The problem of mismatches between CT scan and DXA results

Background. It is reported that radiodensity measured in Hounsfield units becomes more and more popular in bone property assessment, however also mismatch with DXA results is observed.Purpose. The aim of this study is to evaluate the relationships between the results of DXA and CT with a focus on explanations for observed discrepancies.Material and Methods. This is a cross-sectional study; forty patients were enrolled, all patients underwent DXA and CT. A bone mineral density BMD (g/cm2) was calculated for each vertebra of a lumbar spine (L1-L4 inclusive), neck, upper neck, shaft, Wards triangle and trochanter of hip. Bone radiodensity in HU was taken from each vertebral body in the sagittal, axial and coronal planes. A total vertebra body radiodensity including cortical bone and radiodensity of only cancellous bone were calculated. To assess a potential impact on DXA and CT data agreement a mean radiodensity and square of the right and left vertebral pedicles and facet joints were measured for each vertebra.Results. A strong correlation between BMD measured using DXA and CT data was estimated with a multiply r accounting for 0.84169, p < 0.0001, however the most contributing parameters were those calculated for facet joints. It has been detected that both radiodensity of only a cancellous bone and total have a weak correlation with matching BMD measurements of a proximal femur.Conclusion. The results of DXA could be strongly influenced by hypertrophic changes of facet joints. Both CT and DXA measurements taken from a lumbar spine may have a mismatch with figures taken from hip

Comparative analysis of the results using direct lateral interbody spondilodesis and transforaminal lumbar interbody spondilodesis in patients with degenerative diseases of the lumbar spine

Introduction Various spondylodesis techniques are used in patients with degenerative diseases of the lumbar spine, but the benefits of these techniques have not been proven.Objective of the study was to assess the effect of the type of fusion on the incidence of implant instability and related revision surgeries.Material and Methods This monocentric prospective study included 133 patients with degenerative stenosis of the lumbar spine and confirmed instability of spinal motion segments. Patients underwent transforaminal lumbar interbody fusion (TLIF) with a single cage or direct lateral interbody fusion (DLIF) using standard-sized cages. The conventional open technique was used to supplement TLIF with pedicle screws while percutaneous screw placement was applied in patients treated with DLIF. The duration of follow-up was 18 months. Fisher's exact test was used to assess differences in the incidence of fixator instability based on MSCT and revision interventions. Logistic regression was used to assess the association between potential risk factors and complication rates.Results The use of DLIF detected by MSCT (32.9 vs 3.6%, p < 0.0001) resulted in a significant reduction in the incidence of screw instability and associated revision interventions (11.8 vs 0%, p = 0.0122). The results of logistic regression, taking into account factors such as bone density and the number of levels at which spondylodesis was performed, confirm the relationship between the reduced incidence of complications and the use of DLIF technology. Conclusion Using DLIF instead of TLIF in patients with degenerative stenosis at the lumbar spine level can lead to a significant reduction in the frequency of screw instability and associated revision surgeries

Efficacy of Cholecalciferol Baits for Pocket Gopher Control and Possible Effects on Non-Target Rodents in Pacific Northwest Forests

Population reduction measures need to be implemented to reforestation plots infested with pocket gopher in the Pacific Northwest. This 1-year investigation assessed the efficacy of 0.15% cholecalciferol (vitamin D3) bait application to reduce pocket gophers and the long-term effects on non-target small rodent populations within treated plots. The study site was a reforested clear cut containing pocket gopher populations of 10 to 14 animals per ha. Six plots (2.8 ha each) were randomly selected at the study site, 3 plots of untreated controls and 3 plots baited with cholecalciferol. A trap-and-release program was used to assess non-target populations. Radio telemetry and the open hole method were used to monitor pocket gopher activity before and after the fall application of cholecalciferol bait. A 70-80% reduction of pocket gopher activity from telemetered animals occurred in the treated plots, whereas only 10-20% mortality occurred on the control plots. Pocket gopher activity in most of the plots increased by June, and by September of the following year, activity was back to original levels. Time, not treatment, had a significant effect on yellow pine chipmunk, Townsend chipmunk, and golden-mantled ground squirrel populations. We conclude that 0.15% cholecalciferol bait appears to have application for pocket gopher control. Risks to non-target species may exist

Efficacy of Cholecalciferol Baits for Pocket Gopher Control and Possible Effects on Non-Target Rodents in Pacific Northwest Forests

Population reduction measures need to be implemented to reforestation plots infested with pocket gopher in the Pacific Northwest. This 1-year investigation assessed the efficacy of 0.15% cholecalciferol (vitamin D3) bait application to reduce pocket gophers and the long-term effects on non-target small rodent populations within treated plots. The study site was a reforested clear cut containing pocket gopher populations of 10 to 14 animals per ha. Six plots (2.8 ha each) were randomly selected at the study site, 3 plots of untreated controls and 3 plots baited with cholecalciferol. A trap-and-release program was used to assess non-target populations. Radio telemetry and the open hole method were used to monitor pocket gopher activity before and after the fall application of cholecalciferol bait. A 70-80% reduction of pocket gopher activity from telemetered animals occurred in the treated plots, whereas only 10-20% mortality occurred on the control plots. Pocket gopher activity in most of the plots increased by June, and by September of the following year, activity was back to original levels. Time, not treatment, had a significant effect on yellow pine chipmunk, Townsend chipmunk, and golden-mantled ground squirrel populations. We conclude that 0.15% cholecalciferol bait appears to have application for pocket gopher control. Risks to non-target species may exist

High density plasma enhanced chemical vapor deposition of optical thin films

Deposition of pure and Ge-doped silica as well as silicon oxynitride films has been studied in a recently developed matrix distributed electron cyclotron resonance (MDECR) reactor. Process parameters were optimized in order to obtain optical quality thin films at low substrate temperatures and high deposition rates without post-deposition treatment. The choice of injection system is shown to be of crucial importance for the deposition of high quality materials in low pressure PECVD. It has been found that injecting silane near the surface allows to obtain films with a low OH absorption independently of silane flow i.e. growth rate in a certain range of process parameters. On the contrary, in the case of uniform distribution of silane in the reactor volume the hydrogen content increases with silane flow, which affects the quality of films deposited at higher rates. With the optimized injection system, stress-free silica films with a low absorption have been deposited at the rates up to 70 nm/min at temperatures lower than 150 °C. Non-absorbing oxynitride films with a controllable refractive index ranging from 1.46 to 1.86 have been obtained from SiH4/O2/N2 mixtures. Ge-doped silica films with a Ge content of up to 4% has been deposited using a mixture GeH4 in H2 as a dopant. The properties of deposited films have been studied as a function of process parameters. The results show that the MDECR concept, that permits, in principle, unlimited scaling of substrate size, can be technology of choice for the deposition of optical thin films and functional coatings