Pediatric CT: Growing Pains

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Growing up is a tough business. Safety is constantly on the radar; questions seem incessant; solutions can be elusive; and consistency appears improbable. But after 18 or so years, the end result more than justifies the inputs. The similarities between shepherding a toddler to teen years and beyond and managing an imaging modality from near universal utility to safe, targeted use are striking.

Indeed, there are echoes of the turbulent teen years in the spate of headlines questioning the role of pediatric CT. In June, the situation may have reached its apex (or nadir) when a study published in The Lancet linked childhood CT scans with slight increases in risks for leukemia and brain cancer. The researchers preached caution, emphasizing the small, but absolute risk of developing cancer after a CT study.

This study and others have fueled a shift in pediatric CT imaging patterns, particularly in academic medical centers and children’s hospitals. As some sites have sprinted ahead, others are taking baby steps. Lower pediatric patient volumes, less favorable radiologist and technologist staffing ratios and variable levels of technologist expertise present formidable challenges as mainstream radiology practices attempt to keep up with academic medical centers and children’s hospitals.

CT vs. US – A Diagnostic Dilemma
CT vs. US - 163.91 Kb
Left image: Four serial images from a lower dose CT scan for appendicitis. This demonstrates (yellow arrow) an appendicolith blocking the orifice of the appendix. The rest of the appendix (blue arrow) is dilated and there is increased vascularity to the appendix with periappendiceal inflammatory change. Right image: Ultrasound shows a blind ending tubular structure that represents the inflamed appendix. The tip of the appendix (yellow arrow) measures 10 mm. A normal appendix should measure 6 mm or less.
Source: Marilyn J. Goske, MD, Cincinnati Children’s Hospital Medical Center

The curious case of the appendicitis algorithm

Suspected appendicitis may best illustrate the challenges of substituting an alternative imaging modality for CT among pediatric patients. Research supports ultrasound as the initial imaging tool in the evaluation of pediatric patients with suspected appendicitis. However, translating research into practice is a gradual process.

Use of CT in children presenting to emergency departments with nontraumatic abdominal pain increased from 2 percent in 1999 to 16 percent in 2007, according to a study published online April 24 in Radiology. The study mined data from the National Hospital Ambulatory Medical Care Survey for 16.9 million pediatric emergency department visits. The researchers reported one anomaly. Patients at pediatric EDs were more than 25 percent less likely to undergo CT even after adjustment for other characteristics.

Take, for example, Cincinnati Children’s Hospital Medical Center (CCHMC). The center has switched its imaging algorithm for patients with suspected appendicitis, says Marilyn J. Goske, MD, staff radiologist and chair of Alliance for Radiation Safety in Pediatric Imaging. Patients are referred to ultrasound as the initial imaging exam, and proceed to CT, if indicated. CT may be ordered for children with perforations or atypical findings.

The shift from CT to ultrasound was challenging, says Goske. CCHMC has many advantages, including 24/7 coverage of pediatric sonographers. “There is a learning curve when a department tries to switch from CT to ultrasound. There has to be a commitment on the part of surgeons and other clinicians that we may need to perform both studies for a period of time [as sonographers develop skills].”

While children’s facilities are able to overcome such hurdles, general radiology practices may be unable to initiate the change.

1, 2, 3 Tips to Support Dose Reduction
1. Look for online, just-in-time learning modules from CT vendors and professional societies. Options may include live chat, social networking and quick tip sheets embedded into the CT console.

2. Create a structure to support collaboration between technologists, physicists, radiologists and other specialists. Protocol modification can yield significant reductions in radiation exposure by substituting single phase studies for multiple phase scans, reducing the extent of coverage or lowering dose. Lower quality images may suffice for certain indications; however, technologists need to understand parameters and expectations. “Make sure technologists are adhering