ARTERIAL-PHASE 3-DIMENSIONAL CONTRAST-ENHANCED MR-ANGIOGRAPHY OF THE CAROTID ARTERIES

OBJECTIVE. The purpose of this study was to evaluate TV injection of a single dose of gadopentetate dimeglumine for three-dimensional (3D) a rterial phase MR angiography of the carotid arteries. SUBJECTS AND MET HODS. Nine adult patients were serially imaged after IV injection of a single-dose bolus of gadopentetate dimeglumine at 1.5 T with a corona l single-slice spoiled two-dimensional (2D) gradient-echo acquisition encompassing the common carotid arteries and internal jugular veins. R egion-of-interest measurements for the nine patients generated a compo site arteriovenous signal versus time profile. The time interval of ma ximum arteriovenous signal difference was subsequently matched to the center of K-space in a 3D spoiled gradient-echo coronal MR angiography sequence (field of view, 24 or 26 cm; matrix size, 256 x 128; slice t hickness, 3 mm; number of slices, 12; one excitation; bandwidth, 16 kH z; and scan time, 29 sec). This protocol allowed us to selectively enh ance the arterial phase for carotid angiography. The protocol was then tested in 20 adult patients, after which we graded the degree of coin cidental venous enhancement and the presence of artifacts. RESULTS. On the 2D dynamic images, we identified a 10-sec window of selective art erial enhancement that began 20 sec after the start of the injection o f the bolus of gadopentetate dimeglumine, With 3D MR angiography, we s aw selective enhancement during the arterial phase of carotid MR angio graphy in nine of 20 patients, In seven of the remaining 11 patients, we saw the signal intensity of the arterial phase exceed a threshold g reater than two standard deviations from venous signal, In the final f our patients, we saw arterial signal equal to venous signal. We saw no ghosting artifact (from intravascular signal changing too rapidly dur ing phase encoding) in any patient. CONCLUSION, By precisely timing th e infusion of a single dose of gadopentetate dimeglumine, we were able to selectively enhance the arterial phase on 3D MR angiograms of the carotid arteries.