El Sadaney Ahmed O, Ferrero Andrea, Rajendran Kishore, Jasper Soren, Mazza Gina L, Broski Stephen M, Shanblatt Elisabeth, Nowak Tristan, Fletcher Joel G, McCollough Cynthia H, Baffour Francis I
Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905.
Department of Quantitative Health Sciences, Division of Clinical Trials and Biostatistics, Mayo Clinic, Scottsdale, AZ.
AJR Am J Roentgenol. 2025 Jan;224(1):e2431909. doi: 10.2214/AJR.24.31909. Epub 2024 Oct 30.
Spectral localizer images from photon-counting detector (PCD) CT can be used for bone mineral density (BMD) evaluation given their 2D projectional nature and material decomposition capability. As all CT examinations include localizer images, this approach could allow opportunistic osteoporosis screening of patients undergoing clinically indicated imaging with PCD CT. . The purpose of this study was to assess the use of PCD CT spectral localizer images for opportunistic derivation of areal BMD (aBMD) values and T-scores, with dual-energy x-ray absorptiometry (DEXA) used as the reference standard. This prospective study included patients 18 years old or older who were scheduled for a clinically indicated lumbar spine CT examination between October 2023 and February 2024 and who underwent DEXA within the previous 13 months or were scheduled for DEXA within the subsequent 13 months. Participants underwent lumbar spine CT by PCD CT including spectral localizer images. The lumbar spine aBMD was extracted from clinical DEXA reports. ROIs were placed on lumbar vertebral bodies and background soft tissues to extract areal densities from spectral localizer images using material decomposition; areal densities were used to derive lumbar spine aBMD values. The aBMD values were used to derive T-scores, which were classified as representing normal (≥ -1.0) or abnormal (< -1.0) bone mass. DEXA-derived and PCD CT-derived measurements were compared. The study included 51 participants (31 women and 20 men; mean age, 62 years [range, 28-83 years]). The mean DEXA-derived T-score was 0.4 ± 1.6 [SD], and the mean PCD CT-derived T-score was 0.3 ± 1.8 [SD] ( = .29). The Lin concordance correlation coefficient between DEXA-derived and PCD CT-derived T-scores was 0.90. The difference between DEXA-derived and PCD CT-derived T-scores showed a small correlation with patient age ( = -0.13), absolute interval between DEXA and PCD CT ( = 0.15), and BMI ( = 0.28); this difference in scores did not show a significant difference between men and women (0.08 vs 0.13, respectively; = .81). PCD CT-derived T-scores had a sensitivity of 97%, specificity of 71%, PPV of 90%, and NPV of 91% for detecting abnormal bone mass, with DEXA-derived T-scores used as the reference standard. PCD CT spectral localizer images showed clinical utility in deriving aBMD values and, consequently, T-scores. The T-score derived from PCD CT spectral localizer images may serve as an opportunistic screening tool for low bone mass and osteoporosis.
鉴于光子计数探测器（PCD）CT的二维投影特性和物质分解能力，其光谱定位图像可用于骨密度（BMD）评估。由于所有CT检查都包括定位图像，这种方法可以对接受PCD CT临床指征成像的患者进行机会性骨质疏松筛查。本研究的目的是评估使用PCD CT光谱定位图像机会性推导面积骨密度（aBMD）值和T值，以双能X线吸收法（DEXA）作为参考标准。这项前瞻性研究纳入了18岁及以上的患者，他们计划在2023年10月至2024年2月期间进行临床指征的腰椎CT检查，并且在过去13个月内接受过DEXA检查或计划在随后13个月内接受DEXA检查。参与者通过PCD CT进行腰椎CT检查，包括光谱定位图像。腰椎aBMD从临床DEXA报告中提取。在腰椎椎体和背景软组织上放置感兴趣区（ROI），以利用物质分解从光谱定位图像中提取面积密度；面积密度用于推导腰椎aBMD值。aBMD值用于推导T值，T值被分类为代表正常（≥ -1.0）或异常（< -1.0）骨量。比较了DEXA衍生和PCD CT衍生的测量结果。该研究包括51名参与者（31名女性和20名男性；平均年龄62岁[范围28 - 83岁]）。DEXA衍生的平均T值为0.4±1.6[标准差]，PCD CT衍生的平均T值为0.3±1.8[标准差]（P = 0.29）。DEXA衍生和PCD CT衍生的T值之间的林一致性相关系数为0.90。DEXA衍生和PCD CT衍生的T值之间差异与患者年龄（P = -0.13）、DEXA和PCD CT之间的绝对间隔（P = 0.15）以及体重指数（BMI）（P = 0.28）呈小相关性；该得分差异在男性和女性之间未显示出显著差异（分别为0.08对0.13；P = 0.81）。以DEXA衍生的T值作为参考标准，PCD CT衍生的T值检测异常骨量的灵敏度为97%，特异性为71%，阳性预测值为90%，阴性预测值为91%。PCD CT光谱定位图像在推导aBMD值以及因此推导T值方面显示出临床实用性。从PCD CT光谱定位图像推导得到T值可作为低骨量和骨质疏松症的机会性筛查工具。
