Brady John McKee MD, Abstract Co-Author: Nothing to Disclose

Charles Allison, Presenter: Nothing to Disclose

Edward Pinkus MD, Abstract Co-Author: Nothing to Disclose

Christoph Wald MD, PhD, Abstract Co-Author: Nothing to Disclose

Sebastian Flacke MD, Abstract Co-Author: Nothing to Disclose

To establish a threshold coronary calcium score likely to exclude ischemia on adenosine stress Rubidium-82 PET myocardial perfusion imaging (Rb82 MPI) in patients with low to intermediate risk of coronary artery disease (CAD).

72 consecutive patients (31 men; mean age 67 +/- 13 years) with low to intermediate risk of CAD were included.  Patients with known CAD or history of either CABG or coronary stent placement were excluded.  ECG gated coronary calcium score using Agatston approach was performed prior to rest and adenosine stress Rb82 MPI on a GE Discovery 64 slice PET/CT scanner. The sensitivity and specificity of calcium score thresholds of 11, 101, and 401 to exclude ischemia defined as lack of perfusion reversibility, transient ischemic diltation, or decreased left ventricular ejection fraction reserve on Rb82 MPI were calculated retrospectively.

18/72 (22%) patients had evidence of ischemia on Rb82 MPI.  0/18 (0%) had a calcium score less than 11 (sensitivity 100%, specificity 43%, PPV 37%, NPV 100%),  1/18 (6%) had a calcium score less than 101 (sensitivity 94%, specificity 56%, PPV 41%, NPV 97%), and  6/18 (33%) had a calcium score less than 401 (sensitivity 67%, specificity 78%, PPV 50%, NPV 88%).  The one false negative patient with a calcium score less than 101 (calcium score: 18) was a 46 year old male found to have a mid right coronary artery thrombus during subsequent coronary angiography matching the area of ischemia on Rb82 MPI and was treated with stent placement.

A calcium score less than 11 predicts a non-ischemic Rb82 MPI with a sensitivity of 100% and may be considered a threshold level for proceeding with perfusion imaging in patients with low to intermediate risk of CAD.  While relatively sensitive, a calcium score less than 101 failed to exclude ischemia in 1 patient who required percutaneous coronary intervention. A calcium score less than 401 inadequately excludes ischemia with a sensitivity of only 67%. 

A calcium score less than 11 may be considered a gatekeeper for Rb82 MPI resulting in decreased overall radiation exposure and expense in patients with low to intermediate risk of CAD.

McKee, B, Allison, C, Pinkus, E, Wald, C, Flacke, S, Coronary Calcium Score as a Gatekeeper for Rubidium-82 PET Myocardial Perfusion Imaging in Patients with Low to Intermediate Risk of Coronary Artery Disease.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6006973.html