In the modern evaluation of congenital heart defects (CHD) 3 major non invasive modalities are used: echocardiography (echo), magnetic resonance imaging (MRI), and cardiac-gated computerized tomographic angiography (CTA). Echo and MRI have their limitation in demonstrating complex, vascular structures and precise three-dimensional anatomic relationships. The major disadvantage of CTA has been ionizing radiation.
The purpose of this study was to assess the radiation dosage using new generation CT machine for the evaluation of CHD.
Patients and Methods: 87 infants undergoing CTA during a 12 month period for congenital heart disease were included in the study. Scans of the heart and great vessels were performed under sedation, using the advanced CT scanner, GE Revolution, with axial technique, reduction of dose parameters (KV & MA) and using iterative reconstruction to reduce radiation and with coverage of 80-160 mm in one step. Anatomical and other clinically relevant data were recorded. CTA findings that affected clinical management were also recorded. CTA image quality was assessed by the ability to adequately see the coronary arteries. All scans were evaluated by a pediatric cardiologist and pediatric radiologist. Effective radiation dose was calculated for each scan.
Results: A total of 87 CTA scans were performed in 82 infants; mean age was 63 days (range: 1-270), mean weight was 3.65 Kg (range: 1.8-6.5). Diagnostic quality was excellent in 85/87 of the scans. In 81/87 (93%) of cases, CTA supplied additional information over echo, which helped planning for optimal surgical intervention. Calculated average radiation exposure was 0.3 mSv (range- 0.18-0.45) which is low compared to what is written in the literature.
Conclusions: CTA continues to be a promising, fast, non-invasive technique for assessment of infants with CHD. It supplies important complementary information to echo and may frequently obviate the need for catheterization. With the newest generation CT machines, we are able to reduce radiation exposure to a very low level.
