BACKGROUND: Magnetic resonance angiography (MRA) is clinically useful but of limited applicability to small animal models due to poor signal resolution, with typical voxel sizes of 1 mm(3) that are insufficient to analyze vessels of diameter <1 mm. We determined whether surgically implantable, extravascular MRA coils increase signal resolution adequately to examine blood flow dynamics METHODS: A custom MRA coil was surgically implanted near the carotid artery of a New Zealand White rabbit. A stenosis was created in the carotid artery to induce complicated, non-laminar flow. Phase contrast images were obtained on multiple axial planes with 3T MRA and through-plane velocity profiles were calculated under laminar and complicated flow conditions. These velocity profiles were fit to a laminar flow model using ordinary least squares in order to quantify the degree of flow complication (Matlab). Flow was also measured with a Doppler flow probe; vessel diameters and flow velocities were compared with duplex ultrasound RESULTS: Carotid artery blood flow was 24.7 +/- 2.6 ml/min prior to stenosis creation and reduced to 12.0 +/- 1.7 ml/min following injury (n=3). An MRA voxel size of 0.1 x 0.1 x 5 mm was achieved. The control carotid artery diameter was 1.9 +/- 0.1 mm, and cross-sectional images containing 318 +/- 22 voxels were acquired (n=26). Velocity profiles resembled laminar flow proximal to the stenosis, and then became more complicated just proximal and distal to the stenosis. Laminar flow conditions returned downstream of the stenosis CONCLUSION: Implantable, extra-vascular coils enable small MRA voxel sizes to reproducibly calculate complex velocity profiles under both laminar and complicated flow in a small animal model. This technique may be applied to study blood flow dynamics of vessel remodeling and atherogenesis. Copyright 2010. Published by Elsevier Inc.
BACKGROUND: Magnetic resonance angiography (MRA) is clinically useful but of limited applicability to small animal models due to poor signal resolution, with typical voxel sizes of 1 mm(3) that are insufficient to analyze vessels of diameter <1 mm. We determined whether surgically implantable, extravascular MRA coils increase signal resolution adequately to examine blood flow dynamics METHODS: A custom MRA coil was surgically implanted near the carotid artery of a New Zealand White rabbit. A stenosis was created in the carotid artery to induce complicated, non-laminar flow. Phase contrast images were obtained on multiple axial planes with 3T MRA and through-plane velocity profiles were calculated under laminar and complicated flow conditions. These velocity profiles were fit to a laminar flow model using ordinary least squares in order to quantify the degree of flow complication (Matlab). Flow was also measured with a Doppler flow probe; vessel diameters and flow velocities were compared with duplex ultrasound RESULTS: Carotid artery blood flow was 24.7 +/- 2.6 ml/min prior to stenosis creation and reduced to 12.0 +/- 1.7 ml/min following injury (n=3). An MRA voxel size of 0.1 x 0.1 x 5 mm was achieved. The control carotid artery diameter was 1.9 +/- 0.1 mm, and cross-sectional images containing 318 +/- 22 voxels were acquired (n=26). Velocity profiles resembled laminar flow proximal to the stenosis, and then became more complicated just proximal and distal to the stenosis. Laminar flow conditions returned downstream of the stenosis CONCLUSION: Implantable, extra-vascular coils enable small MRA voxel sizes to reproducibly calculate complex velocity profiles under both laminar and complicated flow in a small animal model. This technique may be applied to study blood flow dynamics of vessel remodeling and atherogenesis. Copyright 2010. Published by Elsevier Inc.
Authors: Tamara N Fitzgerald; Benjamin R Shepherd; Hidenori Asada; Desarom Teso; Akihito Muto; Tiffany Fancher; Jose M Pimiento; Stephen P Maloney; Alan Dardik Journal: J Cell Physiol Date: 2008-08 Impact factor: 6.384
Authors: John A Ronald; Rhonda Walcarius; John F Robinson; Robert A Hegele; Brian K Rutt; Kem A Rogers Journal: J Magn Reson Imaging Date: 2007-10 Impact factor: 4.813
Authors: Oliver Kraff; Jens M Theysohn; Stefan Maderwald; Patrick C Kokulinsky; Zeynel Dogan; Alexander Kerem; Stefan Kruszona; Mark E Ladd; Elke R Gizewski; Susanne C Ladd Journal: Invest Radiol Date: 2009-09 Impact factor: 6.016