- Coronal SSFSE / SS TSE / HASTE
- Axial T1 Double IR
- Sagittal Oblique "Candy Cane"T1 Double IR
- Sagittal 3D CE MRA + RECONS
Cardiac Gating
OPTIONAL:
- AX FIESTA
- LAO (CANDY CANE) FIESTA
(Do a second post gad run immediately after first, allowing for a quick 5 sec breathhold)
The thoracic aorta is generally examined using ECG-gated T1-weighted spin echo sequence, ECG-gate cine gradient echo sequences (Higgins, 1992) and contrast enhanced MR angiography (Prince et al., 1996). Occasionally T2-weighted SE is used in areas of aortic wall thickening to identify active inflammation.
The T1-weighted sequences produce a static black blood image where the movement of spins return a signal void, as flowing blood passes through the slice of interest in between a 90 degree and 180 degree RF pulse (Jara & Barish, 1999). The T1-weighted sequences allow the identification of dissecting flap which appears as a thin, linear structure of intermediate signal between the true and false lumens (Nienaber & Knap, 2002). T1-weighted sequences also allow the depiction of aortic wall thickening as in the case of intramural haematoma. Depending on the age of the haematoma, the area of thickening may be isointense or hyperintense relative to skeletal muscle (Krinsky et al., 1997).
--> Anatomic and physiologic information is obtained using ECG-gated cine gradient echo imaging. The sequences results in dynamic bright blood images where flowing blood returns a bright signal due to flow related enhancement by the application of a single radiofrequency pulse followed by rapid gradient refocusing with flow compensation. The magnitude of the signal depends on the flow of blood and thus enables the practitioner to differentiate between true and false lumen in aortic dissection (Flamm et al., 1996) and characterization of intramural haematoma (Murray et al., 1997). In addition 3D contrast-enhanced MRA is a rapid and accurate image sequence that assess the dimension of the dissection, the involvement of the arch vessels and side branches without ECG or respiratory gating. Unfortunately, CEMRA is insensitive to intramural haematoma, and so this sequence compliments black blood imaging protocol
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