Thursday, 13 August 2015

[RNH post #11] Further improvements on the diffusion standard statistics

As I mentioned on my last post, I used the implemented modules to process data acquired with similar parameters to one of the largest world wide project, the Human Connectome project. Considering that I was fitting the diffusion kurtosis model with particularly no pre-processing steps, which are normally required on diffusion kurtosis imaging, kurtosis reconstructions were looking very good (see Figure 2 of my last post).

Despite this, some image artefacts were presented, likely being a consequence of gibbs artefacts and MRI noise. In particular, some low intensity voxels were presented in regions where we expect that MK and RK is high. To correct these artefacts, I decide to add a pre-processing step that denoises diffusion-weighted data (to see the coding details of this, see directly on my pull request). 

Before fitting DKI on the denoised data, this are the amazing kurtosis maps that I obtained:

Figure 1 -  Real brain parameter maps of the mean kurtosis (MK), axial kurtosis (AK), and radial kurtosis (RK) obtain from a HCP-like dataset using the DKI module. These are the maps specific to DKI. The dataset for these reconstructions was kindly supplied by Valabregue Romain, CENIR, ICM, Paris

You can also see the standard diffusion measures obtain from my implemented DKI module and compared to the DTI module previously implemented:

Figure 2. Real brain parameter maps of the diffusion fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) obtain from a HCP-like dataset using the DKI modules (upper panels) and the DTI module (lower panels). Despite DKI involves the estimation of a larger number of parameter, the quality of the diffusion standard measures of the HCP-like dataset from DKI seem be comparable with the standard diffusion measures from DTI.  This dataset was kindly supplied by Valabregue Romain, CENIR, ICM, Paris

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