http://www.paper.edu.cn 中国科技论文在线

1134 Chin Med J 2008;121(12):1134-1136 Clinical experience

Preoperative surgical planning and simulation of complex cranial base tumors in virtual reality

YI Zhi-qiang, LI Liang, MO Da-peng, ZHANG Jia-yong, ZHANG Yang and BAO Sheng-de

Keywords: cranial base neoplasm; three dimensional image; virtual reality

he extremely complex anatomic relationships among Preoperative surgical planning and simulation in VR Tbone, tumor, blood vessels and cranial nerves environment remains a big challenge for cranial base tumor surgery. Through cropping and drilling the skull and tumor, which Therefore, a good understanding of the patient specific can be restored and rehearsed, we can determine the anatomy and a preoperative planning are helpful and optimal surgical approach, head position and the crucial for the neurosurgeons. Three dimensional (3-D) necessary bone work. visualization of various imaging techniques have been widely explored to enhance the comprehension of In case 1, VR system revealed that the right internal carotid volumetric data for surgical planning.1 We used the artery (ICA) bifurcation, proximal anterior carotid artery Destroscope Virtual Reality (VR) System (Singapore, (ACA) and middle carotid artery (MCA) are encased in the Volume Interaction Pte Ltd, software: RadioDexterTM 1.0) tumor. Posterior cerebral artery (PCA) were pushed to optimize preoperative plan in the complex cranial base posteriorly and inferiorly. Good visualization and removal tumors. This system uses patient-specific, coregistered, of the tumor was performed through a frontal-temporal- fused radiology data sets that may be viewed zygomatic approach without orbitotomy. The approach was stereoscopically and can be manipulated in a virtual reality rehearsed under a simulated intraoperative perspective and environment. This article describes our experience with the the simulation suggested that complete removal of the Destroscope VR system in preoperative surgical planning tumor could be achieved safely (Figure 1). and simulation for 5 patients with complex cranial base tumors and evaluates the clinical usefulness of this system. In case 2, the VR system revealed middle cranial fossa (MCF), posterior cranial fossa (PCF), infratemporal fossa CLINICAL DATA (ITF), pterygoid palatine fossa (PPF), parapharyngeal space (PS) and the cranio-cervical junction were involved Patient series by the tumor which were mainly fed by the internal Between July 2007 and November 2007, we used the maxillary artery (IMA) and ascending pharyngeal artery Destroscope VR system to carry out preoperative surgical (APA). The left internal carotid artery (ICA) and vertebral planning and simulation for 5 patients with complex skull artery (VA) are partially encased. The total resection of base tumors. The clinical data for these patients are the tumor was impossible in any single approach and in summarized in Table. one stage due to the massive extent of the tumor and its close relation to vital neurovascular structures. A Data acquisition and 3-D object rendering transmandibular approach to resect the part located in PS Magnetic resonance imaging (MRI) studies were acquired to alleviate the dysphagia which most bothered the patient on a General Electric (GE) 1.5-T unit (FOV=24 cm, is feasible and safe (Figure 2). matrix=512 × 512, slice thickness=2 mm). The com- puterized tomography (CT) data were obtained as axial, In case 3, VR system revealed that MCF, ITF, PPF and PS contiguous 1.0mm slices (FOV=24 cm) on a GE scanner were all involved by the tumor which were mainly fed by (16-D). The MRI, CT and CT angiography (CTA), etc the IMA and APA. The finding most worthy of mention is were scanned with identical FOV for the sake of that the ICA was posterior to, not embedded in, the tumor. automatic coregistration in different image modalities. A combined frontal-temporal and transmandibular The scanning of the patients was scheduled 3 to 5 days approach was rehearsed and selected to be the optimal. before the surgery, and the imaging data were transferred by CD to the Dextroscope system for reconstruction into Department of , Peking University First Hospital, 3-D stereoscopic images. The user can freely reach into Beijing 100034, China (Yi ZQ, Li L, Mo DP, Zhang JY, Zhang Y the 3-D image object as if it were in real space through and Bao SD) electromagnetic sensors shaped in the handle and stylus Correspondence to: Dr. BAO Sheng-de, Department of held in the left and right hands respectively. The skull, Neurosurgery, Peking University First Hospital, Beijing 100034, China (Tel: 86-10-66551122 ext 2472. Fax: 86-10-66551057. blood vessels and tumor can be highlighted by adjusting Email: [email protected] ) resolution, contrast, transparency and brightness easily; This project was sponsored by the Special-purpose Research Fund hence, spatial relations were obtained. of Doctoral Subject in Higher School (No. 20060001124).

