Struct VsharpParams 

pub struct VsharpParams {
    pub threshold: f64,
    pub max_radius: f64,
    pub min_radius: f64,
    pub radius_step: f64,
    pub deconvolve: bool,
    pub ball: VsharpBall,
    pub grid: VsharpGrid,
}

V-SHARP algorithm parameters

Fields

threshold: f64

Deconvolution (TSVD) threshold: k-space frequencies where |1 - S| < threshold are dropped rather than divided through (default: 0.05, QSM.jl vsharp’s and QSM.m vsharp.m’s thr; STI Suite does not deconvolve). Only used when deconvolve is true. Higher values regularise more; 0.2 was QSM.rs’s tuned default before (see the module docs, QSM.jl’s vsharp).

max_radius: f64

Maximum (starting) SMV kernel radius in mm (default: 12.0, STI Suite’s V_SHARP smvsize default, also what its QSM_GUI and the χ-separation toolbox pass)

min_radius: f64

Smallest SMV kernel radius in mm (default: 2.0, STI Suite’s schedule; see radius_step). Voxels where no ball of at least this radius fits are dropped from the output mask.

radius_step: f64

Step between successive radii in mm (default: 1.0). The radii are max_radius, max_radius − radius_step, … down to min_radius, largest first; each voxel takes the largest that fits.

The default schedule, 12, 11, …, 2 mm, is STI Suite’s V_SHARP: it computes balls for r = 1 … smvsize mm in 1 mm steps (ascending, larger radii overwriting, so each voxel ends with the largest ball that fits) and then drops the voxels where only r = 1 fits, so the radii in effect are 2 … 12 mm (black-box probe, ukb-qsmxt docs/08_vsharp_sti.md step 4). Before this parameter existed min_radius was also the step, which cannot express that schedule; the previous default, 12 → 1 mm in 1 mm steps, is min_radius: 1.0, radius_step: 1.0. The ball shape is ball.

Measured against 12 → 1 mm (no deconvolution, 1 mm grid, ROMEO field, then RTS): the output mask loses ~5 % of its voxels, all at the rim. On the voxels both keep, χ on the qsm-forward phantom is unchanged (XSIM 0.257 → 0.256, NRMSE 85.8 → 85.7 %); on an in-vivo 3T Philips scan its agreement with the UK Biobank pipeline’s χ (STI Suite V-SHARP + iLSQR) improves slightly, XSIM 0.704 → 0.714, NRMSE 70.4 → 69.4 %.

deconvolve: bool

Deconvolve the SMV high-passed field by the largest kernel, 1/(1 − Ŝ) with TSVD at threshold. Default false: return the high-passed field φ − S_r∗φ itself, each voxel with the largest radius whose ball fits in the mask, as the authors’ code (STI Suite’s V_SHARP) does. true is the papers’ description (Li 2011, Wu 2012) as QSM.jl implements it. The deconvolution restores low spatial frequencies that 1 − Ŝ attenuated; on real data those are dominated by residual background and field-map error, so false is the more reproducible choice there, while true recovers more low-frequency tissue contrast on a clean field (see the module docs, Defaults).

ball: VsharpBall

The SMV ball (default VsharpBall::StiSuite, STI Suite’s V_SHARP). See the module docs.

grid: VsharpGrid

Grid the background is estimated on (default: VsharpGrid::Isotropic at 1 mm, as STI Suite’s V_SHARP resamples to 1 mm before filtering). See VsharpParams::working_grid for the choice resolved on a given input. VsharpGrid::Native avoids the interpolation and does not coarsen sub-millimetre acquisitions’ background estimate (on 1 mm isotropic data the two agree up to the crop).

Implementations

impl VsharpParams

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

Checks the parameters V-SHARP cannot run with: min_radius and radius_step must be finite and > 0 — at a step of 0 the radius list never ends — and an Isotropic working grid needs a spacing that is finite and > 0.

pub fn working_grid(&self, grid: &Grid) -> VsharpGrid

The working grid V-SHARP will use on grid: Self::grid resolved by VsharpGrid::resolve; never VsharpGrid::IsotropicFinest.

Trait Implementations

impl Clone for VsharpParams

fn clone(&self) -> VsharpParams

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for VsharpParams

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

Formats the value using the given formatter.

impl Default for VsharpParams

fn default() -> Self

Returns the “default value” for a type.

impl Serialize for VsharpParams

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

where __S: Serializer,

Serialize this value into the given Serde serializer.