In this blogpost I describe how to install the DTI-TK NIfTI quicklook plugin for nii files for mac OS.
Category: code
3D-printing nii data
In this blog post, I want to write about pipelines on how to prepare Nifti-brain data and make them printable by a 3D-printer.
Two pipelines are shown. One pipeline describes the 3D-printing the cortical folding structure that is estimated with Freesurfer and subsequently corrected with Meshlab. And another pipeline describes how you can 3D-print any binary nii-volume by using the AFNI-program IsoSurface and correct the output with netfabb. Continue reading “3D-printing nii data”
How to convert any paper figure into a layer-profile
Often we would like to normalize depth-dependent fMRI signals and assign it to specific cytoarchitectonially defined cortical layers. However, we often only have access to cytoarchitectonial histology data in the form to figures in papers. But since we only have the web-view or the PDF available, we cannot easily extract those data as a layer-profile. Since most layering tools are designed for nii data only, paper figures (e.g. jpg or GNP) are not straight-forwardly transformed to layer profiles.
In this blob post, I describe a set of steps on how to convert any paper figure into a nii-file that allows the extraction of layer profiles.
Continue reading “How to convert any paper figure into a layer-profile”
Unwanted spatial blurring during resampling
In layer-fMRI, we spend so much time and effort to achieve high spatial resolutions and small voxel sizes during the acquisition. However, during the evaluation pipeline much of this spatial resolution can be lost during multiple resampling steps.
In this post, I want to discuss sources of signal blurring during spatial resampling steps and potential strategies to account for them.
Continue reading “Unwanted spatial blurring during resampling”
Smoothing within layers
Smoothing within layers can be advantageous for multiple reasons:
- Increasing the CNR without loosing spatial information across cortical depths.
- Visualization of striping pattern across columnar structures.
- Avoiding leakage of physiological noise from CSF space into GM tissue.
BOLD smoothing
VASO smoothing
Quick analysis pipeline of getting layer fMRI profiles without anatomical reference data
This is a step-by-step description on how to obtain layer profiles from any high-resolution fMRI dataset. It is based on manual delineated ROIs and does not require the tricky analysis steps including distortion correction, registration to whole brain “anatomical” datasets, or automatic tissue type segmentation. Hence this is a very quick way for a first glance of the freshly acquired data.
The important steps are: 1.) Upscaling, 2.) Manual delineation of GM, 3.) Calculation of cortical depths in ROI, 4.) Extracting functional data based on calculated cortical depths.
Bias field correction
This post shows the overview of doing bias field correction in in SPM. Doing this helps me a lot to improve the accuracy of FreeSurfer with MP2RAGE data. The members of Polimeni’s group also use it as an additional per-processing step before giving the data to Freesurfer.
The SPM bis field correction is part of the segmentation pipeline in SPM. I use the following bash script and the following matlab stript:
Bias_field_script_job.m and start_bias_field.sh.
