Qdr 4500w

BMD was measured by DXA (Prodigy [GE Healthcare, Madison, WI, USA] or HOLOGIC QDR 4500W [Hologic Inc., Bedford, MA, USA]). In premenopausal women and men < 50 years of age, a Z-score was obtained by comparing each patient’s BMD with the average BMD of the same age group. In postmenopausal women and men ≥ 50 years of age, the T-score was obtained by comparing each patient’s BMD with the BMD of the young adult group.

The subjects stood in an upright position for their height (in centimeters) to be measured to the nearest 1 mm with a Seca standard stadiometer (SecaGmbH, Hamburg, Germany). As for body weight, it was measured in kilograms on a Taurus mechanic scale with a precision of 100 g. The women wore underclothes solely while being weighed. BMI was calculated as body weight divided by height squared (kilogram per square meter). Body composition was evaluated by DXA (HologicQDR-4500 W; Hologic Inc., Waltham, MA). In our medical center, the in vivo coefficients of variation were < 1% for fat and lean mass [4 (link), 5 (link)].We used the skeletal muscle mass index (appendicular skeletal mass (ASM)/height²) to define sarcopenia as previously reported [1 (link)]. Based on DXA results, we calculated the ASM for each participant as the sum of the upper and lower limb muscle mass without fat and bone tissue. A skeletal muscle mass index (SMI) < 5.5 kg/m² for women was defined as the cut-off point for sarcopenia [1 (link)]. The European Working Group on Sarcopenia in Older People to define sarcopenia in women determined this cut-off point [2 (link)].

DXA measurements for assessing bone mineral density and body composition parameters were performed at baseline and 12 months, using Hologic QDR-4500W instrumentation (Hologic Corporation, Waltham, Massachusetts). Data were analysed by a dedicated Endocrinologist (FM).
DXA measurements related to whole body DXA scans were extracted from Apex Software version 3.4.
The densitometric image of each patient was divided, following the manufacturer's instructions, into different body districts including arms, legs, trunk, head and other derived regions such as the android and gynoid zone.
BMD, BMC, fat free mass and fat mass were assessed for every region of interest, where fat free mass was provided by the software in terms of lean soft tissue plus bone mineral content (BMC). Despite the lean mass measured by DEXA counts also skin, connective tissue and some lean components within the adipose tissue [21 (link)], it still correlates highly with TC and MRI measurements and represents a good approximation of the real muscle mass [22 (link)].
Other DXA derived body composition parameters, such as fat mass index (FM/ H2) (FMI), appendicular lean mass index (ALM/H2) (ALMI) and Trunk/Appendicular ratio were then calculated to complete the analysis and the patient characterization.

Anthropometric measures and a structured questionnaire covering lifestyle, diet, family information, medical history, etc. were obtained for all the study subjects. ALM and fat body mass (FBM) were measured using a dual-energy X-ray absorptiometry scanner Hologic QDR 4500 W (Hologic Inc., Bedford, MA, USA), for the all study samples. ALM (kg) was calculated as the sum of lean soft tissue (nonfat, non-bone) mass in the arms and legs. Weight was measured in light indoor clothing, using a calibrated balance beam scale, and height was measured as without shoes using a calibrated stadiometer.

A DXA-scan (Hologic QDR 4500W, Hologic Inc, Bedford, MA, USA) was used to measure BMD of the lumbar spine (L1-L4) (LS), femoral neck (FN) and total hip (TH) of the non-dominant hip. Follow-up data on DXA-scans were available until December 2011. To evaluate osteopenia or osteoporosis status, T-scores and Z-scores were calculated based on the NHANES reference database. Based on WHO criteria a T-score between minus 1 and 2.5 SD reflects osteopenia and minus 2.5 SD or less reflects osteoporosis. As this study comprehends generally younger patients who are supposed to have reached BMD values around the peak bone mass the Z-score is also displayed. The Z-score reflects the BMD SD of the patient compared to healthy age-matched controls with a Z-score of minus 2 SD or less reflecting osteoporosis.