转载 中国科技论文在线 http://www.paper.edu.cn Chinese Medical Journal 2008; 121(12):1134-1136 1135

Table. Clinical data of 5 patients with complex cranial base tumors Tumor Follow-up No. Age (years)/Sex Diagnosis Scanning technique Surgical approach Complication resection (months) right medial sphenoidal 1 64/M CTA Frontal-temporal-zygomatic Total No 5 ridge Meningioma, 5th division of facial nerve 2 52/F left MCF, PCE, CTA MRI (+C) Transmandibular Partial 6 injury ITF, PS, CCJ Meningioma, Combined frontal-temporal and 3 57/F CTA MRI (+C) Subtotal CNS infection 7 left MCF,ITF, PS ,PPF transmandibular CT 4 49/M Neurogenetic benign tumor right PPF Degloving transmaxillary Total Inferior orbital nerve injury 3 MRI (+C) 5 50/F Osteoma, left cranio-orbital CT Transorbital Total No 4 MCF: middle cranial fossa; ITF: infratemporal fossa; PS: parapharyngeal space; PPF: pterygoid palatine fossa; PCF: posterior cranial fossa; CCJ: cranio-cervical junction region.

cm curved incision aside the inner canthus.

Outcomes and follow-up In all the 5 cases, the intraoperative findings correlated well with the preoperative simulation. Total resection was achieved in cases 1, 4 and 5, subtotal in case 3, partial in case 2. No complications related to the operation occurred. In case 4, mild numbness of the right cheek with a possible cause of intraoperative stretching of the inferior orbital nerve occurred postoperatively and the patient began to recover in 3 days and symptoms disappeared within 2 months after operation. In case 2, the chin pulled to the left slightly with the possible reason being a 5th division of facial nerve injury and it has been improving in the 3 months of the follow-up period. In case 3, the dura was spitted and cerebrospinal fluid (CSF) leakage occurred intraoperatively. We sutured the dura closely and reinforced it using lateral pterygoid muscle, buccal pad and gelatin sponge mingled with biogel. The patient was discharged 14 days after operation uneventfully. However, the patient was rehospitalized 1 month postoperatively due to central nervous system (CNS) infection and CSF leakage. The CNS infection was cured by the intravenous and intrathecal administration of sensitive antibiotic combined with consistent CSF external drainage through a lumbar puncture and ventricle puncture for 55 days. Then, a ventriculoperitoneal shunt was successfully placed to treat the hydrocephalus secondary to the CNS infection. Now, in the 7th month after the first operation, the modified Rankin Scale (mRS) of the patient is 3.

