MRA of the thoracic vessels

Imaging of the thoracic aorta

“…High signal intensity/density within the false and true lumina is a finding consistent with patency, and allows for visualization of the intimal flap; in general the true lumen has a higher density/signal intensity than the false lumen, owing to faster flow [18]. Delayed phase imaging can be used to depict the false lumen better [19].…”

“…Flow-based methods of imaging (using time-of-flight [TOF]) or phase contrast (PC) properties yield bright blood images using gradient echo techniques [18]. Limitation of the latter techniques, however, is that they rely on the physical properties of flowing blood (velocity, direction etc.…”

“…Furthermore, the spatial resolution and signal-to-noise ratio provided by these two-dimensional techniques do not allow evaluation of small vessel lesions or small side branches [19]. The most-suited technique currently used in the evaluation of thoracic aortic anatomy and disease is dynamic subtraction magnetic resonance angiography (MRA), using Gadolinium (0.2 mmol/kg, flow rate of antecubital injection 2 mL/s) as intravenous contrast agent [18,[20][21][22][23][24]. Gadolinium shortens the T1 of blood, and therefore allows shorter imaging times.…”

“…After a plain MRI, intravenous contrast is administered. Using bolus timing (either by using a test bolus or real-time fluoroscopic triggering), the arrival of the contrast can be timed, and the contrast-enhanced sequence is performed [18,25]. This is followed by subtraction of the two series.…”

“…at the ductus arteriosus just distal to the origin of the left subclavian artery) [58].Three-dimensional Gadolinium-enhanced imaging is helpful in determinating coarctation severity by demonstrating collateral vessels (e.g. intercostals and bronchial arteries), that are indicative of the hemodyamic significance of the lesion, while black blood images can demonstrate e406 [ ( F i g u r e _ 2 1 ) T D $ F I G ] location and length of the aortic narrowing [18,19] ( figure 18). …”