Control de calidad de la densitometría ósea: precisión reproductibilidad y aplicación clínica / Quality control of bone densitometry: accuracy, precision and clinical application

RESUMEN

Dual energy x-ray absorptiometry (DEXA) is one of the most widely used methods for bone mineral density (BMD), total body mass (TBM), total body fat (TBF), percentage of total body ft (TBF) and total body fat-free mass (TBFFM) measurements. We investigated the in vitro and vivo accuracy and precision of DEXA in repeated measurements of a lumbar espine phantom and in 30 healthy volunteers. Based on precision, the minimal significant variability (MSV) at 95 por ciento confidence level between 2 measurement of the same object or subject was calculated. In vitro accuracy and MSV were 99.8 and 0.9 por ciento respectively. In vivo indexes were 99.4 and 0.9 percent for whole-body BMD. 98.6 and 2 percent for lumbar spine BMD, 96.6 and 4.8 percent for femoral neck BMD, 98 and 2.8 percent for major trochanter BMD, 96 and 5,7 percent for Ward's triangle BMD, 99.5 and 0.7 percent for TBM, 98 and 2.9 percent for TBF, 97.9 and 3 percent for TBF and 99 and 1.4 percent for TBFFM. Our fIndings indicate that DEXA is a very reliable instrument and in order to be 95 percent confident of a real change between 2 scans a difference of at least the calculated MSV must be measured