Overuse of CT challenges pediatric imagers

June 15, 2006

One of the biggest mistakes made by specialists is overuse of CT in pediatrics, according to Dr. Donald Frush, chief of pediatric radiology at Duke University. As critical as multislice CT can be in evaluating pediatric patients, it’s not the right tool all the time.

One of the biggest mistakes made by specialists is overuse of CT in pediatrics, according to Dr. Donald Frush, chief of pediatric radiology at Duke University. As critical as multislice CT can be in evaluating pediatric patients, it's not the right tool all the time.

In a review of the top mistakes imagers make in pediatric CT imaging, Frush cited overuse as number one during a presentation at the Stanford Multidetector-Row CT meeting in San Francisco.

"Implicit in every CT procedure is an agreement that it is indicated," Frush said. "But 30% to 40% of CT exams have questionable indications. Ultimately, we are responsible for the use of CT, for obtaining diagnostic examinations, and for the safety of our patients."

The problem is not easily addressed, he said, acknowledging the lure of new devices combined with radiology business pressures. But ensuring that scans are designed to answer specific clinical questions is one way to reduce overuse.

Changes in technique and protocol can help when it comes to other common mistakes in pediatric practice. Frush sees poor contrast enhancement as one of these.

"One of the most critical aspects of scanning in children is timing the contrast with respect to the CT angiogram, abdomen, and chest," he said. "Timing is everything."

Frush also sees overuse of multiphase exams in pediatric practice. At Duke, only about 5% of all body MSCT exams in children are multiphase. But the average he sees in outside practices is 31%. When multiphase exams are indicated, as with renal studies, imagers should employ a lower dose precontrast exam and a lower contrast delayed exam, he said.

Pediatric exams typically use kVp values that are too high, Frush said. He recommended considering 80 to 120 kVp in chest, musculoskeletal, and CTA studies.

Another common mistake is failure to anticipate the need to perform reformations. To ensure best image quality when scanning for causes of abdominal pain, obstructions, and airways and in CT angiography, imagers should use the thinnest detector configuration possible, Frush said. Thin slices (such as 0.625) with a 30% to 50% overlap abet optimal reconstructions.

Pediatric patients should be prepared properly by scanning fast and sedating when necessary, Frush said. He recommended using intravenous contrast, which carries a low risk in pediatric populations, when indicated but particularly for abdominal pain. Adjusting dose protocols depending on organ systems is also suggested.

"Chest, MSK, and CTA are all amenable to lower dose scanning because they are intrinsically high contrast," Frush said. "Think about dose thresholds. How much do you really need?"