title: Magnetic resonance angiography of collateral vessel growth in a rabbit femoral artery ligation model.
abstract: Collateral vessel growth was visualized in a rabbit femoral artery ligation model by serial contrast-enhanced magnetic resonance angiography (MRA) at 1.5 T in comparison with X-ray angiography (XRA). XRA and MRA were performed directly after femoral artery ligation (day 0+) and after 7 and 21 days. XRA (in-plane resolution, 0.3x0.3 mm) was performed with arterial catheterization for fast injection of iodinated contrast agent just proximal to the aortic bifurcation. MRA (in-plane, 0.6x0.6 mm) was performed at 1.5 T with a five-element phased-array coil and slow injection of gadolinium-based MR contrast agent into an ear vein. Collateral vessel scores on two-dimensional XRA projections and on three-dimensional digitally subtracted rotational MRA maximum intensity projections were obtained by two observers and compared. Collateral vessel counts and minimal detectable vessel diameters for MRA and XRA were combined in a computational flow model to interpret differences in spatial detection limits between imaging modalities in terms of flow. Collateral vessel scores were significantly higher in the ligated limb at day 7 (P < 0.05) and more so at day 21 (P < 0.001), in comparison with day 0+ or in the non-ligated control limb on both XRA and MRA. Significantly more (smaller) vessels were visualized with XRA than with MRA, particularly on day 21 (P < 0.05). Inter-observer agreement was high for both XRA (kappa = 0.82) and MRA (kappa = 0.78). The flow model showed that collateral vessels with diameters > 0.3 mm scored by XRA as well as MRA represent nearly 100% of the total blood flow, whereas smaller (0.1-0.3 mm diameter) vessels that can only be detected with XRA contribute little to the blood flow. Serial contrast-enhanced MRA can non-invasively visualize sub-millimeter collateral vessels that represent nearly 100% of the restored blood flow, in a femoral artery ligation model.
authors.affiliation: Department of Radiology, Maastricht University Hospital, Maastricht, The Netherlands. qdlu@rdia.azm.nl
authors.forename: Quido G
authors.initials: QG
authors.lastname: de Lussanet
authors.forename: Jolanda C G
authors.initials: JC
authors.lastname: van Golde
authors.forename: Regina G
authors.initials: RG
authors.lastname: Beets-Tan
authors.forename: Michiel W
authors.initials: MW
authors.lastname: de Haan
authors.forename: Daniëlle V J
authors.initials: DV
authors.lastname: Zaar
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Post
authors.forename: Maya S
authors.initials: MS
authors.lastname: Huijberts
authors.forename: Nicolaas C
authors.initials: NC
authors.lastname: Schaper
authors.forename: Jos M A
authors.initials: JM
authors.lastname: van Engelshoven
authors.forename: Walter H
authors.initials: WH
authors.lastname: Backes
mesh_terms: D000818:Animals; D001157:Arterial Occlusive Diseases / Q000473:pathology*; D003097:Collateral Circulation / Q000502:physiology*; D003287:Contrast Media; D005263:Femoral Artery / Q000254:growth & development* / Q000293:injuries / Q000473:pathology*; D007089:Image Enhancement / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D018919:Neovascularization, Physiologic; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media