Dual-energy X-ray absorptiometry body composition in patients with secondary osteoporosis

Body composition analysis using dual-energy x-ray absorptiometry in an Egyptian pediatric sickle cell disease cohort

BACKGROUND

Growth failure is commonly encountered in sickle cell disease (SCD). Tissue compartment growth and development are subsequently likely to be altered in such patients.

OBJECTIVE

We aimed to analyze body composition in an Egyptian pediatric SCD cohort using dual-energy x-ray absorptiometry (DEXA), one of the most comprehensive and noninvasive assessment methods available.

METHODS

Forty children with SCD ≤18 years and 40 healthy youngsters age- and gender-matched were enrolled. Patients' demographic, clinical, and laboratory parameters were obtained from their archived files. All patients and controls were subjected to body composition assessment using a MedixDR-Whole Body DEXA System.

RESULTS

In SCD patients; weight and height relative to age Z scores were significantly lower (p < .001), total body lean was significantly higher (p = .006), and total body fat percentage was lower, yet the difference was not statistically significant (p = .09). There were no statistically significant variations in bone mineral density or content, basal metabolic rate, subcutaneous adipose tissue, android/gynoid fat ratio, and visceral adipose tissue. There were no significant gender disparities between SCD patients and controls.

CONCLUSION

Faltering growth in children with SCD should be addressed with a multidisciplinary approach including nutritional support, correction of anemia, and proper medical care. Body composition parameters assessed using DEXA were comparable between cases and controls apart from total body lean. Further clinical studies are needed with multicenter cooperation and a larger sample size to assess the usefulness of DEXA as an assessment tool for body composition in children with SCD.

Sarcopenia: imaging assessment and clinical application

Sarcopenia is a progressive, generalized skeletal muscle disorder characterized by reduction of muscle mass and strength. It is associated with increased adverse outcomes including falls, fractures, physical disability, and mortality, particularly, in elderly patients. Nowadays, sarcopenia has become a specific imaging biomarker able to predict clinical outcomes of patients. Muscle fibre reduction has shown to be an unfavourable pre-operative predictive factor in patients with cancer, and is associated with worse clinical outcomes in terms of postoperative complications, morbidity, mortality, and lower tolerance of chemoradiation therapy. Several imaging modalities, including dual-energy X-ray absorptiometry, CT, MRI, and US can be used to estimate muscle mass and quality to reach the diagnosis of sarcopenia. This article reviews the clinical implications of sarcopenia, how this condition can be assessed through different imaging modalities, and future perspectives of imaging of sarcopenia.

Reproducibility of total and regional body composition using dual-energy X-ray absorptiometry in rheumatoid arthritis and ankylosing spondylitis

Several studies have reported changes in body composition in rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Our study showed that body composition measurements obtained by absorptiometry were highly reproducible in patients suffering from these diseases. This study justifies the use of absorptiometry measurements in longitudinal studies in this population.

PURPOSE

Our study aimed to assess the reproducibility of total and regional body composition in patients with rheumatoid arthritis (RA) and with ankylosing spondylitis (AS) and to compare them to healthy subjects.

METHODS

The study enrolled 80 subjects including 32 healthy subjects, 31 RA patients, and 17 AS patients. Each subject had two scans in one day under the same standard conditions and none ate nor drunk before being repositioned on the table. The reproducibility was assessed through the coefficient of variation (CV), the least significant change (LSC), the intraclass correlation (ICC), and the smallest significant difference (SDD).

RESULTS

Total body composition measurements obtained by dual-energy X-ray absorptiometry (DXA) were highly reproducible, and there was no statistically significant difference between reproducibility in healthy subjects, patients with RA, and patients with AS. For total body fat mass (FM), lean mass (LM), and bone mineral content (BMC) in the total population, CV values were 1.71%, 1.25%, and 1.74%, respectively; ICC values were 0.998, 0.996, and 0.993, respectively; LSC values were 4.88%, 3.7%, and 5.2%, respectively; and SDD values were ± 1.23 Kg, ± 1.47 Kg, and ± 126.0 g, respectively. For regional body FM, LM, and BMC in the total population, CV values in the arms were 8.46%, 4.17%, and 3.79%, respectively; in the legs 6.24%, 3.59%, and 2.04%, respectively, and in the trunk 5.02%, 2.92%, and 5.24%, respectively.

