title: Distribution of bone mineral density in the lumbar spine in health and osteoporosis.
abstract: The significance of variability in bone mineral density (BMD) between lumbar vertebrae L1 to L4 in the same individual was investigated by dual-energy X-ray absorptiometry in 1000 normal women aged 40-60 years (average 52 years) and 145 women aged 45-80 years (average 65 years) with vertebral osteoporosis. The mean BMD increased from L1 to L4 in normal women from 0.841 g/cm2 to 1.017 g/cm2, and in osteoporotics from 0.562 g/cm2 to 0.709 g/cm2. Z scores for osteoporotic women (Z = osteoporotic BMD - age-normal BMD/normal SD) were significantly lower for individual vertebrae compared with L1-4 and at L4 compared with L1, L2 and L3 (p < 0.001). The mean difference between Z scores for the highest and lowest vertebrae in an individual was 0.70 for normals (SD = 0.40) and 0.64 for osteoporotics (SD = 0.36). The mean Z score difference between the L1-4 Z score and the lowest individual vertebral Z score was 0.36 for normals (SD = 0.23) and 0.06 for osteoporotics (SD = 0.31). However, receiver operating analysis (ROC) curves showed that the lowest Z score for any individual vertebra did not provide improved discrimination between normals and osteoporotics when compared with the L1-4 Z score. The area under the ROC curve for L1-4 was significantly greater than for individual vertebrae (p < 0.05) and that for L4 was significantly smaller than for L1, L2 or L3 (p < 0.001). In conclusion, L1-4 BMD gives greater diagnostic sensitivity for osteoporosis than individual vertebrae, and L1, L2 and L3 are better than L4.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Nuclear Medicine, Guy's Hospital, London, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Ryan
authors.forename: G M
authors.initials: GM
authors.lastname: Blake
authors.forename: R
authors.initials: R
authors.lastname: Herd
authors.forename: J
authors.initials: J
authors.lastname: Parker
authors.forename: I
authors.initials: I
authors.lastname: Fogelman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D005260:Female; D006801:Humans; D016014:Linear Models; D008159:Lumbar Vertebrae / Q000502:physiology* / Q000503:physiopathology; D008875:Middle Aged; D010024:Osteoporosis / Q000503:physiopathology*; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity