Cardiac CT in the Preoperative Diagnostics of Neonates with Congenital Heart Disease: Radiation Dose Optimization by Omitting Test Bolus or Bolus Tracking

Abstract

Rationale and Objectives: Congenital heart diseases (CHD) belong to the leading causes of infant mortality worldwide. Prognostic improvements result from multimodal therapy strategies leading to an increased demand for noninvasive imaging. The aim of the study was to further optimize cardiac CT radiation dose by omitting the test bolus or bolus tracking scan, which can have a relevant share of radiation exposure, especially in neonates. Materials and Methods: This retrospective study included 25 neonates with CHD who received a CT angiography (CTA) from 2009 to 2018. The examinations were performed as a high-pitch CTA (pitch 3.4, 80 kV) with manual contrast administration (1.5 ml/kg body weight) and fixed scan delay depending on the respective heart defect. Diagnosis, adverse events, radiation dose parameters, objective (contrastto-noise ratio) and subjective (4-point Likert scale) image quality as well as diagnostic accuracy compared to intraoperative findings was assessed. Results: All examinations were diagnostically evaluable without adverse events. The median CT dose index volume (CTDI vol) was 0.50 mGy (range, 0.15À0.94), the median dose-length product was 8 mGy £ cm (range, 3À17). The estimation of the effective dose by Monte Carlo simulation revealed lower median dose levels 0.66 mSv (range, 0.25À1.40 mSv) than previously published in comparable groups. All examinations achieved a very good mean image quality score of 1.2 § 0.4 with only minimal image noise and mean contrast-to-noise ratio of 16.1 § 7.0. Diagnostic accuracy was 100 % as cardiac anatomy revealed no new diagnoses or significant differences in the subsequent cardiac surgery. Conclusion: Cardiac high-pitch CTA of neonates with CHD can be performed safely and dose-reducing without additional test bolus or bolus tracking scan. With very good image quality, it provides a detailed insight into the cardiac anatomy and thus enables a differentiated, noninvasive therapy planning.

Diagnostic accuracy of lower-dose cardiac CT in evaluating young infants with non-coronary complex congenital heart disease on a 64-slice multidetector CT scanner

“…We reported a mean effective radiation dose of 0.39 ± 1.2. Table 6 displays previously published radiation doses of CCT studies in young infants applying different ECG-gating techniques, using different scanners, and contrast-timing techniques in the context of our study dose (15,16,18,25–30). Our study’s suggested protocol achieved a low dose of radiation compared to previous studies.…”

“…For the adjustment of contrast-opacification timing, Goo and Yang (31) (24). Lastly, Schindler et al tried a scan delay of 8 s, aiming to opacify the pulmonary circulation or the right heart side and 12 s for the opacification of the aorta and the left heart side with some variability according to the heart defect and its associated hemodynamics (15). In our study, we used an estimated scan delay of 4 s, optimized to opacify the right heart side or 8 s for the opacification of the left side or aorta added to the calculated contrast injection time that was not fixed and could be adjusted according to the size of the heart chamber and the expected associated hemodynamics.…”

“…Even though the developed CT techniques and protocols have been used for children with CHD, there are scanty publications on how to perform high-quality exams following the ALARA (as low as reasonably achievable) principle for neonates with CHD (15). Therefore, the aim of the present study was to assess the accuracy of the ultra-low-dose cardiac CT (CCT) for neonates and infants with CHD using non-ECG-gated scans and discarding the use of bolus tracking or test bolus contrast-timing techniques.…”

Radiation dose optimization in diagnostic and interventional radiology: Current issues and future perspectives

“…tube modulation, kV modulation in smaller size and younger patients, z-axis overscan, scan length limitation, use of iterative reconstruction algorithms, use of dual energy (particularly important for contrast enhanced exams in patients with renal function problems), use of machine learning and artificial intelligence algorithms [22,[48][49][50][51][52][53][54]. Cardiac high-pitch CT angiography of neonates with congenital heart diseases can be performed safely and with dose reduction without additional test bolus or bolus tracking scans [55]. Demb et al 2017 provided a comprehensive optimization step approach by analyzing 158,274 diagnostic CT scans and concluding that by reviewing institutional doses and sharing dose-optimization best practices, lower radiation doses for chest and abdominal CT, and more consistent doses for head CT were reported [56].…”