Computed Tomography of the Chest as a Screening Tool for Low Bone Mineral Density

ABSTRACT Introduction Computed tomography (CT) Hounsfield units (HU) recently emerged as a promising screening tool for low bone mineral density (BMD). We hypothesized that CT HU measurements of the thoracic spine would significantly and positively correlate with dual X-ray absorptiometry (DXA) BMD scans of the femoral neck. Materials and methods The study included patients with DXA scans and thoracic CT scans at the Walter Reed National Military Medical Center. One author, blinded to the DXA scans, measured HU from the cancellous bone in T4 vertebrae. Another author statistically compared femoral neck DXA T-scores to the CT HU measurements. Results The study included 145 patients with CT scans and femoral neck DXAs. The osteoporotic and osteopenic groups had a significant difference in HU measurements compared to the normal group within the study (P < .0001 and .002, respectively). A low BMD screening value of 231 HU provided a sensitivity of 90.1% and negative predictive value of 85.7%. Conclusion Thoracic vertebrae HU measurements correlate with a low BMD of the femoral neck as determined by DXA T-scores. A high sensitivity and negative predictive value was achieved with a screening value of 231 HU. Utilization of chest or thoracic spine CT imaging as a screening method provides a quick and available screening tool for assessing low BMD in patients with these scans. Level of Evidence: III (Diagnostic)

MO803THE UTILITY OF BONE HEALTH INDEX SDS SCORES IN MEASURING BONE DENSITY IN CHILDREN WITH END STAGE KIDNEY DISEASE

Background and Aims Decreased bone mineral density (BMD) is well recognised in patients on dialysis. Lower DXA-BMD predicts incident fractures in patients with CKD 3a-5D. However while bone age (BA) Xrays are routinely performed to assess delays in bone age and density, DXA scans are not available widely. We compared the utility of bone density findings using automated measurements performed on routine BA Xrays and DXA scans. Method In our tertiary paediatric renal unit, patients on renal replacement therapy are reviewed within a joint dialysis/endocrine clinic by an nephrologist and endocrinologist,with annual radiological bone health assessment using hand and wrist Xray using Bone Xpert™ software. This automates assessment of BMD on hand Xrays, correcting for delays in bone age and calculates bone health index standard deviation score (BHI-SDS) using measurements of cortical thickness and mineralisation of metacarpal bones. In any patient with abnormal BMD on BA Xray or uncontrolled hyperparathyroidism, DXA was performed (measured as whole body (minus head) and in lumbar spine (L1–L4)). DXA-BMD Z scores were automatically calculated using normative data. A review of the results obtained was performed to compare these investigations of bone mineralisation status in our paediatric dialysis patients. Results 14 patients with ESRD on renal replacement therapy had both BHI-SDS and DXA BMD Z scores measured. Median chronological age was 12.6 years at DXA densitometry (range 5.1-16.3 years) with median BA of 11.5 years (range 4.4-14.8 years). All patients where BA Xray was performed had evidence of renal osteodystrophy radiographically. Median BHI-SDS was -1.2 (range -3.56 to 1.5). Median lumbar spine Z-score was -0.5 (range-3.6-2.9) and median WBMH Z-score was -1.2 (range -2.6-1.5). Pearson correlation coefficients with BHI-SDS were 0.77 and 0.8 respectively. Only 4/15 (27%) who had DXA performed had reported low BMD. Only one had objectively measured loss of vertebral height on vertebral fracture assessment. However there were two patients with undiagnosed scoliosis and one patient with an anterior wedge shaped fracture identified on DXA. These patients were referred for orthopaedic management. Conclusion The utility of BHI- SDS to measure bone density in paediatric patients with ESRD has not been reported. There appears to be good correlation between BHI SDS scores and DXA scan Z score measurements in paediatric patients with ESRD on renal replacement therapy. The advantages of using BHI SDS is that it is less expensive, more easily performed, more widely available and takes into account the delay in bone age often found in these children. BHI-SDS is a measure derived from assessment of the peripheral skeleton, in contrast to DXA, which measures bone health in the total skeleton or spine. BHI-SDS appears to be a useful initial measure to quantify bone density in patients with radiological changes consistent with renal osteodystrophy in the peripheral skeleton. However all children with low BHI-SDS should proceed to DXA scan as this may detect spinal abnormalities in addition.

