University of Wisconsin-Madison, Madison, WI, USA.
University of Wisconsin-Madison, Madison, WI, USA.
J Clin Densitom. 2021 Apr-Jun;24(2):281-286. doi: 10.1016/j.jocd.2020.05.008. Epub 2020 May 21.
Radio-dense artifacts, including contrast material, alter dual-energy X-ray absorptiometry (DXA) results. An apparent diffuse artifact was identified during spine DXA acquisition in a patient without recent radiographic procedures. The patient reported taking sodium zirconium cyclosilicate (SZC; Lokelma®) 10 g 1 h before scanning. SZC is a potassium-binding agent recently marketed to treat hyperkalemia. Given the chemical composition, we hypothesized that SZC may alter DXA results. This study evaluated if SZC affects DXA results using an encapsulated spine and a total body phantom.
An encapsulated spine and total body phantom were scanned using a Lunar iDXA. Each phantom was scanned 5 times serially without repositioning in 5 configurations: (1) Bare, (2) 45 mL tap water, (3) 90 mL water, (4) 10 g SZC in 45 mL of water, and (5) 30 g SZC in 90 mL of water. Water and SZC was contained in plastic quart bags, folded, and placed over L2-3 on the spine phantom and flat over the pelvis/torso of the total body phantom.
Tap water did not change spine phantom measurements, but did increase (p < 0.05) total body phantom lean mass 46 g and 89 g with 45 mL and 90 mL, respectively. SZC 10 g or 30 g increased (p < 0.001) L2 and L3 bone mineral density (BMD) 18%-110%, mean 0.295 and 0.924 g/cm, respectively, while L1 and L4 BMD was statistically, but not clinically, altered by <0.010 g/cm. A dose-dependent change (p < 0.001) in total body phantom trunk measurements was demonstrated. The 10 g dose increased lean mass 16.8% and BMC 1%; fat mass was reduced 16.6%, while 30 g increased lean 41.9%, BMC 3.2%, and decreased fat 42.9%.
SZC confounds BMD and body composition phantom measurements. It is likely that SZC alters DXA results in humans. DXA technologists and interpreters should be aware of this confounder.
包括造影剂在内的高密度伪影会改变双能 X 射线吸收法（DXA）的结果。在一位近期无放射影像学检查的患者中，在脊柱 DXA 采集期间发现了一种明显的弥散性伪影。该患者报告在扫描前 1 小时服用了硅酸锆钠（SZC；Lokelma®）10 g。SZC 是一种最近上市的用于治疗高钾血症的钾结合剂。鉴于其化学成分，我们假设 SZC 可能会改变 DXA 的结果。本研究使用封装脊柱和全身模体评估了 SZC 是否会影响 DXA 结果。
使用 Lunar iDXA 对封装脊柱和全身模体进行扫描。每个模体在不重新定位的情况下连续 5 次以 5 种配置进行扫描：（1）无包装，（2）45 mL 自来水，（3）90 mL 水，（4）45 mL 水包裹的 10 g SZC，（5）90 mL 水包裹的 30 g SZC。水和 SZC 装在塑料夸脱袋中，折叠后放在脊柱模体的 L2-3 上，放在全身模体的骨盆/躯干上。
自来水不会改变脊柱模体的测量值，但会分别增加（p < 0.05）全身模体瘦体重 46 g 和 89 g，分别用 45 mL 和 90 mL 水包装。10 g 或 30 g SZC 分别使 L2 和 L3 骨矿物质密度（BMD）增加 18%-110%，平均值为 0.295 和 0.924 g/cm，而 L1 和 L4 BMD 的变化虽具有统计学意义，但临床意义不大，<0.010 g/cm。还证明了全身模体躯干测量值存在剂量依赖性变化（p < 0.001）。10 g 剂量使瘦体重增加 16.8%，BMC 增加 1%；脂肪量减少 16.6%，而 30 g 剂量使瘦体重增加 41.9%，BMC 增加 3.2%，脂肪量减少 42.9%。
SZC 会干扰 BMD 和身体成分模体的测量值。SZC 很可能会改变人体的 DXA 结果。DXA 技术员和解释者应该意识到这一混杂因素。
