[MR angiography of the heart and thoracic blood vessels. Use of rapid ECG-triggered techniques with multiplanar reconstruction capability]. / MR-Angiographie des Herzens und der thorakalen Gefässe. Anwendung schneller EKG-getriggerter Techniken mit multiplanaren Rekonstruktionsmöglichkeiten.

ABSTRACT

Segmented 2D times-of-flight (TOF) magnetic resonance angiography (MRA) with ECG gating is a suitable adjunct to conventional magnetic resonance tomography. Based on our experience with 106 patients, cardiovascular MRA primarily aids in the diagnosis of congenital heart disease, but is of minor importance for the evaluation of acquired cardiovascular disease, such as aortic aneurysms. Changes in flow dynamics as a result of spin dephasing may render partial signal loss. Due to flow turbulence and resulting signal loss distal to stenoses, difficulties may arise in correctly determining the degree of stenosis and differentiating between partial thrombosis and slowly flowing blood. The most promising approach for optimizing 2D TOF MRA is enhancement of the intravascular signal and suppression of background signal. For the equipment we use with a 0.5 Tesla scanner, the most powerful combination to enhance intravascular signal and suppress back-ground noise was applying a flip angle of 65 degrees and a short inversion prepulse. The influence of the flip angle and prepulse on the intravascular signal varies, dependent on the flow velocities and heart rates. Secondary reconstructions, such as the MIP technique, contribute to better spatial orientation by using rotating projection views. To avoid overprojection artifacts and loss of diagnostic information, 2D single slices should be the primary source of image analysis.