Lortie Jevin, Ufearo Deborah, Hetzel Scott, Pickhardt Perry J, Szczykutowicz Timothy P, Kuchnia Adam J
Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI.
Institute for Clinical and Translational Research, University of Wisconsin-Madison, Madison, WI.
J Comput Assist Tomogr. 2025;49(3):480-485. doi: 10.1097/RCT.0000000000001682. Epub 2024 Nov 13.
Computed tomography (CT) measured muscle density is prognostic of health outcomes. However, the use of intravenous contrast obscures prognoses by artificially increasing CT muscle density. We previously established a correction to equalize contrast and noncontrast muscle density measurements. While this correction was validated internally, the objective of this study was to obtain external validation using different patient cohorts, muscle regions, and CT series.
CT images from 109 patients with kidney tumors who received abdominal CT scans with a multiphase intravenous contrast protocol were analyzed. Paraspinal muscle density measurements taken during noncontrast, venous phase, and delayed phase contrast scans were collected. An a priori correction of -7.5 Hounsfield units (HU) was applied to muscle measurements. Equivalence testing was utilized to determine statistical similarity.
In the sample of 109 patients (mean age: 63 years [SD: 14.3]; 41.3% female), densities in smaller regions of interest within the paraspinal muscles and the entire paraspinal muscle density (PS) in venous and delayed phase contrast scans were higher than in noncontrast. Equivalence testing showed that average corrected contrast and noncontrast muscle densities were within 3 HU for both muscle measures for the total patient sample, and for a majority of male and female subsamples. The correction is suitable for regions of interests of venous contrast (90% CI: -1.90, -0.69 HU) and delayed contrast scans (90% CI: 0.075, 1.29 HU) and within the PS measures of venous contrast (90% CI: -2.04, -0.94 HU) and delayed contrast scans (90% CI: -0.11, 0.89 HU).
The previously established correction for contrast of -7.5 HU was applied in a new patient population, axial muscle region, muscle measurement size, and expanded on previously studied contrast phases. The correction produced contrast-corrected muscle densities that were statistically equivalent to noncontrast muscle densities. The simplicity of the correction gives clinicians a tool that seamlessly integrates into practice or research to improve harmonization of data between contrast and noncontrast scans.
计算机断层扫描（CT）测量的肌肉密度可预测健康结局。然而，静脉注射造影剂会人为增加CT肌肉密度，从而掩盖预后情况。我们之前建立了一种校正方法，以使造影剂增强扫描和未增强扫描的肌肉密度测量结果相等。虽然这种校正方法在内部得到了验证，但本研究的目的是使用不同的患者队列、肌肉区域和CT序列进行外部验证。
分析了109例接受腹部CT多期静脉造影扫描的肾肿瘤患者的CT图像。收集了在未增强扫描、静脉期和延迟期造影扫描期间测量的椎旁肌密度数据。对肌肉测量值进行了-7.5亨氏单位（HU）的先验校正。采用等效性检验来确定统计相似性。
在109例患者的样本中（平均年龄：63岁[标准差：14.3]；41.3%为女性），椎旁肌内较小感兴趣区域的密度以及静脉期和延迟期造影扫描中整个椎旁肌密度（PS）均高于未增强扫描。等效性检验表明，对于整个患者样本以及大多数男性和女性亚样本，两种肌肉测量方法的平均校正造影剂增强扫描和未增强扫描肌肉密度相差均在3 HU以内。该校正适用于静脉期造影感兴趣区域（90%置信区间：-1.90，-0.69 HU）和延迟期造影扫描（90%置信区间：0.075，1.29 HU），以及静脉期造影PS测量值（90%置信区间：-2.04，-0.94 HU）和延迟期造影扫描（90%置信区间：-0.11，0.89 HU）。
之前建立的-7.5 HU造影剂校正方法应用于新的患者群体、轴向肌肉区域、肌肉测量大小，并在之前研究的造影阶段基础上进行了扩展。该校正产生的造影剂校正后肌肉密度在统计学上与未增强扫描肌肉密度等效。该校正方法的简单性为临床医生提供了一种工具，可无缝融入实践或研究中，以改善造影剂增强扫描和未增强扫描之间的数据一致性。
