VERSE

Variable-rate Selective Excitation (VERSE) algorithms and helpers in C, MATLAB, and Python, including PyPulseq integration.

Simple usage with PyPulseq

import pypulseq as pp
import pyverse_pulseq as ppverse # The pypulseq-compatible VERSE library
from math import pi

# Set limits
system = pp.Opts(max_grad=80, grad_unit="mT/m", max_slew=200, slew_unit="T/m/s")
seq = pp.Sequence(system)

# Generate high time-bandwidth product Sinc pulse
rf, gz, gzr = pp.make_sinc_pulse(
    flip_angle      = pi/2,   # 90° (rad)
    apodization     = 0.5,
    slice_thickness = 5.0e-3, # 5 mm (m)
    time_bw_product = 10,
    return_gz       = True
)

# Minimum time VERSE algorithm
rfv, gzv = ppverse.verse(rf, gz, type="mintime", system=system)

# Add non-linear phase ramp for 1 mm slice-offset to RF waveform
rfv_offset = ppverse.apply_offcenter_phase(rfv, gzv, offset=1e-3, system=system)

# Build sequence and plot
seq.add_block(rf, gz)
seq.add_block(gzr)
seq.add_block(rfv, gzv)
seq.add_block(gzr)
seq.add_block(rfv_offset, gzv)
seq.add_block(gzr)
seq.plot(rf_plot='abs')

# Minimum SAR (fixed-duration) VERSE algorithm
rfv, gzv = ppverse.verse(rf, gz, type="minsar", system=system)

# Add non-linear phase ramp for 1 mm slice-offset to RF waveform
rfv_offset = ppverse.apply_offcenter_phase(rfv, gzv, offset=1e-3, system=system)

# Build sequence and plot
seq.add_block(rf, gz)
seq.add_block(gzr)
seq.add_block(rfv, gzv)
seq.add_block(gzr)
seq.add_block(rfv_offset, gzv)
seq.add_block(gzr)
seq.plot(rf_plot='abs')

Features

• Minimum-time VERSE (mintverse)
• Minimum-SAR VERSE (minsarverse; fixed duration)
• Core C implementation for multi-language usage
• MATLAB:
  • Pure MATLAB implementations: mintverse.m, minsarverse.m
  • MEX wrappers around the C library: mintverse_c.m, minsarverse_c.m
• Python:
  • ctypes wrapper around the C library: pyverse_c.py
  • pypulseq helpers: pyverse_pulseq.py

Installation

Python

Build the C shared library used by the ctypes wrapper:

bash build_python_lib.sh

Install the package:

pip install .

build_python_lib.sh produces:

• Linux: python/libverse.so
• macOS: python/libverse.dylib
• Windows (MSYS/Cygwin): python/verse.dll

MATLAB

Pure MATLAB functions require no build:

• matlab/mintverse.m
• matlab/minsarverse.m

To build the C-accelerated MEX functions, run inside MATLAB from the repo root:

build_matlab_mex

This compiles with the -R2017b MEX API and outputs:

• matlab/mintverse_mex.<mexext>
• matlab/minsarverse_mex.<mexext>

Wrappers mintverse_c.m and minsarverse_c.m call these MEX binaries.

If no compiler is configured, run:

mex -setup C

Usage: MATLAB

Pure MATLAB:

[b1v, gv] = mintverse(b1, g, dt, bmax, gmax, smax); % minimum-time
[b1v, gv] = minsarverse(b1, g, dt, gmax, smax);     % minimum-SAR

Mexed C-code (after building MEX):

[b1v, gv] = mintverse_c(b1, g, dt, bmax, gmax, smax);
[b1v, gv] = minsarverse_c(b1, g, dt, gmax, smax);

Repository layout

• c/ — C core (verse.c, verse.h)
• matlab/ — MATLAB API (pure and MEX wrappers)
• python/ — Python API (ctypes + pypulseq helpers)
• build_python_lib.sh — Build script for Python shared library
• build_matlab_mex.m — Build script for MATLAB MEX files
• archive/ — Legacy/testing implementations

Requirements

• C compiler (gcc/clang/MSVC)
• MATLAB R2018a+ recommended (MEX compiled with -R2017b API)
• Python 3.8+ (NumPy, SciPy, matplotlib, pypulseq)

License

See LICENSE

References

If you use the minimum-time VERSE algorithm in your work, please cite the following paper alongside this repository:

Hargreaves BA, Cunningham CH, Nishimura DG, Conolly SM. Variable-rate selective excitation for rapid MRI sequences. Magnetic Resonance in Medicine. 2004;52(3):3. doi:10.1002/mrm.20168

If you use the minimum-SAR VERSE algorithm in your work, please cite the following paper alongside this repository:

Woods JG, Ji Y, Li H, Hess AT, Okell TW. SNR-efficient whole-brain pseudo-continuous arterial spin labeling perfusion imaging at 7 T. Magnetic Resonance in Medicine. 2025;94(3):965-981. doi:10.1002/mrm.30527

Links

• Source: https://github.com/JosephGWoods/VERSE
• Issues: https://github.com/JosephGWoods/VERSE/issues