Carotid Bifurcation

Because it has been proven that there is a link between the development of nephrogenic systemic fibrosis (NSF) and the application of high volumes of magnetic resonance (MR) contrast agents in patients with impaired renal function, interest in non-contrast-enhanced techniques for MR angiography has experienced a renaissance.

This set of images presents 5 different techniques for imaging the carotid bifurcation, one of the most critical and commonly diseased vascular regions within the entire arterial system. Except one (D), for best comparability, all exams were acquired with the same spatial resolution of 0.9 x 0.9 x 0.9 mm3 at 3 T (Magnetom Verio, Siemens Medical Solutions).

A, B and C feature non-enhanced techniques. (A) presents an example of a T2-weighted dark blood technique, which on the one hand offers depiction of the vessel lumen like the other techniques, but on the other hand offers the possibility of assessment of the vascular wall. (B) is an example of the “oldest” technique for MRA, it shows an example of a 3D time of flight (TOF) dataset. Both techniques can achieve very high spatial resolution, but suffer from long acquisition times. (C) is an example of an ECG gated TrueFISP sequence, a recently introduced technique for non-contrast-enhanced MRA.

(D) and (E) are both contrast enhanced techniques, with (D) being specifically one frame of a dynamic TWIST MRA of the carotid arteries and thus suffering from degraded spatial resolution compared to the other techniques. However, it is the only technique providing temporal resolution, in this case 3.5 sec/frame. (E) is the currently accepted standard of reference, contrast enhanced (non-dynamic) MRA.