license: cc-by-4.0
tags:
- mri
- qsm
- quantitative-susceptibility-mapping
- neuroimaging
pretty_name: QSMbly example data
QSMbly example data
One in-vivo subject, used as the "Load example data" dataset in QSMbly and fetched by the browser at runtime.
A single 5-echo 3D gradient-echo acquisition at 1 mm isotropic, acquired on a Siemens MAGNETOM Prisma Fit. Magnitude and phase are split one file per echo, since QSMbly's loader reads 3D volumes and derives the echo count from the file list.
| Matrix | 184 × 256 × 128, 1 mm isotropic |
| Echoes | 5 — TE 5 / 11 / 17 / 23 / 29 ms |
| TR / flip | 35 ms / 15° |
| Sequence | gre_bridge_1mm_psn_adapt (product GRE, GRAPPA R=2) |
| Scanner | MAGNETOM Prisma Fit (XR VA30A) |
| Phase | radians, wrapped |
Field strength
MagneticFieldStrength is 2.8946 T, the accurate field derived from the scanner's
carrier frequency (ImagingFrequency 123.243444 MHz ÷ 42.576384 MHz/T), not the nominal
3.0 T printed on the magnet. QSM scales ppm by this value, so the accurate one is the
correct one to use.
Echo times
Recovered from the exam-card PDFs shipped with the acquisition and, for the Pulseq consensus sequence in the wider study, from HarmonizedMRI/megre_label. They are not the DICOM sidecar values, which carry placeholder timings for some protocols.
Provenance
Packed from the 2026-08-20 QSM harmonization acquisition (MGH bays 4/5) — one subject
scanned on two Siemens 3T scanners under four protocols × 3 runs. The full study is on
OSF at osf.io/gkemr; this repo holds the prisma-bridge-run1
acquisition only, re-split into per-echo files.
The same acquisition is available to QSMxT users via qsmxt example.