Final diagnosis
Aortic dissection.

Differential diagnosis
None.

Discussion
Aortic dissection is in most cases a degenerative process of the media which results in a subintimal hemorrhage, subsequent intimal tear, and extension of a false lumen. The disease may affect thoracic aorta alone, from ascending or descending aorta, or include the abdominal aorta, with or without the iliac arteries. 

In dissection of the ascending aorta, immediate surgery, i.e. operative placement of a graft, is important. Chronic dissection of the descending aorta can usually be treated conservatively when no ischemic complications are evident. The diagnostic information of aortic dissection - including location and extent of the dissection, identification of false and true lumen, thrombus of the false lumen, sites of entry and reentries, supraaortic and abdominal branch vessel involvement, flow rate in the false compared with the true lumen has been given by means of cineangiography and or conventional aortography.

Newer techniques have been developed, i.e. transthoracic or transoesophageal  echocardiography (TTE and TEE), helical CT and CTA, MRI and MRA, which provide similar or better results than those obtained with angiography. Previously conventional T1-weighted spin-echo (SE) sequences and 2D or 3D TOF combined with gradient echo cine sequences have been applied for the assessment of aortal dissection. Nowadays gadolinium-enhanced MR angiography (MRA) is most common in the assessment of thoracic and abdominal aortic dissection.

The described technique enables the whole aorta to be investigated in 15 minutes. The true and false lumen can be visualized, in particular on reformatted transverse slices. On slices (both original and refromatted) it is also possible to see thrombotic masses in the false lumen. The non-nefrotoxic gadolinium contrast is an advantage compared with CT and angiography. Compared with CTA the described technique offers shorter reconstruction times and higher resolution in the direction longitudinal. Another advantage is the possibility to measure the flow rate with MR which facilitates the assessment if the false lumen has an appropriate blood flow at the level of important aortic branches. This has an impact on the choice of treatment , as fenestration through the membrane may be indicated if the flow is too low resulting in ischemic organs. Entries and reentries can be visualized by transverse image reformation and by virtual endoscopy. When diffulties in interpretation occur, complementary transverse ECG-gated T1 SE images or cine gradient echo sequences are suggested for visualisation of the aortic arch and its branches.
Gadolinium-enhanced MRA with phase velocity mapping is a convenient method for assessment of  chronic dissection of the whole aorta. The technique is suggested to give all the information needed. In acute aortic dissection the technique may be used when the patient has impaired renal function.