Introduction of an individually optimized protocol for the injection of contrast medium for coronary CT angiography

Abstract

The aim of this study was to determine whether individually tailored protocols for the injection of contrast medium (CM) result in higher and more homogeneous vascular attenuation throughout the coronary arteries at coronary CT angiography compared with conventional injection protocols using fixed injection parameters. Of 120 patients included in the study, 80 patients were randomized into two groups. Group 1 received 80 mL of CM at 6 mL/s. For group 2 injection parameters were individually adjusted to patient weight, the duration of CT data acquisition, and attenuation parameters following a test bolus. In the control group (group 3) the volume of CM was adjusted to the duration of CT data acquisition and injected at 5 mL/s. Attenuation was measured in the proximal, middle, and distal right coronary artery (RCA), in the proximal and middle left anterior descending artery (LAD), and in cranial and caudal sections of both ventricles. Patient parameters, scan delay, and scan duration did not differ significantly between the groups. Mean CM volume was 82.5 mL (flow rate 5.1 mL/s) in group 2 and 73.5 mL in group 3. Attenuation in both RCA and LAD was significantly higher for group 2 vs. group 3 (RCA: 414.9 + or - 49.9)-396.1(+ or - 52.1) HU vs. 366.0(+ or - 64.3)-341.6(+ or - 72.5) HU; LAD: 398.9(+ or - 48.6)-364.6(+ or - 44.6) HU vs. 356.3(+ or - 69.5)-323.0(+ or - 67.2) HU). For group 1 vs. group 2 only attenuation in the distal RCA differed significantly: 396.1(+ or - 52.1) vs. 370.7(+ or - 70.5) HU. Individually tailored CM injection protocols yield higher attenuation, especially in the distal segments of the coronary vessels, compared with injection protocols using fixed injection parameters.

Contrast Media Administration in Coronary Computed Tomography Angiography – A Systematic Review

“…However, only four CM injection protocols make use of CM concentrations below 320 mg/ml [7,15,19,73]. The variation in injection rate was higher than for CM concentrations, varying between 2.5 ml/s [19] and 6 ml/s [55,63,70]. The majority of the included papers keep injection rate relatively constant when comparing different groups.…”

“…The majority of the included papers keep injection rate relatively constant when comparing different groups. Only a few studies mention substantial differences in flow rates between groups [19,55,61,75]. IDR ranged between 0.99gI/s and 2.22gI/s and proved to be very heterogeneous.…”

“…IDR ranged between 0.99gI/s and 2.22gI/s and proved to be very heterogeneous. A limited number of injection protocols stated usage of an IDR above 1.9gI/s [54,55,63,70]. All included publications that stated a flow rate below 4 ml/s also reported an IDR < 1.4gI/s [7,46,47,61,64,75].…”

“…Conflicting results were reported with regard to the influence of IDR on coronary attenuation. When the IDR differed between subgroups, various publications found significant differences in the attenuation of the coronary arteries in favor of a higher IDR [7,15,16,55,61,62,68,69,75]. When the IDR between subgroups was kept identical, numerous publications did not find statistically significant differences in coronary attenuation [7, 15, 19, 44 -46, 49, 51, 60, 70, 71].…”

“…When the IDR between subgroups was kept identical, numerous publications did not find statistically significant differences in coronary attenuation [7, 15, 19, 44 -46, 49, 51, 60, 70, 71]. In both groups (variable and identical IDR), other injection-related parameters varied substantially, making it difficult to determine the true influence of IDR on coronary attenuation [47,50,53,55,57,63,74]. Three studies report significant differences between CM concentrations in favor of higher CM concentrations [15,16,62].…”