Cardiac PET/CT strikes SPECT like radiological lightning

When it comes to imaging the heart to detect coronary disease and other disorders of the ticker, cardiac PET/CT makes SPECT look silly just for trying. And that’s just on the clinical front. It’s got its economic attributes too.    

Researchers comparing the two modalities at Intermountain Healthcare in Salt Lake City found that cardiac PET/CT (coronary-specific Positron Emission Tomography) came back with precise diagnoses 88% of the time, while SPECT (Single Photon Emission Computed Tomography) managed the feat at just a 30% pace.

They presented their results in San Diego March 15 at the annual scientific session of the American College of Cardiology.

According to a report posted on Intermountain’s website, the findings came to light when cardiologists scrutinized outcomes of patients at the institution’s Heart Institute who were scanned using the SPECT scanner in 2012 alongside those of patients scanned with the cardiac PET system in 2013.

Screening from a pool of 1,000 patients from each of those years, they pruned the study group to 197 SPECT patients and 200 cardiac PET/CT patients who had both an imaging test and a heart catheter.

“What we’ve found is that cardiac PET/CT scans offer higher accuracy and much better image quality,” said Kent Meredith, MD, the lead researcher of the study. “We have much more confidence in the results and there is far less radiation exposure for patients.”

Meredith added that cardiac PET/CT can easily scan patients for whom SPECT is problematic, such as those who are obese or have prominent liver or GI tract activity.

The report noted that cardiac PET/CT imaging uses two high-energy electrons for the radioactive tracers. Since the electrons are high-energy—unlike SPECT’s—a much smaller dose is required and the image quality is far better. The half-life of the radioactive tracer is only two minutes and the radiation is completely out of the patient’s system within 20 minutes.

On the plus side for SPECT, it’s far more readily available and has much more affordable entry points. A quick web search shows that a SPECT gamma camera can be had for $350,000 while a PET/CT scanner can set back a provider upwards of $2 million. SPECT tracers are cheaper too (although their half-life of up to six hours can mean more complications and, with them, higher costs).

Further buttressing the economic case for cardiac PET/CT, Intermountain’s report pointed out that the modality’s more accurate results translate into fewer false positives, warding off unneeded invasive diagnostic procedures and saving dollars in the process.  

“For years, physicians have primarily used SPECT scans to diagnose coronary artery disease and other heart problems,” the report stated. “However, use of cardiac PET/CT imaging is growing.”