List last updated on 1/4/2021
Alzheimer’s Disease Neuroimaging Initiative.
Apparent Diffusion Coefficient (ADC)
A measure of the magnitude of diffusion of water molecules within tissue.
Most commonly clinically calculated using MRI with diffusion-weighted imaging (DWI).
A quantitative imaging biomarker (typically in units mm2/s or μm2/ms) indicative of the mobility of water molecules. High ADC indicates free or less hindered mobility of water; low ADC indicates slow, restricted, or hindered mobility of water molecules.
- The main magnetic field
- When an atom is aligned with B0 that means that it is parallel
- When an atom is aligned in the opposite direction of B0 (antiparallel).
- Known as B1 shimming
- Shimming is the process by which the main magnetic field is made more homogenous
An indication of the strength of diffusion-weighting (typically in units of s/mm2). It depends on a combination of gradient pulse duration, shape, strength, and the timing between diffusion gradient pulses.
Abbreviation for CaliberMRI
- Central nervous system
- Controls most functions of the body and mind
- Consists of two parts: the brain and the spinal cord
- a plane, slice or section made by cutting across the body from side to side and therefore parallel to the coronal suture of the skull.
Digital Imaging and Communications in Medicine standard for distributing and viewing any kind of medical image regardless of the origin. A DWI DICOM header typically contains meta-data reflecting scan geometry and key acquisition parameters (e.g., b-value and gradient direction) required for subsequent generation of ADC maps and ROI statistics. A DWI DICOM macro assigns the required diffusion-specific attributes to public DICOM tags (for example [0018, 9087] & [0018, 9098], which should be available independent of Vendor and scanner software version. Currently, vendors do not universally follow the DWI macro standard, storing b-value and direction metadata in private tags.
- DOT Hazard Classification System
- Placards used to identify the class or division of a material.
- diffusion -weighted imaging
- An indispensable tool in the examination of the CNS
- It is considered useful not only for the detection of acute ischemic stroke but also for the characterization and differentiation of brain tumors and intracranial infections.
- A type of MR image where tissue contrast is dependent on water mobility, diffusion gradient direction, concentration of water signal, and T2 relaxation. On heavily diffusion-weighted images (i.e. high b-value), high signal indicates low water mobility, high proton concentration, and/or long T2.
- Echo planar imaging
- performed using a pulse sequence in which multiple echoes of different phase steps are acquired using rephasing gradients instead of repeated 180 degree radio frequency pulses following the 90°/180° in a spin echo sequence
- Endorectal coil
- a latex (rubber) balloon with a central tube that contains the coils, and is inserted into the rectum and inflated before the scan to hold the coil in position close to the prostate.
- The echo train length
- It will determine the amount of echoes collected within a repetition time
- Fibroglandual tissue mimic
- A mimic made up of ____ that creates a density and composition similar to normal breast tissue
- Field of view
- the distance (in cm or mm) over which an MR image is acquired or displayed
General electric cooperation.
Hazard(s) not otherwise classified
The International Air Transport Association that offers a wide variety of fully compliant hazardous labels for all classes of chemicals.
- International Maritime Dangerous Goods code
- A code forme to prevent all types of pollutants at the sea.
Isotropic (or trace) DWI
Directionally-independent diffusion-weighted images obtained as the composite (geometric average) of three orthogonal DWIs and used for ADC map derivation. Throughout this profile and assessment procedure, the term “DWI” refers to these directionally- independent images unless otherwise noted as a specific single-axis or directional DWI. Even in anisotropic media, directionallyindependent (i.e. scalar) diffusion metrics are measurable using DWI combined from three-orthogonal diffusion gradient acquisitions.
- Liquid crystal thermometer
- A type of thermometer that consists of heat-sensitive liquid crystals in a plastic strip that change color to indicate different temperatures.
- allows measurements at all cervical levels while ensuring minimum PVE contamination.
- Magnetization transfer contrast
- increases the contrast by removing a portion of the total signal in tissue.
The National Institute of Standards and Technology
the electromagnetic signal in the radio-frequency range produced by the precession of the transverse magnetization of the spins. The rotation of the transverse magnetization induces a voltage in a receiving antenna (coil) which is amplified and demodulated by the receiver circuits.
- The net magnetization vector
- the summation of all the magnetic moments of the individual hydrogen nuclei.
- Number of signal averages
- A measurement parameter
- Used to represent the number of times each line of k-space data is acquired and is primarily used to improve signal-to-noise ratio
Occupational Safety and Health Administration.
- Parallel acquisition techniques
- Parallel imaging is a robust method for accelerating the acquisition of magnetic resonance imaging (MRI) data, and has made possible many new applications of MR imaging. Parallel imaging works by acquiring a reduced amount of k-space data with an array of receiver coils.
PBT or vPvB
Annex XIII to the REACH Regulation sets criteria for substances that are persistent, bioaccumulative and toxic (PBT) or very persistent and very bioaccumulative (vPvB).
Phase encoding matrix.
Peripheral Nerve stimulation.
- Prosthetic valve endocarditis
- The infection of one or more prosthetic heart valves
Quantitative Imagining Biomarkers Alliance
- Reach stands for registration, evaluation, authorization and restriction
- They maintain all restricted chemical lists.
Repeatability Coefficient (RC)
Represents measurement precision where conditions of the measurement procedure (scanner, acquisition parameters, slice locations, image reconstruction, operator, and analysis) are held constant over a “short interval”.
- Radio frequency
- Also a technique whereby radio frequency oscillations are gated at a rate of pulses per second
- Region of interest
- Numerical analysis of an area of anatomy being scanned that is of particular importance in the image.
Radiological Society of North America
- Signal-to-noise ratio
- a measure used in science and engineering that compares the level of a desired signal to the level of background noise.
T1 relaxation time
- Also known as the spin-lattice relaxation time
- A measure of how quickly the net magnetization vector (NMV) recovers to its ground state in the direction of B0.
T2 relaxation time
- Also known as spin-spin relaxation and transverse relaxation
- the progressive dephasing of spinning dipoles resulting in decay in the magnetization in the transverse plane (Mxy)
- The echo time
- The time from the center of the RF-pulse to the center if the echo
- The repetition time
- The length of time between corresponding consecutive points on a repeating series of pulses and echos
The University of California at San Francisco
United States Environmental Protection Agency.
Workplace Hazardous Materials Information System.
Within-subject Coefficient of Variance (wCV)
Is often reported for repeatability studies to assess repeatability in test–retest designs. Calculated as seen in the table below:
|1||Calculate the variance and mean for each of N subjects from their replicate measurements.|
|2||Calculate the wCV2 for each of the N subjects by dividing their variance by their mean squared.|
|3||Take the mean of the wCV2 over the N subjects.|
|4||Take the square root of the value in step 3 to get an estimate of the wCV.|