Department of Radiology, The Affiliated Hospital of Shaanxi University of Chinese Medicine, 2# Weiyang Western Road, Xianyang, 712000, China.
Eur Spine J. 2020 May;29(5):1175-1180. doi: 10.1007/s00586-020-06370-2. Epub 2020 Mar 17.
This study aimed to explore the feasibility of the fractal method used in decoding disk heterogeneity, hoping to find a reliable imaging biomarker for the quantitative and continuous grading of intervertebral disks (IVDs).
Totally, 180 IVDs in 65 low back pain patients (29 males, 36 female, 28-69 years) were examined with MRI. Each IVD was manually segmented on axial slice (at the mid-height layer of the disk). All disks were visually evaluated regarding degeneration grade, using Pfirrmann classification, by two experienced radiologists. Fractal dimension (FD) of the IVD was calculated from the defined regions of interest and correlated with Pfirrmann grade.
Fractal dimension differed significantly between any two groups (P < 0.01). The mean FDs for the four grades were as follows: Pfirrmann 1: 1.13 ± 0.02; Pfirrmann 2: 1.30 ± 0.05; Pfirrmann 3: 1.50 ± 0.05; and Pfirrmann 4: 1.65 ± 0.02. The well-hydrated IVDs displayed low fractal dimension. Degenerated IVDs displayed increased fractal dimension caused by disk heterogeneity, where the fractal dimension was shown to correlate strongly with Pfirrmann grade.
Fractal dimension associated well with IVD degeneration, determined with Pfirrmann grading, suggesting that the IVD fractal analysis was a suitable detection tool for the objective and continuous classification of IVD degeneration. These slides can be retrieved under Electronic Supplementary Material.
本研究旨在探讨分形方法在解码椎间盘异质性中的可行性，以期找到一种可靠的影像学生物标志物，用于定量和连续评估椎间盘（IVD）。
共对 65 例腰痛患者（男 29 例，女 36 例，28-69 岁）的 180 个 IVD 进行 MRI 检查。在轴位切片（椎间盘高度的中间层）上手动对每个 IVD 进行分段。由两名有经验的放射科医生对所有椎间盘的退变程度进行视觉评估，使用 Pfirrmann 分级。从定义的感兴趣区域计算 IVD 的分形维数（FD），并与 Pfirrmann 分级相关联。
分形维数在任意两组之间差异有统计学意义（P<0.01）。四个等级的平均 FD 如下：Pfirrmann 1：1.13±0.02；Pfirrmann 2：1.30±0.05；Pfirrmann 3：1.50±0.05；和 Pfirrmann 4：1.65±0.02。水合良好的 IVD 显示出较低的分形维数。退变的 IVD 显示出由于椎间盘异质性导致的分形维数增加，分形维数与 Pfirrmann 分级有很强的相关性。
分形维数与 Pfirrmann 分级确定的 IVD 退变密切相关，提示 IVD 分形分析是一种用于客观和连续评估 IVD 退变的合适检测工具。这些幻灯片可以在电子补充材料中检索到。
