AJR: Chest ultrasound viable alternative to CT for pediatric pneumonia

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Chest ultrasound is a viable alternative to chest CT in evaluating pediatric patients with pneumonia and parapneumonic effusion, according to a study published in the December issue of the American Journal of Roentgenology.

According to Jessica Kurian, MD, department of radiology at Albert Einstein College of Medicine and Montefiore Medical Center in New York City, and colleagues community-acquired pneumonia is common in the pediatric population with 40 cases diagnosed annually per 1,000 children in Europe and North America.

Chest CT has traditionally been used to evaluate the disease process in children but, according to the authors, with the increasing concern with radiation exposure risks, they decided to retrospectively compare chest ultrasound and chest CT in 19 children (nine girls and 10 boys, age eight months to 17 years) admitted with complicated pneumonia and parapneumonic effusion between December 2006 and January 2009.

The researchers evaluated the images for effusion, loculation, fibrin strands, parenchymal consolidation, necrosis and abcess.

Chest ultrasound was performed by two experienced staff ultrasound technologists on an iU22 ultrasound system (Philips Healthcare), an HDI 5000 ultrasound system (Philips Healthcare) or an Acuson Sequoia 512 ultrasound system (Siemens Healthcare). Chest CT was performed on an MX-8000 IDT 16-MDCT scanner (Philips Healthcare), a Brilliance 16-MDCT scanner (Philips Healthcare Electronics) or a LightSpeed VCT 64-MDCT scanner (GE Healthcare).

The researchers found that 18 of the patients had an effusion on both chest ultrasound and chest CT, and one had no effusion on either exam. Fifteen effusions were loculated on chest CT and 13 were loculated on chest ultrasound. Fibrin strands were identified in all patients with effusion on chest ultrasound except for one patient with only trace fluid; some patients showed few fibrin strands, whereas others showed numerous strands of variable thickness.

Although presumably present, the authors wrote that fibrin strands "could not be clearly delineated" on any of the chest CT images.

Of the 14 patients who underwent video-assisted thoracoscopy, five had surgically proven parenchymal abscess or necrosis. Chest ultrasound had been able to show parenchymal abscess or necrosis in four of those patients and chest CT in three.

The authors said their study was limited by its small sample size, as well as the fact that chest ultrasound was not evaluated in real time because the study was retrospective.

Kurian and colleagues concluded that chest CT didn’t provide "any additional clinically useful information" that was not also seen on ultrasound. Considering that chest ultrasound has has an advantage in portability, does not require patient sedation and has superior ability to detect fibrin strands within an effusion, the authors suggested that evaluation of children with complicated pneumonia include chest ultrasound as well as chest radiography.