MR glossary Flashcards
_____________ is a term describing the containment of the static magnetic field through the use of secondary coils attached around the MRI scanner.
Active shielding
: ____________ is a term used to describe the adjustment of the current within the shim coils on a per patient or per sequence basis.
Active shimming
3 : __________ are reconstructed from diffusion weighted images with multiple b-values, and corresponds to the spatially distributed diffusion coefficients of the target tissues
ADC images
: ____________ occurs when tissue outside the Field of View is undersampled, causing a misregistration of anatomical location, in the phase direction, but on the opposite side of the anatomical location, also known as wrap-around artifact
Aliasing artifact
The ____________ is part of the computer system that converts the analog acquired MR signal into a digital signal
Analog-to-digital converter (ADC)
: An ________ comprises a multiprocessor that is switched in sequence and in parallel while simultaneously performing a computing task.
Array processor
An _____________ is one that has uneven measurements, with regards to the phase, frequency and slice thickness dimensions.
Anisotropic voxel
____________ are signal misrepresentations that do not correspond to the spatial location of the specific tissue imaged
Artifacts
: _______________ is defined as the range or spectrum of frequencies (minimum to maximum processed frequency)of a pulse sequence acquired by an RF system.
Bandwidth
The ____________ is an integrated part of the magnet design that acts as its own transceiver coil, with large FOV capabilities, but lacking the high SNR of localized coils
Body coil
The __________ is defined as a factor in diffusion weighted imaging; the higher the factor, the stronger the diffusion weighting.
B-value
The ___________ is defined as the static main magnetic field of an MR system.
B0
The __________ is the alternating magnetic field generated by the RF in a transceiver coil
B1
_____________ prevents or reduces motion artifacts in an MR image caused by the beating heart or pulsating blood flow and enables the images to be acquired synchronized to movement
Cardiac triggering
________________ is due to the difference in resonant frequencies between fat and water, causing a phase shift in voxels containing fat and water
Chemical shift artifact
Describing image display, the ________ function scrolls through the entire sequence’s images, giving the appearance of CSF flowing or cardiac movement, from the cycle of the images acquired.
Cine
: __________ can be defined as the signal strength differences between two adjacent tissue types.
Contrast
_______________ utilizes the reduced T1 relaxation time of blood through the use of an intravenously injected Gadolinium contrast agent
CE MRA
: _______________ occurs when slices are positioned too close together, causing signals from adjacent slices to affect one another
Cross talk artifact
_________ occurs after initial RF application, causing phase differences to appear between precessing spins, resulting in decay of transverse magnetization
Dephasing