Computational protocol: Speed-accuracy strategy regulations in prefrontal tumor patients

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Protocol publication

[…] For all patients, high resolution gadolinium-enhanced T1 and (when available) T2-weighted and/or FLAIR scans were collected to determine tumor location (minimum number of slices: 180, voxel size≤1×1×1 mm3). Only pre-operative scans, used for neuro-navigation by the neurosurgeon, were considered in the reconstruction procedure as, after surgery, lesion locus is usually at least partially replaced by healthy neighboring tissue, possibly creating confusion in the reconstruction of the real lesion boundaries. The 3D region of interest (ROI) reconstructions of lesions were drawn for each patient from MRI slices on the horizontal plane using MRIcroN software (). Reconstructed ROIs included all the areas of altered MRI signal, including edema, which is known to have cognitive effects, as shown both in humans (e.g., ; ) and in animal models (). After ROIs reconstruction, each MRI scan underwent spatial normalization using SPM8 software, in order to match and align images on a common Montreal Neurological Institute (MNI) T1-weighted template. Once the lesion maps were normalized, overlap images were created separately for LPF and RPF patients. Lesion volume was then calculated from each ROI and compared between LPF and RPF patients in order to exclude any potential systematic difference between patient populations. Mean lesion volume (see also ) for the LPF patients was 118.1 cc (sd=73.7), while for RPF was 123.7 cc (sd=58.9). The two groups did not differ in terms of lesion volume [t(23)=−0.21; p=0.835].A Voxel-based Lesion-Symptom Mapping (VLSM) analysis (, ) was also performed to try to better specify cortical areas most critically linked to a lower ‘a’ parameter in patients when switching from speed to accuracy. The VLSM analysis was performed even if only at an exploratory level, since it allows highlighting those voxels that are associated with significantly lower scores in a particular task. VLSM analysis has the advantage to avoid any a-priori grouping of patients and takes into account and compares the performance of all patients at the same time, compared voxel-by-voxel. In this procedure, all patients are classified in two groups according to whether or not the lesion affects a specific voxel. Then, the behavioral performance is compared across groups. Voxel-by-voxel statistical analyses were performed by means of NPM software (, using t-tests with the statistical threshold set at p<0.01 (False Discovery Rate correction applied). […]

Pipeline specifications

Software tools MRIcron, MRIcro
Application Magnetic resonance imaging
Diseases Brain Neoplasms, Neoplasms