Molecular coronary MR imaging of human thrombi using EP-2104R, a fibrin-targeted contrast agent: experimental study in a swine model.
OBJECTIVE
The aim of this study was to investigate the use of a fibrin-specific contrast agent (EP-2104R, EPIX Pharmaceuticals, Lexington, Massachusetts, USA) for targeted molecular magnetic resonance (MR) imaging of human clot material removed from patients in a model of coronary thrombosis in swine.


METHODS
Freshly ex vivo engineered clots from human blood and human in situ developed clots removed from patients were delivered into the coronary arteries of nine domestic swine. For MR imaging a navigator-gated, free-breathing, cardiac-triggered 3D inversion recovery black-blood gradient echo sequence was performed prior to clot delivery (baseline), after clot delivery but prior to contrast media administration, and two hours after systemic (i.v.) injection of 4 micromol/kg EP-2104R. MR images were analyzed by two investigators and the contrast-to-noise ratio and Gadolinium (Gd) concentration in the clots were assessed.


RESULTS
On baseline images and prior to contrast media application no thrombi were visible. Post contrast administration all 10 coronary emboli (five ex vivo engineered clots and five human clots removed from patients) were selectively visualized as white spots with a mean contrast-to-noise ratio to the blood pool and the surrounding tissue of >12 and a mean Gd concentration of >100 microM.


CONCLUSIONS
Molecular MR imaging using the fibrin-targeted contrast agent EP-2104R allows selective visualization of human clot material in a model of coronary thrombosis in swine.
Spuentrup
E
E
Department of Diagnostic Radiology, Aachen Technical University, Aachen, Germany. spuenti@rad.rwth-aachen.de
Katoh
M
M
Wiethoff
A J
AJ
Buecker
A
A
Botnar
R M
RM
Parsons
E C
EC
Guenther
R W
RW
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000627:therapeutic use; D003328:Coronary Thrombosis / Q000188:drug therapy* / Q000473:pathology*; D004195:Disease Models, Animal; D005682:Gadolinium; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010455:Peptides; D013552:Swine
D003287:Contrast Media; C503783:EP-2104R; D010455:Peptides; D005682:Gadolinium