Toft Nielsen Camilla, Boesen Mikael, Henriksen Marius, Nybing Janus Uhd, Bardenfleth Sophia Wiinberg, Rasmussen Christian Kento, Brejnebøl Mathias Willadsen, Poulsen Asbjørn Seenithamby, Aljuboori Saber Muthanna, Bunyoz Kristine Ifigenia, Overgaard Søren, Troelsen Anders, Bliddal Henning, Gudbergsen Henrik, Müller Felix
Department of Radiology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Bispebjerg Hospital, Copenhagen, Denmark.
The Parker Institute, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Frederiksberg Hospital, Copenhagen, Denmark.
Eur Radiol. 2025 Aug 27. doi: 10.1007/s00330-025-11948-9.
The aim of this study was to compare in vivo and ex vivo Photon Counting CT (PCCT) of subchondral bone features in patients with knee osteoarthritis (KOA).
Pre-surgery in vivo and post-surgery ex vivo PCCT of the tibial plateau from participants with severe KOA referred to arthroplasty surgery from January 2022 through September 2023 were compared. Linear regression and Bland-Altman plots were used to assess correlation and agreement between in vivo and ex vivo measures of bone volume fraction (BV/TV), trabecular thickness (Tb.Th.) and attenuation in healthy and sclerotic trabecular bone. Delineated areas of bone sclerosis were compared using the Dice coefficient and Hausdorff distance.
18 in vivo/ex vivo PCCT scans were included. Strong correlations were found for BV/TV, R = 0.82 and attenuation; healthy, R = 0.89, and sclerotic, R = 0.79, bone, while a moderate correlation was found for Tb.Th., R = 0.55. Bias for BV/TV and Tb.Th. was -4.1% and -0.598 mm, respectively, and -41.4 HU and -81.1 HU for healthy and sclerotic bone, respectively. A proportional bias was observed for Tb.Th. and BV/TV. There was excellent agreement between the segmentations of sclerotic areas (Dice coefficient = 0.91, Hausdorff distance = 0.11 mm).
In patients with severe KOA, BV/TV and attenuation can be obtained with a high correlation and small bias between in vivo and ex vivo scans, while Tb.Th. showed moderate correlation and larger bias. Longitudinal studies using in vivo PCCT are feasible, but caution may be advised when measuring Tb.Th. The key OA feature of subchondral bone sclerosis is well translated from ex vivo to in vivo PCCT.
Question Bone changes occur with osteoarthritis development; the role of these changes is unclear, and no method for visualising bone microstructure in vivo exists. Findings Photon-counting CT showed a strong correlation between in vivo and ex vivo subchondral density measures, while a moderate correlation was found for trabecular thickness. Clinical relevance Photon-counting CT is feasible for in vivo longitudinal evaluation of bone in patients with knee osteoarthritis, allowing studies into the earlier stages of the disease.
本研究旨在比较膝关节骨关节炎（KOA）患者软骨下骨特征的体内和体外光子计数CT（PCCT）。
比较了2022年1月至2023年9月因严重KOA接受关节置换手术的参与者术前的体内PCCT和术后胫骨平台的体外PCCT。采用线性回归和Bland-Altman图评估健康和硬化小梁骨的骨体积分数（BV/TV）、小梁厚度（Tb.Th.）和衰减的体内和体外测量值之间的相关性和一致性。使用Dice系数和豪斯多夫距离比较划定的骨硬化区域。
纳入了18例体内/体外PCCT扫描。发现BV/TV（R = 0.82）和衰减之间存在强相关性；健康骨的衰减相关性为R = 0.89，硬化骨的衰减相关性为R = 0.79，而Tb.Th.的相关性中等，R = 0.55。BV/TV和Tb.Th.的偏差分别为-4.1%和-0.598 mm，健康骨和硬化骨的偏差分别为-41.4 HU和-81.1 HU。观察到Tb.Th.和BV/TV存在比例偏差。硬化区域的分割之间具有极好的一致性（Dice系数 = 0.91，豪斯多夫距离 = 0.11 mm）。
在严重KOA患者中，体内和体外扫描之间，BV/TV和衰减具有高相关性和小偏差，而Tb.Th.显示中等相关性和较大偏差。使用体内PCCT的纵向研究是可行的，但在测量Tb.Th.时可能需要谨慎。软骨下骨硬化这一关键的骨关节炎特征在体外和体内PCCT之间能够很好地转换。
问题 骨变化随着骨关节炎的发展而发生；这些变化的作用尚不清楚，并且不存在体内可视化骨微结构的方法。发现 光子计数CT显示体内和体外软骨下密度测量值之间存在强相关性，而小梁厚度的相关性中等。临床意义 光子计数CT对于膝关节骨关节炎患者的骨体内纵向评估是可行的，有助于对疾病早期阶段的研究。
