Functional magnetic resonance imaging. Researcher checking fMRI images Functional magnetic resonance imaging or functional MRI (fMRI) is a functional neuroimaging procedure using MRI technology that measures brain activity by detecting associated changes in blood flow.[1] This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases. The primary form of fMRI uses the Blood-oxygen-level dependent (BOLD) contrast,[2] discovered by Seiji Ogawa. The procedure is similar to MRI but uses the change in magnetization between oxygen-rich and oxygen-poor blood as its basic measure. FMRI is used both in the research world, and to a lesser extent, in the clinical world. Overview[edit] The fMRI concept builds on the earlier MRI scanning technology and the discovery of properties of oxygen-rich blood.
History[edit] Three studies in 1992 were the first to explore using the BOLD contrast in humans. Physiology[edit] Magnetic resonance imaging. Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI), or magnetic resonance tomography (MRT) is a medical imaging technique used in radiology to investigate the anatomy and function of the body in both health and disease. MRI scanners use strong magnetic fields and radiowaves to form images of the body. The technique is widely used in hospitals for medical diagnosis, staging of disease and for follow-up without exposure to ionizing radiation. Introduction[edit] Neuroimaging[edit] MRI image of white matter tracts. MRI is the investigative tool of choice for neurological cancers as it is more sensitive than CT for small tumors and offers better visualization of the posterior fossa. Cardiovascular[edit] MR angiogram in congenital heart disease Cardiac MRI is complementary to other imaging techniques, such as echocardiography, cardiac CT and nuclear medicine.
Musculoskeletal[edit] Liver and gastrointestinal MRI[edit] Functional MRI[edit] Oncology[edit] How MRI works[edit] Diffusion MRI. Diffusion MRI (or dMRI) is a magnetic resonance imaging (MRI) method which came into existence in the mid-1980s.[1][2][3] It allows the mapping of the diffusion process of molecules, mainly water, in biological tissues, in vivo and non-invasively. Molecular diffusion in tissues is not free, but reflects interactions with many obstacles, such as macromolecules, fibers, membranes, etc. Water molecule diffusion patterns can therefore reveal microscopic details about tissue architecture, either normal or in a diseased state.
The first diffusion MRI images of the normal and diseased brain were made public in 1985.[4][5] Since then, diffusion MRI, also referred to as diffusion tensor imaging or DTI (see section below) has been extraordinarily successful. Its main clinical application has been in the study and treatment of neurological disorders, especially for the management of patients with acute stroke.
Diffusion[edit] Given the concentration and flux where D is the diffusion coefficient. . Positron emission tomography. PET/CT-System with 16-slice CT; the ceiling mounted device is an injection pump for CT contrast agent Whole-body PET scan using 18F-FDG Positron emission tomography (PET)[1] is a nuclear medicine, functional imaging technique that produces a three-dimensional image of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule. Three-dimensional images of tracer concentration within the body are then constructed by computer analysis. If the biologically active molecule chosen for PET is fluorodeoxyglucose (FDG), an analogue of glucose, the concentrations of tracer imaged will indicate tissue metabolic activity by virtue of the regional glucose uptake. History[edit] The concept of emission and transmission tomography was introduced by David E.
The logical extension of positron instrumentation was a design using two 2-dimensional arrays. Single photon emission computed tomography. Animation of a SPECT scanning procedure. Single-photon emission computed tomography (SPECT, or less commonly, SPET) is a nuclear medicine tomographic[1] imaging technique using gamma rays. It is very similar to conventional nuclear medicine planar imaging using a gamma camera.[2] However, it is able to provide true 3D information. This information is typically presented as cross-sectional slices through the patient, but can be freely reformatted or manipulated as required.
The basic technique requires delivery of a gamma-emitting radioisotope (called radionuclide) into the patient, normally through injection into the bloodstream. Principles[edit] A Siemens brand SPECT scanner, consisting of two gamma cameras. Instead of just 'taking a picture' of anatomical structures, a SPECT scan monitors level of biological activity at each place in the 3-D region analyzed. SPECT imaging is performed by using a gamma camera to acquire multiple 2-D images (also called projections), from multiple angles. Electroencephalography. Simultaneous video and EEG recording of two guitarists improvising. Electroencephalography (EEG) is the recording of electrical activity along the scalp.
EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain.[1] In clinical contexts, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, usually 20–40 minutes, as recorded from multiple electrodes placed on the scalp. Diagnostic applications generally focus on the spectral content of EEG, that is, the type of neural oscillations that can be observed in EEG signals. EEG is most often used to diagnose epilepsy, which causes obvious abnormalities in EEG readings.[2] It is also used to diagnose sleep disorders, coma, encephalopathies, and brain death. History[edit] Hans Berger In 1934, Fisher and Lowenback first demonstrated epileptiform spikes. In 1947, The American EEG Society was founded and the first International EEG congress was held.