Definition of the vessel outline for contrast-enhanced MR angiography and evaluation of ECG-triggered visualization of the thoracic aorta.

Purpose: The sharpness of the vessel contour in 3D contrast-enhanced MR angiography is defined by particular measurements of the signal intensity. To evaluate the facilities of an EGG-triggered data acquisition to optimize the MRA image quality of the thoracic aorta. Method: In phantom studies the sharpness of the vessel contour was defined as the distance of the extraluminal signal-minimum to the extraluminal maximum. Afterwards 30 examinations of the thoracic aorta with and without the use of an EGG-triggering were evaluated with regard to the sharpness of the vessel outline. Results: The presented definition of the signal intensity is suitable for objective measurements of the vessel outline. At the level of the ascending aorta, EGG-triggered data acquisition increased the image quality significantly. Conclusions: An easy, practicable definition enables measurements of the sharpness of the vessel outline. EGG-triggered data acquisition is recommended for optimal visualization, especially of the ascending aorta.