Published online December 29, 2008
PEDIATRICS Vol. 123 No. 1 January 2009, pp. 294-300 (doi:10.1542/peds.2007-3475)
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ARTICLE

Functional Magnetic Resonance Imaging of the Sensorimotor System in Preterm Infants

Axel Heep, MDa, Lukas Scheef, MD, MScb, Jakob Jankowski, MDb, Mark Born, MDb, Nadine Zimmermannb, Deborah Sival, MDc, Arie Bos, MDc, Jürgen Gieseke, MScb, Peter Bartmann, MD, PhDa, Hans Schild, MDb and Henning Boecker, MDb

Departments of a Neonatology
b Radiology, University of Bonn, Bonn, Germany
c Department of Pediatrics, University Medical Centre, Groningen, Netherlands

OBJECTIVE. Preterm birth at <32 weeks' gestational age has a specific predilection for periventricular white matter injury. Early prediction of concomitant motor sequelae is a fundamental clinical issue. Recently, functional MRI was introduced as a noninvasive method for investigating the functional integrity of the neonatal brain. We aimed at implementing a unilateral passive forearm extension/flexion functional MRI paradigm in a routine clinical MRI setup to allow noninvasive mapping of the sensorimotor system in preterm infants and to relate the functional data to structural and behavioral data.

PATIENTS AND METHODS. Eight patients (median gestational age: 26.5 weeks; median birth weight: 885 g) were included. The functional MRI was performed at term-equivalent age (median: 39 weeks' postconceptional age) under chloral hydrate (50 mg/kg) sedation. In 5 of 8 patients, functional MRI data acquisition was successful. This resulted in 10 functional data sets (5 for passive stimulation of each forearm).

RESULTS. Unilateral stimulation was associated with mainly bilateral activation of the primary sensorimotor cortex (n = 7 of 10 data sets), the prevailing hemodynamic response being a negative blood oxygenation level–dependent signal. Positive blood oxygenation level–dependent response or failure to activate the sensorimotor cortex (n = 3 of 10 data sets) were seen in those patients with aberrant structural/behavioral indices.

CONCLUSIONS. Our data show the feasibility of passive unilateral sensorimotor stimulation during neonatal clinical MRI protocols. The bilateral activation pattern observed at this age is compatible with a bilaterally distributed sensorimotor system. Our data validate initial accounts for a raised incidence of negative blood oxygenation level–dependent responses in the primary sensorimotor cortex at this developmental stage. The negative blood oxygenation level–dependent response is likely to reflect a reduction of the oxy/deoxy–hemoglobin ratio during a maturational stage characterized by rapid formation of synapses, yet ineffective processing. Positive blood oxygenation level–dependent responses or failure to activate the sensorimotor cortex may be an early indicator of abnormal development and will have to be followed up carefully.

Key Words: fMRI • preterm infant • BOLD response • sensorimotor cortex • perinatal brain damage

Abbreviations: GA—gestational age • PWMI—periventricular white matter injury • WM—white matter • fMRI—functional MRI • BOLD—blood oxygenation level dependent • PCA—postconceptional age • GM—general movement • DQ—developmental quotient • IVH—intraventricular hemorrhage • WMD—white matter damage • TR—repetition time • TE—echo time • TSE—turbo spin echo • DEHSI—diffuse excessive high signal intensity • ADC—apparent diffusion coefficient • FWE—family-wise error • FDR: false discovery rate • SMC—sensorimotor cortex • Hb—hemoglobin

Accepted Apr 15, 2008.


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