ABSTRACT
Adequate vascular enhancement is of paramount importance to the success of coronary CT angiography. The injection parameters and resulting synchronization protocols should be optimal (Table 19.1).
Table 19.1 Recommendations for contrast enhancement in CT coronary angiography
Parameters Coronary CTA
Comment Noncoronary CT
Comment
Injection Volume (ml) 100 increase when the scan range, and therefore the
scan time, increases (e.g. CABG) 100 increase when the scan range, and
therefore the scan time, increases (e.g. study of the entire thorax)
Rate (ml/s) 4 increase to 5ml/s when scan time is below 15s and the antecubital vein is large
3 a lower rate is preferable and allows longer enhancement
Iodine concentration (mg/ml)
350-400 preferably 400mg/ml 300-400 —
Synchronization Fixed delay (s)
18-20 increase of 5-10s in patients with reduced cardiac output
18-20 increase of 5-10s in patients with reduced cardiac output
Test bolus volume (ml)
15-20 or 15-20% of the main contrast-material bolus 15-20 or 15-20% of the main contrast-material bolus
rate (ml/s) delay (s)
4 TT+46s
4 TT+46S
Bolus tracking ROI
ascending aorta
positioned in the center of the vessel as seen on axial premonitoring images
ascending aorta
positioned in the center of the vessel as seen on axial premonitoring images
threshold (HU)
+100 no less than 75HU to avoid anticipated triggering from beam-hardening artifacts in the superior vena cava
+100 no less than 75HU to avoid anticipated triggering from beam-hardening artifacts in the superior vena cava
Others Bolus chaser volume (ml)
40 or 35-40% of the contrast-material bolus or same rate as contrast material
— not required
rate (ml/s) 4 — — CM administration site antecubital recommended because it reduces the chances of
contrast-material extravasation and the diffusion of contrast material in collateral venous pathways
antecubital recommended because it reduces the chances of contrast-material extravasation and the diffusion of contrast material in collateral venous pathways
side right recommended because the right subclavian and right recommended because the right subclavian
innominate veins are not crossing the aortic arch
and innominate veins are not crossing the aortic arch
In clinical practice, 16-row (or higher) multislice CT scanners require an injection volume of approximately 100ml for sufficient enhancement during the entire duration of the CT angiography scan. Because the recommended injection rate is 4ml/s, the contrast-material administration time will be 25s, which is a little longer than the average scan time.