CONCLUSION

Total body tissue mass, FM percentage, FM, LM, and BMC measurements obtained by DXA are highly reproducible in RA and AS.

Correlation between muscle mass and quality around the hip and of psoas muscles at L3 level using unenhanced CT scans

OBJECTIVE

CT segmentation of psoas muscles at L3 level is used to measure sarcopenia status, but it is not feasible when L3 is not included in the examination. We tested the correlation of psoas muscle mass and quality estimation at L3 with that of hip muscles, which could be opportunistically used in patients undergoing hip surgery.

MATERIALS AND METHODS

Unenhanced abdominal CT performed in 50 patients (29 males, mean/median age 69/72 years) were reviewed. Regions of interest were drawn to assess cross-sectional area (CSA) and attenuation of psoas muscles at L3. These values were correlated with CSA and attenuation of iliopsoas, rectus femoris, sartorius, and tensor fascia latae at the level of the hip, separately on each side. After applying Bonferroni correction for multiple comparisons, statistical significance was set as P < .002.

RESULTS

Attenuation of each psoas at L3 and ipsilateral hip muscles was significantly correlated (P ≤ .001, r = .491-.754). A significant correlation was observed between CSA of right psoas and ipsilateral muscles (P ≤ .00, r = .432-.525). We observed a significant correlation between CSA of left psoas and ipsilateral rectus femoris, iliopsoas, tensor fascia latae at the apex of the femoral head, and sartorius at the level of the lesser trochanter (P ≤ .001, r = .431-.502). Average time to measure CSA and attenuation of psoas muscles at L3 was 41 s, that of hip muscles was 2 min 12 s.

CONCLUSION

Measurements of mass and quality of hip muscles are feasible and correlate to those of psoas muscles at L3, being potentially used in future works on the association of sarcopenia and outcomes after hip surgery.

Quantitative Musculoskeletal Ultrasound

Ultrasound (US) imaging plays a crucial role in the assessment of musculoskeletal (MSK) disorders. Several quantitative tools are offered by US systems and add information to conventional US imaging. This article reviews the quantitative US imaging tools currently available in MSK radiology, specifically focusing on the evaluation of elasticity with shear-wave elastography, perfusion with contrast-enhanced US and noncontrast superb microvascular imaging, and bone and muscle mass with quantitative US methods. Some of them are well established and already of clinical value, such as elasticity and contrast-enhanced perfusion assessment in muscles and tendons. MSK radiologists should be aware of the potential of quantitative US tools and take advantage of their use in everyday practice, both for clinical and research purposes.

Body composition with dual energy X-ray absorptiometry: from basics to new tools

Dual-energy X-ray absorptiometry (DXA) in nowadays considered one of the most versatile imaging techniques for the evaluation of metabolic bone disorders such as osteoporosis, sarcopenia and obesity. The advantages of DXA over other imaging techniques are the very low radiation dose, its accuracy and simplicity of use. In addition, fat mass (FM) and lean mass (LM) values by DXA shows very good accuracy compared to that of computed tomography and magnetic resonance imaging. In this review we will explain the technical working principles of body composition with DXA, together with the possible limitations and pitfalls that should be avoided in daily routine to produce high-quality DXA examinations. We will also cover the current clinical practical application of whole body DXA values, with particular emphasis on the use of LM indices in the diagnostic workup of reduced muscle mass, sarcopenia and osteosarcopenic obesity according to the most recent guidelines. The possible use of adipose indices will be considered, such as the fat mass index (FMI) or the android/gynoid ratio, as well as lipodystrophy indices and the evaluation of visceral adipose tissue (VAT). Whenever available, we will provide possible cut-off diagnostic values for each of these LM and FM indices, according to current literature and guidelines.

