Abstracts from the 3rd Meeting of the Intraoperative Imaging Society (iOIS)

Abstract

s from the 3rd Meeting of the Intraoperative Imaging Society (iOIS) The 3rd Meeting of the Intraoperative Imaging Society (iOIS) was held in Zurich, Switzerland, from January 16 to January 19, 2011. This was an opportunity for clinicians and scientists working in the field of intraoperative imaging to exchange experience and knowledge. Internationally recognized experts presented and discussed technological advances, clinical applications, and socioeconomic aspects of intraoperative imaging. The editors of Computer Aided Surgery are pleased to present the abstracts for the oral presentations given during the meeting sessions. Session I. Intraoperative MRI state of the art Application of intraoperative MR spectroscopy at 3T to evaluate the extent of resection in low-grade glioma surgery (Invited presentation). M. NECMETTIN PAMIR*, KORAY ÖZDUMAN, ERDEM Y_ ILD_ IZ, AYD_ IN SAV, AND ALP DINÇER Departments of Neurosurgery, Radiology and Pathology, Acibadem University, School of Medicine, Istanbul, Turkey *E-mail: pamirmn@yahoo.com Introduction: Outcome after Low Grade Glioma (LGG) resection has a direct correlation with the extent of resection. We have shown that 3T intraoperative MRI can increase the extent of resection. After resection of the main tumor, a T2 hyper-intense signal around the tumor resection cavity can warrant differential diagnosis between residual tumor and nontumoral changes. Hereby, we tested the efficiency of intraoperative proton MR spectroscopy (MRS) and diffusion weighted imaging (DWI) to guide this differential diagnosis. Methods: Ten patients with LGG, who had T2 changes around the resection cavity, were prospectively included in the study. All patients underwent intraoperative DWI and MRS imaging, and the results of MRS were correlated with biopsy of the suspicious area. Results: Eleven (69%) of 16 T2 hyper-intense areas around the tumor resection cavity were histologically diagnosed as tumor. The sensitivity of intraoperative MRS was 81.8%, the specificity was 100%, the positive predictive value was 100%, and the negative predictive value was 71.4%. The specificity of intraoperative DWI for surgically induced changes was high (100%); however, the sensitivity was only 60%. A positive finding on ioDWI did not exclude the presence of residual tumor. Conclusion: Intraoperative use of MR spectroscopy in 3T is effective in differentiating residual tumor from non-tumoral changes. Experience with the 1.5T IMRIS System (Invited presentation) BAI-NAN XU, XIAOLEI CHEN*, FEI WANG, YAN ZHAO, XINGUANG YU, DONG WANG, AND DINBIAO ZHOU Department of Neurosurgery and Department of Radiology, Chinese PLA General Hospital, Beijing, China *E-mail: chxlei@mail.sysu.edu.ch The authors describe a novel dual-room high-field intraoperative magnetic resonance imaging (iMRI) suite with a movable magnet, and analyze its efficacy with clinical experience of 500 cases. The iMRI suite consists of an operating room with an adjacent diagnostic room. A movable 1.5T magnet can be transferred between these two rooms. From February 2009 to November 2010, 500 cases (mean age 43.2 years; range 6–81 years) were operated in the operating room of the suite, while in the same period of time 3000 diagnostic scans were performed in the diagnostic room. The imaging data of all the operated cases were prospectively collected, and the impact of iMRI on surgery was analyzed. 391 craniotomies, 85 trans-sphenoidal surgeries, 20 frameless biopsies and 4 frameless ablations were performed. Of the 476 cases of lesion resection, iMRI revealed residual lesions in 142 cases (29.8%), resulting in the modification of the surgical strategy (e.g., further resection of the lesion). Eventually, 397 lesions (83.4%) were totally removed. Post-operative longterm morbidity is 4.8% (24 cases). With the MR suite, highquality images, together with functional data, could be obtained intra-operatively. The intra-operative 1.5T MRI and functional neuronavigation can be successfully integrated into standard neurosurgical workflow. Intra-operative MR imaging can provide high-quality images and valuable information for intra-operative modification of the surgical strategy, while the dual-room setting can maximize the efficacy of the system. Session II. CT and multi-modal intraoperative imaging techniques Modern intraoperative neurovascular imaging S.H. HARNOF*, M.H. HADANI, G.R. RIEZ, AND O.G. GOREN Sheba Medical Center, Tel Hashomer, Israel *E-mail: sagi.harnof@sheba.health.gov.il Modern neurovascular surgery faces the rapid development of endovascular techniques, with the result that surgery becomes less popular and the vascular neurosurgeon encounters two major problems: the lack of experience usually gained with relatively simple cases, and the limitation of surgery to the more complicated vascular lesions. The combination of these two issues requires the development and implantation of technology to assist the