays, it continuously transforms into the daughter isotope, Rubidium-82 (Rb-82), ensuring a constant supply is available.
When a dose is needed, a process called elution occurs where a sterile, additive-free 0.9% sodium chloride solution is passed through the generator. Additives are avoided because they can cause the parent Sr-82 to break through into the final dose. The saline washes the Rb-82 off the column while leaving the Sr-82 behind, producing an injectable solution of Rubidium-82 chloride.
A defining characteristic of Rb-82 is its extremely short half-life of approximately 75 seconds. This means that half of its radioactive potential is gone in just over a minute. This rapid decay makes it impossible to produce the agent elsewhere and ship it, as it would lose its effectiveness before use. The on-site generator solves this problem by producing Rb-82 at the time of the scan.
The Patient Experience During a Scan
For a patient, preparation for the scan involves fasting for a few hours and avoiding caffeine, which can interfere with the results. At the clinic, a technologist will explain the procedure and insert an intravenous (IV) line into the patient’s arm. This IV is used to administer the imaging agent and any medications for the stress portion of the test.
The scan has two parts: a “rest” scan and a “stress” scan. For the rest scan, the patient lies on the scanner bed while the first dose of Rubidium-82 is infused. The PET scanner immediately begins taking images to see how blood flows while the body is at rest. The patient only needs to remain still during this painless part of the procedure.
After the rest images are complete, the stress portion begins, which is designed to make the heart work harder. Stress is induced either with a treadmill or a medication that increases heart rate and blood flow. At the peak of this stress period, a second dose of Rb-82 is administered, and another set of images is taken to show blood flow under duress.
Throughout both scans, medical staff monitor the patient’s heart rate, blood pressure, and electrocardiogram (ECG). Patients can resume normal activities shortly after the procedure is finished.
Advantages of Rubidium-82 Imaging
A primary benefit of using Rubidium-82 is the lower radiation exposure for the patient compared to other nuclear imaging agents. Because of its very short half-life, Rb-82 decays and is eliminated from the body quickly. This results in a lower overall radiation dose than agents used in SPECT scans, which have half-lives measured in hours.
The speed of the procedure is another advantage. Since the rest and stress images can be acquired in quick succession, the total time a patient spends in the clinic is often less than an hour. The on-demand production of Rb-82 eliminates delays and allows for an efficient workflow, benefiting both the medical facility and the patient.
Cardiac PET scans using Rb-82 produce high-quality, clear images, which contributes to high diagnostic accuracy. This detailed visualization of blood flow helps physicians detect coronary artery disease with confidence. These images support more informed decisions about treatment plans, ranging from medication to more invasive procedures.