Values of the apparent diffusion coefficient in the differential diagnosis of tumors of the posterior fossa in the pediatric population of Colombia

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Introduction: Posterior fossa tumors are common in the pediatric population and require adequate characterization by means of structural magnetic resonance imaging (MRI) and advanced MRI techniques to achieve an appropriate therapeutic approach. Objectives: To determine the usefulness of apparent diffusion coefficient (ADC) values for the differential diagnosis of posterior fossa tumors in the pediatric population treated at a reference hospital in Bogotá D.C., Colombia. Materials and methods: Diagnostic accuracy study carried out in 28 pediatric patients diagnosed with posterior fossa tumor between 2017 and 2019 at the Fundación Hospital de la Misericordia, a quaternary care institution. ADC values were measured and compared with histopathological diagnosis as gold standard, obtaining sensitivity, specificity, and positive and negative predictive values. Differences between medians were determined using the Kruskall-Wallis test. The p value between the quantitative ADC value and the gold standard was calculated using Pearson's chi-squared test, with a significance level of p<0.05. Results: The mean age of the participants was 83.9 months (SD=57 months), and 64.28% of them were boys. Medulloblastoma was the most frequent tumor (39.29%). For the diagnosis of medulloblastoma, an ADC value of 0.6210x10-³mm²/s was established, obtaining a sensitivity and specificity of 81.82% and 76.47%, respectively. For the diagnosis of pilocytic astrocytoma, an ADC of 1.03x10-³mm²/s was determined, with a sensitivity of 66.67% and a specificity of 89.40%. Conclusions: ADC value is useful to classify and differentiate posterior fossa tumors in the Colombian pediatric population, showing an inversely proportional relationship with the tumor grade.