Resonancia magnetica nuclear contraste
In 1946, techniques were developed independently by Felix Bloch and Edward Purcell that extended NMR to liquids and solids. NMR was first documented in 1939 in a molecular beam by Isidor Rabi, who received the Nobel Prize in Physics in 1944. This article is intended to give an overview of selected topics in MRI beginning with a brief history. MRI is based on nuclear magnetic resonance (NMR), whose name comes from the interaction of certain atomic nuclei in the presence of an external magnetic field when exposed to radiofrequency (RF) electromagnetic waves of a specific resonance frequency. Magnetic resonance imaging (MRI) is a noninvasive imaging technique that enables the observation of anatomic structures, physiological functions, and molecular composition of tissues. Lau, in Encyclopedia of Biomedical Engineering, 2019 Introduction Finally, we then look at an emerging application of MRI – high-resolution MR histology – as an adjunct to pathology studies. Next, we address the role of MR spectroscopy, a technique often complementary to MRI for the identification of disease processes through the assessment of metabolites. We go on to discuss the role of MR contrast agents, including their application to the exciting new areas of molecular and cellular imaging. In the first part of this article, we give an overview of the principles of MRI and some common uses in the diagnosis of pathologies such as stroke and cancer. MRI has transformed the role of radiology in medicine since its initial applications in structural imaging in the early 1980s and now encompasses wider areas of functional and molecular imaging. Crucially, it differs from other techniques such as computed tomography (CT) by producing excellent soft tissue contrast without harmful ionizing radiation. It achieves high spatial resolution, typically of the order of millimeters in the clinical setting. Magnetic resonance imaging (MRI) is a noninvasive modality, which produces multiplanar and true 3D datasets of subjects in vivo. Guimarães, in Pathobiology of Human Disease, 2014 Introduction