Imaging of sarcopenia: old evidence and new insights

To date, sarcopenia is considered a patient-specific imaging biomarker able to predict clinical outcomes. Several imaging modalities, including dual-energy X-ray absorptiometry (DXA), computed tomography (CT), magnetic resonance (MR), and ultrasound (US), can be used to assess muscle mass and quality and to achieve the diagnosis of sarcopenia. With different extent, all these modalities can provide quantitative data, being thus reproducible and comparable over time. DXA is the one most commonly used in clinical practice, with the advantages of being accurate and widely available, and also being the only radiological tool with accepted cutoff values to diagnose sarcopenia. CT and MR are considered the reference standards, allowing the evaluation of muscle quality and fatty infiltration, but their application is so far mostly limited to research. US has been always regarded as a minor tool in sarcopenia and has never gained enough space. To date, CT is probably the easiest and most promising modality, although limited by the long time needed for muscle segmentation. Also, the absence of validated thresholds for CT measurements of myosteatosis requires that future studies should focus on this point. Radiologists have the great potential of becoming pivotal in the context of sarcopenia. We highly master imaging modalities and know perfectly how to apply them to different organs and clinical scenarios. Similarly, radiologists should master the culture of sarcopenia, and its clinical aspects and relevant implications for patient care. The medical and scientific radiological community should promote specific educational course to spread awareness among professionals. KEY POINTS: • DXA is an accurate, reproducible, and widely available imaging modality to evaluate body composition, being the most commonly used radiological tool to diagnose sarcopenia in clinical practice • CT and MR are the gold standard imaging modalities to assess muscle mass and quality, but no clear cutoff values have been reported to identify sarcopenia, limiting the application of these modalities to research purposes • US has shown to be accurate in the evaluation of muscle trophism, especially in the thigh, but its current application in sarcopenia is limited.

MRI-Derived Biomarkers Related to Sarcopenia: A Systematic Review

BACKGROUND

MRI allows quantitatively assessing muscle quantity and quality.

PURPOSE

To summarize the role of MRI as a noninvasive technique for the identification of in vivo surrogate biomarker of sarcopenia.

STUDY TYPE

Systematic review.

POPULATION

In April 2019, a systematic literature search (Medline/EMBASE) was performed to identify articles on the topic at issue.

FIELD STRENGTH/SEQUENCE

No field strength or sequence restrictions.

ASSESSMENT

After a literature search, study design, aim, sample size, demographics, magnetic field strength, imaged body region, MRI sequences, and imaging biomarker were extracted.

STATISTICAL TESTS

Data are presented as frequencies and percentages.

RESULTS

From 69 records identified through search query, 18 articles matched the inclusion criteria. All articles were published from 2012 and had a mainly prospective design (14/18, 78%). Sample size ranged from 9 to 284 subjects, for a total of 1706 enrolled subjects. Healthy subjects were enrolled or retrospectively selected in 8/18 (44%) articles, corresponding to 658 (39%) healthy subjects. Magnetic field strength was 1.5 or 3T in 14/18 (78%) studies. The most analyzed body regions were the thigh (7/18, 39%) and the trunk (6/18, 33%). Stratifying studies according to their aim, 13/18 (72%) studies focused on muscle quality and quantity, 3/18 (17%) studies on outcome prediction, and 2/18 articles (11%) addressed both aims. A wide set of MRI biomarkers have been proposed. Muscle cross-sectional area was the most used for muscle quantity estimation, while quantitative biomarkers of muscle fat content or fiber architecture were proposed to assess muscle quality.

DATA CONCLUSION

The proposed biomarkers were assessed using different MRI sequences for different body regions in different subjects/patient cohorts, pointing out a lack of standardization on this topic. Future studies should test and compare the performance of proposed MRI biomarkers for sarcopenia characterization and quantification using a standardized experimental setup.

LEVEL OF EVIDENCE

1 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:1117-1127.

Quantification of visceral adipose tissue by computed tomography and magnetic resonance imaging: reproducibility and accuracy

Objective

To evaluate the feasibility of quantifying visceral adipose tissue (VAT) on computed tomography (CT) and magnetic resonance imaging (MRI) scans, using freeware, as well as calculating intraobserver and interobserver reproducibility.

Materials and Methods

We quantified VAT in patients who underwent abdominal CT and MRI at our institution between 2010 and 2015, with a maximum of three months between the two examinations. A slice acquired at the level of the umbilicus was selected. Segmentation was performed with the region growing algorithm of the freeware employed. Intraobserver and interobserver reproducibility were evaluated, as was the accuracy of MRI in relation to that of CT.

Results

Thirty-one patients (14 males and 17 females; mean age of 57 ± 15 years) underwent CT and MRI (mean interval between the examinations, 28 ± 12 days). The interobserver reproducibility was 82% for CT (bias = 1.52 cm²; p = 0.488), 86% for T1-weighted MRI (bias = −4.36 cm²; p = 0.006), and 88% for T2-weighted MRI (bias = −0.52 cm²; p = 0.735). The intraobserver reproducibility was 90% for CT (bias = 0.14 cm²; p = 0.912), 92% for T1-weighted MRI (bias = −3,4 cm²; p = 0.035), and 90% for T2-weighted MRI (bias = −0.30 cm²; p = 0.887). The reproducibility between T1-weighted MRI and T2-weighted MRI was 87% (bias = −0.11 cm²; p = 0.957). In comparison with the accuracy of CT, that of T1-weighted and T2-weighted MRI was 89% and 91%, respectively.

