Hyperpolarized gas MRI targets infants’ lung disease

Diffusion hyperpolarized helium-3 MRI could provide a noninvasive means to diagnose and manage children with bronchopulmonary dysplasia, according to a study presented at the 2006 International Society for Magnetic Resonance in Medicine meeting in May.

Bronchopulmonary dysplasia (BPD) affects preterm infants whose lungs start performing the vital gas exchange before their alveoli are fully developed, resulting in inflammation, injury, and deficient lung development. Physicians currently lack the data and means to properly diagnose the condition or assess treatment response.

"It is very difficult for us to really understand what's going on with these children because we don't have many good ways of assessing their lung function. They are much too young to perform spirometry, so we just follow them clinically," said principal investigator Dr. Talissa A. Altes, a pediatric radiologist and lung imaging specialist at the Children's Hospital of Philadelphia.

Altes and a multicenter group of researchers from Philadelphia and Virginia enrolled two groups: 32 healthy subjects aged four to 19 with a history of full-term birth, and 13 subjects aged five to 14 with a history of preterm birth complicated by subsequent BPD. All underwent diffusion MRI at 1.5T during a breath-hold following inhalation of hyperpolarized He-3/nitrogen and spirometry. The investigators performed apparent diffusion coefficient (ADC) mapping for lung volume quantitation.

They found children with a history of preterm birth and BPD had elevated ADC values and the same or slightly lower lung volumes compared with age-matched healthy controls. Findings confirmed histologic data showing children with BPD have larger but fewer alveoli.

The group average of the mean ADC was greater for the BPD subjects (0.198 cm²/sec) than for healthy subjects (0.157 cm²/sec). After correcting for age, the group average of the mean ADC remained elevated for BPD subjects (0.223 cm²/sec) relative to healthy subjects (0.181 cm²/sec). Several other measurements showed a statistically significant difference between healthy and BPD subjects. Researchers graded all coronal ADC maps for healthy subjects as homogeneous. More than one-third of BPD subjects, on the other hand, had heterogeneous ADC maps.

Although some children appear to outgrow their disease, others remain symptomatic, having oxygen requirements, shortness of breath, or poor exercise tolerance. Diffusion hyperpolarized He-3 MRI could provide a valuable tool for the proper diagnosis and management of these patients, Altes said.

"Our hope is that this technique will be a quantitative method to assess the efficacy of treatments and of improving alveolarization in these children," she said.

For more information from the Diagnostic Imaging archives:

Diffusion MR technique shows promise for pediatric lung assessment

Low-dose MSCT sharpens pediatric lung image

MR aids ventilation/perfusion lung studies

Dynamic He-3 MRI captures added lung airway details