Bone strain index (BSI) is a dual-energy X-ray absorptiometry (DXA)-derived index of bone strength obtained from lumbar densitometric scan. A new study published in La Radiologia Medica estimated the reproducibility of BSI in healthy women with different body mass index. This study included postmenopausal women who were divided into three groups (A, B and C) according to body mass index (BMI: < 25; 25-29.9; ≥ 30 kg/m²) and two groups (D and E) according to waist circumference (WC: ≤ 88; > 88 cm) – each of 30 subjects. All participants underwent two DXA examinations with in-between repositioning, according to the International Society for Clinical Densitometry guidelines for precision estimation. Bone mineral density (BMD) and BSI were expressed as g/cm² and absolute value, respectively. The results showed that BSI increased proportionally to BMI and WC and significantly in group C compared to B and A, respectively. BSI was significantly higher in E compared to D, whereas no differences were observed in BMD. Although BSI reproducibility was slightly lower in group C (89%), the differences were not significant between all groups. On the other hand, BMD reproducibility did not significantly differ between all groups. Hence, BSI reproducibility was significantly lower than that of BMD and decreased proportionally to BMI and WC increase. This reduction of BSI reproducibility was more pronounced in patients with BMI ≥ 30 and WC > 88—BSI being a parameter sensible to weight.

Source: La Radiologia Medica. 2019 Dec 27. doi: 10.1007/s11547-019-01118-5