# 8.5.8. Region Extraction using a t-statistical map (3D)ΒΆ

This example shows how to extract regions or separate the regions from a statistical map.

We use localizer t-statistic maps from `nilearn.datasets.fetch_neurovault_auditory_computation_task` as an input image.

The idea is to threshold an image to get foreground objects using a function `nilearn.image.threshold_img` and extract objects using a function `nilearn.regions.connected_regions`.

```from nilearn import datasets

tmap_filename = localizer.images[0]
```

Threshold the t-statistic image by importing threshold function

```from nilearn.image import threshold_img

# Two types of strategies can be used from this threshold function
# Type 1: strategy used will be based on scoreatpercentile
threshold_percentile_img = threshold_img(tmap_filename, threshold='97%')

# Type 2: threshold strategy used will be based on image intensity
# Here, threshold value should be within the limits i.e. less than max value.
threshold_value_img = threshold_img(tmap_filename, threshold=3.0)
```

Visualization Showing thresholding results by importing plotting modules and its utilities

```from nilearn import plotting

# Showing percentile threshold image
plotting.plot_stat_map(threshold_percentile_img, display_mode='z', cut_coords=5,
title='Threshold image with string percentile', colorbar=False)

# Showing intensity threshold image
plotting.plot_stat_map(threshold_value_img, display_mode='z', cut_coords=5,
title='Threshold image with intensity value', colorbar=False)
```

Extracting the regions by importing connected regions function

```from nilearn.regions import connected_regions

regions_percentile_img, index = connected_regions(threshold_percentile_img,
min_region_size=1500)

regions_value_img, index = connected_regions(threshold_value_img,
min_region_size=1500)
```

Visualizing region extraction results

```title = ("ROIs using percentile thresholding. "
"\n Each ROI in same color is an extracted region")
plotting.plot_prob_atlas(regions_percentile_img, bg_img=tmap_filename,
view_type='contours', display_mode='z',
cut_coords=5, title=title)
title = ("ROIs using image intensity thresholding. "
"\n Each ROI in same color is an extracted region")
plotting.plot_prob_atlas(regions_value_img, bg_img=tmap_filename,
view_type='contours', display_mode='z',
cut_coords=5, title=title)
plotting.show()
```

Total running time of the script: ( 0 minutes 2.937 seconds)

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