Adenosine Induced Stress Myocardial Perfusion Imaging Using Dual Source Computed Tomography: a novel technique allowing simultaneous visualization of coronary anatomy and physiology Ron Blankstein MD, David R. Okada AB, Brian B. Ghoshhajra MD MBA, Jose A. Rocha-Filho MD, Wilfred S. Mamuya MD PhD, Thomas J. Brady MD, Ricardo C. Cury MD
Clinical History 59 year old male with tobacco use and obesity but no prior cardiac history presented with chest pain and dyspnea on exertion. He was found to have an abnormal nuclear exercise perfusion which demonstrated moderate to severe exercise induced ischemia in the territory of the LAD. Subsequently, the patient agreed to participate in an IRB approved MGH research protocol designed to assess both stress and rest myocardial perfusion as well as coronary CT angiography (CTA) in a single comprehensive CT protocol. As part of his clinical care, following the abnormal nuclear stress imaging study, he underwent invasive angiography which showed 90% plaque in his proximal LAD involving the bifurcation of the diagonal branch. Subsequently, he was taken to the operating room for coronary artery bypass grafting surgery involving a LIMA to the LAD and a saphenous vein graft to the diagonal branch. Patient has done well since surgery and is now asymptomatic.
(Click on images to enlarge)
Figures A-D. CT perfusion images during adenosine infusion demonstrated a large perfusion defect in the anteroseptal, anterior and anterolateral walls (Figure A). For display purposes, the image provided utilizes a HU based color coding map (i.e. all pixels <40 HU are black). During the same acquisition, CTA was performed and showed a large non-calcified plaque in the proximal LAD. (Figure B). Exercise SPECT images showed a medium size defect of moderate to severe intensity throughout the mid to distal anterior and anteroseptum and apex. (Figure C). Invasive angiography in LAO caudal view showing severe stenosis in LAD prior to take off of first diagonal branch. (Figure D).
Discussion While SPECT myocardial perfusion imaging is a well validated technique which offers accurate diagnostic and prognostic data, it is limited by attenuation artifacts and, less commonly, false negatives related to a balanced reduction of blood flow ("balanced ischemia"). Recent data from our group1 and others2 has showed that Cardiac CT may allow non-invasive simultaneous evaluation of coronary anatomy and physiology in a single study. Analogous to gadolinium based stress MRI protocols, the ability of CT to identify myocardial perfusion abnormalities is based on differences in myocardial uptake of iodinated contrast whereby there is rapid enhancement in healthy myocardium in comparison to ischemic or infarcted territories. Importantly, our comprehensive protocol combining stress and rest myocardial perfusion, CT angiography, and late enhancement imaging, was shown to expose patients to the exact same amount of radiation dose that is was observed during SPECT-MPI.1
While at this time, stress CT perfusion is an investigational technique and is not clinically available, it may in the future offer a highly effective and safe non-invasive method for the simultaneous evaluation of coronary anatomy and physiology.
Blankstein R, Shturman L, Rogers IS, Rocha JA, Okada DR, Sarwar A, Soni AV, Bezerra H, Petranovic M, Loureiro R, Feuchtner G, Gewirtz H, Hoffmann U, Mamuya WS, Brady TJ, Cury RC. Adenosine Induced Stress Myocardial Perfusion Imaging using Dual Source Cardiac Computed Tomography (Journal of the American College of Cardiology, Vol. 54, No. 12, 2009, pages 1072-1084
George RT, Jerosch-Herold M, Silva C, Kitagawa K, Bluemke DA, Lima JA, Lardo AC. Quantification of myocardial perfusion using dynamic 64-detector computed tomography. Investigative Radiology. 2007; 42(12):815-822
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