Dual energy x ray absorptiometry (DXA) scans to measure bone mineral density (BMD) at the spine and hip have an important role in the evaluation of individuals at risk of osteoporosis, and in helping ...clinicians advise patients about the appropriate use of antifracture treatment. Compared with alternative bone densitometry techniques, hip and spine DXA examinations have a number of advantages that include a consensus that BMD results can be interpreted using the World Health Organization T-score definition of osteoporosis, a proven ability to predict fracture risk, proven effectiveness at targeting antifracture therapies, and the ability to monitor response to treatment. This review discusses the evidence for these and other clinical aspects of DXA scanning, including its role in the new WHO algorithm for treating patients on the basis of their individual fracture risk.
White fat contributes to body weight (BW) but accumulates very little
Ffluorodeoxyglucose (
FFDG) in the fasting state. As a result, higher standardised uptake values normalised to BW (SUV) are ...observed in non-fatty tissue in obese patients compared to those in non-obese patients. Therefore, SUV normalised to lean body mass (SUL) that makes tumour uptake values less dependent on patients' body habitus is considered more appropriate. This study aimed to assess ten mathematical equations to predict lean body mass (LBM) by comparison with dual-energy X-ray absorptiometry (DXA) as the reference method.
DXA-based LBM was compared with ten equation-based estimates of LBM in terms of the slope, bias and 95% limits of agreement (LOA) of Bland-Altman plots, and Pearson correlation coefficients (r). Data from 747 men and 811 women aged 60-65 years were included.
Gallagher's equation was optimal in males (slope = 0.13, bias = -2.4 kg, LOA = 12.8 kg and
= 0.900) while Janmahasatian's equation was optimal in females (slope = 0.14, bias = -0.9 kg, LOA = 10.7 kg and
= 0.876). Janmahasatian's equation performed slightly better than Gallagher's in the pooled male and female data (slope = 0.00, bias = -1.6 kg, LOA = 12.3 kg and
= 0.959).
The Gallagher and Janmahasatian equations were optimal and almost indistinguishable in predicting LBM in subjects aged 60-65 years.
Determination of the optimum equation for predicting lean body mass to improve the calculation of SUL for
FFDG PET quantification.
Abstract Epidemiological studies have shown an association between bone loss/osteoporosis and vascular calcification (VC). Recent studies have implicated the Wnt signalling pathway in the ...pathogenesis of VC. We investigated the association between circulating concentrations of Wnt inhibitors; DKK1 and sclerostin with bone mineral density (BMD), abdominal aortic calcification (AAC) and arterial stiffness in post-menopausal women. One hundred and forty six post-menopausal women aged (mean SD) 61.56.5 years were studied. Sclerostin and DKK1 were measured in serum. BMD was measured at the lumbar spine (LS), femoral neck (FN), total hip (TH). AAC was detected by Vertebral Fracture Assessment (VFA) imaging and quantified using an 8- and 24- point scoring methods. Arterial stiffness was determined by aortic pulse wave velocity (PWV). A significant positive correlation was observed between sclerostin and BMD at the FN (r = 0.166, p = 0.043) and TH (r = 0.165, p = 0.044). The association remained significant at the FN (p = 0.045) and TH (p = 0.026) following adjustment for confounders. No significant correlation was observed between DKK1 and BMD. In contrast, there was a significant negative correlation between log DKK1 and AAC (24-point score: r = − 0.25, p = 0.008 and 8-point score: r = − 0.21, p = 0.024). Subjects with AAC score of 1 or less had significantly higher DKK1 (p = 0.01). The association between DKK1 and AAC remained significant following correction for age, blood pressure, cholesterol (24-point score: p = 0.017, 8-point score: p = 0.044). In adjusted linear regression analysis, sclerostin was positively associated with AAC (24-point score: p = 0.048, 8-point score: p = 0.031). Subjects with a PWV > 9 m/s had significantly higher sclerostin than those with PWV < 9 m/s: 23.812.3, vs 29.7 14 pmol/l, p = 0.03). No association was observed between DKK1 and PWV. The opposite association between AAC and the 2 Wnt signaling inhibitors is of interest and merits further investigations. Future longitudinal studies are needed to establish the precise role of sclerostin and DKK1 in the pathogenesis of VC.
Pre-contrast CT is established to evaluate for hepatic steatosis; post-contrast CT has historically been limited for this purpose.
To evaluate the diagnostic performance of portal venous phase ...post-contrast CT in detecting at least moderate hepatic steatosis using liver and spleen attenuation measurements determined by an automated artificial intelligence (AI) tool.
This retrospective study included 2917 patients (mean age, 56.8 years; 1381 men, 1536 women) who underwent a CT examination including at least two series through the liver. Examinations were obtained from an AI vendor's data lake from 24 centers from one U.S. healthcare network and 29 centers from one Israeli healthcare network. An automated deep learning tool extracted liver and spleen attenuation measurements. Reference for at least moderate steatosis was pre-contrast liver attenuation <40.0 HU (i.e., estimated liver fat >15%). A radiologist manually reviewed examinations with outlier AI results to confirm portal venous timing and identify issues impacting attenuation measurements.
