Classical and real-time neuronavigation in pediatric neurosurgery

Introduction Neuronavigation has become a cornerstone of neurosurgery. Navigation systems are categorized into two main groups: those based on preoperative imaging and those based on real-time intraoperative acquired images.Objectives The preoperative imaging systems, either computed tomography (CT)- or magnetic resonance imaging (MRI)-based, are straight-forward systems that are routinely used in most institutions. Image accuracy, however, decreases secondary to brain and lesion shifts that occur during surgery. Intraoperative, real-time navigation systems overcome anatomical shifts by updating the image base of the navigation during surgery, thus, maintaining precise navigation capabilities throughout the surgical procedure.Conclusions In this article, we review the main neuronavigation systems and their applications, emphasizing their unique advantages and usage within the pediatric population.     

Neuronavigation Computerassistierte Neurochirurgie

The use of stereotactic methods for the resection of subcortical lesions is heavily advocated in clinical neurosurgery introducing the term "neuronavigation". Though being an unequivocally elegant technique for the localisation and delineation of pathological lesions in the central nervous system neuronavigation has not been validated by any prospective randomized controlled trial. The method is prone to significant errors as to the intraoperative localisation based upon preoperative three-dimensional images. The maximum error can be up to 2.6 cm depending on the extent of the so-called brain shift. In comparison classical frame based stereotaxy has a mean error of +/- 1 mm and remains the gold standard for the exact three-dimensional localisation of a given lesion. The value of neuronavigation is evident for small deep seated vascular lesions. For metastatic tumors or skull base tumors the usefulness is rather marginal because alternative therapies are available with proven and equivalent efficacy and reduced morbidity on one hand, and because of the anatomy of the tumor which makes neuronavigation unnecessary. For the currently most common application of neuronavigation, i.e. surgery of gliomas, no significant improvements of therapeutic results can be expected from neuronavigation. The biology of gliomas limits any mechanical approaches.     

实时超声导航在脑深部病灶手术中的应用

目的 评价实时超声导航系统在脑深部病变手术中的应用,总结应用术中实时超声解决脑移位、指导病灶切除的经验.方法 应用Vector Vision Compact神经导航系统结合术中实时超声对15例脑深部病灶行手术治疗.术中应用超卢指示病灶位置,在脑组织移位时利用实时超声对病灶进行手术中再定位、导向,并监测残余病灶的切除.结果 术中经超声探查和术前导航影像对比,发现有11例病灶有不同程度的移位,在实时超声的引导下纠正脑移位及切除病灶,全切除12例,近全切除2例,1例炎性病灶行活组织检查证实为慢性肉芽肿.结论 术中实时超声能进行病灶的实时定位引导,监测病灶深度,确定切除范围,避开功能区皮质和深部重要结构,对手术残余进行判断和指导再次切除,故有助于提高手术疗效,降低手术并发症.     

术中磁共振影像神经导航手术的临床初步应用

目的:探讨术中核磁共振影像神经导航(intraoperative MR image-based neuronavigation)技术在神经外科手术的意义。方法:应用PoleStarN-20术中磁共振成像(iMRI)神经导航系统施行神经外科手术22例。对其临床资料、iMRI情况,及其对手术进程和手术结果的影响进行分析。结果:22例手术中,经鼻-蝶垂体瘤切除术10例,幕上开颅肿瘤切除术10例,幕下开颅肿瘤切除术2例。iMRI扫描次数从2～5次不等,平均2.6次。共有9例术中扫描发现有肿瘤残留,其中8例(36.4%),需做进一步的切除,最终肿瘤的全切率从60%提高到86.4%。无与iMRI相关的并发症。结论:iMRI神经导航技术的应用,为神经外科手术入路的选择、皮肤切口的设计、手术进程的指导及手术结果的实时判断提供了客观的依据,从而在提高手术的精确性和安全性的同时,提高了颅脑肿瘤的全切率。     

