This is a retrospective study based on the images contained in the database of the University Hospital of Amiens. There is no further examination. Electroencephalography (EEG) and Near-Infrared Spectroscopy (NIRS). These sources are widely used to specify the source of certain evoked potentials or to better define the sources of epileptic graphoelements, especially in the pre-surgical assessment of refractory epilepsies.

It is therefore important that these regions are more widely available in the constitution of the world, and that they are suitable for use in the design of new technologies. Although MRI is the gold standard for soft tissue segmentation, it is not suitable for bone extraction; especially in the newborn or the bone is very thin. On the other hand, CTscan is an excellent method for extracting bone. The contrast between bone and soft tissue is excellent. In this case, with the CTscan, the fontanelles are identified as discontinuities between the images of the temporal scales.

Magnetic resonance imaging (MRI) and brain scan (CT Scan) are the two main modalities of structural brain imaging that are widely used in routine practice. The extraction of bone from MRI and CTscan images is an important step in the segmentation of the different tissues of the subjects' heads. It is indeed necessary to know precisely the electrical characteristics (conductivities) and optical (absorption, diffraction) of tissues (skin, bone, LCS, gray matter and white matter), or by electric currents or by photons. One of the major problems is the one that is not very poorly visualized in MRIs in CTscan, the bone is well individualized and that inversely the various brain structures are difficult to extract. This justifies the fact of performing a coregistration of images obtained in MRI and CTscan.

The skull of the newborn is an inhomogeneous structure. The fontanelles are invisible in MRI and identifiable in CTscan.

Electroencephalography (EEG) and Near-Infrared Spectroscopy (NIRS). These sources are widely used to specify the source of certain evoked potentials or to better define the sources of epileptic graphoelements, especially in the pre-surgical assessment of refractory epilepsies.

It is therefore important that these regions are more widely available in the constitution of the world, and that they are suitable for use in the design of new technologies.

Although MRI is the gold standard for soft tissue segmentation, it is not suitable for bone extraction; especially in the newborn or the bone is very thin. On the other hand, CTscan is an excellent method for extracting bone. The contrast between bone and soft tissue is excellent. In this case, with the CTscan, the fontanelles are identified as discontinuities between the images of the temporal scales.

Inclusion Criteria:

• children aged between 0 and 2 months new born at term
• with no structural abnormalities

Exclusion Criteria:

• infants > 2 months

Population 150 CTscan and MRI images of children aged between 0 and 2 months with no structural abnormalities when interpreted by the radiologist.

An age group of 50 images of children at term, 50 images of children at one month, 50 images of children at two months for each category (MRI and CTscan) Since these images will be averaged by age group, it is not necessary to obtain the two images for each child.