SeqEyes Online — Pulseq MRI Sequence Viewer

Visualize Pulseq MRI sequences — in your browser, MATLAB, or VS Code. Open text .seq or official binary .bseq files, then inspect RF pulses, gradients, ADC readouts, and triggers with interactive zoom & pan. Includes a GPU‑accelerated 3D k‑space viewer with camera presets. Inspired by SeqEyes.

🌐 Try it Online — No Install Required

🌐 Web Version — Try It Now!

→ bughht.github.io/seqeyes_plugin

No download, no extension, no setup. Just drag & drop a .seq or .bseq file and explore:

• Drag & drop a .seq or .bseq file onto the page (or click 📂 Open)
• All the same features as the VS Code extension — sequence channels, optional M1/PNS, k‑space viewer, 6 themes, tooltips
• GPU‑accelerated 3D k‑space rendered in your browser via WebGL
• Zero‑dependency parsing — the Pulseq engine runs entirely in the browser
• Local files stay local — parsing and calculation run in browser memory without uploading sequence data

VS Code Extension

Deep integration with VS Code — .seq and .bseq files open automatically in the custom editor.

Install

From the Marketplace:

code --install-extension SeqEyesDeveloper.seqeyes-web

Or build from source:

git clone https://github.com/bughht/seqeyes_plugin.git
cd seqeyes_plugin
npm install
npm run package
code --install-extension seqeyes-web-*.vsix --force

Or press F5 to launch Extension Development Host.

🧪 MATLAB Toolbox

Open in-memory Pulseq sequences, text .seq files, or binary .bseq files directly inside MATLAB — call seqeyes(seq), double-click a file in the Current Folder browser, or open an empty viewer with seqeyes().

Setup

Choose one of these two MATLAB setup paths.

Option 1: Install the toolbox. Download seqeyes-*.mltbx from GitHub Releases and double-click to install, or run:

matlab.addons.toolbox.installToolbox('seqeyes-<version>.mltbx')

The installed toolbox is self-contained for MATLAB: it includes seqeyes.m and the bundled web viewer assets, so you do not need to keep a GitHub checkout after installing it.

Option 2: Use the source checkout. Clone or download this repository, then add its matlab folder to the MATLAB path:

addpath(genpath('/path/to/seqeyes_plugin/matlab'))

This source setup does not require installing the .mltbx; seqeyes(seq) uses the web assets from the checkout.

Usage

seqeyes(seq)                  % open an in-memory mr.Sequence object
seqeyes('spiral_inout.seq')   % open a saved .seq file
open('spiral_inout.seq')      % or double-click in Current Folder
seqeyes('gre.bseq')           % open a saved binary .bseq file
open('gre.bseq')              % or double-click in Current Folder

No manual .seq export is needed for mr.Sequence objects; SeqEyes writes a temporary file internally and does not modify Pulseq files or classes. All the same features as the browser & VS Code versions — 7 channels, k-space viewer, themes, tooltips — rendered inside a native MATLAB figure. Requires R2022a+.

🐍 Python Package

Interactive Pulseq sequence viewer for Jupyter notebooks and Python scripts — a drop‑in replacement for pypulseq.Sequence.plot(). Renders directly in notebook cell output or opens in your default browser.

Install

pip install seqeyes-python

For pypulseq integration:

pip install seqeyes-python[pypulseq]

Usage

import seqeyes

# Enable SeqEyes (once per session) — seq.plot() is now interactive
seqeyes.set(theme="dark", time_disp="ms")

# Build your sequence with pypulseq as usual
seq.plot()                          # interactive viewer in Jupyter
seq.plot(show_blocks=True)          # per‑call overrides
seq.plot(time_range=(0, 0.05))      # zoom to first 50 ms

# Restore matplotlib at any time
seqeyes.reset()

All the same features as the other versions — interactive waveforms, k‑space viewer, themes, tooltips — rendered directly in Jupyter or your browser. Requires Python ≥ 3.9.

