Dual-source computed tomography coronary artery imaging in children

Abstract

Computed tomography (CT) has a well-established diagnostic role in the assessment of coronary arteries in adults. However, its application in a pediatric setting is still limited and often impaired by several technical issues, such as high heart rates, poor patient cooperation, and radiation dose exposure. Nonetheless, CT is becoming crucial in the non-invasive approach of children affected by coronary abnormalities and congenital heart disease. In some circumstances, CT might be preferred to other noninvasive techniques such as echocardiography and magnetic resonance imaging for its lack of acoustic window influence, shorter acquisition time, and high spatial resolution. The introduction of dual source computed tomography (DSCT) has expanded the role of CT in the evaluation of pediatric cardiovascular anatomy and pathology. Furthermore, technical advances in the optimization of low-dose protocols represent an attractive innovation. DSCT can play a key role in several clinical settings in children, namely in the evaluation of patients with suspected congenital coronary artery anomalies, both isolated and in association with congenital heart disease. Moreover, it is able to assess acquired coronary artery abnormalities, as in patients with Kawasaki disease and after surgical manipulation, especially in case of transposition of the great arteries treated with arterial switch operation and in case of coronary reimplantation.

Coronary computed tomography angiography in children

“…Dual-source CT scanners have two tubes at a 90° angle, with second- and third-generation dual-source CT scanners achieving a temporal resolution of 66–75 ms, which allows for imaging of the entire heart during a single heartbeat [ 8 ]. This improved temporal resolution has opened the possibility for imaging coronary arteries in pediatric patients with fast heart rates while keeping in line with the ALARA (as low as reasonably achievable) principle.…”

“…Dual-source CT has better temporal resolution, at 66–75 ms vs. 140 ms for volume scanners. However, volume scanners have larger z-axis coverage without table movement, at 160 mm vs. 38.4–57.6 mm for dual-source CT [ 8 ].…”

“…In pediatrics, if coronary artery imaging is requested, often the goal is identifying the origins and proximal course for congenital coronary anomalies for preoperative planning or to evaluate aneurysms or significant stenoses in postoperative patients or those with inflammatory disorders such as Kawasaki [ 8 ]. With modern scanners, this information can frequently be obtained while children are free-breathing [ 8 ]. However, if distal coronary artery course and caliber evaluation are desired by the clinical service, breath-holding often becomes necessary, requiring the use of general anesthesia in younger children.…”

“…Additional artifacts from electrocardiogram (ECG) leads and other support and monitoring devices can affect image quality, particularly at lower kilovoltage peaks (70–80 kVp). ECG leads should be placed away from the thorax, on the arms and abdomen, to reduce this [ 8 , 16 ]. Because of the material differences in ECG leads, some types cause worse artifacts than others, and some leads that are safe for use in MRI also have fewer streak artifacts when used in CT. Also, the child must be in the isocenter of the scanner for optimal dose modulation with modern scanners [ 8 ].…”

“…The length of z-axis coverage plays a significant role in radiation dose, as mentioned. One paper with ranges of effective dose estimates for dual-source CT using different ECG-gating methods listed high-pitch spiral at 0.2–0.5 mSv, prospective ECG sequential (step-and-shoot) at 0.3–1 mSv, and retrospective ECG gated with dose modulation at 2–5 mSv [ 8 ]. For second- and third-generation dual-source CT scanners, a comparison of non-ECG-gated and high-pitch spiral ECG-triggered scans shows a similar effective dose (Table 1 ).…”