Abdominal aortic calcification detection using dual-energy X-ray absorptiometry: validation study in healthy women compared to computed tomography

DXA beyond bone mineral density and the REMS technique: new insights for current radiologists practice

Osteoporosis is the most prevalent skeletal disorder, a condition that is associated with significant social and healthcare burden. In the elderly, osteoporosis is commonly associated with sarcopenia, further increasing the risk of fracture. Several imaging techniques are available for a non-invasive evaluation of osteoporosis and sarcopenia. This review focuses on dual-energy X-ray absorptiometry (DXA), as this technique offers the possibility to evaluate bone mineral density and body composition parameters with good precision and accuracy. DXA is also able to evaluate the amount of aortic calcification for cardiovascular risk estimation. Additionally, new DXA-based parameters have been developed in recent years to further refine fracture risk estimation, such as the Trabecular Bone Score and the Bone Strain Index. Finally, we describe the recent advances of a newly developed ultrasound-based technology known as Radiofrequency Echographic Multi-Spectrometry, which represent the latest non-ionizing approach for osteoporosis evaluation at central sites.

Serum biomarkers for arterial calcification in humans: A systematic review

Aim

To clarify the role of mediators of ectopic mineralization as biomarkers for arterial calcifications.

Methods

MEDLINE and Embase were searched for relevant literature, until January 4th 2022. The investigated biomarkers were: calcium, phosphate, parathyroid hormone, vitamin D, pyrophosphate, osteoprotegerin, receptor activator of nuclear factor-kappa B ligand (RANKL), fibroblast growth factor-23 (FGF-23), Klotho, osteopontin, osteocalcin, Matrix Gla protein (MGP) and its inactive forms and vitamin K. Studies solely performed in patients with kidney insufficiency or diabetes mellitus were excluded.

Results

After screening of 8985 articles, a total of 129 articles were included in this systematic review. For all biomarkers included in this review, the results were variable and more than half of the studies for each specific biomarker had a non-significant result. Also, the overall quality of the included studies was low, partly as a result of the mostly cross-sectional study designs. The largest body of evidence is available for phosphate, osteopontin and FGF-23, as a little over half of the studies showed a significant, positive association. Firm statements for these biomarkers cannot be drawn, as the number of studies was limited and hampered by residual confounding or had non-significant results. The associations of the other mediators of ectopic mineralization with arterial calcifications were not clear.

Conclusion

Associations between biomarkers of ectopic mineralization and arterial calcification are variable in the published literature. Future longitudinal studies differentiating medial and intimal calcification could add to the knowledge of biomarkers and mechanisms of arterial calcifications.

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We researched the association between biomarkers and arterial calcifications.

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This review focused on biomarkers of bone metabolism and Matrix Gla protein.

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Associations between biomarkers and arterial calcification are variable.

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Future studies should differentiate between medial and intimal calcifications.

A Novel Quantitative Computer-Assisted Score Can Improve Repeatability in the Estimate of Vascular Calcifications at the Abdominal Aorta

In CKD and in the elderly, Vascular Calcifications (VC) are associated to cardiovascular events and bone fractures. VC scores at the abdominal aorta (AA) from lateral spine radiographs are widely applied (the 0-24 semiquantitative discrete visual score (SV) being the most used). We hypothesised that a novel continuum score based on quantitative computer-assisted tracking of calcifications (QC score) can improve the precision of the SV score. This study tested the repeatability and reproducibility of QC score and SV score. In forty-four patients with VC from an earlier study, five experts from four specialties evaluated the data twice using a dedicated software. Test-retest was performed on eight subjects. QC results were reported in a 0-24 scale to readily compare with SV. The QC score showed higher intra-operator repeatability: the 95% CI of Bland-Altman differences was almost halved in QC; intra-operator R2 improved from 0.67 for SV to 0.79 for QC. Inter-observer repeatability was higher for QC score in the first (Intraclass Correlation Coefficient 0.78 vs. 0.64), but not in the second evaluation (0.84 vs. 0.82), indicating a possible heavier learning artefact for SV. The Minimum Detectable Difference (MDD) was smaller for QC (2.98 vs. 4 for SV, in the 0-24 range). Both scores were insensitive to test-retest procedure. Notably, QC and SV scores were discordant: SV showed generally higher values, and an increasing trend of differences with VC severity. In summary, the new QC score improved the precision of lateral spine radiograph scores in estimating VC. We reported for the first time an estimate of MDD in VC assessment that was 25% lower for the new QC score with respect to the usual SV score. An ongoing study will determine whether this lower MDD may reduce follow-up times to check for VC progression.

