A PET solution to the technetium crisis

October 8, 2009

It should come as no surprise that the nuclear medicine community is struggling to keep up with the number of prescribed heart and bone exams. Technetium is typically used in the U.S. for more than 16 million nuclear medicine tests each year-but not this year. A survey by the SNM found that three quarters of nuclear medicine physicians are delaying patient tests, in many cases longer than a month. A shortage of medical-grade molybdenum-99 (Mo-99), the isotope critical to generating technetium, is the reason.

It should come as no surprise that the nuclear medicine community is struggling to keep up with the number of prescribed heart and bone exams. Technetium is typically used in the U.S. for more than 16 million nuclear medicine tests each year-but not this year. A survey by the SNM found that three quarters of nuclear medicine physicians are delaying patient tests, in many cases longer than a month. A shortage of medical-grade molybdenum-99 (Mo-99), the isotope critical to generating technetium, is the reason.

And diagnosis delayed is only one facet of a growing crisis. The SNM survey found that more than 80% of physicians are decreasing the dosage of technetium-based radiopharmaceuticals to stretch their supply of the isotope, raising the potential of less effective imaging scans.

Much of the hand wringing and many of the proposed solutions to the isotope shortage have focused on the unreliability of nuclear reactors now supplying Mo-99, reactors whose scheduled-and unscheduled-maintenance has thrown a monkey wrench into the technetium works. Late last month, however, Bracco Diagnostics began promoting an idea as significant as it is old: switch heart scans from gamma-based technetium to positron-based rubidium.

Bracco has a vested interest in the adoption of this idea. Its CardioGen-82 generator of rubidium isotope is the only FDA-approved generator-based PET myocardial perfusion product available. The ease of use and low cost of technetium, along with the widespread availability of gamma cameras for cardiac studies, have worked against its adoption. With the technetium shortage likely to continue into next year, however, cardiac PET with rubidium deserves to be considered seriously.

Bracco lately has been trying to make this argument to government agencies and professional societies. Most recently the Italian pharmaceutical firm sent a letter to healthcare professionals extolling the virtues of its PET product, outlining how PET can solve the immediate problems facing nuclear cardiology and provide other benefits.

The company makes a persuasive case, noting that the strontium-based product does not rely on the unstable supply chain that underpins Mo-99. Also, use of CardioGen-82 is reimbursable for the evaluation of coronary artery disease.

PET scans with rubidium offer the additional benefit of better diagnostic certainty than technetium-based ones: 96% versus 82%. And PET scans running 30 to 45 minutes for gated rest and stress studies take substantially less time than similar studies done with technetium.

Bracco claims it can make enough CardioGen-82 to meet the shortfall for clinical cardiac scans created by the technetium shortage. The rapid expansion in the number of PET scanners in the U.S. until a couple of years ago has created an extensive overcapacity among PET sites that might be partly absorbed by cardiac exams.

Given the current and increasingly dire circumstances, it makes sense to switch at least some cardiac scans from technetium to rubidium. At the very least, rubidium-based PET offers a short-term answer to a problem that has no other near-term solutions.