Validation of thoracic quantitative computed tomography as a method to measure bone mineral density

MRI-based vertebral bone quality score compared to quantitative computed tomography bone mineral density in patients undergoing cervical spinal surgery

PURPOSE

The vertebral bone quality (VBQ) score based on magnetic resonance imaging (MRI) was introduced as a bone quality marker in the lumbar spine. Prior studies showed that it could be utilized as a predictor of osteoporotic fracture or complications after instrumented spine surgery. The objective of this study was to evaluate the correlation between VBQ scores and bone mineral density (BMD) measured by quantitative computer tomography (QCT) in the cervical spine.

METHODS

Preoperative cervical CT and sagittal T1-weighted MRIs from patients undergoing ACDF were retrospectively reviewed and included. The VBQ score in each cervical level was calculated by dividing the signal intensity of the vertebral body by the signal intensity of the cerebrospinal fluid on midsagittal T1-weighted MRI images and correlated with QCT measurements of the C2-T1 vertebral bodies. A total of 102 patients (37.3% female) were included.

RESULTS

VBQ values of C2-T1 vertebrae strongly correlated with each other. C2 showed the highest VBQ value [Median (range) 2.33 (1.33, 4.23)] and T1 showed the lowest VBQ value [Median (range) 1.64 (0.81, 3.88)]. There was significant weak to moderate negative correlations between and VBQ Scores for all levels [C2: p < 0.001; C3: p < 0.001; C4: p < 0.001; C5: p < 0.004; C6: p < 0.001; C7: p < 0.025; T1: p < 0.001].

CONCLUSION

Our results indicate that cervical VBQ scores may be insufficient in the estimation of BMDs, which might limit their clinical application. Additional studies are recommended to determine the utility of VBQ and QCT BMD to evaluate their potential use as bone status markers.

Accuracy and precision of volumetric bone mineral density assessment using dual-source dual-energy versus quantitative CT: a phantom study

Background

Dual-source dual-energy computed tomography (DECT) offers the potential for opportunistic osteoporosis screening by enabling phantomless bone mineral density (BMD) quantification. This study sought to assess the accuracy and precision of volumetric BMD measurement using dual-source DECT in comparison to quantitative CT (QCT).

Methods

A validated spine phantom consisting of three lumbar vertebra equivalents with 50 (L1), 100 (L2), and 200 mg/cm³ (L3) calcium hydroxyapatite (HA) concentrations was scanned employing third-generation dual-source DECT and QCT. While BMD assessment based on QCT required an additional standardised bone density calibration phantom, the DECT technique operated by using a dedicated postprocessing software based on material decomposition without requiring calibration phantoms. Accuracy and precision of both modalities were compared by calculating measurement errors. In addition, correlation and agreement analyses were performed using Pearson correlation, linear regression, and Bland-Altman plots.

Results

DECT-derived BMD values differed significantly from those obtained by QCT (p < 0.001) and were found to be closer to true HA concentrations. Relative measurement errors were significantly smaller for DECT in comparison to QCT (L1, 0.94% versus 9.68%; L2, 0.28% versus 5.74%; L3, 0.24% versus 3.67%, respectively). DECT demonstrated better BMD measurement repeatability compared to QCT (coefficient of variance < 4.29% for DECT, < 6.74% for QCT). Both methods correlated well to each other (r = 0.9993; 95% confidence interval 0.9984–0.9997; p < 0.001) and revealed substantial agreement in Bland-Altman plots.

Conclusions

Phantomless dual-source DECT-based BMD assessment of lumbar vertebra equivalents using material decomposition showed higher diagnostic accuracy compared to QCT.

Pedicle Screws Challenged: Lumbar Cortical Density and Thickness Are Greater in the Posterior Elements Than in the Pedicles

STUDY DESIGN

Controlled laboratory study.

OBJECTIVE

To measure the total bone mineral density (BMD), cortical volume, and cortical thickness in seven different anatomical regions of the lumbar spine.

METHODS

Using computed tomography (CT) images, 3 cadaveric spines were digitally isolated by applying filters for cortical and cancellous bone. Each spine model was separated into 5 lumbar vertebrae, followed by segmentation of each vertebra into 7 anatomical regions of interest using 3-dimensional software modeling. The average Hounsfield units (HU) was determined for each region and converted to BMD with calibration phantoms of known BMD. These BMD measurements were further analyzed by the total volume, cortical volume, and cancellous volume. The cortical thickness was also measured. A similar analysis was performed by vertebral segment. St Mary's Medical Center's Institutional Review Board approved this study. No external funding was received for this work.