After outlier review, analysis included 2777 patients with portal venous phase images. Prevalence of at least moderate steatosis was 13.9% (387/2777). Patients without and with at least moderate steatosis had mean post-contrast liver attenuation of 104.5±18.1 HU and 67.1±18.6 HU (p<.001), mean post-contrast liver-spleen attenuation difference of -7.6±16.4 HU and -31.8±20.3 HU (p<.001), and mean liver enhancement of 49.3±15.9 HU vs 38.6±13.6 HU (p<.001). Diagnostic performance for at least moderate steatosis was higher for post-contrast liver attenuation (AUC=0.938) than post-contrast liver-spleen attenuation difference (AUC=0.832) (p<.001). Post-contrast liver attenuation had sensitivity and specificity for at least moderate steatosis of 77.8% and 93.2% at <80 HU and 90.5% and 78.4% at <90 HU; post-contrast liver-spleen attenuation difference had sensitivity and specificity of 71.4% and 79.3% at <-20 HU, and 87.0% and 62.1% at <-10 HU.
Post-contrast liver attenuation outperformed post-contrast liver-spleen attenuation difference for detecting at least moderate steatosis in a heterogeneous patient sample, evaluated using an automated AI tool. Splenic attenuation is likely not needed to assess for at least moderate steatosis on post-contrast images,
The technique could promote early detection of clinically significant non-alcoholic fatty liver disease through individualized or large-scale opportunistic evaluation.
OBJECTIVETo assess the diagnostic performance of post-contrast CT for predicting moderate hepatic steatosis in an older adult cohort undergoing a uniform CT protocol, utilizing hepatic and splenic ...attenuation values.MATERIALS AND METHODSA total of 1676 adults (mean age, 68.4 ± 10.2 years; 1045M/631F) underwent a CT urothelial protocol that included unenhanced, portal venous, and 10-min delayed phases through the liver and spleen. Automated hepatosplenic segmentation for attenuation values (in HU) was performed using a validated deep-learning tool. Unenhanced liver attenuation < 40.0 HU, corresponding to > 15% MRI-based proton density fat, served as the reference standard for moderate steatosis.RESULTSThe prevalence of moderate or severe steatosis was 12.9% (216/1676). The diagnostic performance of portal venous liver HU in predicting moderate hepatic steatosis (AUROC = 0.943) was significantly better than the liver-spleen HU difference (AUROC = 0.814) (p < 0.001). Portal venous phase liver thresholds of 80 and 90 HU had a sensitivity/specificity for moderate steatosis of 85.6%/89.6%, and 94.9%/74.7%, respectively, whereas a liver-spleen difference of -40 HU and -10 HU had a sensitivity/specificity of 43.5%/90.0% and 92.1%/52.5%, respectively. Furthermore, livers with moderate-severe steatosis demonstrated significantly less post-contrast enhancement (mean, 35.7 HU vs 47.3 HU; p < 0.001).CONCLUSIONModerate steatosis can be reliably diagnosed on standard portal venous phase CT using liver attenuation values alone. Consideration of splenic attenuation appears to add little value. Moderate steatosis not only has intrinsically lower pre-contrast liver attenuation values (< 40 HU), but also enhances less, typically resulting in post-contrast liver attenuation values of 80 HU or less.CLINICAL RELEVANCE STATEMENTModerate steatosis can be reliably diagnosed on post-contrast CT using liver attenuation values alone. Livers with at least moderate steatosis enhance less than those with mild or no steatosis, which combines with the lower intrinsic attenuation to improve detection.KEY POINTSThe liver-spleen attenuation difference is frequently utilized in routine practice but appears to have performance limitations. The liver-spleen attenuation difference is less effective than liver attenuation for moderate steatosis. Moderate and severe steatosis can be identified on standard portal venous phase CT using liver attenuation alone.
Quantitative computed tomography (QCT) measurements of volumetric bone mineral density (vBMD) are subject to errors due to variations in the amount of bone marrow adipose tissue (BMAT). The purpose ...of our study was to describe and validate a novel method to correct lumbar spine trabecular vBMD measurements for BMAT using chemical shift-encoded magnetic resonance imaging (CSE-MRI).
CSE-MRI measurements of proton density fat fraction (PDFF) were used to correct QCT spine vBMD measurements for BMAT based on the H2O and K2HPO4 basis set equivalent densities of bone, red and yellow bone marrow. BMAT corrected and uncorrected vBMD measurements of the L1 vertebra were compared with dual-energy QCT (DEQCT) measurements in 18 subjects (mean age: 68 y, range 60 to 93 y). A further 400 subjects (mean age: 53 y, range 21 to 82 y) had 120 kVp single-energy QCT and CES-MRI scans of L2–L4 and the data used to simplify the adipose tissue correction by deriving a linear equation between the CSE-MRI vBMD correction and fractional BMAT content.
Application of the CSE-MRI derived vBMD correction changed the bias (95% limits of agreement) compared with DEQCT from 26.7 (11.0 to 42.4) mg/cm3 to 2.2 (−9.5 to 13.9) mg/cm3 at 80 kVp, and from 22.4 (3.3 to 41.6) mg/cm3 to 2.9 (−12.6 to 18.4) mg/cm3 at 120 kVp. Data for the 400 subjects gave the following relationship valid at 120 kVp: vBMD correction (mg/cm3) = −12.96 + 75.76 × BMAT.
CSE-MRI measurements of PDFF can be used to correct for BMAT content and improve the accuracy of lumbar spine QCT vBMD measurements calibrated using a K2HPO4 phantom.
•Single energy QCT vBMD measurements are subject to errors due to variations in the amount of marrow adipose tissue•We describe and validate a method of using MRI measurements of marrow adipose tissue to correct spine vBMD•The method was validated in 18 subjects who had vBMD measurements using dual-energy QCT scans•Measurements in 400 subjects were used to develop a linear equation between the vBMD correction and marrow adipose tissue
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