Properly screened children who are younger than 5 can remain awake while undergoing thoracic CT angiography (CTA) without compromising image quality, according to a retrospective study. The results support the use of thoracic CTA without general anesthesia in a select group of pediatric patients, the authors suggested.

The study was published in the January issue of the American Journal of Roentgeneology.

Thoracic CTA is used to evaluate disorders of the heart and lungs in pediatric patients, but obtaining motion-free images may be difficult with infants and young children who may move during the scans. Consequently, physicians must weigh the risks and benefits of ordering general anesthesia or sedation against the possibility of having to repeat procedures that expose the child to additional radiation.

Many radiologists opt for general anesthesia because they lack sufficient evidence about the outcomes of one approach compared with the other. To address that gap, Keira P. Mason, MD, of Children’s Hospital Boston, and colleagues designed a retrospective study to evaluate the quality of CTA images from young children and infants who received either general anesthesia or remained awake during the procedures.

They identified records of 135 patients 5 years old or younger (mean age, 1 year) who underwent thoracic CTA studies with a 64-MDCT scanner (Sensation 64, Siemens Healthcare) between 2005 and 2010 at their institution. The hospital had evaluated all pediatric patients to identify candidates who would be appropriate for undergoing thoracic CTA while awake. The screening process involved preappointment discussions with parents to assess the child’s tractability and the sleeping patterns of infants; incentives to keep the child still; and a mock trial on the CTA scanner table.

Of the 135 pediatric patients in the study, 70 percent had been selected to remain awake during their scans. The two patient groups were comparable in age and sex.

Two radiologists reviewed the CTA images independently. The images were deidentified and randomized before reviewers evaluated them for the presence and degree of motion artifacts in three anatomical zones: upper, middle and lower lung. Motion artifacts were defined as either double-imaged structures, blurring of the pulmonary vessels or pulsation artifacts. The degree of motion artifact was graded 0 to 3, from none to severe. They also reviewed images for the presence of atelectasis.

The radiologists were in agreement on 96 percent of the studies, and reached consensus on the remaining 4 percent. Image quality did not differ significantly between scans performed in awake and anesthetized children. In any combination of lung zones, 38 percent of studies of the awake group were affected by motion compared with 28 percent of studies of the general anesthesia group. There was no significant difference between the groups when the number of lobes with motion artifact was calculated for each thoracic CTA study. Atelectasis was present in 55 percent of studies in the awake group and 55 percent of studies in the general anesthesia group.

Based on the results, Mason and colleagues suggested that infants and children who fulfill the screening guidelines can remain awake when undergoing thoracic CTA studies, with imaging quality outcomes comparable to children who receive anesthesia.  

“The advantages of awake thoracic CTA studies are numerous, including reduced risk of morbidity related to sedation and anesthesia, flexibility of scheduling because the examination is not reliant on the availability of the anesthesia service, reduced cost of anesthesia services, and increased utilization of the CT scanner because the time the scanner is occupied decreases when anesthesia is not used,” they wrote. “Our findings show that screening of pediatric patients 5 years and younger for possibly undergoing thoracic CTA without general anesthesia has the potential to substantially reduce the sedation rate to 30 percent of patients.”

The authors recommended future studies using mock scanner training in children younger than 5 years be conducted to evaluate if the technique, in addition to screening, can help identify which children are appropriate candidates for remaining awake during CTA studies.

They listed several limitations in their study: The number of patients in the anesthesia group was small (40); and because all studies were performed on a 64-MDCT scanner, the results may not apply to other scanners and scanning speeds.