Greg Freiherr, Industry Consultant
Greg Freiherr, Industry Consultant

Greg Freiherr has reported on developments in radiology since 1983. He runs the consulting service, The Freiherr Group.

Blog | Greg Freiherr, Industry Consultant | July 28, 2011

CardioGen Reveals Cardiac PET’s Soft Underbelly

Typically, the only radiation facing travelers is from the airport scanners they must walk through to board airplanes. Not so, however, for two travelers who set off radiation alarms when crossing the U.S. border earlier this month, an incident whose fallout threatens the future of cardiac PET.

Early this week the FDA warned U.S. healthcare providers to stop using the radioisotope generator commonly used to perform PET exams of the heart. Soon after Bracco Diagnostics, the maker of CardioGen-82, voluntarily recalled the cardiac generator (“FDA: Stop Using CardioGen-82 Due to Increased Radiation Exposure”).

An investigation by the FDA had found that CardioGen-82 had months earlier led to the dosing of the two travelers not only with rubidium-82,  the very short half-life isotope needed for their cardiac scans, but also with strontium, a much longer lived isotope. The inadvertent dosing, according to the FDA, was due to a failure in the manufacturing process called “strontium breakthrough.”

The resulting exposure of patients to excess radiation illustrates the vulnerability of imaging devices that depend on radioisotopes. Anyone familiar with nuclear cardiology, which depends heavily on the radioisotope technetium, understands how vulnerable these devices are.

An aging Canadian reactor with a distressingly long history of shutdowns supplies the molybdenum radioisotope that generate most of the technetium used in the U.S. for cardiac SPECT studies. When this reactor shut down, spurring a 15-month technetium shortage, PET advocates – led by Bracco Diagnostics – began recruiting nuclear cardiologists to switch from SPECT to PET. (“Time for a New Normal in Nuclear Cardiology?”). This alternative, they said, was not vulnerable to such shortages.  For those who were convinced, the recent news is not only ironic, but troubling.

In its warning to healthcare providers, the FDA noted that “the risk of harm from this exposure is minimal” and that “it would take much more radiation to cause any severe adverse health effects in patients.” (“CardioGen-82 PET Scan: Drug Safety Communication - Increased Radiation Exposure”)  Yet estimates derived from mathematical modeling done at the Los Alamos National Laboratory indicate that exposure for the two patients may be as high as 90 mSv – more than 30 times the normal dose of a cardiac PET scan. And it is not certain that these two patients are the only ones who have been so exposed. The FDA is now trying to find out how many, if any, more patients suffered excess radiation dose due to strontium breakthrough.

One question not being asked is why this unexpected exposure was detected at a U.S. border crossing instead of the PET suites where the scans were performed. Moreover, how could such excess doses occur in the first place? Are no tests required to ensure the purity of rubidium chloride before it is injected into patients?

Toward that end, the FDA is looking into the sufficiency of the testing procedures used to detect strontium breakthrough at clinical sites using CardioGen-82. Obviously, they are not sufficient, at least not everywhere. But they will have to be soon, or cardiac PET may have a tough time recovering from a shortage that should have never been.

Editor's note: For additional information about this incident and the product recall, visit www.cardiogen.com.

Related Content

Lightvision near-infrared fluorescence imaging system
News | Women's Health | September 11, 2018
Shimadzu Corp.
The Siemens Biograph Vision PET-CT system was released in mid-2018.

The Siemens Biograph Vision PET-CT system was released in mid-2018.

Feature | Nuclear Imaging | September 07, 2018 | By Dave Fornell
Nuclear imaging technology for both single photon emission computed tomography (SPECT) and positron emission tomography...
PET Imaging Agent Predicts Brain Tau Pathology, Alzheimer's Diagnosis
News | PET Imaging | September 05, 2018
Eli Lilly and Co. and Avid Radiopharmaceuticals Inc. announced a Phase 3 study of positron emission tomography (PET)...
Brain Study of 62,454 Scans Identifies Drives of Brain Aging
News | SPECT Imaging | August 27, 2018
In the largest known brain imaging study, scientists from five institutions evaluated 62,454 brain single photon...
Abnormal Protein Concentrations Found in Brains of Military Personnel With Suspected CTE

Researchers are using the tracer, which is injected into a patient, then seen with a PET scan, to see if it is possible to diagnose chronic traumatic encephalopathy in living patients. In this image, warmer colors indicate a higher concentration of the tracer, which binds to abnormal proteins in the brain. Credit UCLA Health.

News | PET Imaging | August 24, 2018
August 24, 2018 — In a small study of
PET Tracer Identifies Estrogen Receptor Expression Differences in Breast Cancer Patients
News | PET Imaging | August 09, 2018
In metastatic breast cancer, prognosis and treatment is largely influenced by estrogen receptor (ER) expression of the...
Novel PET Imaging Method Could Track and Guide Type 1 Diabetes Therapy
News | PET Imaging | August 03, 2018
Researchers have discovered a new nuclear medicine test that could improve care of patients with type 1 diabetes. The...
Researchers Trace Parkinson’s Damage in the Heart
News | PET Imaging | July 17, 2018
A new way to examine stress and inflammation in the heart will help Parkinson’s researchers test new therapies and...
Siemens Healthineers Announces FDA Clearance of syngo.via VB30 Molecular Imaging Software
Technology | Nuclear Imaging | July 16, 2018
At the 2018 Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging (SNMMI), June 23-26 in Philadelphia...
Overlay Init