Detection of coronary stenosis and myocardial viability using a single intravenous bolus injection of BR14.
OBJECTIVE
The aim of the study was to determine whether coronary stenosis can be detected and myocardial viability assessed after myocardial infarction from a single venous bolus injection of BR14, a new ultrasound contrast agent.


BACKGROUND
BR14 is an ultrasound contrast agent that, like (201)Tl, demonstrates redistribution. Whether this principle can be used to determine myocardial viability is not known.


METHODS
Non-critical (n = 6) or flow-limiting (n = 4) stenoses were placed on coronary arteries of 10 open-chest dogs, which then underwent 2 h of coronary occlusion followed by reperfusion through the stenosis. Hyperemia was induced to create flow mismatch in the dogs with non-critical stenosis. Hyperemia was not induced in dogs with reduced resting coronary blood flow. All dogs were given 2 ml of BR14 as a bolus injection and serial images were obtained. Myocardial blood flow (MBF) was measured using radiolabeled microspheres. At the end of the experiment, tissue staining was performed to determine infarct size and topography.


RESULTS
Initial images demonstrated flow mismatch between the normal bed and that subtended by the stenosis (during hyperemia in dogs without critical stenosis and during rest in those with reduced resting MBF). The perfusion defect size correlated well with radiolabeled microsphere-derived hypoperfused zone (r = 0.89). Regions within the hypoperfused zone that had not undergone necrosis showed redistribution, whereas the necrotic regions showed a persistent defect, the size of which correlated well with infarct size (r = 0.80).


CONCLUSIONS
Because of its ability to redistribute, BR14 can define regions of relative hypoperfusion and also discriminate between infarcted and viable tissue within the hypoperfused zone after a single venous injection. This property lends itself to assessing myocardial perfusion during exercise stress.
Fisher
Nicholas G
NG
Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia, Charlottesville, Virginia 22908, USA.
Leong-Poi
Howard
H
Sakuma
Tadamichi
T
Rim
Se Joong
SJ
Bin
Jian Ping
JP
Kaul
Sanjiv
S
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D002470:Cell Survival / Q000502:physiology*; D003287:Contrast Media / Q000008:administration & dosage*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004195:Disease Models, Animal; D004285:Dogs; D004452:Echocardiography; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D007275:Injections, Intravenous; D008863:Microspheres; D008955:Models, Cardiovascular; D009206:Myocardium / Q000166:cytology* / Q000473:pathology / Q000648:ultrastructure*; D015588:Observer Variation
D003287:Contrast Media