Struct StarParams 

pub struct StarParams {
    pub pad: [usize; 3],
    pub echo_times: Vec<f64>,
    pub te: EchoTime,
    pub b0: f64,
}

Parameters for star_qsm. The defaults are STI Suite’s: the GUI’s padding, and QSM_star’s defaults otherwise.

Fields

pad: [usize; 3]

Zero padding per side in voxels, per axis (x, y, z in voxel axes): STI’s 'padsize'.

Default STAR_GUI_PAD = [8, 8, 20]: what STI Suite 3.0’s QSM_GUI passes to QSM_star, so the default gives what STI Suite’s GUI users get. It is a constant in the GUI, not derived from the data. Probed in MATLAB R2023b by driving QSM_GUI headless (load, “3D GRE data”, “star QSM”, and the “Single button for QSM” path) with a logging wrapper around QSM_star: 'padsize' was [8 8 20] on all 14 grid / voxel-size combinations tried (32 to 128 voxels per axis, axes permuted; 0.5 to 3 mm voxels, isotropic and anisotropic) and with other mask sizes and positions, field strengths, B0 directions and V-SHARP radii. The GUI has no padding control. The 20 is on the third voxel axis whatever the B0 direction. (The GUI’s phase unwrapping fails on odd matrix sizes, so it never gives QSM_star an odd grid; see step 1 of the module docs for odd grids here.)

QSM_STAR_DEFAULT_PAD ([0, 0, 0]) is what QSM_star does when called without 'padsize'. STI_Templates.m lists [12 12 12] as the default (STI_TEMPLATES_STAR_PAD), but that is not what the function does. Any other padding can be given per axis.

B0 direction (a deliberate deviation from the GUI). The GUI takes 'H' from its H_Vector field, which loading the data does not fill from the scan (the same probe: the loader returned an oblique direction and QSM_star still got [0 0 1]), so GUI users get [0 0 1] unless they type a direction in. star_qsm instead takes the direction as its bdir argument, and the pipeline passes the scan’s B0 direction (from the affine, as for every other inversion), which is correct for oblique acquisitions. For the GUI’s result, pass (0, 0, 1) explicitly; for axial scans the two agree.

echo_times: Vec<f64>

Echo times in seconds, in acquisition order (default [0.04], STI’s 40 ms). The pipeline sets them from the scan metadata.

te: EchoTime

Which echo time the field is converted to phase at (see the module docs, Units). Default EchoTime::Sum, as STI Suite 3.0’s multi-echo pipeline (QSM_GUI) gives QSM_star its phase. Probed in MATLAB R2023b with logging wrappers, on 3 synthetic echoes: loading the data sets its sum_TE field (TE_value) to 1000·sum(TEs); “3D GRE data” (VSHARPCallBackFcn) runs V_SHARP on the sum of the echoes’ Laplacian-unwrapped phases (MRPhaseUnwrap), bit for bit, and divides that tissue phase by 2π·ΣTE for its frequency map; “star QSM” (starQSMCallBack) calls QSM_star(TissuePhase, NewMask, 'TE', sum_TE, ...). So the phase is the field over ΣTE. (STI_Templates.m line 107’s TE=40 is that field’s default.)

b0: f64

Field strength in tesla (default 3). The pipeline sets it from the scan metadata.

Implementations

impl StarParams

pub fn validate(&self) -> Result<(), String>

Checks the parameters: the echo time te picks must be finite and > 0, and so must b0.

pub fn rad_per_ppm(&self) -> f64

Radians of phase per ppm of field at the echo time te picks and B0, with STI’s γ = 42.575 MHz/T.

Panics

If te cannot be resolved from echo_times (validate checks).

Trait Implementations

impl Clone for StarParams

fn clone(&self) -> StarParams

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StarParams

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for StarParams

fn default() -> Self

Returns the “default value” for a type.

impl Serialize for StarParams

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.