神经导航整合超声(双超和多普勒)技术在术中血管解剖标记的作用

目的探讨神经导航整合超声技术在术中标记血管中的作用。方法建立在神经导航中整合进超声平面视频影像的技术，并将该技术应用于47例患者（动静脉畸形22例、胶质瘤17例、海绵状血管瘤8例）的手术中。结果该系统支持超声平面函数与术前获得导航资料的结合。多普勒超声和双向超声可以显示术中血管解剖结构，并确定其界标。这些界标可以自动整合入神经导航数据集中，用来提供血管解剖的术中更新影像。本组病例应用该技术的成功率是45／47（96％），45例患者手术过程顺利、全切病灶，且保护了病灶周围的血管结构。结论超声和双向超声所显示的血管解剖资料整合入神经导航数据集中在技术上是可行的。该技术为复杂脑部病变的手术提供有价值的术中信息，尤其显示血管的解剖结构。     

超声导航辅助显微神经外科手术(附29例分析)

目的 探讨术中超声导航在显微神经外科手术中的应用价值。方法对29例神经外科显微手术中采用实时超声影像引导病变定位。指引手术路径选择，并动态了解病变位置的变化情况、手术切除程度。蛛网膜囊肿6例，脑膜瘤1例，动静脉畸形2例，胶质瘤2例，转移瘤5例，脑内血肿8例。椎管内神经纤维瘤4例，脑脓肿1例。结果所有病变均得到全切，术后病人恢复良好，神经功能保存完好，无额外的神经功能损害和手术并发症。结论术中超声导航操作简便，定位准确，能够实现实时影像导航；与显微神经外科配合能够有效起到降低手术副损伤，提高手术精度的作用。     

Integrated PET/MRI for planning navigated biopsies in pediatric brain tumors

Introduction

An integrated PET/MRI scanner has been used in selected cases of pediatric brain tumor patients to obtain additional metabolic information about lesions for preoperative biopsy planning and navigation.

Patients and methods

Four patients, age 9–16 years, received PET/MRI scans employing [¹¹C]methionine positron emission tomography (PET) and contrast-enhanced 3D-MR sequences for neuronavigation. PET and MR sequences have been matched for neurosurgical guidance. An infrared camera-based neuronavigation system was employed with co-registered MR and PET images fused to hybrid images for preoperative planning, stereotactic biopsy planning, and/or intraoperative guidance.

Results

All patients showed hot spots of increased amino acid transport in PET and contrast-enhancing lesions in MRI. In three of the four patients, PET hot spots were congruent with contrast-enhancing areas in MRI. In two patients, frame-based stereotactic biopsies were taken from thalamo-mesencephalic lesions. One patient underwent second-look surgery for the suspicion of recurrent malignant glioma of the posterior fossa. One incidental frontal mass lesion was subtotally resected. No complications occurred. Hybrid imaging was helpful during the procedures to obtain representative histopathologic specimens and for surgical guidance during resection. Co-registered images did match with intraoperative landmarks, tumor borders, and histopathologic specimens.

Conclusion

The integrated PET/MRI scanner offers co-registered multimodal, high-resolution data for neuronavigation with reduced radiation exposure compared to PET/CT scans. One examination session provides all necessary data for neuronavigation and preoperative planning, avoiding additional anesthesia in the small patients. Hybrid multimodality imaging may improve safety and yield additional information when obtaining representative histopathologic specimens of brain tumors.     

