ABSTRACT
High resolution proton nuclear magnetic resonance spectroscopy (¹H MRS) can be used to detect biochemical changes in vitro caused by distinct pathologies. It can reveal distinct metabolic profiles of brain tumors although the accurate analysis and classification of different spectra remains a challenge. In this study, the pattern recognition method partial least squares discriminant analysis (PLS-DA) was used to classify 11.7 T ¹H MRS spectra of brain tissue extracts from patients with brain tumors into four classes (high-grade neuroglial, low-grade neuroglial, non-neuroglial, and metastasis) and a group of control brain tissue. PLS-DA revealed 9 metabolites as the most important in group differentiation: γ-aminobutyric acid, acetoacetate, alanine, creatine, glutamate/glutamine, glycine, myo-inositol, N-acetylaspartate, and choline compounds. Leave-one-out cross-validation showed that PLS-DA was efficient in group characterization. The metabolic patterns detected can be explained on the basis of previous multimodal studies of tumor metabolism and are consistent with neoplastic cell abnormalities possibly related to high turnover, resistance to apoptosis, osmotic stress and tumor tendency to use alternative energetic pathways such as glycolysis and ketogenesis.
Subject(s)
Adult , Aged , Humans , Middle Aged , Brain Neoplasms/metabolism , Magnetic Resonance Spectroscopy , Brain Neoplasms/classification , Brain Neoplasms/pathology , Case-Control Studies , Discriminant Analysis , Least-Squares Analysis , Magnetic Resonance Spectroscopy/methods , Neoplasm Staging , Tissue ExtractsABSTRACT
Foram estudados, do ponto de vista ecocardiografico, 30 pacientes portadores de comunicacao interventricular isolada e 28 normais que serviram como controle. Os autores propoem um novo indice ecocardiografico para avaliar o trato de saida do ventriculo direito, permitindo separar os pacientes com obstrucao a este nivel. A correlacao deste indice com o gradiente de pressao intraventricular direita foi significativa (r = 0,84; P<0,001)