Quantification of deep gray matter in preterm infants at term-equivalent age using manual volumetry of 3-tesla magnetic resonance images.
OBJECTIVE
Nonhypothesis-based MRI-analysis techniques including deformation-based morphometry and automated tissue segmentation have suggested that preterm infants at term-equivalent age have reduced tissue volume in the basal ganglia and thalami, which is most apparent among infants with supratentorial lesions. The aim of our study was to test this hypothesis by direct measurement of thalamic and lentiform nuclei volumes in preterm infants at term-equivalent age and term-born controls using manual volumetry.


METHODS
Forty preterm infants at term-equivalent age (median gestational age: 29.5 weeks; median birth weight: 1.3 kg) and 8 term-born controls were examined using a 3-T Philips (Best, Netherlands) system. T1-weighted volume images and T2-weighted fast-spin echo pseudovolumes were acquired. There was no significant difference in postmenstrual age at image acquisition between the 2 groups. ImageJ 1.34 (National Institutes of Health, Bethesda, MD) was used for manual segmentations.


RESULTS
The median thalamic and lentiform nuclei volumes for preterm infants at term-equivalent age were 13.6 and 3.07 cm3, respectively, significantly smaller than term-control volumes of 16.3 and 5.6 cm3, respectively. Ten preterm infants at term-equivalent age had supratentorial lesions (intraventricular hemorrhage, periventricular leukomalacia, or hemorrhagic parenchymal infarction), and the median thalamic and lentiform volumes for this group were 10.4 and 1.7 cm3, respectively. When this group was excluded, the remaining infants who had mild or moderate diffuse excessive high signal intensity in the white matter on T2-weighted images had a smaller, yet significant, volume reduction compared with controls. Tissue volumes were not related to weight and gestational age at birth.


CONCLUSIONS
Manual volumetry confirms that preterm infants at term-equivalent age have reduced thalamic and lentiform volumes compared with controls. This was most marked among infants with supratentorial lesions but was also seen among those with nonfocal white matter abnormalities.
Srinivasan
Latha
L
Department of Pediatrics, Hammersmith Hospital, Du Cane Road, London W12 0NS, United Kingdom.
Dutta
Robin
R
Counsell
Serena J
SJ
Allsop
Joanna M
JM
Boardman
James P
JP
Rutherford
Mary A
MA
Edwards
A David
AD
D001479:Basal Ganglia / Q000196:embryology / Q000473:pathology*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D007363:Intensive Care Units, Neonatal; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015588:Observer Variation; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D047929:Term Birth; D013788:Thalamus / Q000196:embryology / Q000473:pathology*