摘要:目的: 探讨磁共振波谱(MRS)对鉴别桥小脑角神经鞘瘤与脑膜瘤的价值。 方法 :对8例神经鞘瘤和8例脑膜瘤病例进行MRI平扫和增强扫描,并采用点分辨波谱序列(PRESS,TR/TE=2000/136ms)进行单体素波谱分析。从事磁共振诊断专业的医师根据肿瘤的MRI及MRS表现特征进行鉴别诊断。 结果 :尽管多数神经鞘瘤(5/8)和脑膜瘤(6/8)具有典型的MRI表现特征并仅经MRI即可得到正确鉴别,但部分病例(5/16)为不典型表现者,如脑膜瘤呈长T1长T2信号并伴有囊变,以及神经鞘瘤呈等信号、均匀强化且不伴有囊变或内听道扩大者,鉴别诊断困难。MRS显示脑膜瘤的胆碱/肌酸比值(Cho/Cr)(2.74±1.47)略高于神经鞘瘤(2.70±1.21),但差异无统计学意义。丙氨酸(Ala)在脑膜瘤中的出现率(4/8)显著高于神经鞘瘤(0/8)(Plt;0.05),谷氨酸盐/谷氨酰胺(Glx)在脑膜瘤中的出现率(5/8)也高于神经鞘瘤(2/8);而肌醇(Ins)在神经鞘瘤中的出现率(4/8)高于脑膜瘤(2/8)。结合MRS表现,在MRI上尚难鉴别的病例可被明确诊断,并与最终病理结果相符。 结论 : MRI有助于多数桥小脑角神经鞘瘤与脑膜瘤的鉴别诊断,但对不典型病例有一定局限性;MRS对不典型病例的鉴别具有重要的参考价值。Abstract: Objective: To explore the value of magnetic resonance spectroscopy (MRS) in the differentiation of neurinoma and meningioma in the cerebellopontine angle. Methods : 16 cases, including 8 cases of meningiomas and 8 cases of neurinomas, underwent MRI (plan and gadoliniumenhanced scan) and singlevoxel proton MRS (PRESS series, TR/TE=2000/136ms). MRI and MRS results were reviewed and differential diagnoses were made by professional radiologists. Results : Although most cases (11/16) were typical and clearly classified on MRI, atypical cases were also observed, such as meningioma of long T1/T2 signal intensity with small cystic foci, and neurinoma of isointensity and homogenous enhancement without cystic change or enlargement of internal acoustic meatus. The choline to creatine ratio (Cho/Cr) of meningioma (2.74±1.47) was higher than that of neurinoma (2.70±1.21), however the difference was not significant (Pgt;0.05). Alanine was observed in 4/8 meningiomas but none of neurinomas (Plt;0.05), and glutamine/glutamate was more frequently visualized in meningiomas (5/8) than in neurinomas (2/8), whilemyoinositol was more frequently observed in neurinomas (4/8) than in meningiomas (2/8). With MRS, cases difficult to differentiate were clearly and correctly classified. Conclusion : Although most CPA neurinomas and meningiomas can be diagnosed by MRI, MRS is useful for the differential diagnosis of atypical cases.
ObjectiveTo investigate the effect of microsurgical therapy and the key techniques in resection of large bilateral olfactory groove meningiomas via unilateral subfrontal approach.MethodsThe clinical data and follow-up results of 181 patients with large bilateral olfactory groove meningiomas who underwent microsurgical removal between June 2007 and May 2014 were retrospectively analyzed. The initial symptom was headache or (and) dizzy in 95 cases, hyposmia or anosmia in 53, impairment of visual function or (and) visual field deficits in 26, cognitive deficits in 3, epilepsy in 2, and accidentally discovered in 2. Unilateral subfrontal approach was applied in all patients (neuroendoscopy was applied in some cases in the later period); incision of falxcerebri, and when necessary, ligation of superior sagittal sinus to resect contralateral tumor were performed. Simultaneous or staged period resection of tumors invading skull base such as ethmoid sinus and superior meatus and reconstruction of the skull base were performed.ResultsThere was no perioperative mortality. Simpson grade Ⅰ resection was obtained in 33 cases, grade Ⅱ resection was in 141, grade Ⅲ resection was in 4, and grade Ⅳ resection was in 3. Among the 229 eyes with preoperative visual impairment, postoperative visual improvement was found in 215 eyes, unimproved was in 12, and aggravation was in 2. The 59 sides which lost their function of olfactory nerve before surgery obtained no recoveries after surgery, while olfactory nerve with residual function preoperative still kept sensing after surgery in 149 lateral sides (149/303). The patients were followed up for (76.9±43.8) months, and postoperative recurrence or residual tumor growth were found in 21 cases.ConclusionsBecause of the contralateral ocular and (or) nasal compensation, early discovery is very difficult for patients with olfactory groove meningioma. The unilateral subfrontal approach can provide sufficient exposure for resection of large bilateral olfactory groove meningiomas and improve the visual acuity and visual field deficits. But it is poor at the preservation of olfactory function. The approach, better with the aid of neuroendoscopy, can improve the total cutting rate, with the advantages of minimally invasion and fewer complications. It is a worthy priority for these tumors.