Mass General Hospital
SEPTEMBER 2009
ISSUE 19


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.

Figure 1. Multiplanar reformat (1A) of CT angiography (CTA) in aortic candy-cane view and 3-D volume rendered reconstruction (1B) demonstrates a focal area of duplication of the aortic arch, representing the normally present 4th arch and the persistent lower 5th arch (asterisks and arrows).
Figure A
Figure 1. Multiplanar reformat (1A) of CT angiography (CTA) in aortic candy-cane view and 3-D volume rendered reconstruction (1B) demonstrates a focal area of duplication of the aortic arch, representing the normally present 4th arch and the persistent lower 5th arch (asterisks and arrows).
Figure B
Figure 2. Coronal multiplanar reformat through the superior aspect of the thoracic spine shows a hemivertebrum at T2 (red arrow) and bifid 1st ribs (green arrows).
Figure C
Figure 3. 3-D volume rendered reconstruction of the facial bones shows a defect in the left aspect of the hard palate (blue arrow) which is contiguous with the nasal cavity consistent with the patient’s known cleft palate.
Figure D

(Click on images to enlarge)


Figure 1. 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.

REFERENCES
1. 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
2. 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

If you have enjoyed Cardiovascular Images eNewsletter, please forward to a friend!

Click here if you would like to unsubscribe to Cardiovascular Images eNewsletter.

Editors:
Suhny Abbara, MD
MGH Department of Radiology
Wilfred Mamuya, MD, PhD
MGH Department of Cardiology

Phone: 617-726-5954