surgeon for better results. Intra-operative imaging in vascular surgery has three aims: 1. Navigation; 2. Flow patency on parent arteries this is a unique task applied especially to vascular surgery and less so for tumor surgery; ISSN 1092-9088 print/ISSN 1097-0150 online Informa UK Ltd. DOI: 10.3109/10929088.2012.723406 3. Clipping and resection control. To allow these three aims, the NeuroVascular Neurosurgery team at Sheba Medical Center implanted four intra-operative modalities to the modern OR, namely intra-operative MRI, digital subtraction angiography, real-time ICG-based videoangiography, and microdoppler techniques. The author will present and demonstrate the usage of those modalities, the required technology and resources needed, and the pros and cons of each modality. Intraoperative use of portable computerized tomography and concomitant neuronavigation applications – a first year experience F. SENCAN*, A. SENCER, Y. ARAS, AND T. KIRIS Department of Neurosurgery, Istanbul Medical Faculty, Istanbul University, Turkey *E-mail: fahirs@hotmail.com Aim: The usage of portable computerized tomography (CereTom, Neurologica) and neuronavigation (BrainLAB) in our institution was analyzed. The aim of the study was to report the efficacy of imaging performed in surgical settings. Methods: Patient reports and computerized tomography data of the patients admitted between April 2009 and September 2010 were analyzed retrospectively. Results: A total of 255 patients underwent imaging in our surgical setting between the aforementioned dates. Of these studies, the major field of use was early postoperative imaging (206 patients). CT guided neuronavigation was used in 33 patients, whereas intra-operative CT imaging was performed in 16. With the help of early postoperative imaging it was realized that 6 of the 206 patients needed additional intervention because of surgical complications. When the patients who were operated with CT neuronavigation or intra-operative CT acquisition were analyzed, it was seen that the majority of patients were operated on because of a mass lesion (n1⁄4 27 and n1⁄4 12, respectively). We have realized that with the help of intra-operative imaging one could achieve a more extensive and yet safer excision of mass lesions. Conclusions: Imaging done during or immediately after surgical procedures reduces surgery-related morbidity and mortalities. One of those imaging modalities is computerized tomography. The main advantage of operative imaging done via CT over MRI is its convenience in terms of rapidity, low costs and its selectivity over blood products. Further studies should be conducted to display the correlation of intra-operative CT imaging with other modalities like MRI to argue its reliability in terms of complete excision of mass lesions. The utility of immediate post-operative CT imaging in predicting clinical deterioration after elective cranial neurosurgical procedures D. LOW*, T.W. TAN, N. KON, AND I. NG National Neuroscience Institute, Singapore *E-mail: neuro_surg@hotmail.com Background: The use of intra-operative CT (iCT) allows immediate post-operative acquisition of brain scans for radiological assessment. The aim of our study was to evaluate the predictive value of immediate post-operative scans on the clinical outcome of patients within 7 days post-operatively. This was defined as clinical deterioration requiring reintubation, readmission to the ICU, re-operation or death. Methods: We retrospectively reviewed all patients who underwent elective cranial neurosurgical procedures performed in the iCT from September 2007 to June 2010. Patients who had immediate post-operative scans performed were identified for review. Patients who underwent emergency operations were excluded as these patients were liable to have a complicated postoperative course related to their initial pathology. Results: 290 cases were available for analysis. Clinical deterioration occurred in 14 cases (4.8%) within 7 days post-operatively. In 11 cases (3.8%), the cause of deterioration was unrelated to the initial intracranial pathology and was associated with complications arising from existing medical conditions. In the remaining 3 cases (1%), review of the CT findings showed features which suggested a possible risk of post-operative deterioration. Conclusion: All patients in our study who had post-operative deterioration due to their initial intracranial pathology had ominous features on their immediate post-operative CT scan. This suggests that post-operative CT scans can be used to predict the subsequent clinical outcome. This, however, excludes highrisk patients who have significant medical co-morbidities and may deteriorate despite a satisfactory post-operative scan. The Indian perspective on intraoperative imaging (Invited presentation) AJAYA NAND JHA*, ADITYA GUPTA, SUDHIR DUBEY, AND KARANJEET SINGH Department of Neurosurgery, Medanta, The Medicity, NCR, India *E-mail: Ajaya.Jha@Medanta.org The initial experience in intraoperative imaging