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GLM for fMRI data analysis Lab Exercise 1 March 19, 2015 Medical - PowerPoint PPT Presentation

AUDIO 1st level Getting Started The Batch Interface GLM for fMRI data analysis Lab Exercise 1 March 19, 2015 Medical Image Processing Lab Medical Image Processing Lab GLM for fMRI data analysis AUDIO 1st level Getting Started The Batch


  1. AUDIO 1st level Getting Started The Batch Interface GLM for fMRI data analysis Lab Exercise 1 March 19, 2015 Medical Image Processing Lab Medical Image Processing Lab GLM for fMRI data analysis

  2. AUDIO 1st level Getting Started The Batch Interface Outline 1 Getting Started 2 AUDIO 1 st level Preprocessing Model Specification, Review and Estimation Inference and Results 3 The Batch Interface 2 / 26

  3. AUDIO 1st level Getting Started The Batch Interface Getting the Software and Data ● get the SPM software package and the two data sets from http://miplab.epfl.ch/teaching/micro-513/download/ or from the the direct links below ● SPM toolkit ● Dataset (single subject) ● For this practical, three files are required: spm8.zip glm data1.zip 3 / 26

  4. AUDIO 1st level Getting Started The Batch Interface fMRI Data Set AUDIO single subject auditory data, 16 blocks, TR=7s, 1 st level analysis, SPM8 manual Chapter 28, available at http://www.fil.ion.ucl.ac.uk/spm/data/auditory/ 4 / 26

  5. AUDIO 1st level Getting Started The Batch Interface Medical Imaging Datatypes DICOM (Digital Imaging and Communications in Medicine) ● file name suffix .dcm ● one file per slice ● meta information stored in every file ● vendor-specific meta-information ● standard for archiving in hospital environment ● incompatible with SPM8 ANALYZE ● file name suffix header/matrix .hdr,.img ● header contains voxel-to-world mapping ● matrix contains the raw data matrix ● compatible with SPM8 NIfTI (Neuroimaging Informatics Technology Initiative) ● file name suffix .nii ● matrix and voxel-to-world mapping in one file ● standard format of SPM8 5 / 26

  6. AUDIO 1st level Getting Started The Batch Interface Start SPM8 ● extract glm spm8.zip into /tmp ● alternatively, start fMRI mode directly after adding path ● verify that there is a folder /tmp/spm8 ● add SPM8 to the Matlab path and start it % s t a r t d i r e c t l y i n fMRI mode spm( ' fMRI ' ) ; % add SPM8 path to Matlab path v a r i a b l e addpath ( genpath ( ' /tmp/spm8 ' ) ) ; % s t a r t SPM8 g r a p h i c a l u s e r i n t e r f a c e spm ● choose fMRI 6 / 26

  7. AUDIO 1st level Getting Started The Batch Interface SPM8 Interface ● access the most used functions ● status messages, progress bar, selections, etc. ● view results, images, etc. Figure : SPM8 “Menu” (top-left), “Interactive” (bottom-left) and “Graphics” (right) window. 7 / 26

  8. AUDIO 1st level Getting Started The Batch Interface File Selection Window ● one click to select/deselect files Ed button allows manual change or entering ● of path Done button confirms selection ● ● keeps history of previously visited paths ● regexp-like filtering ● works also in scripts, e.g. files=spm select; ● current Matlab path is the default path Figure : SPM select dialog. 8 / 26

  9. AUDIO 1st level Getting Started The Batch Interface Inspect the Data AUDIO see SPM8 manual, chapter 28, for detailed tutorial using this data set ● Decompress glm data1.zip into /tmp . ● Verify that there is a folder /tmp/GLMLAB/AUDIO ● Browse the files, there is one folder containing the structural image (i.e. sM00223 ) and one folder for the functional volumes (i.e. fM00223 ). ● start the check registration tool from command line % check the image r e g i s t r a t i o n q u a l i t y s p m c h e c k r e g i s t r a t i o n ● or click Check Reg button ● choose one or more images, e.g. one functional Figure : Functional and structural and the structural images before co-registration. 9 / 26

  10. AUDIO 1st level Getting Started The Batch Interface Preprocessing Headers, Pre-, and Suffixes SPM functions modify the data in different ways ● change affine world-to-voxel mapping stored in header *.hdr ● write new file, often pre- or suffixed Prefixes r* re-sliced and usually also realigned mean* mean image c1* gray matter c2* white matter c3* cerebro-spinal fluid m* bias-field corrected structural image w* warped (non-linearly transformed) image, e.g. into MNI s* spatially smoothed image Suffixes * seg sn.mat non-linear forward transformation from subject to MNI space * seg inv sn.mat non-linear reverse transformation from MNI to subject space 10 / 26

