Coronary angiogenesis: detection in vivo with MR imaging sensitive to collateral neocirculation--preliminary study in pigs.
OBJECTIVE
To assess the ability to track neovascularization over time with a magnetic resonance (MR) imaging technique sensitized to new intramyocardial collateral development as a means of evaluating therapeutic angiogenesis.


METHODS
Magnetization preparation plus spatial frequency reordering was applied to distinguish new intramyocardial collateral vessels from normal circulation on the basis of geometric differences. A vascular occluder was inserted in 34 pigs, and they were assigned randomly to treatment groups with either placebo or angiogenic growth factor. Collateral extent determined with collateral-sensitive MR imaging was correlated with direct measurements by means of three-dimensional (3D) computed tomography (CT), coronary blood flow distribution determined with microspheres, and findings at histologic examination. Changes in the signal at collateral-sensitive MR imaging before and after treatment were assessed by two observers blinded to treatment.


RESULTS
The collateral extent determined with collateral-sensitive MR imaging correlated well with findings at 3D CT (r = 0.95) and with microspheres (r = 0.86). Furthermore, the collateral extent determined with collateral-sensitive MR imaging increased significantly (P < .001) in response to the administration of an angiogenic growth factor but not to placebo. The correspondence of findings at collateral-sensitive MR imaging to collateral neovascularization was confirmed at histologic examination.


CONCLUSIONS
The presence of intramyocardial collateral microvessels was accurately determined with collateral-sensitive MR imaging. The technique may be useful in clinical studies of therapeutic angiogenesis.
Pearlman
J D
JD
Department of Medicine, Cardiovascular Angiogenesis Research Center, Beth Israel Deaconess Medical Center-East, Boston, MA 02215, USA. jdp@shogi.bidmc.harvard.edu
Laham
R J
RJ
Simons
M
M
D000818:Animals; D003097:Collateral Circulation / Q000502:physiology; D003327:Coronary Disease / Q000175:diagnosis* / Q000503:physiopathology; D003331:Coronary Vessels / Q000503:physiopathology*; D017352:Echo-Planar Imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008955:Models, Cardiovascular; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000503:physiopathology; D018919:Neovascularization, Physiologic / Q000502:physiology*; D019047:Phantoms, Imaging; D013552:Swine; D014057:Tomography, X-Ray Computed