1Department of Orthopaedic Surgery, University of Louisville School of Medicine.
2Norton Leatherman Spine Center, Louisville, Kentucky.
J Neurosurg Spine. 2024 Jan 12;40(4):513-518. doi: 10.3171/2023.11.SPINE23890. Print 2024 Apr 1.
Hounsfield unit (HU) measurements of bone density on CT are increasingly used for preoperative planning in spine surgery. Postmyelogram CT is another common preoperative diagnostic study. However, there is no current literature evaluating whether HU measurements on CT are affected by the presence of myelography dye. The purpose of the current study was to determine if the presence of myelography dye affects HU measurements of bone density in CT studies.
Twenty-nine preoperative spine surgery patients who underwent both standard and postmyelography CT performed within 6 months of each other were identified. HU measurements were obtained from an elliptical region of interest using the available software on a standard PACS. Measurements were obtained on the axial cut at the midvertebral body on all lumbar vertebrae on three separate occasions and an average value was calculated for comparative analysis. A 6-week gap was used between measurements of the CT scans and the CT myelograms to diminish bias.
The mean age of the cohort was 69 years and the average BMI was 32 kg/m2. Five patients were male and 24 were female. Six of the patients had instrumentation placed prior to the initial CT scan. The average HU measurements for CT levels L1-5 were 165, 171, 145, 154, and 225, respectively, whereas HU measurements for CT myelography of levels L1-5 were 168, 177, 148, 170, and 239, respectively. Strong correlations were noted between the HU measured on CT and CT myelography for L1 (r2 = 0.951), L2 (r2 = 0.966), L4 (r2 = 0.820), and L5 (r2 = 0.900), and moderate for L3 (r2 = 0.668).
The presence of myelography dye had no clear effect on CT HU measurements of bone density. The results of this study support the use of CT myelograms for bone density assessment in the absence of standard CT images.
CT 上的骨密度亨氏单位（HU）测量值越来越多地用于脊柱手术的术前规划。脊髓造影后 CT 是另一种常见的术前诊断研究。然而，目前尚无文献评估脊髓造影染料是否会影响 CT 上的 HU 测量值。本研究的目的是确定脊髓造影染料的存在是否会影响 CT 研究中骨密度的 HU 测量值。
确定了 29 例在 6 个月内先后进行标准 CT 和脊髓造影后 CT 的术前脊柱手术患者。使用标准 PACS 上可用的软件从椭圆形感兴趣区域获得 HU 测量值。在所有腰椎的矢状位中，在椎体中部的轴位上进行 3 次测量，并计算平均值进行比较分析。在 CT 扫描和 CT 脊髓造影之间使用 6 周的间隔以减少偏差。
该队列的平均年龄为 69 岁，平均 BMI 为 32kg/m2。5 名患者为男性，24 名患者为女性。6 名患者在初始 CT 扫描前接受了器械植入。CT 水平 L1-5 的平均 HU 测量值分别为 165、171、145、154 和 225，而 CT 脊髓造影水平 L1-5 的 HU 测量值分别为 168、177、148、170 和 239。在 L1（r2=0.951）、L2（r2=0.966）、L4（r2=0.820）和 L5（r2=0.900）上，CT 和 CT 脊髓造影之间的 HU 测量值之间存在强相关性，而在 L3 上的相关性则为中度（r2=0.668）。
脊髓造影染料的存在对 CT 骨密度 HU 测量值没有明显影响。本研究的结果支持在没有标准 CT 图像的情况下使用 CT 脊髓造影进行骨密度评估。
