Nuclear imagers adjust to practice without Mo-99 during lengthy shortage

With the return of routine Mo-99/Tc-99 generator deliveries still at least four months away, nuclear imagers are discovering clinical alternatives from old and new diagnostic protocols to keep their practices alive. An online survey by the SNM and the National Association of Nuclear Pharmacies (NANP) has found the shutdown of the National Research Universal Reactor at Chalk River, ON, has disrupted 60% of radiopharmacies in the U.S.

Despite the shortage, about 40% of respondents said they have been able to fill more than half of client prescriptions for Tc-99m during the shortage. Only 6% said they were able to fill less than 25% of prescriptions.

The e-mail survey, jointly sponsored in August by the two societies, is somewhat difficult to interpret because nonresponse to questions was not recorded. But data collected from 710 SNM and 97 NANP members suggests that many nuclear imagers and radiopharmacists have been forced to make major clinical adjustments because of the supply crisis.

About one-third of respondents said they do not have access to alternative sources of Tc-99m generators, while 30% said they did have an alternative source. The alternative source appeared to be manufacturers with access to isotopes produced in reactors outside of North America.

Other findings include:

• Sixty-five percent of pharmacists and nuclear physicians said they have canceled orders because of shortages;
• Three of four admitted to rescheduling patient orders to another day or time;
• About 81% have decreased radioisotope dosages;
• About 84% have eluted older Mo-99/Tc-99m generators more often to draw off as much technetium isotope as possible;
• About 82% said they are using thallium-201 instead of Tc-99m agents for cardiac imaging;
• About 6% are performing F-18 FDG-PET bone imaging, and about 9% said they have shifted to F-18 sodium fluoride (NaF), another isotope used for skeletal procedures; and
• Indium-111 (5%), gallium-67 (2%), and nitrogen-14 ammonia (1%) were also cited as alternatives.

Though clinically acceptable results can be obtained with alternative isotopes, the reports of procedural delays are troubling to Dr. Michael M. Graham, SNM president.

"Getting information early in the disease progression is critical, and is one of the real benefits of molecular imaging (a term referring to imaging that measures physiological processes)," he said in a news release.

The 51-year-old NRU reactor, operated by Atomic Energy Canada Ltd., was shut down May 14 after heavy water was found leaking outside the containment vessel. Inspectors found corrosion requiring repair at several locations on the vessel. Isotope production is not expected to resume until repairs are completed in late February 2010, according to AECL.