Anthropometric data for magnetic resonance imaging of the carotid bifurcation

To provide anthropometric data applicable to the design of protocols for high-resolution magnetic resonance imaging (MRI) of the carotid bifurcation, particularly those aimed at elucidating the role of local factors in carotid atherogenesis.

Axial black-blood MR images of the carotid bifurcation were acquired from 25 young, healthy volunteers and 25 older, asymptomatic patients, from which were measured a variety of quantities related to the orientation and placement of the bifurcation within the neck.

Descriptive statistics were obtained for the following quantities: separation of the bifurcation apices within (57.8+/-6.7 mm) and between (4.9+/-4.1 mm) axial slices; orientation of the bifurcation within the axial plane (31.7+/-26.9 degrees ), and of the common carotid artery (CCA) relative to the sagittal (7.5+/-7.1 degrees ) and coronal (7.9+/-7.8 degrees ) planes; depth of the bifurcation from the skin surface (29.5+/-7.2 mm); and neck width (125.9+/-14.4 mm).

In most cases, both carotid arteries may be captured, without aliasing, within a 12-cm field-of-view axial image; however, the two apices will rarely be captured within the same axial slice. The CCA is significantly oblique to the body axis, but at angles sufficiently acute to permit the use of axial slices. Finally, a significant linear relationship between neck width and carotid depth may be used to inform radio frequency (RF) coil selection prior to scanning a subject, and hence facilitate optimal imaging in light of the wide anatomic variations observed.