ASSESSMENT OF THE BONE-MINERAL DENSITY IN THE LUMBAR VERTEBRAE OF NEWBORNS BY QUANTITATIVE COMPUTED-TOMOGRAPHY

Objective. To assess the true mineral density (BMD, in g/cm(3)) of the lumbar spine in newborns. Design and patients. A postmortem analysis of five infants with gestational ages ranging from 35 to 40 weeks, and birth weights from 2765 to 3200 g, was conducted using dual-energy qu antitative computed tomography (QCT; Siemens Somatom DR). A 2 or 4 mm thick slice was obtained for each lumbar vertebra from L1 to L4. The d ensity measured in these vertebrae was corrected by reference to a sol id phantom (Osteo-CT) measured simultaneously. A three-dimensional ima ge of the spine (Elscint CT Twin), as well as a photomicrograph of his tological preparation from L2 vertebra, were also obtained in another term baby for comparison with the CT results. Results and conclusions. In the range of Values studied, the vertebral densities were not depe ndent on birth weight. BMD Values measured in L2, L3 and L4 were not s ignificantly different, but were 10% lower than in L1 in four of five infants. The spatial resolution of the QCT protocol used (0.4 mm) did not permit the differentiation of trabecular and cortical bone, and th e vertebral bodies appeared Very homogeneous and dense, with a mean de nsity value of 210+/-30 mg Ca/cm(3), which is 2.5 times higher than th e mean maximum value found in young normal adults. These preliminary r esults highlight the potential of QCT in neonatology. Special protocol s will, however, need to be developed for in vivo measurements in this particular paediatric field.