PET Superior to SPECT for Imaging Occlusive Coronary Disease

October 05, 2012

By Will Boggs, MD

NEW YORK (Reuters Health) Oct 03 - Rubidium-82 positron emission tomography (PET) is more accurate than single-photon emission computed tomography (SPECT) perfusion imaging for diagnosing obstructive coronary disease, researchers say.

"There is continuing controversy over the optimal nuclear method to diagnose coronary artery disease," Dr. Kiran Nandalur of Oakland University William Beaumont Hospital School of Medicine, Royal Oak, Michigan told Reuters Health. "However, PET offers several advantages, including apparent superior sensitivity and specificity, better spatial and temporal resolution, and shorter imaging time. In other words, PET is likely more accurate, clearer, and faster. If I had to undergo one or the other for potential coronary disease, I would choose PET over SPECT."

Dr. Nandalur was responding to results from a systematic review by Dr. Rob S. Beanlands and colleagues from University of Ottawa Heart Institute in Ontario, Canada that compared the accuracy of Rb-82 PET vs SPECT for diagnosing obstructive coronary artery disease (CAD).

Their review, published online today in the Journal of the American College of Cardiology, included 15 PET studies (involving 1,394 patients) and eight SPECT studies (with 1,755 patients).

Overall, Rb-82 PET had sensitivity of 90% and specificity of 88% for detecting obstructive CAD, compared with 85% sensitivity and 85% specificity for Tc-99m SPECT, resulting in a superior accuracy of PET overall (p<0.0001).

When patients with low likelihood ratio were excluded, the superior accuracy of PET was even more pronounced, the researchers say.

Four studies directly compared Rb-82 PET with SPECT (but only one used Tc-99m SPECT), and pooled analysis of these studies also showed PET to be more accurate.

Most of the studies (10/15 PET and 5/8 SPECT) were affected by referral bias, the authors found.

Although radiation exposure with Rb-82 PET was estimated to be four- to five-fold lower than with Tc-99m-based SPECT, the estimated cost per scan is higher for PET (around $1850) than for SPECT (around $1000), the researchers note.

"Rb-82 PET has high diagnostic accuracy and should be considered when it is available for patients being assessed for myocardial ischemia who cannot exercise," Dr. Beanlands told Reuters Health. "With the combination with strong prognostic data, wider use of Rb-82 PET would be appropriate."

Dr. Nandalur pointed out, "SPECT is vastly more available and cheaper, so that should play a role in decision making given the rising costs of medical care."

And, Dr. Nandalur added, "Insurance coverage is generally broader for SPECT than PET for coronary artery disease. However, PET has been shown to be cost effective relative to SPECT, largely due to the better accuracy, which often makes additional testing unnecessary."

"PET is largely considered by physicians as a tool in diagnosing and staging cancer, but is a robust method in evaluating the heart, especially coronary artery disease," Dr. Nandalur concluded.

Dr. Beanlands added, "Physicians should have alternatives for myocardial perfusion imaging, and there should be flexibility in the system to be able to consider other imaging modalities when access to one becomes a challenge."


J Am Coll Cardiol 2012.