Radiologic assessment of abdominal aortic calcifications, atherosclerotic burden levels and statistical bias affecting the reliability

INTRODUCTION

AAC-8 and AAC-24 are two widely used scales to evaluate abdominal aortic calcification (AAC) on X-ray images. Levels of ≥3 (AAC-8) and ≥5 points (AAC-24) are of high relevance since they are associated with greater risk of cardiovascular events. Given that it is unknown, our aim was to determine the reliability of both scales at those levels of atherosclerotic burden.

METHODS

The sample (93 subjects, 67.3 ± 9.7 years, BMI 28.8 ± 3.8, 57.6% smokers, 64.1% with hypertension) was classified according to quartiles of calcification. Six clinicians evaluated AAC independently with both scales on lateral lumbar spine X-ray images. We analyzed inter-rater agreement with the intraclass correlation coefficient (ICC) and the Bland-Altman scatterplots.

RESULTS

We assessed 15 pairs of raters. Scores in both scales were significantly correlated with cardiovascular risk (r = 0.31 and r = 0.32; p < 0.005). Agreement was very high in the first quartile and moderate in the rest (p < 0.05). At cut-off points, ICC = 0.70 (95%CI, 0.54-0.86) and ICC = 0.68 (95%CI, 0.60-0.85) with AAC-8 and AAC-24. With the Bland-Altman method, mean of the differences ranged between 0 and 0.4 (AAC-8), and between 0.2 and 1 (AAC-24), while 95% limits of agreement showed values between 2.9 and 4.4 (AAC-8), and between 6 and 11.2 (AAC-24). Analyzing entire scales, ICC = 0.97 (95%CI, 0.97-0.98) and ICC = 0.98 (95%CI, 0.97-0.98) for AAC-8 and AAC-24, respectively.

CONCLUSION

Both scales presented only moderate reliability at levels of atherosclerotic burden. Analyzing quartiles with ICC and the Bland-Altman plot showed concordant results. High global ICC values traditionally reported with both scales are likely biased.

IMPLICATIONS FOR PRACTICE

AAC predicts subsequent vascular morbidity and mortality and should implicate evaluation of cardiovascular risk. Optimal visualisation of AAC and its correct assessment are mandatory in order to maximize patient care.

Evaluation of aortic 18F-NaF tracer uptake using PET/CT as a predictor of aortic calcification in postmenopausal women: A longitudinal study

Introduction

Aortic calcification as detected by computed tomography is associated with arterial stiffening and is an important predictor of cardiovascular morbidity and mortality. Uptake of ¹⁸F-sodium fluoride (¹⁸F-NaF) in the aortic wall reflects metabolically active areas of calcification. The aim of this study was to determine if ¹⁸F-NaF uptake in the aorta is associated with calcification and progression of calcification as detected by computed tomography.

Methods

Twenty-one postmenopausal women (mean age 62 ± 6 years) underwent assessment of aortic ¹⁸F-NaF uptake using positron emission tomography/computer tomography at baseline and a repeat computed tomography scan after a mean follow-up of 3.8 ± 1.3 years. Tracer uptake was quantified by calculating the target-to-background (TBR) ratios at baseline and follow-up. Calcification was assessed at baseline and follow-up using computed tomography.

