Jongmin John Lee MD, PhD, Presenter: Nothing to Disclose

Ju-Young Kwon BSC, Abstract Co-Author: Nothing to Disclose

Jongmin Park, Abstract Co-Author: Nothing to Disclose

Jihoon Hong, Abstract Co-Author: Nothing to Disclose

Eun-Ju Kang, Abstract Co-Author: Nothing to Disclose

Sung Won Youn MD, Abstract Co-Author: Nothing to Disclose

For compounder-less evaluation of the impact by scanning and enhancing parameters on the first-pass contrast bolus geometry during dynamically enhanced CT angiography

A self-made closed-circuit pulsatile flow system was used for simulating pulmonary-aortic circulation. Heart rate setting ranged from 50 to 90bpm. The other flow parameters were set to be constant. Contrast injection rate was 1-5ml/sec and injection duration was fixed to 2 seconds. Iodine concentration of contrast media was 270-379mg/cc. CT tube voltage was set as 80, 100, and 120kVp. The other CT scanning parameters were fixed as constants. After bolus enhancement, at scanning module in flow system, 0.45-sec interval, single slice 16-channel CT scan repeated for 90 seconds. A time-HU curve was plotted on aortic lumen at every data set. Time-HU curve parameters were compared with input variables using a step-wise multiple regression analysis. 

Total 135 data sets were acquired. The peak enhancement increased mainly by faster iodine deliver rate (IDR) and additionally by lower tube voltage (R2=0.816 and 0.919, p<0.001). Whereas, iodine concentration of contrast media and heart rate showed no incremental impact on peak enhancement. The time-to-peak enhancement was shortened by higher heart rate and additionally by faster IDR (R2=0.860 and 0.900, p<0.001). The bolus expansion ratio was decreased by higher heart rate (R2=0.807, p<0.001). This influence increased by sequentially adding IDR and iodine concentration. Significantly influencing factors to the maximum ascending and descending gradients were IDR, tube voltage, and heart rate (p<0.001). Recirculation density was influenced by IDR, tube voltage, heart rate, and iodine concentration (p<0.022).

Among four input variables in this study, IDR and heart rate were critical variables to bolus geometry during first-pass arterial enhancement. Next, the tube voltage influenced on bolus geometry significantly, whereas iodine concentration of contrast media was revealed as an insignificant factor. Proper kVp and IDR would generate proper bolus geometry independently on the formulation of iodine contrast media.

The iodine delivery rate and kVp, rather than iodine concentration, are critical parameters for superior bolus geometry during dyanmically enhanced CT. 

Lee, J, Kwon, J, Park, J, Hong, J, Kang, E, Youn, S, Dynamic CT Scanning and Enhancing Parameters’ Impact on Contrast Bolus Geometry during First-pass Arterial Enhancement: Well-controlled in Vitro Evaluation Using a Pulsatile Flow Model.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045621.html