Department of Cardiology, Gødstrup Hospital, Herning, Denmark.
Department of Rheumatology, Aarhus University Hospital, Aarhus Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
J Clin Densitom. 2024 Jan-Mar;27(1):101441. doi: 10.1016/j.jocd.2023.101441. Epub 2023 Nov 3.
Osteoporosis is under-diagnosed and often co-exists with other diseases. Very low bone mineral density (BMD) indicates risk of osteoporosis and opportunistic screening for low BMD in CT-scans has been suggested. In a non-contrast enhanced thoracic CT scan, the scan-field-of-view includes vertebrae enabling BMD estimation. However, many CT scans are obtained by administration of contrast material. If the impact of contrast enhancement on BMD measurements could be quantified, considerably more patients are eligible for screening.
This study investigated the impact of intravenous contrast on thoracic BMD measurements in cardiac CT scans pre- and post-contrast, including different contrast trigger levels of 130 and 180 Hounsfield units (HU). BMD was measured using quantitative CT with asynchronous calibration.
In 195 participants undergoing cardiac CT (mean age 57±9 years, 37 % females) contrast increased mean thoracic BMD from 116±33 mg/cm (non-enhanced CT) to 130±38 mg/cm (contrast-enhanced CT) (p<0.001). Using clinical cut-off values for very low (<80 mg/cm) and low BMD (<120 mg/cm) showed that 24 % (47/195 participants) were misclassified when BMD was measured on contrast-enhanced CT-scans. Of the misclassified patients, 6 % (12/195 participants) were categorized as having low BMD despite having very low BMD on the non-enhanced images. Contrast-CT using a higher contrast trigger level showed a significant increase in BMD compared to the lower trigger level (119±32 vs. 135±40 mg/cm, p<0.01).
For patients undergoing cardiac CT, using contrast-enhanced images to assess BMD entails substantial overestimation. Contrast protocol trigger levels also affect BMD measurements. Adjusting for these factors is needed before contrast-enhanced images can be used clinically.
Osteoporosis is under-diagnosed. Contrast-enhanced CT made to examine other diseases might be utilized simultaneously for bone mineral density (BMD) screening. These scans, however, likely entails overestimation of BMD due to the effect of contrast. Adjusting for this effect is needed before contrast-enhanced images can be implemented clinically for BMD screening.
骨质疏松症的诊断率较低，且常与其他疾病共存。骨矿物质密度（BMD）非常低表明有骨质疏松症的风险，因此建议在 CT 扫描中进行机会性低 BMD 筛查。在非增强胸部 CT 扫描中，扫描视野包括椎体，从而能够估算 BMD。但是，许多 CT 扫描是通过给予造影剂来完成的。如果可以量化造影增强对 BMD 测量的影响，那么将有更多的患者符合筛查条件。
本研究调查了静脉内造影剂对心脏 CT 扫描前后胸部 BMD 测量的影响，包括 130 和 180 亨氏单位（HU）的不同造影剂触发水平。使用异步校准的定量 CT 进行 BMD 测量。
在 195 名接受心脏 CT 检查的参与者中（平均年龄 57±9 岁，37%为女性），造影剂将平均胸部 BMD 从 116±33mg/cm（非增强 CT）增加到 130±38mg/cm（增强 CT）（p<0.001）。使用非常低（<80mg/cm）和低（<120mg/cm）BMD 的临床截止值表明，当在增强 CT 扫描上测量 BMD 时，24%（195 名参与者中的 47 名）被错误分类。在被错误分类的患者中，6%（195 名参与者中的 12 名）尽管在非增强图像上具有非常低的 BMD，但被归类为具有低 BMD。与较低的触发水平相比，使用较高的造影剂触发水平进行对比 CT 显示 BMD 有显著增加（119±32 vs. 135±40mg/cm，p<0.01）。
对于接受心脏 CT 检查的患者，使用增强图像评估 BMD 会导致显著高估。造影剂方案的触发水平也会影响 BMD 测量。在可以将增强图像用于临床 BMD 筛查之前，需要对这些因素进行调整。
