ConductScienceConductScience
ToolsConductScience tool
NMR & MRI SystemsFree in-browser calculator

MRI Sequence Parameter Calculator.

Calculate scan time, resolution, SNR, and SAR for MRI pulse sequences with clinical and research presets.

Run calculator Request a Quote
PrivateData stays in your browser
LiveNo sign-up required
Validated2026-04-08
CitableMethods and citation included

Calculator

Results update in place

Try it out

Load example MRI Sequence Parameter Calculator data to see the full workflow

Sequence Preset

Scanner

Geometry

Timing Parameters

Acquisition

When to use

  • Plan MRI acquisition protocols for clinical or research studies
  • Estimate scan time before booking scanner time slots
  • Evaluate resolution and SNR trade-offs when optimizing protocols
  • Check SAR safety margins for high-flip-angle sequences at 3T or 7T
  • Generate standardized methods text for publications and grant applications
  • Compare different sequence configurations (e.g., parallel imaging vs. averaging)

Do not use for

  • For exact SAR values — use your scanner vendor’s SAR monitor for regulatory compliance
  • For absolute SNR — the calculator provides relative units for comparison, not calibrated measurements
  • As a substitute for sequence simulation software (e.g., Bloch equation simulators) for contrast optimization

Use parallel imaging wisely

GRAPPA/SENSE factor of 2 halves scan time with modest SNR penalty (~15–30%). Factor 3+ causes significant noise amplification. For clinical protocols, factor 2 is the standard trade-off.

ETL dramatically reduces TSE scan time

Echo train length of 16 in T2-TSE reduces scan time by 16× compared to conventional spin echo. However, long echo trains cause T2 blurring in the phase-encode direction. Balance ETL against acceptable blur.

Averages are expensive

Doubling NEX doubles scan time but only increases SNR by 41% (sqrt(2)). Before adding averages, consider whether increasing voxel size by 10–15% could achieve the same SNR gain at the same scan time.

3T SAR limits constrain refocusing pulses

At 3T, SAR scales 4× relative to 1.5T. T2-TSE with 180° refocusing may exceed limits at short TR. Variable refocusing flip angle trains (e.g., hyperecho) are the standard workaround.

1

Method

Scan time computed from TR, phase steps, ETL, parallel factor, and acquisition mode (2D/3D/fMRI). Resolution from FOV/matrix. SNR proportional to voxel volume ×\times sqrt(NEX) ×\times field strength. SAR proportional to flip angle2\text{angle}^{2} ×\times slices / TR ×\times field strength². Formulas follow Bernstein et al. (2004) and standard MR physics conventions.

2

Validated

Last validated 2026-04-08. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.

3

How to cite

How to Cite

ConductScience MRI Sequence Parameter Calculator (v1.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/mri-sequence-parameter-calculator

Bernstein MA, King KF, Zhou XJ. Handbook of MRI Pulse Sequences. Academic Press. 2004.

Reeder SB et al. Practical approaches to the evaluation of signal-to-noise ratio performance with parallel imaging. Magn Reson Med. 2005;54(3):748–754.

MRI Sequence Parameter Fundamentals

MRI acquisition parameters control three interdependent properties: image quality, scan time, and patient safety.

Spatial Resolution is determined by FOV / matrix size. Smaller voxels provide finer anatomical detail but reduce SNR proportionally to voxel volume.
Signal-to-Noise Ratio (SNR) scales with voxel volume, the square root of averages (NEX), and field strength. Doubling field strength from 1.5T to 3T doubles SNR.
Scan Time depends on the sequence type. For spin-echo sequences, time = TR ×\times phase steps / (ETL ×\times parallel factor). Turbo spin echo (TSE) sequences use echo trains to acquire multiple phase-encode lines per TR, dramatically reducing scan time.
SAR (Specific Absorption Rate) increases with the square of both flip angle and field strength. At 3T with refocusing pulses (150°), SAR limits become a practical constraint on sequence design.

Common Pitfalls in MRI Protocol Design

Several factors can compromise MRI protocol quality:

• SAR limits at 3T: Spin-echo sequences with 180° refocusing pulses may exceed SAR limits at short TR. Use variable flip angle refocusing or lower parallel factors • Partial volume effects: Thick slices (>5 mm) mix signals from different tissues, reducing diagnostic sensitivity for small lesions • Motion artifacts in long scans: Scan times >8 minutes significantly increase motion artifact risk. Consider parallel imaging or partial Fourier to reduce time • EPI distortion: fMRI and DWI use EPI readouts that are sensitive to B0 inhomogeneity, causing geometric distortion near air-tissue interfaces • Parallel imaging noise: GRAPPA/SENSE acceleration >3 introduces significant g-factor noise penalty. Acceleration of 2 is the typical sweet spot • Inadequate averages: Single average (NEX=1) may be insufficient for small-FOV or high-resolution protocols. SNR increases with sqrt(NEX) but scan time increases linearly

Frequently asked

325
Free tools
1,200+
Institutions
100%
Client-side
0
Uploads required

Next steps

Equipment

NMR & MRI Systems

MRI scanners, coils, and accessories for research

Browse Equipment

Imaging & Analysis

Complete imaging solutions for preclinical research

Browse Equipment

Animal Monitoring

Physiological monitoring during MRI scans

Browse Quote

Need help?

Get a quote on equipment or talk to the ConductScience team.

Request quote