Martha Kerr

November 28, 2011

November 28, 2011 (Chicago, Illinois) — Approximately half of the neonates who receive extracorporeal membrane oxygenation (ECMO) have cerebral atrophy. Magnetic resonance imaging (MRI) has shown that the N-acetylaspartate/creatine (NAA/Cr) ratio was reduced in these children in frontal and parietal white matter and in the pons, researchers reported here at the Radiological Society of North America 97th Scientific Assembly and Annual Meeting.

A team from the Children's Hospital of Pittsburgh, led by Ashok Panigrahy, MD, from the Department of Radiology, University of Pittsburgh, Pennsylvania, used MRI to compare the metabolic profiles in the brains of 34 neonates (mean postconceptional age, 43.4 ± 3.3 weeks) surviving ECMO with those of 60 age-matched control subjects.

Reasons for ECMO included sepsis, meconium aspiration, primary pulmonary hypertension, and congenital diaphragmatic hernia. Neonates with congenital heart disease were excluded.

The researchers examined 4 brain regions: white matter in the parietal and frontal regions of the cortex, the pons, and occipital grey matter. Absolute concentrations and metabolite ratios in the different regions in the 2 groups were compared. "All studies were performed on a 1.5T scanner using a single-voxel PRESS with an echo time of 35 ms," the researchers report in their abstract. Two radiologists reviewed the MRI results independently.

The researchers analyzed 70 spectra from the ECMO group and 127 from the control group. The NAA/Cr ratio was lower in parietal white matter (P < .01), frontal white matter (P < .05), and the pons region (P < .05) in the ECMO group than in the control group, but there was no difference in gray matter between the 2 groups. Choline was higher in the ECMO group than in the control group at all 4 locations.

There was a subgroup of neonates who underwent ECMO who had "unremarkable" findings on MRI (28 studies in 14 patients). The researchers found significantly elevated levels of choline and creatine (P < .05 for both), but NAA levels and NAA/Cr ratios did not reach significance. In contrast, in ECMO patients with abnormal MRI findings, NAA and NAA/Cr were highly significantly decreased (P < .001 and P < .000001, respectively).

"Metabolic abnormalities, predominantly in white matter, were observed in ECMO patients. Reduced NAA and NAA/Cr in immature white matter may reflect axonal and/or preoligodendrocyte injury," the researchers write. As far as the clinical relevance of the findings, "this study highlights the ability of [MRI] to be a surrogate imaging biomarker of selective white matter injury in neonates treated with ECMO."

Disclosure information was not available on the authors.

Radiological Society of North America (RSNA) 97th Scientific Assembly and Annual Meeting: Abstract MSVP11-02. Presented November 27, 2011.

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