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[Techniques for the optimisation of coronary artery opacification in non-invasive angiography with a 16-row multislice computed tomography].

PURPOSE
To compare two different techniques to improve vessels opacification in coronary angiography with multislice CT (MSCT) scanner.


MATERIALS AND METHODS
Thirty consecutive patients were divided into two groups. In group 1, the synchronisation was obtained administering 20 ml of cm at 4 ml/s during a dynamic monitoring sequence. In group 2, the real time monitoring of the main bolus was used to trigger the scan. The CT angiography was performed in both groups by administering 100 ml of cm at 4 ml/s, with MSCT scanner and the following parameters: collimation 16 x 0.75 mm, rotation time 0.42 s, retrospective ECG gating. Three regions of interest were created in order to measure attenuation at: 1) ascending aorta (ROI 1); 2) descending aorta (ROI 2); 3) pulmonary artery (ROI 3). Attenuation was also measured at the origin of the main coronary arteries and their larger branches.


RESULTS
The average time/density curve showed lower enhancement in group 1 compared to group 2 in the first 4 s and 7 s in ROI 1 and ROI 2, respectively (p<0.05). The maximum enhancement value were 342 HU and 347 HU for group 1 in ROI 1 and ROI 2, and 356 HU and 352 HU for group 2 in ROI 1 and ROI 2, respectively. The attenuation at the origin of the main coronary arteries was higher in group 2 than in group 1 (p<0.05).


CONCLUSIONS
Real time monitoring technique allows to use 20% less cm and provides better and more homogeneous enhancement.