Thamburaj K, Radhakrishnan V V, Thomas B, Nair S, Menon G
Department of Imaging Sciences, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India.
AJNR Am J Neuroradiol. 2008 Mar;29(3):552-7. doi: 10.3174/ajnr.A0887. Epub 2007 Dec 13.
Vestibular schwannomas (VS) may be difficult to differentiate from cerebellopontine angle (CPA) meningiomas. Demonstration of microhemorrhages in VS on T2*-weighted gradient-echo (GRE) sequences may have potential value to differentiate VS from CPA meningiomas.
In this prospective study of 20 patients, MR imaging was performed with T2*-weighted GRE in addition to all basic sequences. Histopathologic examination was performed after surgery. Intratumoral hemosiderin was confirmed by pigment staining.
There were 15 patients in the VS group with 16 VS and 5 in the meningioma group with 5 posterior fossa meningiomas. Fourteen of the 16 VS and all 5 meningiomas were treated surgically and were confirmed on histopathologic examination. T2*-weighted GRE identified microhemorrhages on T2*-weighted sequence in 15 (93.75%) of the 16 VS. CT excluded calcification in all VS. T2-weighted turbo spin-echo (TSE) and fluid-attenuated inversion recovery (FLAIR) images recognized microhemorrhages in 2 cases. Pigment staining confirmed hemosiderin in all 14 surgically treated VS, and none of the meningiomas showed microhemorrhages on MR imaging. For the detection of microhemorrhages, T2*-weighted GRE showed a sensitivity of 93.8%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 83.3%. The sensitivity of T2 TSE and FLAIR for microhemorrhage was 12.5%. The Fisher exact test showed a statistically significant difference in the differentiation of VS from meningioma on the basis of detection of microhemorrhages (P < .01).
Most VS demonstrate microhemorrhages on T2*-weighted GRE. This finding is useful to differentiate VS from CPA meningiomas. T2*-weighted GRE should be used as a basic sequence to evaluate CPA tumors. Identification of microhemorrhages may have the potential to assess the aggressive biologic behavior of VS.
前庭神经鞘瘤（VS）可能难以与桥小脑角（CPA）脑膜瘤相鉴别。在T2 *加权梯度回波（GRE）序列上显示VS中的微出血可能对VS与CPA脑膜瘤的鉴别具有潜在价值。
在这项对20例患者的前瞻性研究中，除了所有基本序列外，还采用T2 *加权GRE进行了磁共振成像（MR成像）。术后进行了组织病理学检查。通过色素染色确认瘤内含铁血黄素。
VS组有15例患者，共16个VS；脑膜瘤组有5例患者，共5个后颅窝脑膜瘤。16个VS中的14个和所有5个脑膜瘤接受了手术治疗，并经组织病理学检查证实。T2 *加权GRE在16个VS中的15个（93.75%）的T2 *加权序列上发现了微出血。CT排除了所有VS中的钙化。T2加权快速自旋回波（TSE）和液体衰减反转恢复（FLAIR）图像在2例中识别出微出血。色素染色证实了所有14个接受手术治疗的VS中存在含铁血黄素，而所有脑膜瘤在MR成像上均未显示微出血。对于微出血的检测，T2 *加权GRE的敏感性为93.8%，特异性为100%，阳性预测值为100%，阴性预测值为83.3%。T2 TSE和FLAIR对微出血的敏感性为12.5%。Fisher精确检验显示，基于微出血的检测，VS与脑膜瘤的鉴别存在统计学显著差异（P <.01）。
大多数VS在T2 *加权GRE上显示微出血。这一发现有助于VS与CPA脑膜瘤的鉴别。T2 *加权GRE应作为评估CPA肿瘤的基本序列使用。微出血的识别可能有潜力评估VS的侵袭性生物学行为。
