Function r2star_arlo 

pub fn r2star_arlo(
    magnitude: &[f64],
    mask: &[u8],
    echo_times: &[f64],
    nx: usize,
    ny: usize,
    nz: usize,
) -> (Vec<f64>, Vec<f64>)

R2* mapping using ARLO for equi-spaced echo times (≥3 echoes).

For each masked voxel, computes consecutive signal ratios to estimate the mono-exponential decay rate. Falls back to log-linear fitting for voxels with unreliable ratio estimates.

Arguments

• magnitude - Multi-echo magnitude data, flattened as [voxel0_echo0, voxel0_echo1, ..., voxel1_echo0, ...] i.e. shape (n_voxels, n_echoes) in row-major order, where n_voxels = nx*ny*nz
• mask - Binary brain mask [nx*ny*nz] (1 = process, 0 = skip)
• echo_times - Echo times in seconds [n_echoes] (must be equi-spaced)
• nx, ny, nz - Volume dimensions

Returns

(r2star_map, s0_map) - R2* in Hz and S0 (proton density), both [nx*ny*nz]

Panics

Panics if echo_times.len() < 3 or echo times are not equi-spaced.