Results

Over the follow-up period, aortic calcium volume increased from 0.46 ± 0.62 to 0.71 ± 0.93 cm³ (P < 0.05). However, the change in calcium volume did not correlate with baseline TBR either unadjusted (r = 0.00, P = 1.00) or adjusted for age and baseline calcium volume (beta coefficient = −0.18, P = 0.42). TBR at baseline did not differ between participants with (n = 16) compared to those without (n = 5) progression in calcium volume (2.43 ± 0.46 vs. 2.31 ± 0.38, P = 0.58). In aortic segments identified to have the highest tracer uptake at baseline, calcium volume did not significantly change over the follow-up period (P = 0.41).

Conclusion

In a cohort of postmenopausal women, ¹⁸F-NaF uptake as measured by TBR in the lumbar aorta did not predict progression of aortic calcification as detected by computed tomography over a four-year follow-up.

Long-Term Atherosclerotic Vascular Disease Risk and Prognosis in Elderly Women With Abdominal Aortic Calcification on Lateral Spine Images Captured During Bone Density Testing: A Prospective Study

Lateral spine images are captured using bone densitometers for vertebral fracture assessment (VFA) in older women. Abdominal aortic calcification (AAC) is commonly seen on these images; however, the long-term prognosis in women with AAC remains uncertain. In a prospective study of 1052 community-dwelling ambulant white women over 70 years old abdominal aortic calcification 24 scale (AAC24) scores were calculated from digital lateral spine images captured during bone density testing in 1998 or 1999. Cardiovascular risk factors were assessed in 1998, whereas 14.5-year atherosclerotic vascular disease (ASVD)-related hospitalizations and deaths (events) were available through linked health records. Using established cut points for AAC 471 women (45%) had low AAC (AAC24 score 0 or 1), 387 (37%) moderate AAC (AAC24 score 2-5), and 197 (19%) had high AAC (AAC24 score ≥6). Over 14.5 years, 420 women experienced an ASVD event. Increasing severity of AAC was associated with increased absolute risk of ASVD events (37%, 39%, and 49%, respectively, p = 0.008 for trend), ASVD deaths (15%, 21%, and 27%, respectively, p < 0.001 for trend), and all-cause mortality (30%, 38%, and 44%, respectively, p < 0.001 for trend). After adjusting for Framingham risk scores, women with high AAC had increased relative hazard for ASVD events, HR 1.37 (95% CI, 1.07 to 1.77; p = 0.013) compared to women with low AAC. Similarly, women with moderate AAC and high AAC had increased relative hazards for ASVD deaths HR 1.41 (95% CI, 1.03 to 1.94; p = 0.034) and HR 1.80 (95% CI, 1.26 to 2.57; p = 0.001), or any deaths HR 1.30 (95% CI, 1.03 to 1.64; p = 0.026) and HR 1.53 (95% CI, 1.17 to 2.00; p = 0.002), compared to women with low AAC. In conclusion, more advanced AAC on images captured for VFA is associated with long-term ASVD hospitalizations and deaths before and after adjusting for Framingham risk scores. AAC assessment could be considered in addition to VFA to identify individuals who may benefit for more aggressive cardiovascular primary prevention strategies. © 2018 American Society for Bone and Mineral Research.