RESULTS

The lamina and inferior articular process contained the highest total BMD, thickest cortical shell, and largest percent volumes of cortical bone. The vertebral body demonstrated the lowest BMD. The BMDs of the L4 and L5 segments were lower; however, there were no statistically significant differences in BMD between the L1-L5 vertebral segments.

CONCLUSION

Extrapedicular regions of the lumbar vertebrae, including the lamina and inferior articular process, contain denser bone than the pedicles. Since screw pullout strength relies greatly on bone density, the lamina and inferior articular processes may offer stronger fixation of the lumbar spine.

[The future of computer-aided diagnostics in chest computed tomography]

Recently, more and more attention has been paid to the utility of artificial intelligence in medicine. Radiology differs from other medical specialties with its high digitalization, so most software developers operationalize this area of medicine. The primary condition for machine learning is met because medical diagnostic images have high reproducibility. Today, the most common anatomic area for computed tomography is the thorax, particularly with the widespread lung cancer screening programs using low-dose computed tomography. In this regard, the amount of information that needs to be processed by a radiologist is snowballing. Thus, automatic image analysis will allow more studies to be interpreted. This review is aimed at highlighting the possibilities of machine learning in the chest computed tomography.

The relation of low levels of bone mineral density with coronary artery calcium and mortality

Osteoporosis and atherosclerosis are two prevalent major healthcare concerns that frequently coexist. The clinical outcome of 5590 consecutive subjects who underwent coronary artery calcium (CAC) scanning and thoracic bone mineral density (BMD) measurement was assessed. A significant link between low BMD levels and CAC with increased risk of mortality in both genders across ethnicities noted.

INTRODUCTION

While a relation of CAC with lower levels of BMD reported previously; it is unclear whether low levels of BMD would be an independent risk factor for CAC and mortality. This study investigated the relation of BMD levels with CAC and mortality in both genders across ethnicities.

METHODS

This study consisted of 5590 consecutive at-risk subjects without known coronary artery disease (CAD), age 57 ± 12, and 69% male, who underwent non-enhanced cardiac computed tomography, and were followed for mean of 8 years. The subjects' CAC (Agatston score) and thoracic BMD levels (mg/cm³) were measured. CAC stratified based on the severity to CAC 0, 1-100, 101-400, and 400+. Low-BMD levels defined as BMD levels below median (180 mg/cm³). Physician verified that all-cause mortality was assessment hard-endpoint. Multivariate regression analysis, adjusted for age, gender, and other cardiovascular risk factors, was used to assess the relationship between BMD and CAC.

RESULTS

The BMD levels were proportionally lowering with the severity of CAC in both genders, especially in postmenopausal women (p < 0.05). The risk of each standard deviation reduce in BMD levels increased with the severity of CAC, as compared to CAC = 0 across ethnicities (p < 0.05). Low BMD levels were an independent predictor of mortality and event-free survival rate decreased from 99% in those within normal BMD levels to 93% in those with low BMD levels (p = 0.0001). Furthermore, a significant link between low BMD levels and CAC > 0 with increased risk of mortality was noted (p = 0.0001). The relative risk of death was 2.8, 5.9, and 14.3-folds higher in CAC 1-100, 101-400, and 400+ with low BMD levels, compared to CAC = 0 and within normal BMD levels, respectively (p < 0.05).

CONCLUSIONS

The lower BMD levels are independently associated with the severity of CAC that predicts mortality.

Sex-related variations in cortical and trabecular bone of the femoral neck in an elderly Chinese population

Quantitative computed tomography (QCT) was used to investigate sex-related variations in cortical and trabecular bone of the femoral neck. Cortical bone thickness of women in the superior quadrant was thinner than that of men, and the cortex in all four quadrants was negatively associated with age in women.

INTRODUCTION

This cross-sectional study aimed to investigate sex-related similarities and differences in femoral neck structure in an elderly Chinese population by QCT bone investigational toolkit (BIT) analysis.

