Table 3.
Essential and recommended standards to be reported in a scientific publication containing 4D Flow MRI data
| Explanation | Technical studies | Clinical studies | Example | |
|---|---|---|---|---|
| Hard- and software | ||||
| Contrast agent administration | If contrast agent used: Which contrast agent, dose, and timing in relation to 4D Flow CMR | Essential, if contrast agent used | Essential, if contrast agent used | gadolinium contrast agent (insert name here) was injected prior to the data acquisition |
| Manufacturer | Manufacturer of MRI system | Essential | Essential | GE, Philips, Siemens, etc |
| Scanner software version | Version of the scanner software during the study | Essential | Recommended | R11.2, VE11A |
| Field strength | Field strength in Tesla | Essential | Essential | 1.5T |
| 4D Flow CMR sequence | Description (clinical or research, through vendor, through academic partnership, in-house developed) | Essential | Essential | WIP |
| Coil type and channels | Coil types, number of elements | Essential | Recommended | 16 channel cardiac coil |
| Acquisition parameters | ||||
| Motion encoding scheme | 4, 5, 7 or 8-point encoding, variable venc encoding or other multi-venc approaches, as well as flow compensation versus two-point encoding | Essential | Recommended | [Example] |
| k-space filling method | Type of k-space acquisition such as cartesian, radial, spiral, pseudo-random, EPI, etc | Essential | Essential | Cartesian k-space filling |
| Acquired spatial resolution |
Resolution of the acquired data before Fourier transform (FOV/matrix size) |
Essential | Essential | 2.5 × 2.5 × 2.5 mm3 |
| Reconstructed spatial resolution | Spatial resolution of the reconstructed data (often interpolated during reconstruction) | Essential | Recommended | 1.0 × 1.0 × 1.0 mm3 |
| Effective temporal resolution | Typically: TR x flow encodings x # segments | Essential | Essential | 35 ms |
| Reconstructed number of timeframes | Number of timeframes after reconstruction (often interpolated during reconstruction) | Recommended | Recommended | 30 |
| Echo time (TE) | Time between RF excitation and echo | Essential | Essential | 2.6 ms |
| Repetition time (TR) | Time between to subsequent RF excitations | Essential | Essential | 5.2 ms |
| Flip angle (FA) | Flip angle | Essential | Essential | 5 |
| Velocity encoding limit (VENC) | Maximum VENC | Essential | Essential | 120 cm/s |
| Cardiac gating | Prospective triggering or retrospective cardiac gating, ECG, pulse oximeter or other devices | Essential | Essential | retrospective vector cardiogram controlled cardiac gating |
| Respiratory motion suppression | If respiratory motion suppression is performed | Essential | Essential | Navigator width (insert here) or acceptance window (insert here) |
| Acceleration method and factor | Acceleration approach used, such SENSE, GRAPPA, compressed SENSE, etc.) | Essential | Essential | parallel imaging (SENSE) speed up factors = 3 (AP direction), 1.6 (RL direction) |
| Typical scan time | Scan time assuming a regular heart rhythm of 60 bpm and regular breathing pattern or the average and range of the scan time of all subjects | Essential | Essential | 10:30 min |
| Field of view (FOV) | Important to choose correctly to eliminate wrap; impacts spatial resolution | Recommended | Recommended | 250.1 ± 10.2 × 280.1 ± 15.2 × 70.1 ± 10.8 mm3 |
| Matrix size | Impacts spatial resolution | Recommended | Recommended | |
| Slab orientation | Orientation of the FOV | Essential | Essential | sagittal oblique orientation |
| Phase-encoding direction | Direction of the phase-encoding direction (were wrap around effects can be expected) | Recommended | Recommended | Phase-encoding direction in the inferior-superior direction |
| k-space segmentation factor | Number of k-space lines acquired per heartbeat | Essential | Recommended | 2 |
| Postprocessing | ||||
| Analysis software | Description (clinical or research, through vendor, through academic partnership, in-house developed, open-source availability) | Essential | Essential | In-house developed, availability at Github |
| Background phase offset corrections | Eddy currents, concomitant gradient fields, and distortions | Essential | Recommended | corrected for concomitant gradient field and eddy currents induced offset using a 2nd order correction |
| Velocity aliasing correction (phase unwrapping) | Description of velocity anti-aliasing algorithm, sharing of results if available | Essential | Essential | correction for velocity aliasing using a 4D Laplacian phase unwrapping (ref, github) |
| Segmentation method |
Description of segmentation method used, if used for quantification and/or segmentation (Systolic segmentation, or time-resolved segmentation. Based on absolute velocity, magnitude weighting for each time frame and sum of squares, temporal absolute velocity average with magnitude weighting, piecewise pseudo complex difference, atlas-bases segmentation, AI based segmentation) |
Essential, if used | Essential, if used | delineation of the aorta based on piecewise pseudo complex difference PC-MRA |
| Quantification | ||||
| Analysis software | Description (clinical or research, through vendor, through academic partnership, in-house developed, open-source availability) | Essential | Essential | Clinical analysis software package (insert name here) |
|
Plane-wise analysis (peak velocity, flow rate, regurgitation volume) |
Description of the plane positioning method (Manual, automatic, Fixed or valve tracking) | Essential | Essential | A 2D plane was manually located at the aortic valve at a fixed/valve tracking location over the cardiac cycle |
|
Volumetric analysis (peak velocity, wall shear stress, turbulent kinetic energy, flow component analysis) |
Description of the segmentation method (Manual, automatic, semi-automatic, Static or varying over the cardiac cycle) | Essential | Essential | The heart chambers and large vessels were segmented automatically over the cardiac cycle using AI (ref) |
|
Gradient calculations (wall shear stress, viscous energy loss, pressure difference) |
Description of the numerical difference method (Forward-, backward-, central-difference 1st order or higher order differences, Finite element method) |
Essential | Recommended | 2nd order central difference |
| Results | ||||
| Data quality assessment | Results of the data quality assessment both visual and quantitative such as conservation of mass error | Essential | Essential | Data quality assessment showed that … |
| Number of subjects included and excluded | Number of subjects included and excluded, and the reason for exclusion | Essential | Essential | Data was acquired in 52 subjects, of which 1 was excluded due to ecg gating issues and 3 due to insufficient data quality |
| Illustrations | Insightful illustrations and movies including annotations, color scaling and descriptions, clarifying which particle traces are used | Essential | Essential | Streamline visualization of aortic flow (movie in supplementary material) |
| Discussion | ||||
| Limitations | Discussion of the effect of uncommon or varying acquisition settings | Essential, if applicable | Essential, if applicable | Spatial resolution varied between the subject, but not between the subgroups. This is expected to |
| References | ||||
| Reference list | References to original work | Essential | Essential | |