DISCUSSION

Several groups have evaluated the usefulness of a variety Figure 1. Supine position with the head left turn 15 degree. A of neurosurgical planning programs with 3-D imaging frontal-temporal-zygomatic approach can provide good 2-6 visualization and exposure for the tumor (green mass). data. However, common to all these planning systems Figure 2. As the main feeding artery for the tumor, the MA and is the fact that interaction with the increasingly APA are obviously enlarged. The ICA and VA are partially sophisticated 3-D data sets is still achieved in a rather 2-D embedded in the extensive tumor (green mass). fashion by moving a screen-bound cursor with a mouse. The Destroscope system enables the surgeon to interact In case 4, it was found that the tumor basically occupied intuitively and in a user friendly manner with complex the PPF and eroded the great wing of the sphenoid with 3-D graphics in a natural, easy, and direct manner dura integrity. The degloving transmaxillary approach resembling the way one interacts with real objects. provided the shortest avenue and good cosmetic results. Moreover, the user can segment the scalp, skull, blood vessel, lesion, ventricle, etc. and paint them in different In case 5, the frontal sinus and left orbital cavity were colors, which help to reveal the relationship among them. involved with dura integrity. A transorbital approach was On the individualized 3-D object, one can simulate the rehearsed to drill the lesion away completely through a 2 operative environment: zooming, measuring (length, 中国科技论文在线 http://www.paper.edu.cn 1136 Chin Med J 2008;121(12):1134-1136 width, height, volume, area, angle, etc.), cropping, and intraoperative guidance can appear only in 2-D format (like drilling (for simulating a drilling or a suctioning tool) in the images in this article), thereby losing much of the 3-D different head positions, surgical approaches and information. Furthermore, if the system can be linked exposure extensions. The Destroscope system has been directly to the CT and MRI scanners, the data transfer and reported to apply in intracranial tumor operations and in loading work would be more convenient. Along with the clipping simulations.7-11 The Destroscope development of the high speed computer and image system also can simulate the angioscopy technique which identification technique, the registration of multimodality can be used to observe intralumen structures, such as the images and segmentation of the target structures would be atheromatous plaque, angiostenosis and the neck of an highly automated. This application of the Destroscope aneurysm which will undoubtedly facilitate cerebral system integrated with the intraoperative navigation will vascular disease treatment. The diffusion tensor imaging provide surgeons more extensive and practical potential in (DTI) technique can reveal the relationship between the the surgery. lesions and white matter tracts which is crucial to identify and reserve the vital tracts. Overall, the system REFERENCES substantially contributed to surgical planning primarily by (1) providing a faster and better understanding of the 1. Satava RM. Virtual reality, telesurgery, and the new world intracranial 3-D anatomic and abnormal spatial order of medicine. J Image Guid Surg 1995; 1: 12-16. relationships, (2) optimizing the craniotomy and the 2. Gandhe AJ, Hill DL, Studholme C, Hawkes DJ, Ruff CF, Cox required cranial base exposure through a rehearsal of TC, et al. Combined and three-dimensional rendered bone removal, and (3) simulating intraoperative views.7 multimodal data for planning cranial base surgery: a prospective evaluation. Neurosurgery 1994; 35: 463-471. The visualization and manipulation capabilities of the 3. Hu XP, Tan KK, Levin DN, Galhotra S, Mullan JF, Destroscope system were the most useful in the area of Hekmatpanah J, et al. Three-dimensional magnetic resonance the cranial base, in which the computer-generated 3-D images of the brain: application to neurosurgical planning. J surgical area of interest usually consists of multitechnique Neurosurg 1990; 72: 433-440. imaging information, depicting soft tissue (MRI), blood 4. Kikinis R, Gleason PL, Moriarty TM, Moore MR, Alexander vessels (MRA, CTA and MRV), and bone (CT). However, E 3rd, Stieg PE, et al. Computer-assisted interactive even the most detailed information can not replace the three-dimensional planning for neurosurgical procedures. neurosurgeon’s judgment and management in the surgical Neurosurgery 1996; 38: 640-651. procedure. In case 3, we attributed the main cause of the 5. Gorman PJ, Meier AH, Krummel TM. Simulation and vitual CNS infection to the questionable repair for the split dura, reality in surgical education real or unreal? Arch Surg 1999; which should be fixed from intracranial, not inferiorly to 134: 1203-1208. the cranial base. Because the dura fix from extracranial is 6. Rosahl SK, Gharabaghi A, Hubbe U, Shahidi R, Samii M. vulnerable to the buccal cavity movement. The Virtual reality augmentation in skull base surgery. Skull Base 2006; 16: 59-66. communication between the oral cavity and the intracranial 7. Kockro RA, Serra L, Tseng-Tsai Y, Chan C, Yih-Yian S, cavity then resulted in severe infection. The biggest lesson Gim-Guan C, et al. Planning and simulation of neurosurgery learned from the failed case is that we can not in a virtual reality environment. Neurosurgery 2000; 46: overemphasize the importance of skull base reconstruction. 118-137.

8. Anil SM, Kato Y, Hayakawa M, Yoshida K, Nagahisha S, Clearly, this Destroscope system is very useful in the Kanno T. Virtual 3-dimensional preoperative planning with the training of residents or neurosurgeons unfamiliar with a dextroscope for excision of a 4th ventricular . particular surgical approach. Furthermore, surgeons using Minim Invasive Neurosurg 2007; 50: 65-70. this device may be able to preoperatively evaluate various 9. Wong GK, Zhu CX, Ahuja AT, Poon WS. Craniotomy and surgical approaches and choose the best one. Likewise, it clipping of in a stereoscopic virtual is an excellent tool in surgical education.12 reality environment. Neurosurgery 2007; 61: 564-569.

10. Bu B, Xu BN, Zhou DB, Yu XG, Zhang YZ, Wei SB. Though the Destroscope system has demonstrated great Utilization of Destroscope operation planning system in potentials, it also has limitations. First, this system provides intracranial lesions operations: evaluations and analysis of 30 only a rough approximation of the actual anatomy and clinical cases. Chin J Neurosurg (Chin) 2007; 23: 750-753. pathological features. Many structures, such as the cranial 11. Zhang XL, Wu JS, Mao Y, Zhou LF, Li SQ, Wang YF. nerves and small blood vessels, are beyond the current Application of the virtual reality techniques in preoperative resolution of MRI or CT technology and therefore cannot be planning of neurosurgery. Chin J Microsurg (Chin) 2006; 29: segmented and displayed as 3-D structures. Second, it does 415-418. not provide any new information on the properties and 12. Nakajima S, Atsumi H, Bhalerao AH, Jolesz FA, Kikinis R, intraoperative movement of tissue. Likewise, it does not Yoshimine T. Computer-assisted surgical planning for simulate the feel or texture that a surgeon senses during an cerebrovascular neurosurgery. Neurosurgery 1997; 41: 403-410. operation. However, sensory feedback is very important to a neurosurgeon for a true virtual reality experience. Third, an effective stereoscopic image cannot be rendered in print and (Received April 15, 2008) snapshots of the planning procedure that could be used for Edited by SHEN Xi-bin and LIU Huan