2121 spin-labeled projection MR angiography of the carotid arteries
© Ioannis et al; licensee BioMed Central Ltd. 2008
Published: 22 October 2008
Magnetic resonance angiographic assessment of the extracranial carotid arteries is typically performed with use of gadoliunium-based contrast media. Gadolinium-based contrast media, however, have been shown to be causative of nephrogenic systemic fibrosis .
To present an arterial spin-labeling method for rapidly generating projection MR angiograms of the carotid arteries without use of contrast media.
This study was approved by our hospital's institutional review board. The imaging method is similar to that described by Sardashti  and Edelman  and consists of acquiring two images sets that, upon conclusion of the scan, are subtracted. The first image set is acquired after blood upstream of the imaging volume is tagged by an RF pulse, while the second image set is acquired without application of a tagging RF pulse. Subtraction of image sets in the complex domain eliminates background signal and creates a selective arteriogram. Imaging of 7 carotid arteries was performed on a Siemens Avanto 1.5 T scanner with a standard 6-channel head and neck coil. Imaging parameters were: sagittal-oblique slice orientation (parallel to the axis of the carotid bifurcation), single-shot balanced SSFP acquisition with TR/TE = 3.6/1.8 ms, 90 degree flip angle, GRAPPA acceleration factor of 2, 24 × 24 cm field-of-view, 256 × 256 matrix, 35 mm slice thickness, 2.5 sec between acquisition of image sets, 0.9 sec between RF tag and image acquisition, RF tag flip angle = 180 degrees, 4 averages, 20 sec imaging time. Contrast between the arterial and background signal, defined by the relation (A-B)/B where A and B denote arterial and background signal, was computed. Projected vessel lengths were also measured.
The proposed projection-based arterial spin-labeled angiographic technique depicts extensive lengths of the extracranial carotid arteries in only 20 seconds. Moreover, unlike previously described non-contrast approaches, cardiac gating is not required. Future work will investigate the usefulness of the method as a fast screening technique and evaluate the technique's accuracy in grading arterial stenoses.
This article is published under license to BioMed Central Ltd.