医学图像处理技术在神经导航手术中的初步应用 (附35例临床报道)

目的探讨神经导航相关的图像重建和融合技术在神经外科微创手术中的应用价值。方法利用史赛克导航仪,对不同颅内病变的影像学资料进行重建、融合,指导神经外科显微手术。结果图像重建、图像融合均成功。在导航指导下,33例病变全切率为78.79%,2例动脉瘤夹闭满意。结论利用先进图像处理技术进行神经导航辅助显微神经外科手术,具有术前计划周密详尽、术中定位准确可靠、手术创伤小、病变全切率高等突出优点,在微创神经外科领域具有广泛的临床应用前景。     

Functional cranial neuronavigation. Direct integration of fMRI and PET data

OBJECTIVE: We report our first experiences with the direct integration of fMRI data into cranial neuronavigation. Method: For navigation we used the MKM system and thin-sliced T1 contrast enhanced images. As a first step 21 patients had fMRI for localization of the precentral gyrus, 2 patients for Broca area detection. By anatomical correlation, these functional data were indirectly compared to the intraoperative findings using cortical SSEP (n=20) or cortical stimulation (n=3). Encouraged by these preliminary results, we started the direct integration of fMRI into neuronavigation in June 1999, followed by PET in January 2000, enabling us to compare functional images with intraoperative findings directly. fMRI and PET data were integrated by landmark matching referring on skin fiducials. Meanwhile, fMRI data of 8 patients (6 motorcortex, 2 Broca) and PET images of 1 patient were directly integrated into neuronavigation. Six out of 8 patients had additional cortical monitoring, 2/8 were exclusively operated on by functional neuronavigation. RESULTS: Using indirect comparison between fMRI and intraoperative findings we observed a good correlation in every case for the motorcortex, but only in 1/2 for the speech area. In all 6 direct integrated fMRI cases, these findings corresponded well to the conventional ones. Both patients with sole functional navigation did not have any postoperative neurological deficit. The inaccuracy of the fMRI ifT1 matching was 2. 7 mm (sigma=0.9 mm) and 1.3 mm (sigma=0.4 mm) of the subsequent referenciation of the navigation. The tumor delinement shown by 11C-methionine PET could be proven by intraoperative biopsy outside its indicated tumor margin. The inaccuracy of the PET matching was 0. 8 mm. CONCLUSION: Functional neuronavigation enables to visualize and preserve relevant brain areas. Other functional areas like short-term memory, which solely can be detected by fMRI might also be monitored in the future. The integration of PET data expect to gain a better differentiation of tumor and edema.     

神经内镜与神经导航辅助显微镜下经鼻蝶入路切除垂体瘤的疗效比较

目的比较神经内镜与神经导航辅助显微镜下经鼻蝶入路切除垂体瘤的临床疗效。 方法选取湖北医药学院附属襄阳市第一人民医院自2016年1月至2018年7月收治的160例垂体瘤患者,用硬币投掷法随机将患者分为神经内镜组（神经内镜下经鼻蝶入路切除垂体瘤）和神经导航组（神经导航辅助显微镜下经鼻蝶入路切除垂体瘤）,每组80例。比较2组患者治疗前后催乳素（PRL）、生长激素（GH）、促肾上腺皮质激素（ACTH）含量,观察2组患者手术指标、临床疗效、并发症的发生情况。 结果神经内镜组手术时间短于神经导航组患者,神经内镜组术中出血量少于神经导航组,神经内镜组术后住院时间短于神经导航组。治疗后比较,神经导航组患者PRL、GH、ACTH含量显著高于神经内镜组。神经内镜组患者有效率（92.50%）高于神经导航组（81.25%）。神经内镜组的尿崩症、视力障碍、鼻腔出血发生率均显著低于神经导航组（P<0.05）。 结论神经内镜相较于神经导航辅助显微镜下经鼻蝶入路切除垂体瘤,临床疗效更佳,并发症少,患者垂体功能恢复情况更好。     

