[en] PERFUSION ANALYSIS Analysis of perfusion measures using the cortical and subcortical segmentations from FreeSurfer. This analysis only works for 'Signa HDxt 3.0T GE Healthcare' systems (versions 15x and 16x) and '3D pulsed continuous' ASL sequences. DATA ANALYSIS: This method processes the Arterial Spin Labelling (ASL) data to get perfusion measures in cortical and subcortical brain structures. The cortical and subcortical segmentations are obtained using Freesurfer (surfer.nmr.mgh.harvard.edu). The main analysis includes the following steps: Cerebral Blood Flow (CBF) quantification for pCASL sequences using the ASL difference image and the Proton density image. The CBF map is calculated using the formula described in (1). Partial volume effect (PVE) correction. PVE is a consequence of limited spatial resolution in ASL, where the low signal-to-noise ratio leads to the need to employ larger voxels. The method described in (2) is applied, using a kernel size of 5. Also, for PVE correction the segmentation of grey and white matter is required. This segmentation is performed using the SPM8 software (www.fil.ion.ucl.ac.uk/spm/) over the 3D T1 image. Finally, it is required the co-registration between ASL and structural images (using SPM8). The co-registration is made in the native space of the ASL data, down-sampling the resolution of the structural scan and the tissue probabilities maps The perfusion measures are calculated over the PVE corrected CBF map using the normalized 3D T1 and the subcortical segmentations from Freesurfer. (1) Alsop, D.C., et al (2014). Recommended implementation of arterial spin-labeled perfusion MRI for clinical applications: A consensus of the ISMRM perfusion study group and the European consortium for ASL in dementia. Magnetic resonance in medicine. (2) Asllani, I., et al (2008). Regression algorithm correcting for partial volume effects in arterial spin labeling MRI. Magnetic resonance in medicine; 60(6): 1362-1371. INPUTS: - T1-weighted 3D volume: Structural image needed for PVE correction. - ASL difference image: Control - Labelled image. - T1 Freesurfer: Normalized structural image obtained with Freesurfer. - Cortical Map: Cortical map obtained with Freesurfer. OUTPUTS: - Cerebral Blood Flow Map: CBF map. - MNI Normalized Cerebral Blood Flow Map: CBF map spatially normalized to the MNI standard space. - Perfusion report: Report with the perfusion measures. - Perfusion measures: Perfusion measures in a CSV file. [es] PERFUSION ANALYSIS Analysis of perfusion measures using the cortical and subcortical segmentations from FreeSurfer. This analysis only works for 'Signa HDxt 3.0T GE Healthcare' systems (versions 15x and 16x) and '3D pulsed continuous' ASL sequences. DATA ANALYSIS: This method processes the Arterial Spin Labelling (ASL) data to get perfusion measures in cortical and subcortical brain structures. The cortical and subcortical segmentations are obtained using Freesurfer (surfer.nmr.mgh.harvard.edu). The main analysis includes the following steps: Cerebral Blood Flow (CBF) quantification for pCASL sequences using the ASL difference image and the Proton density image. The CBF map is calculated using the formula described in (1). Partial volume effect (PVE) correction. PVE is a consequence of limited spatial resolution in ASL, where the low signal-to-noise ratio leads to the need to employ larger voxels. The method described in (2) is applied, using a kernel size of 5. Also, for PVE correction the segmentation of grey and white matter is required. This segmentation is performed using the SPM8 software (www.fil.ion.ucl.ac.uk/spm/) over the 3D T1 image. Finally, it is required the co-registration between ASL and structural images (using SPM8). The co-registration is made in the native space of the ASL data, down-sampling the resolution of the structural scan and the tissue probabilities maps The perfusion measures are calculated over the PVE corrected CBF map using the normalized 3D T1 and the subcortical segmentations from Freesurfer. (1) Alsop, D.C., et al (2014). Recommended implementation of arterial spin-labeled perfusion MRI for clinical applications: A consensus of the ISMRM perfusion study group and the European consortium for ASL in dementia. Magnetic resonance in medicine. (2) Asllani, I., et al (2008). Regression algorithm correcting for partial volume effects in arterial spin labeling MRI. Magnetic resonance in medicine; 60(6): 1362-1371. INPUTS: - T1-weighted 3D volume: Structural image needed for PVE correction. - ASL difference image: Control - Labelled image. - Proton Density volume: Needed for CBF quantification. - T1 Freesurfer: Normalized structural image obtained with Freesurfer. - Cortical Map: Cortical map obtained with Freesurfer. OUTPUTS: - Cerebral Blood Flow Map: CBF map. - MNI Normalized Cerebral Blood Flow Map: CBF map spatially normalized to the MNI standard space. - Perfusion report: Report with the perfusion measures. - Perfusion measures: Perfusion measures in a CSV file.