66 - TIPS AND TRICKS FOR RADIATION OPTIMIZED COMPUTED TOMOGRAPHY ANGIOGRAPHY IN 298 CHILDREN WITH KD: OUR EXPERIENCE OVER 10 YEARS

Background/

Aim: Coronary artery abnormalities (CAAs) of KD mandate precise diagnosis at presentation and on follow-up. ECHO is currently the standard for imaging coronary arteries has several limitations. Computed tomography coronary angiography (CTCA) is now being increasingly used for assessment of KD. Concerns of inordinate radiation exposure had been limiting its optimal integration into clinical practise.

The aim of this paper is to elaborate radiation optimization techniques on 128- detectors/ 192-detectors-dual-source (DSCT) and present our experience on 298 children in last 10 years (2013-2023).

Methods:

Scanning details: Initially for first 2-years (2013-2015; 34-children) we performed retrospective electrocardiographic (ECG)-triggered scanning as children have inherently high rates, but this technique resulted in high radiation (mean: 2.84 ± 0.62 mSv). Thereafter, we switched to ADAPTIVE electrocardiographic (ECG)- triggered scanning with current modulations (CorAdSeq). Innovative techniques to limit radiation were: low tube peak Kilovoltage-kV (fixed at 80), body size-adapted protocols (Seimens iDose), limited area coverage and field-of-view.

Use of Beta-blockers: We used oral Metoprolol 2mg/kg body weight two hours before the procedure.

Sedation: children < 5 years- Syrup triclofos (50mg/kg) was given 30 minutes before procedure; Intravenous midazolam (0.1mg/kg) was given to children not sedated by triclofos. Above 5 years, sedation was not required.

Calculation of radiation exposure: Effective radiation dose millisievert (mSv) was calculated by multiplying system generated Dose length product (DLP) with an appropriate conversion factor as per ICRP 103 publication recommendations (Table- 1).

Results:

CTCA was done on 298 patients with KD. Radiation exposure details of children where scanning was done retrospective electrocardiographic (ECG)-triggering (34) and tube kV > 80 (n=34) were excluded.  Radiation exposure data of 252/298 children where tube kV of 80 and scanning with CorAdSeq is presented.

There were 186 (73.9%) male and 66 (26.1%) female children with median age of 5 years [IQR=5(7,2)];  range (2 months to 11years).

As per ICRP publication 103 recommendations age group wise radiation exposure in presented in Table-2.

A CT dose less than 1 mSv was achieved in all children (mean 0.41 millisieverts). Image quality was appropriate and no patient required a repeat study. 

Conclusion:  In our experience, dual source CTCA is a feasible low radiation dose modality in evaluation in patients with KD that explicitly demonstrates CAAs of KD along the entire course of coronaries. This is an important advance in imaging of children with KD and has the potential of becoming the standard of care for evaluation of CAAs in KD.