NEURORADIOLOGY Iran J Radiol. 2020 July; 17(3):e97047. Published online 2020 June 24. doi: 10.5812/iranjradiol.97047. Research Article Pre- and Post-Operative Volume Estimation of Medulloblastoma Using Magnetic Resonance Imaging: A Stereological Study Farzaneh Dehghani 1, 2 , Seyede Fatemeh Hosseini 1, 2, * , Reza Jalli 3 , Fatemeh Karimi 1, 2 , Narges Sotoudeh 1, 2 and Mohammad Sadegh Masoudi 4 1 Histomorphometry and Stereology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran 2 Anatomy Department, Shiraz University of Medical Sciences, Shiraz, Iran 3 Medical Imaging Research Center, Shiraz University of Medical Sciences, Shiraz, Iran 4 Neurosurgery Department, Shiraz University of Medical Sciences, Shiraz, Iran * Corresponding author: Anatomy Department, Shiraz University of Medical Sciences, Shiraz, Iran. Tel: +98-9910826194, Email: shosseini2020.15@gmail.com Received 2019 August 11; Revised 2020 April 26; Accepted 2020 May 02. Abstract Background: Brain tumors are among the most lethal and devastating cancers. Medulloblastoma tumor is a common solid brain malignancy, arising in the posterior fossa. Stereological methods are used in combination with magnetic resonance imaging (MRI) to obtain unbiased estimation of the total volume of the structure of interest. Objectives: In the current study, we evaluated cerebellar tumor volume pre- and post-operative in patients suffering from medu- loblastoma tumor using MRI and Cavalieri method. Patients and Methods: The study was performed on 16 subjects consisting of two groups of eight people including patient and control groups. Slide direction were in both sagittal and axial planes. Pre- and post-operative volume of medulloblastoma tumor were determined on MR scanning images using the point-counting approach of Cavalieri method. Results: The post-operative tumor volume in both sagittal (P = 0.028) and axial (P = 0.046) MR images was statistically reduced by 90% compared to the pre-operative volume. Moreover, the pre-operative volume of the cerebellum in patients increased by 38% in patients as compared to the normal subjects (P = 0.028). Conclusion: It could be concluded that MRI-estimated tumor-volume might be useful in evaluating the efficiency of surgical treat- ment and prognostication of tumor regression rate. Keywords: Meduloblastoma, Cavalieri method, MRI 1. Background In recent years, numerous studies have been con- ducted on brain tumors. The cerebellar tumors are often known as infratentorial or posterior fossa tumors (1). Pos- terior fossa tumors constitute 75% of all pediatric brain tumors (1-3). Pilocytic astrocytoma, a low grade glial tu- mor, is the most common pediatric central nervous sys- tem (CNS) tumor, accounting for about 35% of all diag- noses (4, 5). Infratentorial ependymoma includes 15% of posterior fossa tumors in children and is more common in males than females (6, 7). Atypical teratoid rhabdoid tumors (ATRTs) are infrequent and highly aggressive CNS tumors that primarily occur in infants less than 3 years of age (8, 9). Medulloblastoma (MB) is a common malignant ectodermal tumor accounting for 7 to 15% of all brain tu- mors (10, 11). Based on World Health Organization (WHO) clas- sification, medulloblastoma is subdivided into five major groups: classic, anaplastic, large cell, desmoplastic, and extensive nodularity subtypes (12). The mean overall inci- dence of MB is estimated at approximately six children per million and the survival rate is 50% to 65% for 5-years (10- 12). Treatment strategies for this malignant neoplasm in- clude a combination of surgery, chemotherapy, and follow- ing radiotherapy (13). Recently, quantitative techniques, such as computed tomography (CT) scans or magnetic resonance imaging (MRI), is developing for effective volume measuring of a structure with arbitrary shape and size (14). MRI is the best imaging modality in the diagnosis of intracranial tumors due to its high soft tissue contrast and multiplane capabil- ity. On the other hand, under a proper sampling design, stereological methods may be applied to estimate geomet- ric parameters of any object (14, 15). For example, the Cav- alieri method is used in combination with point counting to obtain an assumption-free estimate of the total volume Copyright © 2020, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.