功能神经导航和术中磁共振引导下精确切除毗邻大脑运动功能区的致(癎)病变

目的 评估功能神经导航和术中MRI引导对毗邻运动功能区致(癎)病变切除术的效果.方法 回顾性分析接受神经导航引导手术的14例癫(癎)病人,其中10例采用术中MRI.术前MRI扫描,融合影像,设计病变切除范围及入路,三维计划输入导航系统并投射至手术显微镜辅助手术.术中复查MRI,对残余病变重新定位,实施手术切除.术后定期进行随访.结果 病人均成功实施了功能神经导航,致(癎)病变、运动区皮质和锥体束投射在手术显微镜下,精确切除病变,同时运动区皮质和锥体束获得有效保护;术中MRI末次扫描提示致(癎)灶病变的切除范围达到术前计划.术后随访6～24个月,癫(癎)发作控制达Engel Ⅰ级12例,Engel Ⅱ级2例.未出现肢体肌力下降.结论 对于毗邻运动功能区的致(癎)病变,通过功能神经导航和术中MRI精准定位病灶和功能区,可以达到精准切除病变并保护正常脑功能的目的.     

术中磁共振成像在经鼻-蝶入路垂体瘤切除术中的应用研究

目的探讨术中磁共振成像结合神经影像导航系统在经鼻-蝶入路垂体肿瘤切除术中的应用价值。方法采用术中MRI扫描辅助神经导航系统指导经鼻-蝶入路垂体肿瘤切除范围,分析术中MRI对手术过程和患者预后的影响。结果术中MRI扫描系统平均扫描(2.11±0.41)次,所需时间15～20min/次;手术时间共延长47～60min,平均(51.20±0.66)min。38例患者术中MRI共发现11例存在肿瘤残余,其中8例于更新神经导航计划后进一步扩大手术范围全切除肿瘤,3例因肿瘤质地坚韧且与周围解剖结构粘连紧密,仅行部分切除;初次全切除率为71.05%(27/38),在术中MRI导航系统辅助下最终全切除率达92.10%(35/38),提高了21.05%(8/38;χ2=4.290,P=0.018)。术后无一例发生与磁共振检查相关性并发症。结论经鼻-蝶入路垂体肿瘤切除术中应用MRI结合神经导航技术,为指导手术进程及实时判断手术效果提供了客观依据,从而避免了因术中脑组织漂移造成的术前导航偏差,提高肿瘤全切除率。     

The benefit of neuronavigation for neurosurgery analyzed by its impact on glioblastoma surgery

Neuronavigation, today a routine method in neurosurgery, has not yet been systematically assessed in direct comparison with conventional microsurgical techniques. The aim of the present study was the direct comparison of the impact of neuronavigation on glioblastoma surgery regarding time consumption, extent of tumor removal and survival. For each of 52 patients operated for primary glioblastoma with neuronavigation, a patient operated on without navigation was matched. Completeness of tumor resection, including volumetric analysis, was examined by early post-operative MRI. Operating and survival times were obtained for all patients. At a rate of 86.5%, surgeons' opinions about neuronavigation were positive. Operating times were identical in the two groups, while preparation times were 30.4 min longer with navigation. Radiological radicality was achieved in 31% of navigation cases vs. 19% in conventional operations. The absolute and relative residual tumor volumes were significantly lower with neuronavigation. Radical tumor resection was associated with a highly significant prolongation in survival (median 18.3 vs. 10.3 months, p < 0.0001). Survival was longer in patients operated on using neuronavigation (median 13.4 vs. 11.1 months). Neuronavigation increases radicality in glioblastoma resection without prolonging operating time. Regarding the problem of brain shift, neuronavigation should be optimized by intraoperative real-time imaging.     

术中实时超声导航在脑深部肿瘤切除术中的应用

目的 利用Brain Lab整体超声导航实时监测并切除脑深部肿瘤,探讨术中超声结合导航在神经外科手术中的价值.方法 应用Brain Lab整体超声导航系统对30例脑深部肿瘤进行显微神经外科手术,结合导航图像,术中超声动态了解病变移位情况,实时显示病变边界,进行移位后病灶的全切除.结果 术中实时超声证实在30例导航手术过程中均有不同程度的病灶移位,在超声引导下,探寻残余肿瘤并在监测下进一步全切除,术后未出现明显的并发症.结论 术中整体超声导航不仅可以在移位情况下重新准确定位肿瘤边界,而且可以在实时超声监测下进一步切除肿瘤,缩短手术时间,增加了全切除率,提高了手术的安全性.     

