Utilidad de la tomografía por emisión de positrones/ tomografía computada (PET/CT) en pacientes con diagnóstico de meduloblastoma / Usefulness of Positron Emission Tomography/Computed Tomography (PET/CT) in Patients Diagnosed with Medulloblastoma

Resumen: La tomografía por emisión de positrones/tomografía computada (PET/CT) por sus siglas en inglés, es una modalidad de imagen única que proporciona evidencia in vivo de actividades tanto bioquímicas como fisiológicas en diferentes órganos y estructuras del cuerpo. El meduloblastoma es el tumor maligno más frecuente del sistema nervioso central (SNC) en pacientes pediátricos, por este motivo el PET/CT juega un papel importante en el manejo de estos pacientes ya que proporciona información sobre el grado y extensión del tumor, así como a determinar el sitio adecuado para la toma de biopsia, valorar la respuesta al tratamiento y determinar el pronóstico del paciente. Existen diferentes radiofármacos para la evaluación de los tumores de sistema nervioso central, pero se ha estudiado que el 18F-FDG (flúor-2-fluoro-2-desoxi-D-glucosa) y el 68Ga-DOTA-NOC (68Ga-DOTA0-1NaI3-octreotide) nos ayudan a evaluar y dar seguimiento a pacientes con diagnóstico de meduloblastoma. El meduloblastoma tiene una sobreexpresión de transportadores de glucosa, principalmente tipo 1 y sobreexpresión de receptores de somatostatina predominantemente tipo 2, lo cual permite que exista una gran afinidad por estos radiofármacos.

Abstract: PET/CT (positron emission tomography/computed tomography, for its acronym in English) is a unique imaging method that provides in vivo evidence of both biochemical and physiological activities of the brain, spinal cord and tumors that involve these structures. Medulloblastoma is the most common malignant tumor of the central nervous system (CNS) in pediatric patients, so PET/CT plays an important role as it provides information on the grade and extent of the tumor, as well as to determine the appropriate site for the biopsy, assessing the response to the treatment and the patient's prognosis. There are different radiopharmaceuticals for the evaluation of central nervous system tumors, but 18F FDG (Fluor-2-fluoro-2-desoxy-D-glucose) and 68Ga-DOTA-NOC (68Ga-DOTA0-1NaI3-octreotide) have been studied to help us evaluate and follow up patients diagnosed with medulloblastoma. Medulloblastoma has an overexpression of glucose transporters, mainly type 1, and an overexpression of predominantly type 2 somatostatin receptors, which allows a high affinity for these radiopharmaceuticals.

Radiolabeled somatostatin analogs for radionuclide imaging and therapy in patients with gastroenteropancreatic neuroendocrine tumors.

Gastroenteropancreatic neuroendocrine tumours (GEP-NETs) are a rare type of cancer that can arise from the diffused endocrine system, located in the gastrointestinal (GI) tract (carcinoids) and in the pancreas (insular tumors). Approximately 2% of all malignant tumours of the gastrointestinal system are GEP-NETs which can express somatostatin receptors. 111In-pentetreotide (octreoscan) and 68Ga-DOTA NOC (68Ga-labelled [1,4,7,10- tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-Nal3-Octreotide) are the commonly used radiopharmaceuticals for imaging. Once localized using 68Ga DOTA NOC or octreoscan, these tumours can be successfully targeted with radiolabelled somatostatin analogues. This review focuses on common nuclear medicine procedures used in both imaging and treatment of these tumors.