Part III Flashcards
3 Parts of MRI Suites
Gantry
Control Console
Computer Network/System
Operating console is composed of :
-imaging acquisition
-image processing
Operating console [added]
Start-up
Image acquisition
Prescan Calibrators
Image Scanning
Image Processing/Display/Manipulation
MRI computers is composed of:
Multitasking operating system
Control Computer
Acquisition Control System
Image Reconstruction
Processing Computer
MRI system electronics
Frequency Synthesizer
RF Amplifier
Gradient Coil Power Supply
Sequencing System
Digital Signal Acquisition System
Digital Image Processing System
Ancillary Equipment
Power Injectors
Infusion Pumps
Pads and Pillows
Cryogenic Filling Equipment
CM used in MRI
Gd DPTA -contrast (paramagnetic)
Diethylenetriamine Penta-acetic acid
[ancillary equip.] Facilitate introduction of CM, Nonmagnetic
Power injectors
[ancillary equip.] Used for introduction of saline/fluid, automatic set rate/amount
Infusion Pumps
[ancillary equip.] used for pt comfort, headphones, pillows, blankets
Pads and pillows
[ancillary equip.] cooling system used to ensure magnetic property
Cryogenic filling equipment
[operating console-start- up] energizes the system
Power On/Off
[operating console-start- up] should be used if the pt is in danger (in case of adverse fx, claustrophobic)
Emergency Off
[operating console-start- up] installed with TV system for communication
Intercom - speaker and Tv monitor to ensure pt is not moving
[operating console-start- up] selection of pulse sequence, pulse delay timings, other parameters
Scan Control Module
[operating console-start- up] SLICES (no of gaps); scout images
Image-Guided Graphical Prescription
[operating console-start- up] review the image (display windowing), parametric imaging processing
Image Display System
[operating console] involves stimulation of H and receiving of signal
Image Acquisition
[operating console-image acquisition] often automatic, accommodate the body part/FOV
Tuning Control
[operating console-image acquisition] RT can modify, 90-90deg..90-180deg/..
Pulse Sequence Selection
[operating console-image acquisition] selection of repetion time [TR] and echo time [TE]
Timing selection
[operating console-image acquisition] optimize image contrast and SNR (reduce artifacts)
X and y axis to get FID
RF pulse flip angle selection
[operating console-image acquisition] Matrix Size
256x256; larger matrix size = better image, longer imaging time
[operating console-image acquisition] FOV
reduced FOV = better spatial resolution (requires more signal acquisition)
[operating console-image acquisition] amount of FID needed
Number of Signal Acquisitions (NSA)
Number of Excitations (NEX)
Number of Averages (NA)
[operating console-image acquisition] Slice Thickness
Reduced slice thickness improves spatial resolution
Thicker slice = < detail
[operating console-image acquisition] affects the SNR and chemical shift artifact
Range of frequency/signals
Receiver Bandwidth (BW)
[operating console-image acquisition] pre saturation pulses to eliminate signals from certain samples (fats and water)
Magnetization Preparation Schemes
[operating console-image acquisition] 2D and 3D images, usually for advanced imaging system - possible in MRI arteriogram
Reconstruction Strategies
[operating console-image acquisition] number. Of slices, gaps b/w slices, orientations - sagittal , coronal, axial
Slice Positioning and Orientation
[operating console] role of computer system
Prescan Calibrators
[operating console-prescan calibrators] accommodate the patient’s size - adjust RF coil to match patient habitus
Transmit/Receive Coil Tuning
[operating console-prescan calibrators] establishes the slice position and resonance frequency of fats and water photons (automatic)
Center Frequency Tuning
[operating console-prescan calibrators] sets the duration that radio frequency is on and the amount of power to generate the radio frequency (if short-blurry)
Pulse Amplitude Calibration
[operating console-prescan calibrators] ensures that signal is not too low (noisy image) or too high (image distortion)
Receiver Gain Control
[operating console-prescan calibrators] makes the MF homogenous
Autoshimming