X-rays are a form of electromagnetic radiation. They were first discovered by a German scientist Roentgen in 1895. They are, therefore, also referred to as “Roentgen rays”. They have a very wide range of use in medicine. The principle is established on acquiring an image based on tissue penetration characteristics of a certain particle, called photon.
Softer tissues allow higher penetration of the rays. Therefore, bones and metals appear white and almost white on roentgen films, while soft tissues are visualized in various tones of gray. Today, roentgenograms are used especially for traumas in the neurosurgery discipline.
They are useful to detect fracture, collapse, dislocation and similar conditions in head and spine traumas. However, computerized tomography or MRI is required for many patients, as this modality does not offer sufficient details about the soft tissue.
A catheter is inserted into a blood vessel in the groin and advanced to the carotid artery in the neck; next, a contrast agent is instilled in order to image the cerebral blood vessels.
Today, DSA is used in neurosurgery and vascular disorders of the brain. The most significant ones are aneurysms and AVMs.
MAGNETIC RESONANCE IMAGING (MRI)
This modality uses high-strength magnets and radio waves to image the tissues.
Magnetic resonance allows acquiring very detailed images by using characteristics of hydrogen atoms residing in the tissue. Since this method does not use X-rays, the problems arising out of X-rays will not be faced. This method can even be used to evaluate an intrauterine fetus if required. The magnets used in this device create a strength that is almost 10,000 times higher than Earth’s magnetic field.
The magnets align the hydrogen atoms inside the tissue in a certain order and in a certain direction and the simultaneously emitted radio waves alter the sequence of atoms to acquire images. Thus, very detailed images of tissues with varying structures are created.
The strength of magnets used in the device is directly proportional to the definition and quality of images. Today, the strength of the available MRI scanners varies from 0.2 Tesla to 3 Tesla. It is expected that MRI scanners with higher strength will be introduced to the clinical practice in close future.
Today, MRI is very commonly used for the diagnosis of all brain and spinal cord diseases in the neurosurgery discipline.
POSITRON EMISSION TOMOGRAPHY (PET)
This imaging modality involves the administration of a radioactive substance. Information is obtained about various diseases depending on the intensity of uptake in tissues relative to the expected uptake intensity of the radioactive substance.
PET-CT is commonly used particularly in neurosurgery. Here, a PET scan is combined with a Computerized Tomography scan to obtain cross-sectional images of the brain and the tumors larger than approximately 5 mm can be shown. The technique is usually used in the diagnosis of metastasis and glial tumor.
COMPUTERIZED TOMOGRAPHY (CT)
It implies the use of X-rays for cross-sectional evaluation of the brain, skull, and spine. In this method, X-rays are emitted in a circular form to the body, and images are acquired and created by computer software to evaluate the interior structure of the body.
Today, it is used especially for traumas in the neurosurgery discipline. CT is scanned to evaluate both structures of bones and whether there is trauma-derived damage in soft tissues (brain, nerves, spinal cord, etc.).