Conclusion

The program employed can be used in order to quantify VAT on CT, T1-weighted MRI, and T2-weighted MRI scans. Overall, the accuracy of MRI (in comparison with that of CT) appears to be high, as do intraobserver and interobserver reproducibility. However, the quantification of VAT seems to be less reproducible in T1-weighted sequences.

Cumulative Effective Dose and Cancer Risk of Pediatric Population in Repetitive Whole-Body Scan Using Dual-Energy X-Ray Absorptiometry

This study aims to quantitatively evaluate the cumulative effective dose and associated cancer risk of pediatric patients of US and Hong Kong population undergoing repetitive whole-body scans with dual-energy X-ray absorptiometry (DXA) during their diagnosis and follow-up periods. Organ-absorbed doses of pediatric patients undergoing DXA whole-body scan have been computer simulated using patient imaging parameters input to the Monte Carlo software PCXMC. Gender- and age-specific effective doses have been calculated with the simulated organ-absorbed doses using the ICRP-103 approach. The associated radiation-induced cancer risk, expressed as lifetime attributable cancer risk (LAR), has been estimated according to the method introduced in the Biological Effects of Ionizing Radiation VII report. Mathematical fitting for effective dose and for LAR, as a function of age at exposure, has been analytically obtained to quantitatively estimate the cumulated effective dose and LAR for pediatric patients of US and Hong Kong population with repetitive DXA whole-body scan during their follow-up period. The effective dose of a single DXA whole-body scan for patients exposed at the age between 5 and 18 years was calculated as 8.47-17.68 µSv. The corresponding LAR for US and Hong Kong population was between the range of 4.57 × 10^-7 and 7.14 × 10^-7. The cumulative effective dose of DXA whole-body scan for patients exposed annually at age between 5 and 18 years was calculated as 180 µSv for girls and 168 µSv for boys. The corresponding cumulative LAR for US and Hong Kong population was calculated as 3.77 × 10^-6 to 5.48 × 10^-6. Girls would be at a statistically significant higher cumulated cancer risk than boys under the same whole-body DXA protocol (p = 0.03). The probability of cumulative LAR for pediatric populations undergoing annual DXA whole-body scan is regarded as minimal. We demonstrate the use of computer simulation and analytic formulation to quantitatively obtain the cumulated effective dose and cancer risk at any age of exposure, which are useful information for medical personnel to track patient radiation dose and to alleviate patients' parents concern about radiation safety in repetitive whole-body scan using DXA.

Diagnostic imaging of osteoporosis and sarcopenia: a narrative review

Osteoporosis and sarcopenia represent two major health problems with an increasing prevalence in the elderly population. The correlation between these diseases has been widely reported, leading to the development of the term "osteosarcopenia" to diagnose those patients suffering from both diseases. Several imaging methods for the diagnosis and management of osteoporosis exist, with dual-energy X-ray absorptiometry (DXA) being the most commonly used for measuring bone mineral density (BMD). Imaging technique other than DXA is represented by conventional radiography, computed tomography (CT) and ultrasound (US). Similarly, the imaging technologies used to detect loss of skeletal muscle mass in sarcopenia include DXA, CT, US and magnetic resonance imaging (MRI). These methods differ in terms of reliability, radiation exposure and costs. CT and MRI represent the gold standard for evaluating body composition (BC), but are costly and time-consuming. DXA remains the most often used technology for studying BC, being quick, widely available and with low radiation exposure.

Imaging of metabolic bone disease

Osteoporosis is the most important metabolic bone disease, with a wide distribution among the elderly. It is characterized by low bone mass and micro architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk. Identify bone weakening with an appropriate and accurate use of diagnostic imaging is of critical importance in the diagnosis and follow-up of osteoporotic patients. The aim of this review is to evaluate the detection rates of the different imaging modalities in the evaluation of bone strength, in the assessment of fracture risk and in the management of fragility fractures. (www.actabiomedica.it)