Vitamin D status and abdominal aortic calcification in postmenopausal women

Vitamin D has an important role in bone metabolism and may be involved in the process of vascular calcification. The objective of this study was to evaluate the effect of vitamin D status on the presence of abdominal aortic calcification (AAC). We enrolled, in a cross-sectional study, 429 postmenopausal women [mean age, weight, and BMI of 59.5 ± 8.3 (50-83) years, 75.8 ± 13.3 (35-165) kg, and 29.9 ± 5.2 (14.6-50.8) kg/m², respectively]. Lateral vertebral fracture assessment (VFA) images and scans of the lumbar spine and proximal femur were obtained using a Lunar Prodigy densitometer. Vertebral fractures (VFs) were defined using the Genant semiquantitative (SQ) approach. We used the Kauppila score to assess AAC extension. Clinical risk factors of osteoporosis were collected, and 25-hydroxy vitamin D was measured using electrochemiluminescence (Roche). Prevalence of osteoporosis and hypovitaminosis D (<20 ng/ml) was 21.0% and 78.1%, respectively. VFs grade 2/3 were identified in 76 patients (17.7%). Two thirds of the evaluable participants did not have any detectable AAC. The prevalence of significant atherosclerotic burden, defined as a radiographic 24-point AAC score of 5 or higher, was 7.9%. The group of women with extended AAC were older and had a statistically significant higher menopause duration and more prevalent grade 2/3 VFs. Compared to women with normal values of vitamin D, women with vitamin D insufficiency (<20 ng/ml) and deficiency (<10 ng/ml) had a lower BMD and more prevalent VFs. No difference was noted with regard to AAC among the three groups. Multiple stepwise conditional logistic regression analysis showed that the presence of AAC was associated significantly with age and the presence of VFs. Extended aortic calcifications are independently associated with prevalent VFA-identified VFs but not with serum vitamin D levels in postmenopausal women. VFA imaging using DXA may detect at the same time prevalent VFs and AAC, an important cardiovascular disease risk factor.

Abdominal aortic calcification on dual-energy X-ray absorptiometry: Methods of assessment and clinical significance

Abdominal aortic calcification (AAC) can be accurately recognized on lateral spine images intended for vertebral fracture assessment, that are obtained with dual-energy X-ray absorptiometry (DXA). Greater amounts of AAC are common in the older population for whom DXA is routinely done, and have been consistently associated with incident atherosclerotic cardiovascular disease (ASCVD) events. AAC has also been associated with incident fractures in some prospective studies, but not in others. However, further research is needed to quantify the extent to which measurement of AAC improves prediction of ASCVD events and its impact on physician and patient ASCVD risk management. Additionally, research to develop better, more precise, automated, quantitative methods of AAC assessment on lateral spine densitometric images will hopefully lead to better prediction of clinical outcomes. In conclusion, although the prime indication for densitometric lateral spine imaging remains vertebral fracture assessment, AAC that is found incidentally on lateral spine images should be reported, so that patients and their health care providers are aware of its presence.

Abdominal Aortic Calcification Identified on Lateral Spine Images From Bone Densitometers Are a Marker of Generalized Atherosclerosis in Elderly Women

OBJECTIVE

Dual-energy x-ray absorptiometry is a low-cost, minimal radiation technique used to improve fracture prediction. Dual-energy x-ray absorptiometry machines can also capture single-energy lateral spine images, and abdominal aortic calcification (AAC) is commonly seen on these images.

APPROACH AND RESULTS

We investigated whether dual-energy x-ray absorptiometry-derived measures of AAC were related to an established test of generalized atherosclerosis in 892 elderly white women aged >70 years with images captured during bone density testing in 1998/1999 and B-mode carotid ultrasound in 2001. AAC scores were calculated using a validated 24-point scale into low (AAC24 score, 0 or 1), moderate (AAC24 scores, 2-5), and severe AAC (AAC24 scores, >5) seen in 45%, 36%, and 19%, respectively. AAC24 scores were correlated with mean and maximum common carotid artery intimal medial thickness (rs=0.12, P<0.001 and rs=0.14, P<0.001). Compared with individuals with low AAC, those with moderate or severe calcification were more likely to have carotid atherosclerotic plaque (adjusted prevalence ratio (PR), 1.35; 95% confidence interval, 1.14-1.61; P<0.001 and prevalence ratio, 1.94; 95% confidence interval, 1.65-2.32; P<0.001, respectively) and moderate carotid stenosis (adjusted prevalence ratio, 2.22; 95% confidence interval, 1.39-3.54; P=0.001 and adjusted prevalence ratio, 4.82; 95% confidence interval, 3.09-7.050; P<0.001, respectively). The addition of AAC24 scores to traditional risk factors improved identification of women with carotid atherosclerosis as quantified by C-statistic (+0.075, P<0.001), net reclassification (0.249, P<0.001), and integrated discrimination (0.065, P<0.001).

