Department of Ophthalmology and Visual Sciences (AH, JDT), (Kellogg Eye Center), Ann Arbor, Michigan; Department of Radiology (JK, EL) (Neuroradiology), Ann Arbor, Michigan; and Department of Neurology (JDT), University of Michigan, Ann Arbor, Michigan.
J Neuroophthalmol. 2023 Mar 1;43(1):126-130. doi: 10.1097/WNO.0000000000001655. Epub 2022 Jul 13.
Imaging diagnosis of clival cancer may be difficult, in part because of normal variation in marrow signal with aging. Identifying whether clival cancer has damaged the sixth cranial nerve is a further challenge because minimal clival abnormalities could impinge on the nerve, which travels very close to the clivus.
Two neuroradiologists, who were unaware of previous imaging and clinical diagnoses, reviewed MRI studies of 25 patients with cancer but no clival involvement and no sixth nerve palsy, 24 patients with clival cancer but without sixth nerve palsy, and 31 patients with clival cancer and sixth nerve palsy. The radiologists were tasked with determining whether there was clival cancer, whether there was a sixth nerve palsy and its laterality, and with indicating the pulse sequences used to make those determinations.
Both neuroradiologists correctly identified all 25 cases with a normal clivus. In about half of those cases, they depended on finding a homogeneously bright marrow signal; in the remaining cases, they excluded cancer by determining that the clivus was not expanded and that there were no focal signal abnormalities. Both neuroradiologists correctly identified clival cancer in 54 (98%) of the 55 cases with and without sixth nerve palsy. In doing so, they relied mostly on clival expansion but also on focal signal abnormalities. Both neuroradiologists were at least 80% correct in identifying a sixth nerve palsy, but they often incorrectly identified a palsy in patients who did not have one. When there was a one-sided signal abnormality or the clivus was expanded in one direction, both neuroradiologists were accurate in identifying the side of the sixth nerve palsy.
Current MRI pulse sequences allow accurate differentiation of a normal from a cancerous clivus. When the marrow signal is not homogeneously bright in adults, cancer can be diagnosed on the basis of clival expansion or focal signal abnormalities. MRI is less accurate in predicting the presence of a sixth nerve palsy. However, the side of a unilateral palsy can be predicted when the clivus is clearly expanded in one direction or there is a focal signal abnormality on one side.
颅底肿瘤的影像学诊断可能较为困难，部分原因是骨髓信号随年龄变化而存在正常变异。确定颅底肿瘤是否损伤了第六颅神经是一个进一步的挑战，因为颅底的微小异常可能压迫神经，而神经非常靠近颅底。
两位神经放射科医生，他们不知道先前的影像学和临床诊断，对 25 例无颅底受累和第六颅神经麻痹的癌症患者、24 例有颅底癌但无第六颅神经麻痹的患者和 31 例有颅底癌和第六颅神经麻痹的患者的 MRI 研究进行了回顾。放射科医生的任务是确定是否有颅底癌，是否有第六颅神经麻痹及其偏侧性，并指出用于做出这些确定的脉冲序列。
两位神经放射科医生都正确地识别了所有 25 例正常颅底的病例。在这些病例中，约一半依赖于发现骨髓信号均匀明亮；在其余病例中，他们通过确定颅底未扩张且无局灶性信号异常来排除癌症。两位神经放射科医生正确地识别了 55 例有或无第六颅神经麻痹的患者中的 54 例（98%）颅底癌。在这样做的过程中，他们主要依赖于颅底扩张，但也依赖于局灶性信号异常。两位神经放射科医生在识别第六颅神经麻痹方面的准确率至少为 80%，但他们经常错误地识别出没有麻痹的患者的麻痹。当出现单侧信号异常或颅底向一侧扩张时，两位神经放射科医生都能准确地识别出第六颅神经麻痹的侧别。
目前的 MRI 脉冲序列允许准确地区分正常和癌性颅底。当成年人的骨髓信号不均匀明亮时，可以根据颅底扩张或局灶性信号异常诊断癌症。MRI 在预测第六颅神经麻痹的存在方面准确性较低。然而，当颅底明显向一侧扩张或一侧出现局灶性信号异常时，可以预测单侧麻痹的侧别。
