Personalization of CM Injection Protocols in Coronary Computed Tomographic Angiography (People CT Trial)

Abstract

Aim. To evaluate the performance of three contrast media (CM) injection protocols for cardiac computed tomography angiography (CCTA) based on body weight (BW), lean BW (LBW), and cardiac output (CO). Materials and methods. A total of 327 consecutive patients referred for CCTA were randomized into one of the three CM injection protocols, where CM injection was based on either BW (112 patients), LBW (108 patients), or CO (107 patients). LBW and CO were calculated via formulas. All scans were ECG-gated and performed on a third-generation dual-source CT with 70–120 kV (automated tube voltage selection) and 100 kVqual.ref/330 mAsqual.ref. CM injection protocols were also adapted to scan time and tube voltage. The primary outcome was the proportion of patients with optimal intravascular attenuation (325–500 HU). Secondary outcomes were mean and standard deviation of intravascular attenuation values (HU), contrast-to-noise ratio (CNR), and subjective image quality with a 4-point Likert scale (1 = poor/2 = sufficient/3 = good/4 = excellent). The t-test for independent samples was used for pairwise comparisons between groups, and a chi-square test (χ2) was used to compare categorical variables between groups. All p values were 2-sided, and a p<0.05 was considered statistically significant. Results. Mean overall HU and CNR were 423 ± 60HU/14 ± 3 (BW), 404 ± 62HU/14 ± 3 (LBW), and 413 ± 63HU/14 ± 3 (CO) with a significant difference between groups BW and LBW (p=0.024). The proportion of patients with optimal intravascular attenuation (325–500 HU) was 83.9%, 84.3%, and 86.9% for groups BW, LBW, and CO, respectively, and between-group differences were small and nonsignificant. Mean CNR was diagnostic (≥10) in all groups. The proportion of scans with good-excellent image quality was 94.6%, 86.1%, and 90.7% in the BW, LBW, and CO groups, respectively. The difference between proportions was significant between the BW and LBW groups. Conclusion. Personalization of CM injection protocols based on BW, LBW, and CO, and scan time and tube voltage in CCTA resulted in low variation between patients in terms of intravascular attenuation and a high proportion of scans with an optimal intravascular attenuation. The results suggest that personalized CM injection protocols based on LBW or CO have no additional benefit when compared with CM injection protocols based on BW.

A patient‐ and acquisition‐tailored injection approach for improving consistency of CT enhancement towards a target CT value in coronary CT angiography

“…Yanaha et al 27 . and Eijsvoogel et al 21 ,. and can be explained by a smaller dependence on body fat and an improved correlation with the cardiac output, which is known to relate to image enhancement.…”

“…Two target enhancements were investigated: a conservative HU target value of 525 HU (G2A), as well as a value of 425 HU (G2B) which falls within the ideal range for enhancement of the coronary arteries from 325 to 500 HU. 2 , 3 , 21 The total injected volume was kept fixed at 55 ml delivered at a rate of 5 ml/s to avoid an impact on the time‐to‐peak of the time‐enhancement curve. As an exception, high FFM‐patients with estimated optimal dilution percentages exceeding 100% received prolonged injection of undiluted CM until the optimal total iodine dose (TID) was delivered.…”

“…In the prospective study, phase 1 of the injection protocol was altered by diluting the CM with saline so as to inject the optimal iodine concentration (mgI/ml) to result in a predefined target arterial enhancement (HU target ). Two target enhancements were investigated: a conservative HU target value of 525 HU (G2A), as well as a value of 425 HU (G2B) which falls within the ideal range for enhancement of the coronary arteries from 325 to 500 HU 2,3,21 . The total injected volume was kept fixed at 55 ml delivered at a rate of 5 ml/s to avoid an impact on the time‐to‐peak of the time‐enhancement curve.…”

Effect of different injection rates and doses of contrast medium on the image quality of computed tomographic angiography in African grey parrots (Psittacus erithacus)

“…To distinguish plaques from vessel lumina, optimal vessel attenuation of 250-300 HU has been reported and enhancement > 350 HU may interfere with arterial calcifications [21]. Some scholars postulate that optimal attenuation should be higher for these small arteries and ideally lie at 325-500 HU, and that attenuation > 500 HU is unnecessarily high and leads to an underestimation of coronary calcifications [15,[23][24][25]. CTA accuracy is affected considerably by vessel attenuation.…”

Effect of Different Injection Rates and Doses of Contrast Medium on the Image Quality of Computed Tomographic Angiography in African Grey Parrots (Psittacus Erithacus)

“…To distinguish plaques from vessel lumina, optimal vessel attenuation of 250-300 HU has been reported and enhancement > 350 HU may interfere with arterial calci cations [30]. Some scholars postulate that optimal attenuation should be higher for these small arteries and ideally lie at 325-500 HU, and that attenuation > 500 HU is unnecessarily high and leads to an underestimation of coronary calci cations [22,[32][33][34]. CTA accuracy is affected considerably by vessel attenuation.…”