Enter MRI Protocol Inputs
The page stays in a single vertical flow, while the calculator fields use a responsive 3-column, 2-column, and 1-column grid.
Example Data Table
These sample protocols illustrate how field of view, matrix, and timing choices affect calculated pixel size, voxel volume, and estimated scan time.
| Example | FOV (mm) | Matrix | Slice (mm) | BW (kHz) | TR (ms) | NEX | ETL | Pixel Size (mm) | Voxel (mm³) | Approx Time (sec) |
|---|---|---|---|---|---|---|---|---|---|---|
| Brain Axial TSE | 220 × 220 | 256 × 224 | 5.0 | 50 | 500 | 1 | 8 | 0.86 × 0.98 | 4.22 | 13.48 |
| Knee Detail | 160 × 160 | 320 × 256 | 3.5 | 35 | 650 | 2 | 10 | 0.50 × 0.63 | 1.09 | 14.35 |
| Fast Abdomen | 380 × 304 | 320 × 192 | 6.0 | 62.5 | 4.2 | 1 | 1 | 1.19 × 1.58 | 11.28 | 0.36 |
Formula Used
Pixelfreq = FOVfreq ÷ Matrixfreq
Pixelphase = FOVphase ÷ Matrixphase
Pixel Area = Pixelfreq × Pixelphase
Voxel Volume = Pixel Area × Slice Thickness
BW per Pixel = Receiver Bandwidth (Hz) ÷ Matrixfreq
Coverage = (Number of Slices × Slice Thickness) + ((Number of Slices - 1) × Slice Gap)
Effective Phase Steps = Matrixphase × (1 + Oversampling) × Partial Fourier ÷ Parallel Imaging
Time ≈ TR × Matrixphase × (1 + Oversampling) × Partial Fourier × NEX ÷ (ETL × Parallel Imaging)
Relative SNR Index ∝ Voxel Volume × √NEX ÷ √Bandwidth
The SNR index is a comparative planning indicator. It is not an absolute scanner-calibrated SNR measurement.
How to Use This Calculator
- Enter the frequency and phase field of view values in millimeters.
- Enter the acquisition matrix for both frequency and phase directions.
- Set slice thickness, slice count, and optional slice gap.
- Provide receiver bandwidth, TR, NEX, and echo train length.
- Add phase oversampling, partial Fourier, and parallel imaging settings.
- Press Calculate MRI Resolution to show results above the form.
- Review pixel size, voxel volume, scan time, and bandwidth-per-pixel outputs.
- Use the Plotly graph to inspect phase-resolution and timing tradeoffs.
- Export the displayed results to CSV or PDF when needed.
FAQs
1) What does MRI resolution mean here?
Here it means spatial sampling size. Smaller pixels and thinner slices improve detail, but they can reduce signal strength or increase scan time.
2) How does field of view affect pixel size?
For a fixed matrix, a larger field of view creates larger pixels. Larger pixels collect more signal, but fine anatomical detail becomes less sharp.
3) Why does a larger matrix improve detail?
Increasing matrix size divides the same field of view into more samples. That reduces pixel size and can improve detail, though scan time or noise may worsen.
4) What is bandwidth per pixel used for?
Bandwidth per pixel helps evaluate frequency-direction noise and distortion behavior. Higher bandwidth often reduces chemical shift and distortion, but it may lower SNR.
5) Why is slice thickness included in voxel volume?
Voxel volume combines in-plane pixel area with slice thickness. Thicker slices raise signal and coverage, but partial-volume blur becomes more noticeable.
6) What does phase oversampling change?
Phase oversampling improves wraparound protection by collecting extra phase information. It usually increases the encoding workload and can lengthen acquisition time.
7) How do partial Fourier and parallel imaging help?
Both reduce the amount of acquired data. That speeds scanning, but they may introduce reconstruction penalties, artifacts, or lower effective SNR.
8) Is this calculator suitable for diagnostic decisions?
No. It is an engineering and protocol-planning aid. Final clinical settings should always follow scanner capabilities, physicist guidance, and radiologist requirements.