Image-guided transoral surgery in childhood

Objective  The study aims to report a preliminary experience of image guidance during transoral surgery in a paediatric population. In paediatric practice, the small size of the oropharynx and the distortion of the craniocervical junction anatomy (whether congenital or acquired) are both factors that may compromise the transoral approach. Prior immobilisation of the craniocervical axis by virtue of posterior fixation or external halo body orthosis permits the use of intra-operative image guidance to navigate this region. Method  Neuronavigation was used during transoral surgery in six paediatric cases. Preliminary immobilisation of the craniocervical junction was ensured in all patients. Volumetric imaging was then obtained prior to the transoral procedure which was then carried out using neuronavigation assistance (Stealth Station Medtronic). Early post-operative imaging was obtained in each case to assess the extent of the surgical resection. Results  Neuronavigation was found to correlate well with the intra-operative findings and, in all cases, the surgical objective, decompression of the neuraxis, was achieved. Post-operative imaging reflected the operating surgeon’s perception regarding the extent of the decompression. In one case, there was a transient neurological deterioration; there was no mortality and no instances of wound-related complications or cerebrospinal fluid leakage. Conclusion  Intraoperative neuronavigation during transoral surgery is feasible in the paediatric population. In this unusual patient population, the technique appears to be of value in negotiating complex anatomy and achieving a safe and predictable decompression.     

5-aminolevulinic acid and neuronavigation in high-grade glioma surgery: results of a combined approach

In high-grade glioma surgery, several techniques are used to achieve the maximum cytoreductive treatment preserving neurological functions. However, the effectiveness of all the methods used alone is reduced by specific limitations of each. We assessed the reliability of a multimodal strategy based on 5-aminolevulinic acid (5-ALA) and neuronavigation. We prospectively studied 18 patients with suspected, non eloquent-area malignant gliomas amenable for complete resection. Conventional illumination was used until the excision appeared complete. The cavity was then systematically inspected in violet-blue light to identify any residual tumour. Multiple biopsies of both fluorescent and non-fluorescent tissue were performed in all cases. Each specimen was labelled according to the sampling location (inside or outside the boundary set by the neuronavigator). The samples were analysed by a neuropathologist blinded to the intraoperative classification. We reviewed the results of both methods, either singly or in combination. Individual analysis showed higher 5-ALA reliability compared to neuronavigation. However, several false-negative fluorescent specimens were detected. With the combined use of fluorescence and neuroimaging, only 1 sample (negative for both 5-ALA and navigation) was tumoral tissue. In our experience, the combined approach showed the best sensitivity and it is recommended in cases of lesions involving non-eloquent areas.     

Intraoperative visualization for resection of gliomas: the role of functional neuronavigation and intraoperative 1.5 T MRI

OBJECTIVE: To investigate how functional neuronavigation and intraoperative high-field magnetic resonance imaging (MRI) influence glioma resection. METHODS: One hundred and thirty-seven patients [World Health Organization (WHO) grade I: 20; II: 19; III: 41; IV: 57] underwent resection for supratentorial gliomas in an operative suite equipped with intraoperative high-field MRI and microscope-based neuronavigation. Besides standard anatomical image data including T1- and T2-weighted sequences, various functional data from magnetoencephalography (n=37), functional MRI (n=65), positron emission tomography (n=8), MR spectroscopy (n=28) and diffusion tensor imaging (n=55) were integrated in the navigational setup. RESULTS: Intraoperative MRI showed primary complete resection in 27% of all patients (I: 50%; II: 53%; III: 2%; IV: 28%). In 41% of all patients (I: 40%; II: 26%; III: 66%; IV: 28%) the resection was extended owing to intraoperative MRI increasing the percentage of complete resections to 40% (I: 70%; II: 58%; III: 17%; IV: 40%). Integrated application of functional navigation resulted in low post-operative morbidity with a transient new neurological deficit in 10.2% (paresis: 8.8% and speech disturbance: 1.4%) decreasing to a permanent deficit in 2.9% (four of 137 patients with a new or increased paresis). CONCLUSIONS: The combination of intraoperative MRI and functional navigation allows safe extended resections in glioma surgery. However, despite extended resections, still in the majority of the grade III and IV gliomas no gross total resection could be achieved owing to the extension of the tumor into eloquent brain areas. Intraoperative MRI data can be used to localize the tumor remnants reliably and compensate for the effects of brain shift.     

