[The aortic aneurysm in the magnetic resonance tomogram].
Aortic aneurysms can be visualised in the transverse, sagittal and coronary planes using magnetic resonance (MR) thereby enabling their cranio-caudal distension as well as their breadth and depth to be accurately determined. The important question concerning the vessel exits of the main branches of the aorta and their involvement in the aneurysm can be reliably answered. In the case of dissecting aortic aneurysms, the two lumina as well as the dissected vessel wall can be seen in the image. By choosing suitable recording parameters it is possible to differentiate between flowing blood and a thrombus attached to the vessel wall. The thrombus is recognisable from the decrease it causes in the signal intensity of the T2-selected image, whereas flowing blood emits a stronger signal in the T2-selected image than in the T1-selected image. An indication of the flow behaviour and flow rate of blood can be obtained from the differences in the signal intensity distribution in the vessel lumen.