FDA-cleared software increases throughput for flurpiridaz back-to-back rest-stress imaging
As adoption continues to expand for positron emission tomography (PET) in nuclear cardiology, there is interest in increasing patient throughput as a way to increase the ROI on the major capital expenditure for a new scanner. One of the drivers for that growth is the new availablity of the F-18 flurpiridaz (Flyrcado) radiotracer, which enables lower-volume centers to order single doses on demand, but beccause of its longer half life, its use requires a waiting period for radiotracer decay between rest and stress scans.
A new software algorithm may help eliminate that waiting period, according to a study published online this week in the Journal of Nuclear Cardiology.[1] Results demonstrated that immediate back-to-back rest/stress scanning can be performed accurately and reliably.
“The ability to image both rest and stress in a single, 15-20 minute procedure addresses the throughput challenges of imaging with flurpiridaz, greatly reducing total procedure time and improving the patient experience,” explained co-author Panithaya Chareonthaitawee, director of the nuclear cardiology laboratory at Mayo Clinic and current president of the American Society of Nuclear Cardiology (ASNC) in a statement. “Larger scale studies and real-world experience are warranted to determine the full benefit of the approach."
Until recently, commercially available cardiac PET tracers were limited to rubidium-82 (Rb-82) generators, which can cost $30,000 or more per month to operate. The cost requires a center to have high cardiac PET imaging volumes to cover the cost. Flurpiridaz now offers an option for centers doing lower volumes of cardiac scans by offering single unit dose purchasing on demand. This offers centers getting into cardiac PET time to ramp up scan volume, or remain at lower volumes using the more economical purchasing model.
Ammonia N-13 can also be used for cardiac PET, but requires production in an onsite cyclotron, limiting its widespread use outside of large academic centers. Rb-82 has a 75 second half life, so rest and stress can be done quickly during the same scan. But N-13 has a longer 9.9-minute half life, which requires waiting for tracer decay before performing a stress scan. To speed this up, the mfiVerse software from MultiFunctional Imaging and developed to enable both scans to be done back to back. The software does this by identifying and separating and the rest and stress tracer activity distributions, outputting separate, corrected images at both rest and stress. This enables rapid imaging at both rest and stress in a single session without degradation from residual tracer activity. It is cleared for use with all cardiac PET tracers, including flurpiridaz.
In the new study, researchers at Mayo Clinic and Mass General wanted to test the efficacy of the software with flurpiridaz, which has a much longer half life of 108 minutes. While this enables production and transport from commercial, regional cyclotrons, it can cause scheduling issues or limits with patients waiting for their second scan as the tracer decays.
The researchers retrospectively obtained separate scan dynamic rest and pharmacologic stress flurpiridaz images in 11 subjects They modeled a 15 minute rest/stress procedure with rest scan from 0-8 minutes, and stress scan from 8-15 minutes. They compared modeling of residual tracer effects included both distributed activity and stress effects upon residual arterial input. Residual activity biased mean stress pixel values and myocardial blood flow (MBF) by +31% and +64%, respectively, as compared to the reference stress images without residual activity, the authors wrote. But, these biases were each reduced to less than 1% after residual activity correction using the software. Linear regression analysis found that corrected stress pixel values (r=0.998) and MBF (r=0.994) closely matched reference stress values. Summed Stress Scores averaged 2.5 points lower for uncorrected images vs. the reference images, and averaged 0.4 points lower after correction.
Dave Fornell has covered healthcare for more than 17 years, with a focus in cardiology and radiology. Fornell is a 5-time winner of a Jesse H. Neal Award, the most prestigious editorial honors in the field of specialized journalism. The wins included best technical content, best use of social media and best COVID-19 coverage. Fornell was also a three-time Neal finalist for best range of work by a single author. He produces more than 100 editorial videos each year, most of them interviews with key opinion leaders in medicine. He also writes technical articles, covers key trends, conducts video hospital site visits, and is very involved with social media. E-mail: [email protected]