Carotid magnetic resonance angiography: improved image quality with dual 3-inch surface coils

Abstract

Magnetic resonance angiography (MRA) hs inherent artifacts due to variation in velocity and direction of flowing blood in the carotid bulb and regions of stenosis. We examined the efficiency of dual 3-inch surface coils to delineate carotid artery flow better. Carotid MRA was performed on ten healthy volunteers and six patients, on a 1.5 T system. A special adapter was constructed to use with 3-inch (receive-only) coils, which were placed over the carotid bifurcations. Routine anterior neck coils were also used. Contiguous axial two-dimensional (45/8.7, 1.5 mm, flip angle 60 degrees) time-of-flight sequences were used. Image matrix was 256 x 256 with two signals averaged and acquisition time 6-10 min. These images were postprocessed and reformatted into angiographic views using a maximum intensity projection algorithm. Computer simulation of carotid artery blood flow throughout the cardiac cycle based on vessel contours derived from digital subtraction angiography was carried out by finite element analysis. Improved definition of vessel margin, particularly at the carotid bifurcation, and substantially increased signal-to-background ratio of flowing blood were obtained with 3-in-chcoils. Apparent loss of signal in the carotid bulb was diminished. In one patient, contiguous flow throughout a high-grade stenosis was well defined, with the surface coil method, while drop-off of signal was observed with routine neck coil imaging.

Advanced MRI for carotid plaque imaging

“…Several studies comparing T1-, T2-, and proton density-weighted black-blood techniques at 1.5- and 3-T have observed significant improvements in the signal-to-noise (SNR) and contrast-to-noise ratios and the overall image quality using the higher field strength system [ 14 – 16 ]. Further improvements to image quality can be achieved through the use of dedicated surface coils by boosting the SNR and minimizing the propagation of flow artifacts [ 17 , 18 ].…”

A three-coil comparison for MR angiography

“…Phased‐array coils (9–11), which consist of multiple surface coil elements, can provide significant coverage with very high sensitivity at the brain periphery and better depth sensitivity than a single surface coil. Phased‐array coils have been used for numerous MRA applications including peripheral (12, 13), abdominal, and cervical imaging (14–16). Recent coil designs have started to integrate phased‐array elements into volume‐like coils (17, 18).…”

Suboptimal contrast-enhanced carotid MR angiography from the left brachiocephalic venous stasis

“…To improve the quality of contrast-enhanced carotid MRA, many studies on new MR sequences have been published (3,4). However, certain factors such as venous stasis have not yet been considered.…”