Prediction of Myostatin on Carcass Composition in Crossbred Lambs

In order to maintain consumer acceptance of lamb meat, producers are aiming to produce leaner lambs through breeding for certain carcass characteristics. The Texel breed is known for its superior muscling phenotype due to a myostatin mutation. Because of this mutation, Texel and Texel cross lambs have been shown to have improved carcass lean with less fat in various locations throughout the carcass. The objective of this study was to observe the impacts of different sire and dam breeds on carcass composition. Lambs (n = 41) were produced by mating two dam breeds (Southdown or Suffolk) and two sire breeds (Southdown or Texel). Lambs were harvested and a hot carcass weight was obtained. At 24 h postmortem, a chilled carcass weight was taken, and each carcass was split in half. The left side of the carcass was cut into the four primal cuts and scanned using a DXA. The right half was used for standard carcass variables. After DXA scans, each primal was weighed and the major muscles were dissected from the primal cuts and weighed. Subsamples of muscles were used for total lipid analysis and Warner-Bratzler Shear Force testing. DXA scans showed a difference in the primal cut mass (P = 0.0207) with the Suffolk-Texel cross having the highest average primal cut mass at 12.52 kg. Southdown-Southdown lambs had the highest fat percentage (dam P = 0.0398; sire P = 0.0116). Dam breed had a more significant effect on muscle toughness (P < 0.0035). Southdown sired lambs had a higher SFA (P = 0.0046) and MUFA (P < .0001) but Texel sired lambs had a higher overall fatty acid ratio (P < .0001). On average, the Suffolk-Texel cross was shown to have heavier average weight for the primal cuts in the rack and leg, which are where some of the more profitable cuts of meat are located.

Body Mass and Body Composition Changes over 7 Years in a Male Professional Rugby Union Team

The purpose of this study was to investigate longitudinal body mass and body composition changes in one professional rugby union team (n=123), (i) according to position [forwards (n=58) versus backs (n=65)], analysis of players with 6 consecutive seasons of DXA scans (n=21) and, (iii) to examine differences by playing status [academy and international], over 7 years. Players [mean age: 26.8 y, body mass index: 28.9+kg.m2] received DXA scans at fourtime points within each year. A modest (but non-significant) increase in mean total mass (0.8 kg) for professional players was reflected by increased lean mass and reduced body fat mass. At all-time points, forwards had a significantly greater total mass, lean mass and body fat percentage compared to backs (p<0.05). Academy players demonstrated increased total and lean mass and decreased body fat percentage over the first 3 years of senior rugby, although this was not significant. Senior and academy international players had greater lean mass and lower body fat percentage (p<0.05) than non-international counterparts. Despite modest increases in total mass; reflected by increased lean mass and reduced fat mass, no significant changes in body mass or body composition, irrespective of playing position were apparent over 7 years.

Effects of Myo-inositol Hexaphosphate (SNF472) on Bone Mineral Density in Patients Receiving Hemodialysis

Background and objectivesIn the CaLIPSO study, intravenous administration of SNF472 (300 or 600 mg) during hemodialysis significantly attenuated progression of coronary artery and aortic valve calcification. SNF472 selectively inhibits formation of hydroxyapatite, the final step in cardiovascular calcification. Because bone mineral is predominantly hydroxyapatite, we assessed changes in bone mineral density in CaLIPSO.Design, setting, participants, & measurementsPatients with coronary artery calcification at screening (Agatston score of 100–3500 U) were randomized 1:1:1 to receive placebo, 300 mg SNF472, or 600 mg SNF472 as an intravenous infusion during hemodialysis three times weekly for 52 weeks. Dual-energy x-ray absorptiometry (DXA) scans were obtained at baseline (screening) and end of treatment, and between-group changes from baseline were compared using analysis of covariance.ResultsAmong 274 randomized patients, 202 had evaluable DXA scans at baseline and postrandomization (the DXA-modified intention-to-treat population). Mean (95% confidence interval) changes in total-hip bone mineral density from baseline to week 52 were −1.5% (−2.7% to −0.3%), −1.5% (−2.7% to −0.4%), and −2.5% (−3.8% to −1.2%) in the placebo, 300 mg SNF472, and 600 mg SNF472 groups, respectively. Mean (95% confidence interval) changes in femoral-neck bone mineral density from baseline to week 52 were −0.3% (−1.6% to 1.0%), −1.0% (−2.3% to 0.2%), and −2.6% (−4.0% to −1.3%), respectively. Regression analyses showed no correlation between change in coronary artery calcium volume and change in bone mineral density at either location. Changes in serum alkaline phosphatase, calcium, magnesium, phosphate, and intact parathyroid hormone levels were similar across treatment groups. Clinical fracture events were reported for four of 90, three of 92, and six of 91 patients in the placebo, 300 mg SNF472, and 600 mg SNF472 groups, respectively.ConclusionsBone mineral density decreased modestly in all groups over 1 year. In the 600 mg SNF472 group, the reduction appeared more pronounced. Reported fractures were infrequent in all groups.Clinical Trial registry name and registration number:Effect of SNF472 on Progression of Cardiovascular Calcification in End-Stage-Renal-Disease (ESRD) Patients on Hemodialysis (HD), NCT02966028