  11. AUDIO 1st level Getting Started The Batch Interface Preprocessing Preprocessing Overview Inputs Preprocessing Step Outputs rfM00223 *. { img,hdr } fM00223 *. { img,hdr } Realign (Estimate & Reslice) meanfM00223 004. { img,hdr } meanfM00223 004. { img,hdr } Coregister (Estimate) sM00223 002.hdr sM00223. { img,hdr } c { 1,2,3 } sM00223 002. { img,hdr } sM00223 002 seg sn.mat sM00223 004. { img,hdr } Segmentation sM00223 002 seg inv sn.mat msM00223 002. { img,hdr } wmsM00223 002. { img,hdr } sM00223 seg sn.mat Normalise (Write) wrfM00223 *. { img,hdr } rfM00223 *. { img,hdr } wrfM00223 *. { img,hdr } Smooth swrfM00223 *. { img,hdr } 11 / 26

  12. AUDIO 1st level Getting Started The Batch Interface Preprocessing Spatial Normalization Realignment ● rigid-body transform (translation and rotation) ● within modality ● within subject Co-registration ● affine transform (translation, rotation and scaling) ● across different modalities ● within same or across subjects Normalize ● non-linear invertible transformation ● usually to reference space, i.e. MNI 12 / 26

  13. AUDIO 1st level Getting Started The Batch Interface Preprocessing 1st Level Analysis Dataset AUDIO /tmp/GLMLAB/AUDIO/ 13 / 26

  14. AUDIO 1st level Getting Started The Batch Interface Preprocessing Realignment of functional volumes Perform realignment of the volumes of the time series to the mean image. ● select Realign (Est & Res) from the Realign pull-down menu ● highlight data, select New Session , then highlight the newly created Session option. ● Select Specify Files and use the SPM file selector to choose all of your functional images fM000*.img . There should be 96 files ● Save the job file as eg. ./jobs/realign.m . ● Press the ▶ button in the batch editor ● headers will be rewritten ● mean image meanfM00223 004.img will be created Figure : Rigid body realignment parameters. 14 / 26

  15. AUDIO 1st level Getting Started The Batch Interface Preprocessing Co-registration Co-register the structural to the mean functional image. ● Select Coregister (Estimate) from the Coregister pulldown menu. ● Highlight Reference Image and then select the mean fMRI scan from realignment meanfM00223 004.img . ● Highlight Source Image and then select the structural image sM00223 002.img . ● Press the Save button (floppy disk symbol) and save the job as coreg.m . ● Then press the ▶ button. ● Verify that alignment is correct. Figure : Image coregistration result. 15 / 26

  16. AUDIO 1st level Getting Started The Batch Interface Preprocessing Segmentation Create tissue probability maps of gray matter (GM), white matter (WM) and cerebro-spinal fluid (CSF), and obtain normalization parameters to warp image into MNI space. ● Press the Segment button. ● Highlight the Data field and then select the subjects registered anatomical image sM00223 002.img . ● Highlight . Cerebro-Spinal Fluid and choose Native Space . ● Save the job file as segment.m , and then press ▶ button. ● Open the tissue probability maps c1sM00223 002.img (GM), c2sM00223 002.img (WM), c3sM00223 002.img (CSF), and msM00223 002.img (bias-field corrected T1). Figure : Segmentation result. 16 / 26

  17. AUDIO 1st level Getting Started The Batch Interface Preprocessing Normalized Normalize volumes of time series into MNI space and re-slice to 3mm isotropic voxel size. ● Select Normalise (Write) from the Normalise pull-down menu. ● Highlight Data , select New Subject . ● Highlight Parameter File and select the sM00223 0020 seg sn.mat . ● Highlight images to write and select all of the realigned functional images rfM000*.img and the structural image sM00223 0020.nii . ● Open Writing Options , and change Voxel sizes from [2 2 2] to [3 3 3]. ● Save the job as normalise.m and then press the ▶ button. Figure : wmsM00223 0020.img (top) and single subject T1 template /spm8/canonical/single subj T1.nii 17 / 26

  18. AUDIO 1st level Getting Started The Batch Interface Preprocessing Smoothing Apply spatial smoothing with isotropic Gaussian filter with 6mm FWHM. ● Press Smooth button. ● Select Images to Smooth and then select the spatially normalised files created in the last section i.e. ^wrf.* ● Highlight FWHM and change [8 8 8] to [6 6 6]. This will smooth the data by 6mm in each direction. ● Save the job as smooth.m and press the ▶ button. Figure : wrfM00223 004.img (top) and swrfM00223 004.img (bottom) 18 / 26

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