GE MRI protocols descriptions list for the GE Signa Excite 1.5T MRI and 3T MRI systems. Detailed overview of scan setup, considerations, limitations, MRI sequences, and more. This page is part of our growing library of GE MRI technologist resource library. New content is uploaded daily so check back often for the latest GE MRI operator manual resources.
Use the links in the table of contents to quickly find resources for your GE MRI protocol scan setup
GE Signa Excite MRI Protocols
Description of general GE MRI protocols and scan sequences. Includes scan considerations, limitations and procedure notes. Use the table of contents for quick navigation links.
*Auto prescan tuning is performed prior to each scan series to determine optimal center frequency, RF output, and offset values. Images are not produced during the prescan tuning phase.
Localizer (3-Plane Localizer)
The 3 plane localizer produces reference images in the axial, sagittal and coronal plane. MRI technologists use the images produced to plan the slice selection in the series to follow.
Spin Echo (SE)
The Spin Echo PSD is a single plane imaging sequence which consists of a 90 degree excitation pulse with at least one 180 degree refocusing pulse. The 90 degree excitation pulse provides transverse magnetization, while the 180 degree pulse flips the protons to provide spin echo signals.
Spin echo pulse sequence imaging applications include T1, Proton Density, and T2 contrast weighted scan protocols. This MRI pulse sequence can be used to image all anatomical areas.
Compatible Imaging Options include: Classic, ZIP 512, NPW, EDR, FC, Mag Transfer,
RC, Sq Pixel, Cardiac Gating, VBw,
Spin Echo Scan Considerations
This section examines the effects of changing TR and TE values during the MRI scan setup.
TR and TE considerations for Proton Density and T2 Scanning:
-As TR increases: CNR, SNR, Number of Slice, and Scan Time Increase
-As TE increases: CNR increases, SNR and Number of Slices decreases, Scan Time remains constant
R and TE considerations for T1 Scanning:
-As TR increases: CNR Decreases, SNR, Number of Slices, and Scan Time Increases
-As TE increases: CNR, SNR and Number of Slices Decrease, Scan time remains constant
The effect of Changing flip angle on T1 Contrast:
-As flip angle increases with a TR greater than 600, the T1 contrast Increases.
Inversion Recovery (IR)
IR imaging utilizes a spin echo pulse sequence that starts with a 180 degree inversion pulse. This creates inverse proton magnetization in the longitudinal plane. A 90 degree RF pulse follows the inverse magnetization pulse.
The period of time in between the 180 degree and 90 degree pulse is known as (TI) Inversion Time. TI is the primary factor that determines image contrast. To clarify, TI is more easily defined as the amount of time it takes tissue to recover from the longitudinal plane to the transverse plane.
Fast Spin Echo (FSE)
FSE pulse sequences are adapted for 2D and 3D imaging protocols. The sequence begins with a 90 degree pulse followed by additional 180 degree RF pulses. Learn more about the individual fast spin echo pulse sequences below.
FSE-XL
The FSE-XL pulse sequence is an accelerated fast spin echo scan that applies optimized RF pulses to shorten echo space. As a result, images show reduced edge blurring, enhanced tissue contrast, and faster scan times. FSE-XL scan sequences are primarily used in cardiac, abdominal and brain MRI scan sequences.
Blurring correction and blood suppression techniques help to improve image quality in cardiac, kidney, brain, and other similar techniques.
This scan sequence uses increased RF output as compared to the FSE sequence, expect increased MRI scan noise levels during this pulse sequence
Imaging Applications
Accelerated fast spin echo scan sequences are primarily used in cardiac, abdominal and brain MRI scan sequences. Blurring correction and blood suppression techniques help to improve image quality in cardiac, kidney, brain, and similar techniques. Furthermore, FSE-XL produces T1-weighted, Proton Density (PD), and T2-weighted contrast images.
Important FSE-XL Scan Considerations
[Minimum] echo option is not available when scanning FSE-XL sequences.
Effective TE increases to the ESP value if selected TE is less than ESP.
This scan sequences uses increased RF output as compared to FSE sequence, expect increased TG value during prescan.
FSE-XL is susceptible to fine line artifacts. To reduce likelihood of artifact, use an even NEX value. It is important to note that NEX of 2 with No Phase Wrap is actually a NEX of 1. It is recommended to turn off NPW whenever possible.
If turning off NPW is not feasible, the following software modifications may occur to obtain an even NEX scan. If field of view is 16 cm, or below, and slice thickness is 5 cm, or below, expect fewer slices per acquisition and increased echo space.
Odd value NEX selection may reduced spatial resolution when compared to a scan with an even value NEX
SSFSE-XL
Single Shot Fast Spin Echo XL (SSFSE-XL) is a modified fast spin echo pulse. SSFSE-XL pulse sequences reduce motion artifact and produce proton density weighted images with increased T2 contrast.