CONCLUSIONS

AAC identified on images from a dual-energy x-ray absorptiometry machine were strongly related to carotid ultrasound measures of atherosclerosis. This low-cost, minimal radiation technique used widely for osteoporosis screening is a promising marker of generalized extracoronary atherosclerosis.

Femoral neck and spine bone mineral density-Surrogate marker of aortic calcification in postmenopausal women

OBJECTIVE

Osteoporosis and abdominal aortic calcification (AAC) are associated with increased morbidity and mortality in postmenopausal women. The aim of this study was to determine the accuracy of anterior-posterior (AP) dual-energy X-ray absorptiometry (DXA) compared with that of X-ray lateral lumbar radiography (LLR) in detecting and scoring AAC.

METHODS

In this cross-sectional study conducted in 56 postmenopausal asymptomatic females aged 59.0 ± 9.3 years and who never used medications to treat osteoporosis before, we determined femoral neck and lumbar spine bone mineral density (BMD) by AP DXA and AAC by X-ray LLR. We hypothesized that the subtracted femoral neck BMD (BMDFN) from lumbar spine BMD (BMDLS) presented as ΔBMD=BMDLS-BMDFN would have a diagnostic value in detecting abdominal vascular calcification.

RESULTS

The mean BMDFN was 0.744 ± 0.184 g/cm(2), and the mean BMDLS was 0.833 ± 0.157 g/cm(2) (p<0.0001); the mean ΔBMD was 0.089 ± 0.077 g/cm(2), and the mean AAC score was 2.182 ± 1.982. Bivariate Pearson's correlation analysis revealed a significant positive correlation between AAC and ΔBMD (r=0.449, p=0.0006); by linear regression analysis, R(2)=0.2019, and by multiple regression analysis, βst=13.5244 (p<0.0001). We found a sensitivity of 64.3% and specificity of 82.9% by receiver operating characteristic [ROC; area under the ROC curve (AUC=0.759)] in the prediction of AAC by ΔBMD.

CONCLUSION

This AP subtracting BMD DXA method provides a useful tool for detecting and scoring subclinical and extensive AAC in postmenopausal women using a simple, semiquantitative, and accurate scoring system with minimal radiation exposure and low cost.

Lifetime, untreated isolated GH deficiency due to a GH-releasing hormone receptor mutation has beneficial consequences on bone status in older individuals, and does not influence their abdominal aorta calcification

The GH/IGF-I axis has essential roles in regulating bone and vascular status. The age-related decrease in GH secretion ("somatopause") may contribute to osteoporosis and atherosclerosis, commonly observed in the elderly. Adult-onset GH deficiency (GHD) has been reported to be associated with reduced bone mineral density (BMD), increased risk of fractures, and premature atherosclerosis. We have shown the young adult individuals with isolated GHD (IGHD) due to a homozygous for the c.57+1G>A GHRH receptor gene mutation have normal volumetric BMD (vBMD), and not develop premature atherosclerosis, despite adverse risk factor profile. However, the bone and vascular impact of lifetime GHD on the aging process remains unknown. We studied a group of ten older IGHD subjects (≥60 years) homozygous for the mutation, comparing them with 20 age- and gender-matched controls (CO). Areal BMD was measured, and vBMD was calculated at the lumbar spine and total hip. Vertebral fractures and abdominal aortic calcifications (expressed as calcium score) were also assessed. Areal BMD was lower in IGHD, but vBMD was similar in the two groups. The percent of fractured individuals was similar, but the mean number of fractures per individual was lower in IGHD than CO. Calcium score was similar in the two groups. A positive correlation was found between calcium score and number of fractures. Untreated lifetime IGHD has beneficial consequences on bone status and does not have a deleterious effect on abdominal aorta calcification.