METHODS

This study included 207 male (67.9 ± 7.7 years; range, 55-87 years) and 400 female subjects (68.0 ± 8.7 years; range, 55-96 years). BIT module was used to measure cortical and trabecular bone in anatomic quadrants of the femoral neck. Measurements of cortical thickness (Ct.Th), cortical vBMD (Ct.vBMD), trabecular vBMD (Tb.vBMD), and integral vBMD (It.vBMD) at the femoral neck were determined in four anatomical sectors.

RESULTS

The greatest difference between sexes, after adjusting for age, height, and weight, was in Ct.Th of Quadrant Supero-anterior (SA), which was 27.4% lower in women (p<0.001). Ct.Th of Quadrant Supero-posterior (SP) was 15.1% lower in women (p = 0.027). Ct.Th and Tb.vBMD in all four quadrants appeared to be negatively associated with age in females, whereas no significant relationship was observed in males, except Ct.Th of Quadrant SP.

CONCLUSIONS

The superior femoral neck geometry between males and females was significantly different, even after adjustment for body size and age, and the sub-regional cortical and trabecular bone negatively age-related changes in women indicated that women apparently have a more vulnerable geometrical outcome with age for fractures than men.

Bone and vitamin D metabolism in HIV

Human immunodeficiency virus (HIV) infection has progressed to a chronic disease and HIV positive individuals are living longer lives. This has lead to an increase in morbidity and mortality due to secondary issues, one being HIV bone disease. HIV infected pediatric and adult populations have a greater incidence in reduction of BMD as compared to the controls. Osteoporosis has been reported to be present in up to 15 % of HIV positive patients. We are starting to understand the mechanism behind the changes in HIV bone disease. Viral proteins interfere with osteoblastic activity either by direct interaction or by the inflammatory process that they induce. Anti-viral management, including highly active antiretroviral therapy (HAART), protease inhibitors, and nucleoside/nucleotide reverse transcriptase inhibitors (NRTI) also are involved in disrupting proper bone metabolism. Vitamin D levels have strong correlation with bone disease in HIV patients, and are dependent not only to chronic disease state, but interaction of pharmacologic management and inflammatory process as well. Work up of the secondary causes of osteopenia and osteoporosis should be undertaken in all patients. DEXA scan is recommended in all post-menopausal women with HIV, all HIV infected men 50 years of age or older and in those with a history of fragility fractures regardless of age or gender. Preventive measures include adequate nutrition, calcium and Vitamin D intake daily, muscle strengthening and balance exercises to increase BMD and reduce fractures. Bisphosphonates are considered to be the first line for the treatment of HIV associated bone disease. This review will describe how the balanced mechanism of bone metabolism is interrupted by the HIV infection itself, the complications that arise from HIV/AIDS, and its treatment options.

Bone mass in children and adolescents infected with human immunodeficiency virus

OBJECTIVE

To describe bone mineral density (BMD) and bone mineral content (BMC) in children and adolescents infected with the human immunodeficiency virus (HIV), and to compare them with data from the National Health and Nutrition Examination Survey IV (NHANES IV).

METHOD

The study included 48 children and adolescents (7 to 17 years old) infected with HIV through vertical transmission. BMC and BMD were measured by dual energy absorptiometry X-ray, by calculating z-scores based on data from NHANES IV. The information on clinical and laboratory parameters of infection by HIV was obtained from medical records. Physical activity, calcium intake, and skeletal maturation were also assessed. Descriptive and inferential statistical procedures were used, with levels of significance set at 5%.

RESULTS

Seropositive patients presented lower values compared to data from NHANES IV in all z-scores of bone mass (mean=-0.52 to -1.22, SD=0.91 and 0.84, respectively). Based on the subtotal z-BMD, there was a prevalence of 16.7% of children and adolescents with low bone mass for age. Individuals using protease inhibitors presented a lower total z-BMD when compared to the group that did not use (-1.31 vs. -0.79, p=0.02). There were no bone mass differences in relation to physical activity and calcium intake.

CONCLUSIONS

In the present sample children and adolescents living with HIV have low bone mass for age, and the use of protease inhibitors appears to be related to such decreases.

Secondary complications and co-infections in the HIV-infected adolescent in the antiretroviral era

PURPOSE OF REVIEW

The number of HIV-infected adolescents is increasing dramatically. With combination antiretroviral therapy, they are expected to live well into adulthood. However, complications are emerging at a higher rate in the HIV-infected population compared to the general population. HIV-infected adolescents are also at a high risk of sexually transmitted co-infections. This article reviews the main secondary complications and co-infections in the HIV-infected adolescent.

