Department of Orthopaedic Surgery, Nishitaga National Hospital, Sendai, Japan.
Spine (Phila Pa 1976). 2012 Jul 15;37(16):E985-92. doi: 10.1097/BRS.0b013e31821038f2.
We compared the sizes of the dural sac among conventional magnetic resonance imaging (MRI), axial loaded MRI, and upright myelography in patients with lumbar spinal canal stenosis (LSCS).
To determine whether axial loaded MRI can demonstrate similar positional changes of the dural sac size as were detected by upright myelography in LSCS.
In patients with LSCS, constriction of the dural sac is worsened and symptoms are aggravated during standing or walking. To disclose such positional changes, upright myelography has been widely used. Recently, axial loaded MRI, which can simulate a standing position, has been developed. However, there has been no study to compare the dural sac size between axial loaded MRI and upright myelography.
Forty-four patients underwent conventional MRI, axial loaded MRI, and myelography. Transverse and anteroposterior diameters and the cross-sectional areas of the dural sac from L2-L3 to L5-S1 were compared. Pearson correlations of the diameters between the MRIs and the myelograms were analyzed. On the basis of the myelograms, all disc levels were divided into severe and nonsevere constriction groups. In each group, the diameters and the cross-sectional areas were compared. Sensitivity and specificity to detect severe constriction were calculated for the conventional and axial loaded MRI.
Transverse and anteroposterior diameters at L4-L5 in the axial loaded MRI and myelogram were significantly smaller than those observed in the conventional MRI (P < 0.001). Cross-sectional areas in the axial loaded MRI were significantly smaller than those in the conventional MRI at L2-L3, L3-L4, and L4-L5 (P < 0.001). Between the axial loaded MRI and the myelography, Pearson correlation coefficients of the transverse and anteroposterior diameters were 0.85 and 0.87, respectively (P < 0.001), which were higher than those for conventional MRI. Reductions of the dural sac sizes in the axial loaded MRI were more evident in the severe constriction group. The axial loaded MRI detected severe constriction with a higher sensitivity (96.4%) and specificity (98.2%) than the conventional MRI.
The axial loaded MRI demonstrated a significant reduction in the dural sac size and significant correlations of the dural sac diameters with the upright myelogram. Furthermore, the axial loaded MRI had higher sensitivity and specificity than the conventional MRI for detecting the severe constriction observed in the myelogram. Therefore, the axial loaded MRI can be used to represent positional changes of the dural sac size detected by the upright myelography in patients with LSCS.
我们比较了常规磁共振成像（MRI）、轴向加载 MRI 和腰椎椎管狭窄症（LSCS）患者直立脊髓造影的硬脑膜囊大小。
确定轴向加载 MRI 是否可以显示 LSCS 中硬脑膜囊大小的类似位置变化，这些变化是通过直立脊髓造影检测到的。
在 LSCS 患者中，硬脑膜囊的收缩在站立或行走时加重，症状加重。为了揭示这种位置变化，广泛使用了直立脊髓造影。最近，开发了一种可以模拟站立位置的轴向加载 MRI。然而，尚未有研究比较轴向加载 MRI 和直立脊髓造影的硬脑膜囊大小。
44 例患者接受了常规 MRI、轴向加载 MRI 和脊髓造影。比较 L2-L3 至 L5-S1 的硬脑膜囊的横径和前后径以及横截面积。分析 MRI 和脊髓造影之间直径的 Pearson 相关性。根据脊髓造影，所有椎间盘水平均分为严重和非严重狭窄组。在每组中，比较直径和横截面积。计算常规和轴向加载 MRI 检测严重狭窄的敏感性和特异性。
轴向加载 MRI 和脊髓造影的 L4-L5 横径和前后径明显小于常规 MRI（P<0.001）。轴向加载 MRI 在 L2-L3、L3-L4 和 L4-L5 的横截面积明显小于常规 MRI（P<0.001）。轴向加载 MRI 与脊髓造影之间，横径和前后径的 Pearson 相关系数分别为 0.85 和 0.87（P<0.001），高于常规 MRI。轴向加载 MRI 中硬脑膜囊尺寸的减小在严重狭窄组更为明显。轴向加载 MRI 检测严重狭窄的敏感性（96.4%）和特异性（98.2%）高于常规 MRI。
轴向加载 MRI 显示硬脑膜囊大小明显减小，与直立脊髓造影的硬脑膜囊直径具有显著相关性。此外，轴向加载 MRI 检测脊髓造影中观察到的严重狭窄的敏感性和特异性均高于常规 MRI。因此，轴向加载 MRI 可用于代表 LSCS 患者直立脊髓造影检测到的硬脑膜囊大小的位置变化。
