A comparison between two different concentration of contrast media with multi-detector CT for the study of abdominal vascular system [Confronto tra due diverse concentrazioni di mdc in TC multistrato per lo studio del sistema vascolare addominale ottimizzazione della metodica]

Purpose. To evaluate two different concentrations of contrast medium (CM) and two different acquisition techniques to obtain vascular images with multislice spiral CT (msCT). Materials and methods. Thirty patients referred for msCT examinations of the kidney or upper abdomen underwent evaluation of the abdominal aorta during the arterial phase, after giving their consent (GE Light Speed Plus). In the first part of the study (20 patients) the enhancement values measured at six different levels of the aortoiliac axis (celiac trunk, suprarenal aorta, subrenal aorta, aortal bifurcation, right iliac and left iliac) were compared after administering two different concentrations of iodinated contrast medium (300 and 370 mgI/ml) with two different acquisition techniques (HQ and HS). The flow rate was 3 ml/sec. In the second part of the study 10 patients were examined by changing the flow rate (2 and 4 ml/sec). Both quantity and quality assessments were conducted on axial images and on vascular reconstructions. Results. In the first part of the study the best results were obtained with the 370 mgI/ml concentration and with the HQ acquisition technique (pitch 3, table feed 7.5 mm/rotation, gantry rotation speed 0.5 s). The quality of reconstructions gradually improved before reaching 240 HU, above which image quality remained constant. The patients examined with a flow rate of 2 ml/sec showed a poor image quality, unlike those examined with a flow rate of 4 ml/sec where we observed the maximum threshold values and constant optimal vascular opacification, with no significant differences from the patients studied at 3 ml/sec. Conclusion. Our results indicate that, albeit on a limited number of patients, a higher concentration of CM and the use of an HQ technique allow a high quality examination to be obtained. The HS technique yields results comparable to those obtained with higher concentrations.