RESUMEN
Glioblastoma multiforme (GBM) is the most common and lethal malignant glioma in adults. Currently, the modality of choice for diagnosing brain tumor is high-resolution magnetic resonance imaging (MRI) with contrast, which provides anatomic detail and localization. Studies have demonstrated, however, that MRI may have limited utility in delineating the full tumor extent precisely. Studies suggest that MR spectroscopy (MRS) can also be used to distinguish high-grade from low-grade gliomas. However, due to operator dependent variables and the heterogeneous nature of gliomas, the potential for error in diagnostic accuracy with MRS is a concern. Positron emission tomography (PET) imaging with (11)C-methionine (MET) and (18)F-fluorodeoxyglucose (FDG) has been shown to add additional information with respect to tumor grade, extent, and prognosis based on the premise of biochemical changes preceding anatomic changes. Combined PET/MRS is a technique that integrates information from PET in guiding the location for the most accurate metabolic characterization of a lesion via MRS. We describe a case of glioblastoma multiforme in which MRS was initially non-diagnostic for malignancy, but when MRS was repeated with PET guidance, demonstrated elevated choline/N-acetylaspartate (Cho/NAA) ratio in the right parietal mass consistent with a high-grade malignancy. Stereotactic biopsy, followed by PET image-guided resection, confirmed the diagnosis of grade IV GBM. To our knowledge, this is the first reported case of an integrated PET/MRS technique for the voxel placement of MRS. Our findings suggest that integrated PET/MRS may potentially improve diagnostic accuracy in high-grade gliomas.
Asunto(s)
Neoplasias Encefálicas/diagnóstico por imagen , Glioma/diagnóstico por imagen , Espectroscopía de Resonancia Magnética/métodos , Tomografía de Emisión de Positrones/métodos , Neoplasias Encefálicas/patología , Femenino , Glioma/patología , Humanos , Persona de Mediana Edad , Clasificación del Tumor , Sensibilidad y EspecificidadRESUMEN
A 68-year-old diabetic, hypertensive man presented with a left sixth cranial nerve palsy. MRI demonstrated an inhomogeneous sellar mass encroaching on the left cavernous sinus. Two days later, a left third cranial nerve palsy developed. Within 24 hours, the patient went into cardiac arrest and died. An autopsy showed hemorrhage within a pituitary macroadenoma ("pituitary apoplexy"). Pituitary apoplexy should be considered a cause of acute isolated sixth cranial nerve palsy and may represent a life-threatening emergency that can be averted with emergent hormonal replacement and hypophysectomy.