Imaging Applications
The SSFSE-XL pulse sequence is optimized to improve contrast to noise ratio and signal to noise ratio in MRCP scans. Compared to the original SSFSE PSD, SSFSE-XL introduces flexible TE range, selectable TR values, additional receiver bandwidth options, partial phase FOV ranges, and additional user CV parameters.
Gradient Echo (GRE)
Gradient Echo (GRE) protocols use short TR and flip angles of less than 90 degrees. GRE uses reverse magnetization techniques to flip protons and create a scan echo.
Gradient echo pulse sequences are general purpose PSDs used to produce 2D and 3D reconstructions. GRE uses short TR and flip angles of less than 90 degrees to excite only a portion of the longitudinal magnetization.
GE MRI Protocols (Neuro)
T1 FLAIR
The T1 FLAIR MRI fast inversion recovery sequence designed to achieve better tissue contrast-to-noise ratio as well as better signal to noise in a shorter amount of time when compared to a spin echo scan sequence.
T2 FLAIR GE MRI Protocols
Fluid attenuated inversion recovery (FLAIR) is a fast inversion recovery technique based on the null point of cerebrospinal fluid. T2 FLAIR produces a bright CSF signal which helps to differentiate T2-weighted image structures next to fluid filled structures. The Inversion time is the primary driver for the image contrast. The TI value should match the time it takes for CSF tissue or structure to relax, approximately 2000-2300 ms.
DW-EPI (DWI)
Diffusion weighted echo planar imaging, commonly referred to as DWI, is a single shot EPI protocol sequence. DWI MRI scans differentiate tissue with restricted diffusion from tissue with normal diffusion coefficients.
DWI utilizes the gradient coils to provide an echo, as opposed to relying on the RF pulse echo. Additionally, DWI MRI uses partial k-space reconstruction algorithms to reduce scan times. Diffusion Imaging produces images based on relative Brownian motion of molecules in the tissue.
Imaging Applications
Diffusion weighted imaging pulse sequences are highly gradient-intensive, T2- weighted scan protocols. This scan sequence is ideal when imaging anatomical microstructures. DWI MRI is an ideal scan sequence for brain, breast, prostate, and liver MRI scan techniques.
Important DWI Scan Considerations
B-value determines strength of diffusion weighting. Maximum B-value is dependent on gradient hardware configuration (possible B-value range of 1,000 to 7,000). As B-value (diffusion weighting) increases, gradient strength increases, and SNR decreases.
Increasing NEX increases the use of Bulk Acquisition Memory (BAM). The system will post a message if the system cannot allocate enough BAM for the prescribed sequence. Reduce matrix, number of slices, or NEX to resolve issue. Post process the exam in Clariview to utilize the SCIC option, as it is not available for DWI sequences.
Click here for in-depth information about the DWI MRI scan protocol.
GE Signa Excite Spectroscopy PSD’s
PROBE
Proton brain examine, commonly referred to as PROBE MRI, is a spectroscopy option that includes PROBE-S and PROBE-P. Additionally, this spectroscopy package includes a voxel localized autoshim and an optional water suppression package, CHESS (Chemical Selective Suppression).
PROBE analyzes return signal from myo-inositol, N-acetyl groups, choline and SNR of creatine to apply in the reconstruction algorithm. Sampled spectrum values affect phase, residual eddy currents, and artifact correction for the water suppressed data.
PROBE 2D CSI
Chemical Shift Images (CSI)
PROSE
Prostate Spectroscopy and Imaging Examination pulse sequence, PROSE, is an optimized acquisition sequence designed to acquire spectra from the prostate gland. PROSE pulse sequences employed to assess post-biopsy hemorrhage in the prostate, presence of pelvic lymph nodes and bone metastases.
Optional GE MRI Protocols
SSFSE-IR, FSE-IR, 2D FRFSE-XL, 3D FRFSE-XL. Spectroscopy, Spoiled Gradient Echo (SPGR), Fast GRE, SPGRE, FGRE, FSPGR for Bilateral Breast, 3D FIESTA, SE- EPI, GRE-EPI, FLAIR EPI, GE Signa Excite MRI Vascular PSD List, 2D TOF GRE/SPGR, 3D TOF GRE/SPGR, 2D Fast TOF GRE/SPGR, Fast 3D TOF GRE/SPGR, TRICKS, 2D Phase Contrast, 3D Phase Contrast, Fast 2D Phase Contrast, DW-EPI Tensor, Propellor DWI, 3D FIESTA-C, Propellor T2, PROBE 3D CSI, Multi-Nuclear Spectroscopy.
Conclusion
The MRI technologist training resources library empowers you with information. Our goal is to provide the best information regarding your GE MRI system so you always have a solution to you imaging queries. See the additional GE MRI PSD resources section below for additional links to helpful resources.
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Additional GE MRI PSD Resources
Find in-depth information about MRI artifacts at https://www.medicalimagingsource.com/signa-voyager-mri-artifact-solutions-guide/
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