Fluorescence and image guided resection in high grade glioma

The extent of resection in high grade glioma is increasingly been shown to positively effect survival. Nevertheless, heterogeneity and migratory behavior of glioma cells make gross total resection very challenging. Several techniques were used in order to improve the detection of residual tumor. Aim of this study was to analyze advantages and limitations of fluorescence and image guided resection. A multicentric prospective study was designed to evaluate the accuracy of each method. Furthermore, the role of 5-aminolevulinc acid and neuronavigation were reviewed.Twenty-three patients harboring suspected high grade glioma, amenable to complete resection, were enrolled. Fluorescence and image guides were used to perform surgery. Multiple samples were obtained from the resection cavity of each lesion according to 5-ALA staining positivity and boundaries as delineated by neuronavigation. All samples were analyzed by a pathologist blinded to the intra-operative labeling. Decision-making based on fluorescence showed a sensitivity of 91.1% and a specificity of 89.4% (p < 0.001). On the other hand, the image-guided resection accuracy was low (sensitivity: 57.8%; specificity: 57.4%; p = 0.346). We observed that the sensitivity of 5-ALA can be improved by the combined use of neuronavigation, but this leads to a significant reduction in specificity. Thus, the use of auxiliary techniques should always be subject to critical skills of the surgeon. We advocate a large-scale study to further improve the assessment of multimodal approaches.     

显微镜导航在功能区手术中的应用

目的 探讨显微镜导航在功能区手术中的应用价值。方法 对52例功能区病变病人进行磁共振扫描，其中14例进行了功能性磁共振扫描，图像资料传人ASA—610V导航工作站，将工作站与导航显微镜相连，实时获取显微镜的焦距数值，导航显微镜的聚焦点就成为虚拟的导航棒棒尖点，指导功能区病变的显微手术。结果 全切除40例，次全切除12例。3例病人出现神经功能障碍加重，14例功能性磁共振导航病人术后无神经功能障碍加重。结论 导航显微镜可以独立地起到实时引导、精确找寻病灶、了解周围结构的作用，有助于全切除病灶，减少功能损害。     

术中磁共振联合显微镜下导航在难治性癫癎脑深部小病变切除术中的应用

目的探讨术中MRI联合显微镜下导航在难治性癫癎病人脑深部小病灶切除中的价值。方法回顾性分析10例脑深部小病灶难治性癫癎病人的临床资料,所有病人行弥散张量纤维束重建,并在术中MRI及显微镜导航下切除病灶,记录骨瓣的大小、手术时间、病灶移位距离、术中MRI扫描次数、术后癫癎发作情况及功能缺失情况。结果本组病人开颅骨窗（44.60±9.19）cm2,手术时间（3.99±0.81）h,病变移位距离（10.50±2.92）mm。病灶移位距离与骨瓣大小、手术时间无明显关系（P〉0.05）。所有病人术中MRI共扫描19次,病灶全部切除。5例病人术后出现肢体偏瘫及视野缺失,术后1年症状改善。术后1年随访癫癎控制疗效：EngelⅠ级5例,Ⅱ级2例,Ⅲ级2例,Ⅳ级1例。结论在伴有癫癎的脑深部小病灶切除术中,应用术中MRI可以及时纠正病灶移位,减少术后神经功能缺失,疗效肯定。