Determination and Validation of Aortic Calcification Measurement from Lateral Bone Densitometry in Dialysis Patients

Abstract

Vascular calcification (VC) contributes to increased cardiovascular (CV) disease in dialysis patients and is inversely correlated with bone mineral density (BMD). Screening for VC may determine patients at greater CV risk and bone densitometry may have dual role in assessing VC as well as BMD. The aim of this study was to determine measurement of VC using dual-energy x-ray absorptiometry (DXA) with correlation to gold standard computed tomography (CT). Forty hemodialysis patients had abdominal aortic CT and lateral DXA of lumbar spine to determine aortic VC and BMD. Semiquantitative measurement of aortic VC from lateral DXA was determined using previously validated 24- and 8-point scales and correlated with aortic VC with CT. Anteroposterior (AP) and lateral DXA-reported BMD was compared with BMD from L2 through L4 with CT. Patients, 70% men, 38% diabetic, had median age 58.5 yr. Aortic VC was present in 94% with CT and 68% on lateral DXA. For 24- and 8-point scores, intraclass correlation coefficients for intrarater agreement were 0.93 and 0.88, respectively. DXA-measured VC correlated with CT. Sensitivity and specificity for CT aortic VC > or = 500 HU was 50 and 86%, respectively, for DXA VC > or = 6 on a 24-point scale. Lateral DXA-reported BMD significantly correlated with BMD from CT, but AP DXA did not. Lateral DXA may be useful because images may provide concurrent assessment of aortic calcification as well as more accurate lumbar spine BMD, avoiding some of the limitations of AP DXA.