Introduction: Malignant disease of the central nervous system accounts as the primary etiology for oncologic mortality in the pediatric population. It has been well documented that outcomes in pediatric neurosurgery rely on the extent of tumor resection. Therefore, techniques that improve surgical results have significant clinical implications. Intraoperative ultrasound (IOUS) offers real-time surgical guidance and a more accurate means of detecting residual tumor inconspicuous to the naked eye.

Methods: This study consists of a retrospective chart review of the medical charts of all pediatric neurosurgical tumor patients treated between August 2009 and July 2015 at our academic institution. Inclusion criteria: age < 21 years, brain or spinal tumor resection, IOUS utilization during tumor resection and with documented postoperative MRI (with and without contrast) performed within 1 week of surgery. We measure the correlation, negative predictive value and sensitivity of IOUS compared with MRI in our case series.

Results: Sixty-two patients met inclusion criteria for the study (33 males, mean age of 10.0 years). IOUS results very significantly correlated with postoperative MRI results; f = 0.726, p = 0.000000011 with a negative predictive value of 86.3% [73.7%; 94.3%]. These results exemplify a 71% overall gross total resection rate and 80% intended gross total resection using IOUS (i.e. excluding cases performed only for debulking purposes).

Conclusions: IOUS may play an important role in achieving greater extent of resection by providing real time information on tumor volume and location in the setting of brain shift throughout the course of an operation. We support the use of IOUS in pediatric CNS tumor surgery to improve clinical outcomes with minimal additional OR time, no identified additional risk and at low cost.

Patient Care: Application of intraoperative ultrasonography will improve rates of gross total resection for improved clinical outcomes in pediatric CNS tumor surgery. Intraoperative ultrasonography can also assist in visualization of eloquent anatomy so as to avoid significant postoperative neurologic deficits.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) describe the importance of the extent of CNS tumor resection on clinical outcomes in pediatric neurosurgery, 2) Discuss how intraoperative ultrasonography provides real-time assistance for adapting to dynamic changes during surgery, 3)Identify that the benefit of intraoperative ultrasound in pediatric neurosurgery outcomes far exceeds the minimal risk of additional OR time and low cost.

References: [1] Linabery AM, Ross JA. Trends in childhood cancer incidence in the U.S. (1992-2004). Cancer. 2008;112(2):416-32. [2] Ostrom QT, de Blank PM, Kruchko C, et al. Alex's Lemonade Stand Foundation Infant and Childhood Primary Brain and Central Nervous System Tumors Diagnosed in the United States in 2007-2011. Neuro-oncology. 2015;16 Suppl 10:x1-x36. [3] Auer LM, Van Velthoven V. Intraoperative ultrasound (US) imaging. Comparison of pathomorphological findings in US and CT. Acta Neurochir (Wien). 1990;104(3-4):84-95. [4] Enzmann DR, Wheat R, Marshall WH, et al. Tumors of the central nervous system studied by computed tomography and ultrasound. Radiology. 1985;154(2):393-9. [5] Van Velthoven V. Intraoperative ultrasound imaging: comparison of pathomorphological findings in US versus CT, MRI and intraoperative findings. Acta Neurochir Suppl. 2003;85:95-9. [6] Chen SS, Shao KN, Chiang JH, et al. Intracranial pathology: comparison of intraoperative ultrasonography with computerized tomography and magnetic resonance imaging. Zhonghua Yi Xue Za Zhi (Taipei). 1999;62(8):521-8. [7] Le Roux PD, Berger MS, Ojemann GA, Wang K, Mack LA. Correlation of intraoperative ultrasound tumor volumes and margins with preoperative computerized tomography scans. An intraoperative method to enhance tumor resection. J Neurosurg. 1989;71(5 Pt 1):691-8. [8] Le Roux PD, Berger MS, Wang K, Mack LA, Ojemann GA. Low grade gliomas: comparison of intraoperative ultrasound characteristics with preoperative imaging studies. J Neurooncol. 1992;13(2):189-98. [9] Unsgaard G, Ommedal S, Muller T, Gronningsaeter A, Nagelhus Hernes TA. Neuronavigation by intraoperative three-dimensional ultrasound: Initial experience during brain tumor resection. Neurosurgery. 2002;50(4):804-12. [10] Hammoud MA, Ligon BL, Elsouki R, Shi WM, Schomer DF, Sawaya R. Use of intraoperative ultrasound for localizing tumors and determining the extent of resection: a comparative study with magnetic resonance imaging. J Neurosurg. 1996;84(5):737-41. [11] Chacko AG, Kumar NK, Chacko G, Athyal R, Rajshekhar V. Intraoperative ultrasound in determining the extent of resection of parenchymal brain tumours- a comparative study with computed tomography and histopathology. Acta Neurochir (Wien). 2003;145(9):743-8. [12] Ulrich NH, Burkhardt JK, Serra C, Bernays RL, Bozinov O. Resection of pediatric intracerebral tumors with the aid of intraoperative real-time 3-D ultrasound. Childs Nerv Syst. 2012;28(1):101-9. [13] El Beltagy MA, Aggag M, Kamal M. Role of intraoperative ultrasound in resection of pediatric brain tumors. Childs Nerv Syst. 2010;26(9):1189-93. [14] Kremkau, F. W. (1980). Diagnostic ultrasound: physical principles and exercises. New York: Grune & Stratton. [15] Cheon JE. Intraoperative neurosonography revisited: Effective neuronavigation in pediatric neurosurgery. Ultrasonography. 2015;34(2):79-87. [16] McGirt MJ, Chaichana KL, Attenello FJ, et al. Extent of surgical resection is independently associated with survival in patients with hemispheric infiltrating low-grade gliomas. Neurosurgery. 2008;63(4):700-7. [17] McGirt MJ, Chaichana KL, Gathinji M, et al. Independent association of extent of resection with survival in patients with malignant brain astrocytoma. J Neurosurg. 2009;110(1):156-62. [18] Sun MZ, Ivan ME, Clark AJ, et al. Gross total resection improves overall survival in children with choroid plexus carcinoma. J Neurooncol. 2014;116(1):179-85. [19] Safaee M, Oh MC, Mummaneni PV, et al. Surgical outcomes in spinal cord ependymomas and the importance of extent of resection in children and young adults. J Neurosurg Pediatr. 2014;13(4):393-9.