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

Abstract

Background and objectives: Vascular calcification (VC) contributes to increased cardiovascular (CV) disease in dialysis patientsand 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).Design, setting, participants, & measurements: 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.Results: 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 > 500 HU was 50 and 86%, respectively, for DXA VC > 6 on a 24-point scale. Lateral DXA-reported BMD significantly correlated with BMD from CT, but AP DXA did not.Conclusions: 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.

Quantitative Assessment of Abdominal Aortic Calcifications Using Lateral Lumbar Radiograph, Dual-Energy X-ray Absorptiometry, and Quantitative Computed Tomography of the Spine

“…0.0001) using lateral DXA (13). This simplified 8-point score may provide a quick, accurate tool for assessment of AAC, consistent with other studies that have shown good correlation between the 2 methods (0.95) (8) and good reproducibility of the 8-point score (2,16,17).…”

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

“…Regarding agreement with other imaging modalities for aortic calcification, DXA-based AAC24 scores have good-very good agreement with radiography 34, 35 and moderate-good agreement with CT 36, 37 . The two studies comparing DXA-based AAC24 scores and standard radiographs were large studies with experienced investigators and reported ICC of between 0.80-0.82 34, 35 , however the studies comparing DXA-based AAC24 scores with CT were considerable smaller (n=40-100), and only one study reported an ICC of 0.93 37 while the other study 36 used Spearman rank correlation (r s =0.58, P<0.0001) which does not measure agreement between tests 38 .…”

“…The two studies comparing DXA-based AAC24 scores and standard radiographs were large studies with experienced investigators and reported ICC of between 0.80-0.82 34, 35 , however the studies comparing DXA-based AAC24 scores with CT were considerable smaller (n=40-100), and only one study reported an ICC of 0.93 37 while the other study 36 used Spearman rank correlation (r s =0.58, P<0.0001) which does not measure agreement between tests 38 . Therefore the evidence for the agreement between AAC by DXA-based techniques with CT remains limited.…”

Bone microarchitecture is more severely affected in patients on hemodialysis than in those receiving peritoneal dialysis

“…DXA is limited by the presence of aortic calcifications, that are common in dialysis patients and that may lead to an overestimation of spine aBMD and T-score. 22 This could explain the lack of difference in spine T-score in HD and PD patients compared with controls, whereas their hip T-score was lower. DXA has other technical limitations.…”