RECENT FINDINGS

HIV-infected adolescents are at a high risk of sexually transmitted infections. A careful, age-appropriate and developmentally appropriate inquiry into the individual's sexual behavior to assess risk is paramount, in addition to regular screening at medical visits. Treating co-infections is not only important for HIV-infected individuals, but also limits HIV transmission to others. In addition, monitoring and addressing modifiable secondary risk factors for complications such as renal disease, osteopenia or osteoporosis, and cardiovascular disease are critical, well before the onset of clinically apparent disease. Using antiretroviral therapy to suppress viral replication and inflammation appears to be a promising strategy for decreasing secondary complication risk, and likely overshadows the toxicities associated with the long-term use of certain antiretrovirals.

SUMMARY

Assessing and addressing the risk of secondary complications and co-infections in the HIV-infected adolescent is crucial for optimal length and quality of life.

Hypovitaminosis D in chronic kidney disease

BACKGROUND AND OBJECTIVES

Recent studies show high prevalence of suboptimal 25-hydroxyvitamin D levels in chronic kidney disease patients. This study sought to test the hypothesis that the prevalence of 25-hydroxyvitamin D deficiency is significantly higher in chronic kidney disease patients and, in diabetic nephropathy, low serum 25-hydroxyvitamin D is associated with abnormal serum parathyroid hormone, bone mineral density, and coronary artery calcification.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Study A used data from the Third National Health and Nutrition Examination Survey. Study B was a post hoc analysis of an observational study of coronary artery calcification in non-dialysis-dependent diabetic nephropathy.

RESULTS

In study A, the adjusted odds for 25-hydroxyvitamin D deficiency were 32% higher in chronic kidney disease patients. This higher prevalence of 25-hydroxyvitamin D deficiency, however, could not be explained by differences in total vitamin D intakes. The consequences of suboptimal 25-hydroxyvitamin D levels were analyzed in 146 patients with diabetic nephropathy. The significant, inverse relationship between serum 25-hydroxyvitamin D and parathyroid hormone levels was attenuated to a nonsignificant level on multivariate adjustment. There was a significant, inverse relationship between bone mineral density and coronary artery calcification scores; neither was independently associated with serum 25-hydroxyvitamin D. The serum 25-hydroxyvitamin D levels declined modestly in 72 patients studied after 12.4 +/- 0.4 mo.

CONCLUSIONS

25-Hydroxyvitamin D deficiency is more common in chronic kidney disease, but this higher prevalence is unlikely to be a result of lower vitamin D intakes. The consequences of suboptimal 25-hydroxyvitamin D levels remain to be definitively elucidated.

Assessment of bone quality in the proximal humerus by measurement of the contralateral site: a cadaveric analyze

INTRODUCTION

The presence of osteoporosis decreases the success of osteosynthesis, especially in the proximal humerus. Estimation of the bone mineral density (BMD) at the fracture site could aid in the decision making for surgical treatment and potential implant choice with regard to the individual bone properties. BMD measurement at a fracture site is prone to inaccuracies and alternative measurement sites need to be identified. In the case of a proximal humerus fracture, promising alternative measurement sites are at the same contralateral or at a different ipsilateral location. The aim of this study was to determine if the BMD for the humeral head can be predicted by BMD measurements from the ipsilateral distal humerus or the contralateral proximal humerus.

MATERIAL AND METHODS

Cancellous BMD values were obtained from 88 paired human cadaver humeri (age 75.8+/-13.5 years) at the humeral head and at the distal metaphyseal area by pQCT. Correlations between BMD values of the ipsi- and contralateral sites were computed.

RESULTS

Correlations between proximal and distal BMD values within one bone were moderate for both left (R2=0.37) and right humeri (R2=0.40). BMD comparison between left and right humeri revealed high correlations for both the distal (R2=0.90) and the proximal humerus (R2=0.74) (all P<0.01). Elderly specimen (>or=70 years) showed better intersite correlations between all regions than younger specimen (<70 years).

CONCLUSION

High correlations between contralateral BMD values may be the result of similar biomechanical loading conditions. Although a relationship between proximal and distal bone quality of the same bone was found, the moderate coefficient suggests that ipsilateral measurements do not provide a good prediction of humeral head BMD. Bone quality at the humeral head is best predicted by BMD measurements at the contralateral location rather than the ipsilateral distal site.