Carotid MRA--what advantages do the turbo field-echo and 3D phase-contrast sequences offer?

Our purpose was to investigate some of the newer MR angiography (MRA) techniques for studying the carotid arteries. Forty-two arteries in seven asymptomatic, healthy volunteers were studied using five MRA sequences: two conventional time-of-flight sequences, 2D time-of-flight (2DTOF) and 3D time-of-flight (3DTOF); 2D and 3D magnetisation-prepared, segmented time-of-flight sequences (2DTFE and 3DTFE); and a 3D phase contrast angiography (3DPCA) sequence. A protocol that could be realistically employed in a routine clinical situation was chosen. 2DTOF had significantly (P < 0.05) better signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) than 2DTFE. 3DTOF demonstrated better SNR than 3DTFE but 3DTFE demonstrated better CNR than 3DTOF. 3DPCA provided maximal anatomical coverage. No one sequence provided optimal anatomical coverage, accurate demonstration of the carotid bulb and maximal SNR and CNR. The combination of 3DPCA and a 3D inflow sequence was best. 2DTOF sequences are useful when only one brief sequence is practicably feasible.