Kok Joeri, Bevers Melissa S A M, van Rietbergen Bert, Oei Edwin H G, Booij Ronald
Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Department of Orthopaedic Surgery, Maastricht University, Maastricht, The Netherlands.
Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Department of Internal Medicine, VieCuri Medical Center, Venlo, The Netherlands; NUTRIM Institute of Nutrition and Translational Research In Metabolism, Maastricht University, Maastricht, The Netherlands.
Eur J Radiol. 2024 Dec;181:111717. doi: 10.1016/j.ejrad.2024.111717. Epub 2024 Sep 2.
Accurate measurements of trabecular bone microarchitecture are required for a proper assessment of bone fragility. Photon-counting detector CT (PCD-CT) has different technical properties than conventional CT, resulting in higher resolution and thereby potentially enabling in-vivo measurement of trabecular microarchitecture. The purpose of this study was to quantify trabecular bone microarchitectural parameters with PCD-CT at varying radiation doses and compare this to µCT as gold standard.
Both distal radii, distal tibiae, femoral heads, and two vertebrae were dissected from one human. All specimens were scanned ex-vivo on a PCD-CT system (slice increment 0.1 mm; pixel size 0.1042-0.127 mm) and a µCT system (isotropic voxel size 49-68.4 µm). The radiation doses of the PCD-CT scans were varied from 2.5 to 120 mGy based on the volume CT dose index (CTDI). For the PCD-CT scans, contrast-to-noise ratio and trabecular sharpness were calculated and compared between radiation doses. µCT and PCD-CT scans were registered. The trabecular bone was then segmented from all PCD-CT and µCT scans and split into cubes with 6-mm edge length. For each cube, bone volume over total volume, trabecular thickness, trabecular number, and trabecular heterogeneity were calculated and compared between corresponding PCD-CT and µCT cubes.
With increasing dose, contrast-to-noise ratio and trabecular sharpness values increased for the PCD-CT images. Already at the lowest dose, high correlations between the trabecular microarchitectural parameters between µCT and PCD-CT were found (R = 0.55-0.95), which improved with increasing radiation dose (R = 0.76-0.96 at 20 mGy).
PCD-CT can be used to quantify trabecular bone microarchitecture, with accuracy comparable to µCT and at clinically relevant radiation doses.
准确测量小梁骨微结构对于正确评估骨脆性至关重要。光子计数探测器CT（PCD-CT）具有与传统CT不同的技术特性，可实现更高分辨率，从而有可能对小梁微结构进行活体测量。本研究的目的是使用PCD-CT在不同辐射剂量下对小梁骨微结构参数进行量化，并将其与作为金标准的µCT进行比较。
从一名人类受试者身上解剖出双侧桡骨远端、双侧胫骨远端、股骨头和两个椎体。所有标本在PCD-CT系统（层厚增量0.1毫米；像素大小0.1042-0.127毫米）和µCT系统（各向同性体素大小49-68.4微米）上进行离体扫描。基于容积CT剂量指数（CTDI），PCD-CT扫描的辐射剂量在2.5至120毫戈瑞之间变化。对于PCD-CT扫描，计算不同辐射剂量下的对比度噪声比和小梁清晰度并进行比较。对µCT和PCD-CT扫描进行配准。然后从所有PCD-CT和µCT扫描中分割出小梁骨，并将其切成边长为6毫米的立方体。对于每个立方体，计算骨体积分数、小梁厚度、小梁数量和小梁异质性，并在相应的PCD-CT和µCT立方体之间进行比较。
随着剂量增加，PCD-CT图像的对比度噪声比和小梁清晰度值升高。在最低剂量时，µCT和PCD-CT之间的小梁微结构参数就已呈现高度相关性（R = 0.55-0.95），随着辐射剂量增加相关性进一步提高（20毫戈瑞时R = 0.76-0.96）。
PCD-CT可用于量化小梁骨微结构，其准确性与µCT相当，且辐射剂量具有临床相关性。