Features

• Custom editor for .seq and .bseq files — opens automatically on double‑click
• 📂 Open button — switch between sequences without closing the editor
• Browser URL import — open raw .seq or .bseq files from web links in the standalone web app; fetched bytes stay in browser memory
• 7 primary channels: RF · φ · Gx · Gy · Gz · ADC · Trigger
• Optional M1 channels: calculate M1x, M1y, and M1z on demand
• Optional SAFE PNS prediction: load a user-provided Siemens ASC profile to display PNS X/Y/Z/Norm
• Gradient spectrogram: time × frequency content of the physical (rotation-applied) gradient waveforms over exactly the visible time window, with a frequency-spectrum sub-pane, selectable colormaps, and radiology-style window/level
• Acoustic resonance bands: forbidden bands read from the same ASC profile, overlaid on both sub-panes
• Simulated gradient sound: play the visible window with a playhead that tracks the audio clock (simulated, not calibrated — see the caveat below)
• ADC phase curve on φ axis — continuous $\phi(t) = \phi_0 + 2\pi \cdot f_{offset} \cdot (t - t_0)$
• Analysis panel: one panel, three states — closed, WebGL‑accelerated 3D k‑space scatter (millions of points @ 60 fps) with camera presets, or the gradient spectrogram
• Camera presets (xy / xz / yz) rotate the 3D view; any drag reverts to free 3D
• Interactive Canvas: cursor‑anchored time zoom, per‑row y‑axis zoom, drag‑pan, hover tooltips
• 6 built‑in themes: One Light · One Dark · Dracula · Nord · GitHub Light · GitHub Dark (+ system auto)
• Vertical cursor with live time readout
• Unit switchers for time (s / ms / µs) and gradient (Hz/m / mT/m / G/cm)
• K‑space unit toggle (1/m ↔ rad/m) with auto‑updating axis ticks
• Block boundary lines — toggle in toolbar
• Optimized for large files — binary k‑space encoding, bounds-checked parsers, and no text conversion for .bseq
• Pulseq format support — text .seq v1.2.0–v1.5.x and official binary .bseq v1.5.2 reading
• Current .bseq hosts — standalone web, VS Code, MATLAB seqeyes('file.bseq'), Python SeqEyesViewer.from_file(), and the k-space export CLI

Gradient spectrogram and acoustic bands

The analysis panel has three states, cycled by one toolbar button: closed, k-space trajectory, and gradient spectrogram.

What the spectrogram shows

The time × frequency content of the three physical gradient axes — the logical channels with each block’s rotation extension applied, because acoustic behaviour is a property of the coils, not of the logical axes. Values are magnitudes in mT/m (or T/m/s for dG/dt), displayed in dB, and the fourth trace in the spectrum sub-pane is the root-sum-of-squares across the axes.

It is computed over exactly the time window the waveform panel is showing, and recomputed as you pan and zoom. This is a deliberate departure from pulseq’s mr.Sequence.gradSpectrum, which averages over 50 ms segments of the whole sequence: that average can be diluted by dummy scans, preparation blocks and quiet stretches, so a sequence with a real resonance excitation inside one TR can be padded until it looks compliant. Keeping the full matrix means a hot 20 ms shows up as a hot column.

The readout under the panel always states the resolution actually achieved (dt, df), because a heavily zoomed view genuinely cannot resolve fine frequency detail, and the panel says so rather than implying otherwise.

Acoustic resonance bands

Load ASC (PNS/Acoustic) reads both the SAFE PNS coefficients and the acoustic resonance table from a Siemens ASC profile. The two are parsed independently: a profile carrying only one of them still loads, and the viewer reports which it found. Bands are drawn as translucent spans across both sub-panes, in a fixed warning colour so they never blend into the active colormap.

When gradient energy inside a band renders at the top of the current display window, the band edge is highlighted and the viewer says so. This is advisory. It compares against your current window/level setting, not against a scanner limit, and it is not a compliance check.

Simulated gradient sound

The play button synthesises audio from the physical gradient waveforms, following pulseq’s Sequence.sound(): x to the left channel, y to the right, z split between them, lightly smoothed and peak-normalised.

This is simulated, not calibrated. It reproduces the spectral character of the gradient waveform. It is not sound pressure level, and it says nothing about how loud the scanner will actually be — that would need the coil transfer function, which the ASC does not contain. Windows shorter than 250 ms loop so there is something to hear; windows longer than 120 s are refused.

Limits

The spectrogram is scoped to the visible window, so when a request exceeds the interactive budget the viewer asks you to zoom in rather than offering a “calculate anyway” override — unlike whole-sequence k-space, zooming always solves it. For the same reason the spectrogram stays available on sequences where k-space is refused, and the k-space safety dialog offers it as a way out.

Usage

License

MIT © Bughht

SAFE PNS prediction components are distributed under the BSD 3-Clause License. See THIRD_PARTY_NOTICES.md. PNS output is an advisory prediction, not a clinical, scanner-vendor, or regulatory safety certification.

The .bseq reader behavior and committed parser fixtures are derived from the MIT-licensed pulseq/pulseq reference implementation. SeqEyes currently reads .bseq; it does not write or convert binary sequence files.

The gradient spectrogram and the simulated gradient sound are derived from pulseq’s gradSpectrum.m and Sequence.m::sound(), and the acoustic ASC key names from pypulseq. See THIRD_PARTY_NOTICES.md for the pinned revisions. Spectrogram and audio output are simulations of gradient waveform content, not acoustic measurements or a compliance assessment.