Department of Medicine 3, Friedrich-Alexander-University Erlangen-Nürnberg and Universitätsklinikum Erlangen, Erlangen, Germany.
Institute of Medical Physics, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.
J Bone Miner Res. 2023 Nov;38(11):1689-1699. doi: 10.1002/jbmr.4917. Epub 2023 Oct 1.
Opportunistic screening is a new promising technique to identify individuals at high risk for osteoporotic fracture using computed tomography (CT) scans originally acquired for an clinical purpose unrelated to osteoporosis. In these CT scans, a calibration phantom traditionally required to convert measured CT values to bone mineral density (BMD) is missing. As an alternative, phantomless calibration has been developed. This study aimed to review the principles of four existing phantomless calibration methods and to compare their performance against the gold standard of simultaneous calibration (ΔBMD). All methods were applied to a dataset of 350 females scanned with a highly standardized CT protocol (DS1) and to a second dataset of 114 patients (38 female) from clinical routine covering a large range of CT acquisition and reconstruction parameters (DS2). Three of the phantomless calibration methods must be precalibrated with a reference dataset containing a calibration phantom. Sixty scans from DS1 and 57 from DS2 were randomly selected for this precalibration. For each phantomless calibration method first the best combination of internal reference materials (IMs) was selected. These were either air and blood or subcutaneous adipose tissue, blood, and cortical bone. In addition, for phantomless calibration a fifth method based on average calibration parameters derived from the reference dataset was applied. For DS1, ΔBMD results (mean standard deviation) for the phantomless calibration methods requiring a precalibration ranged from 0.1 2.7 mg/cm to 2.4 3.5 mg/cm with similar means but significantly higher standard deviations for DS2. Performance of the phantomless calibration method, which does not require a precalibration was worse (ΔBMD DS1: 12.6 13.2 mg/cm , DS2: 0.5 8.8 mg/cm ). In conclusion, phantomless BMD calibration performs well if precalibrated with a reference dataset. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
机会性筛查是一种新的有前途的技术，可使用最初为与骨质疏松无关的临床目的而采集的计算机断层扫描（CT）来识别骨质疏松性骨折高风险的个体。在这些 CT 扫描中，传统上用于将测量的 CT 值转换为骨矿物质密度（BMD）的校准体模缺失。作为替代方法，已经开发出无体模校准。本研究旨在综述四种现有的无体模校准方法的原理，并将其性能与同时校准的金标准（ΔBMD）进行比较。所有方法均应用于一组使用高度标准化 CT 方案（DS1）扫描的 350 名女性数据集和一组来自临床常规的 114 名患者（38 名女性）数据集，涵盖了广泛的 CT 采集和重建参数（DS2）。其中三种无体模校准方法必须使用包含校准体模的参考数据集进行预校准。从 DS1 中随机选择 60 个扫描，从 DS2 中随机选择 57 个扫描进行此预校准。对于每种无体模校准方法，首先选择最佳的内部参考材料（IM）组合。这些材料可以是空气和血液，也可以是皮下脂肪组织、血液和皮质骨。此外，还应用了一种基于从参考数据集导出的平均校准参数的第五种无体模校准方法。对于 DS1，需要预校准的无体模校准方法的 ΔBMD 结果（平均值 标准差）范围为 0.1 2.7 mg/cm 至 2.4 3.5 mg/cm，均值相似，但 DS2 的标准差明显更高。不需要预校准的无体模校准方法的性能较差（DS1：12.6 13.2 mg/cm ，DS2：0.5 8.8 mg/cm ）。总之，如果使用参考数据集进行预校准，无体模 BMD 校准的性能良好。© 2023 作者。《骨与矿物质研究杂志》由 Wiley 期刊出版社代表美国骨与矿物质研究协会（ASBMR）出版。
