Reproducibility of lateral spine scans using dual energy X-ray absorptiometry

Abstract

Reproducibility of lateral spine dual energy X-ray absorptiometry (LAT DEXA) scans using a Lunar DPX-L scanner was assessed in a cadaveric phantom and in patients. One hundred phantom measurements over 7 months demonstrated a longitudinal stability of 1.7% (coefficient of variation, CV). Additional scans were performed with the phantom rotated by up to 20 degrees in each of the three orthogonal planes to assess the effects of variable patient positioning. Horizontal and vertical rotation of the spine had little effect on the estimated bone mineral density (BMD), however, axial rotation of greater than 8 degrees led to errors in the BMD measurement. One hundred consecutive patients had two lateral scans performed within 1 month. BMD (range 0.10-1.6 g/cm2) was determined for each scan by one operator. Significant overlap from ribs and pelvis was often seen with L2 and L4 vertebrae but one vertebra (L3) could be measured in every case. Intraoperator and interoperator variability was assessed by three experienced operators, each analyzing 10 patients' scans on five separate occasions, and was found to be less than 1.1% for a single vertebra. BMD estimation of vertebral bodies and midslices by lateral DEXA scans (CV% of 3.8% and 4.6%) have a 95% confidence interval of 0.074 g/cm2 and 0.096 g/cm2, respectively for two vertebrae. This variability is due mainly to axial rotation, with operator variability, horizontal rotation, and vertical rotation having little effect on BMD estimation.

Quantitative computed tomography at the axial and peripheral skeleton

“…To increase the sensitivity of DXA it has been suggested that BMD be measured with the patient in the lateral decubitus position [35]. There are several reasons for measuring bone mineral from a lateral projection in the vertebral body.…”

The effect of combined androgen blockade on bone turnover and bone mineral densities in men treated for prostate carcinoma

“…The in vivo precision was 1.7% for measurements of the lumbar spine, 3.6% for measurements of the femoral neck, 3.3% for measurements of Ward's triangle, and 2.2% for measurements of the femoral trochanter. 16 BMD measurements were expressed in absolute terms as g/cm 2 and as a percentage of the initial value. Osteoporosis was defined as a BMD measurement Ͼ2.5 standard deviations below the mean for a healthy population group ages 20 -40 years.…”

Biochemical, histomorphometric and densitometric changes in patients with multiple myeloma: effects of glucocorticoid therapy and disease activity

“…Their data was compared to 25 case controls matched for age (Ϯ2 years) and years since the menopause (Ϯ5 years), who were selected from a group of healthy volunteers, recruited for longitudinal densitometric assessment and undergoing yearly bone mineral density measurements (Larnach et al, 1992). In the prospective study, 15 of the 25 patients with stage II and III myeloma were re-evaluated after 12 months of follow-up.…”