Physiologic and anatomic assessment of a canine carotid artery stenosis model utilizing phase contrast with vastly undersampled isotropic projection imaging.

Abstract

BACKGROUND AND PURPOSE:

Noninvasive assessment of the hemodynamic significance of carotid stenosis is often performed with MR angiography and supplemented with carotid Doppler sonography. Phase contrast with vastly undersampled isotropic projection reconstruction (PC-VIPR), a novel MR imaging technique, accelerates phase-contrast MR flow imaging and provides both images of the vessels and measurements of blood-flow velocities. For this study, we determined the accuracy of PC-VIPR blood-flow velocity measurements to determine pressure gradients across an experimental carotid stenosis.

MATERIALS AND METHODS:

A focal stenosis was surgically created in each common carotid artery of 6 canines. Digital subtraction angiography (DSA) was performed, and the degree of stenosis was determined using the North American Symptomatic Carotid Endarterectomy Trial methodology. A microcatheter was positioned in the carotid artery proximal and distal to the stenosis, and pressures were measured in the vessel through the catheter. PC-VIPR was then performed on a 1.5T MR imaging scanner with parameters producing 0.8-mm isotropic voxel resolution. From the velocity measurements, pressure gradients were calculated from the Navier-Stokes relationship to compare with the pressures measured by a catheter.

RESULTS:

Carotid stenoses in the 50%-85% range were produced in the 12 arteries. Pressure gradients across the stenoses ranged from 6 to 26 mm Hg. The pressure gradient calculated from the PC-VIPR data correlated (r = 0.91, P < .0001) with the actual pressure measurements.

CONCLUSION:

With PC-VIPR, a novel MR imaging technique, the hemodynamic effect of a stenosis on flow and pressure can be evaluated.

• Authors: A S Turk, K M Johnson, D Lum, D Niemann, B Aagaard-Kienitz, D Consigny, J Grinde, P Turski, V Haughton, C Mistretta
• Journal: AJNR. American journal of neuroradiology (AJNR Am J Neuroradiol) Vol. 28 Issue 1 Pg. 111-5 (Jan 2007) ISSN: 0195-6108 [Print] United States
• PMID: 17213435 (Publication Type: Journal Article)

Topics

• Animals
• Blood Flow Velocity (physiology)
• Blood Pressure (physiology)
• Carotid Artery, Common (pathology, physiopathology)
• Carotid Stenosis (pathology, physiopathology)
• Diastole (physiology)
• Disease Models, Animal
• Dogs
• Female
• Image Enhancement (methods)
• Image Processing, Computer-Assisted (methods)
• Magnetic Resonance Angiography (methods)
• Systole (physiology)