(1) Background: Most of the currently used radiological criteria for craniovertebral junction (CVJ) were developed prior to the popularity of magnetic resonance images (MRIs). This study aimed to evaluate the efficacy of a novel triangular area (TA) calculated on MRIs for pathologies at the CVJ. (2) Methods: A total of 702 consecutive patients were enrolled, grouped into three: (a) Those with pathologies at the CVJ (n = 129); (b) those with underlying rheumatoid arthritis (RA) but no CVJ abnormalities (n = 279); and (3) normal (control; n = 294). TA was defined on T2-weighted MRIs by three points: The lowest point of the clivus, the posterior-inferior point of C2, and the most dorsal indentation point at the ventral brain stem. Receiver operating characteristic (ROC) analysis was used to correlate the prognostic value of the TA with myelopathy. Pre- and post-operative TA values were compared for validation. (c) Results: The CVJ-pathology group had the largest mean TA (1.58 ± 0.47 cm²), compared to the RA and control groups (0.96 ± 0.31 and 1.05 ± 0.26, respectively). The ROC analysis calculated the cutoff-point for myelopathy as 1.36 cm² with the area under the curve at 0.93. Of the 81 surgical patients, the TA was reduced (1.21 ± 0.37 cm²) at two-years post-operation compared to that at pre-operation (1.67 ± 0.51 cm²). Moreover, intra-operative complete reduction of the abnormalities could further decrease the TA to 1.03 ± 0.39 cm². (4) Conclusions: The TA, a valid measurement to quantify compression at the CVJ and evaluate the efficacy of surgery, averaged 1.05 cm² in normal patients, and 1.36 cm² could be a cutoff-point for myelopathy and of clinical significance.

中文翻译：

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颅椎交界处的三角形区域：磁共振图像量化的脑干压缩。

（1）背景：目前大多数颅脑交界处（CVJ）的放射学标准是在磁共振图像（MRI）普及之前制定的。这项研究的目的是评估在MRI上计算出的CVJ病理上新的三角形区域（TA）的疗效。（2）方法：共纳入702名连续患者，分为三类：（a）CVJ有病理的患者（n = 129）；（b）患有类风湿关节炎（RA）但无CVJ异常的患者（n = 279）；和（3）正常（对照；n= 294）。在T2加权MRI上，TA被定义为三个点：锁骨的最低点，C2的后下点和腹侧脑干的最大背凹点。接受者操作特征（ROC）分析用于关联TA与脊髓病的预后价值。比较术前和术后的TA值进行验证。（c）结果：与RA组和对照组相比，CVJ病理组的平均TA值最大（1.58±0.47 cm ²），分别为0.96±0.31和1.05±0.26。ROC分析计算出脊髓病变的临界点为1.36 cm ²，曲线下面积为0.93。在81名手术患者中，TA降低了（1.21±0.37 cm ²），与手术前（1.67±0.51 cm ²）相比。此外，术中完全减少异常可将TA进一步降低至1.03±0.39 cm ²。（4）结论：TA是量化CVJ压迫和评估手术效果的有效方法，正常患者的平均1.05 cm ²和1.36 cm ²可能是脊髓病的临界点，具有临床意义。