Neuroimaging techniques

2021-07-01 01:08 PM

Currently, the generation of multi-detector multi-segment computed tomography machines, it has helped to make significant progress in cranial nerve imaging and spinal cord imaging.

Routine X-ray technique

The routine X-ray technique, also known as conventional, has been a classic for more than 100 years for the evaluation of brain and spinal cord injuries. Indications for X-rays of the skull and spine are now considered as directional images for modern Tomography techniques. Includes techniques:

Capture the entire skull with three basic planes:

Forehead plane: straight posture.

Middle longitudinal plane: inclined posture.

Axial plane: Hirtz pose.

Scan the spine in each area: (neck, back, waist) and hinges at the neck, back, and back.

Direct magnified X-ray of an area: C2

X-ray with dynamic position: Take the spine maximally flexed or maximally inflated, to evaluate vertebral waist injuries.

Supersonic

Ultrasound is not very indicated for the nervous system. However, in some cases, ultrasound with transducers with frequency from 5 to 10 MHz, through the thin bone window or fontanel, allows evaluating the shift of midline structure during the displacement of one hemisphere of the brain. .

With the color Doppler ultrasound technique, it is possible to identify abnormalities of vascular flow, thereby further suggesting the diagnosis of cerebrospinal fluid.

Ultrasound also guides puncture and orientation during surgery for lesions deep in brain tissue, cerebellum.

Computed tomography (CLVT)

Also using X-rays, combined with a device that measures the attenuation of X-rays (Detector) after passing through the body, with computer processing, we can reproduce images by spatial resolution. and proportion. Thus, on computed tomography images instead of only 4 densities as conventional radiographs (contrast bone - soft tissue - fat - gas) provide more than 4000 gray degrees called Hounsfield units, allowing assessment of the nature of the injury.

Currently, the generation of multi-detector multi-segment computed tomography machines has helped to make significant progress in cranial nerve imaging and spinal cord imaging. From trauma, cerebrovascular accidents, cerebral vascular malformations to brain tumors, spinal diseases; Computed tomography has basically solved the major problems of the nervous system. Therefore, computed tomography images are increasingly popular in clinical practice at the grassroots to central levels.

Magnetic Resonance

As a more complex tomography method, while computed tomography mainly cuts in the axial plane, magnetic resonance allows cutting many longitudinal, transverse, and forehead planes; Simultaneously create images with different pulse sequences; before and after contrast injection. Magnetic resonance imaging has analyzed the lesions in soft tissue, the cerebrospinal nerve is very ideal.

Compared with computed tomography, magnetic resonance is more sensitive and specific, so it is increasingly widely used to supplement the diagnosis of computed tomography and other methods.

Myelography and Contrast Spinal Cord Tomography (Myelo scanner)

At present, the indications for injecting iodine contrast material into the subarachnoid space of the spinal canal can be taken into the spinal canal, nerve root sheath, or tomography, which have become less and less since the development of magnetic resonance. Contrast-enhanced spinal angiography can diagnose disc herniation and subarachnoid root sheath pathology. Computed tomography with intravenous contrast injection, combined with intravenous contrast injection, can diagnose diseases in the epidural space, in the spinal cord. However, it still cannot replace magnetic resonance.

Angiography

Inject water-soluble iodinated contrast agent into an artery or vein, following direct or indirect injection through a catheter (sonde). This method evaluates the distribution circuit for normal or pathological nervous system, contributes to the diagnosis of lesions with changes in vascular distribution, in benign or malignant tumors in the skull and spinal cord is the foundation of circuit intervention.

Direct and indirect angiography techniques for diagnosis are now gradually replaced by digital angiography such as computed tomography angiography (CTA), magnetic resonance angiography (MRA). The role of angiography remains only the interventional function.

Scintigraphy 

With radioactive isotopes introduced into the body, thanks to a device to measure radiation, record images, evaluate the distribution of elimination velocity.

The advantage of this technique is functional assessment.

Modern techniques such as PET, SPECT have completely complemented the diagnosis of the nervous system.