Abstract:
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Purpose: Distribution volume of contrast (CDV) in myocardium has been used for studying myocardial viability after ischemic injury. We developed a technique to measure CDV using CT scanning.
Methods and Materials: 6 dogs were used in 5 non-transmural and 1 transmural ischemic studies. Non-transmural and transmural ischemia were created by complete occlusion below and above the 1st branch of the left anterior descending (LAD) artery respectively for 2 h before reperfusion. For CDV measurement, a 30 s cine scan was taken using a GE Medical Systems CT scanner without contrast and then repeated after constant infusion of contrast for 1 h (1 ml/kg of Qmnipague 300). To eliminate cardiac motion, images were reconstructed at 0.1 s interval and those at end-diastole (ED) were selected by image registration and averaged. CDV maps were generated by subtracting the averaged non-contrast enhanced ED image from the corresponding averaged constant infusion image and dividing the difference image by the enhancement in the aorta. CDV was measured in each dog at baseline and repeated at 4 h reperfusion and also at day 4, 7, 14, 21 and 28 post. In 4/6 dogs, the heart was removed following CDV measurement at day 28 post and scanned ex-vivo before it was sliced and stained with TTC.
Results: For non-transmural injury, mean CDV in the apical subendocardium peaked above 0.87±0.04 ml/g immediately after reperfusion from a baseline value of 0.38±0.07 ml/g (p<0.01 vs baseline), and gradually normalized to 0.5 ml/g at day 28 from day 7 post. CDVs in the lateral free wall of the left ventricle (LV) and the septum were 0.39±0.03 ml/g, and below 0.5 ml/g in the apical subepicardium at all times. For transmural injury, CDV in the apical subendocardium stayed above 0.9 ml/g at all post-baseline time points; CDV in the apical subepicardium decreased from 0.8 ml/g immediately after reperfusion to 0.6 ml/g at day 28 post. In all ex-vivo scans, a hyperenhanced rim was seen at the region that showed high CDV (>0.8 ml/g) in the corresponding CDV map. TTC staining further confirmed that the hyperenhanced rim was infarcted tissue.
Conclusion: Constant infusion CT imaging is a useful and non-invasive imaging technique for studying myocardial damage from ischemia and its evolution with time.
(T. L. : General Electric Medical Systems, Consultant (Self), Grant (Self))
Questions about this event email: tlee@imaging.robarts.ca
So, A,
Constant infusion CT imaging to assess myocardial injury. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3103305.html
