spinal cord mri t1 longitudinal view radiograph
This is a magnetic resonance image (MRI) of the vertebral column and spinal cord, viewed in a midsagittal plane. This is called a TI-weighted image, in which the cerebrospinal fluid (CSF) is dark. (The various radiological techniques used to image the nervous system are discussed below.) This image is from an adult, in which no pathology was found in the spinal cord radiological examination.
Because of the length of the spinal cord, it is being shown in two parts — upper and lower. The vertebral bodies, the intervertebral discs and the spinous processes posteriorly have been labeled, as well as the ligamentum flavum (discussed with the previous illustration). The vertebral bodies have been numbered at various levels — C2, T1, L1, and S1.
The UPPER portion shows the spinal cord to be a continuation of the medulla of the brainstem, at the lowermost border of the skull, the foramen magnum. The pons, medulla, and cerebellum are seen above foramen magnum occupying the posterior cranial fossa.
The spinal cord tissue is located in the middle of the vertebral column, surrounded by the meninges (which can dimly be visualized), with the dura-arachnoid separating the subarachnoid space containing CSF from the space outside the meninges, the epidural space, between the meninges and vertebra (see Figure 1). The epidural space in the lower thoracic region and in the lumbar and sacral regions often contains fat (epidural fat), which is seen as bright on this image.
The LOWER portion of the spinal cord shows the spinal cord itself, tapering as the conus medullaris and terminating around the level of vertebra L1-L2. Below that level is the enlarged subarachnoid space — called a cistern, the lumbar cistern — within which are the nerve roots, dorsal and ventral, for the lower extremity (shown in the previous illustration).
Additional Detail
The sphenoid air sinus of the skull has been identified, as well as the air-containing (dark) nasal portion of the pharynx (the nasopharynx). The aorta (dark) is also labeled.
Radiological Imaging
Ordinary x-rays show the skull and its bony structures but not the brain. A remarkable revolution occurred in clinical neurology and our understanding of the brain when imaging techniques were developed that allowed for visualization of the brain. This now includes:
• Computed tomography (CT) (often pronounced as a "CAT" scan, meaning computer assisted tomography see Figure 28A). This is done using x-rays, and there is a computer reconstruction of the brain after a series of views are taken from a large number of perspectives. In this view the bones of the skull are bright and the CSF is dark, with the brain tissue "gray" but not clear. This image can be obtained in several seconds, even with a very sick patient.
• Magnetic resonance imaging (MRI) does not use x-rays; the image is created by capturing the energy of the hydrogen ions of water. An extremely strong magnet is used for MRI, and capturing the images requires more time. Again, there is a computer reconstruction of the images. The brain itself looks "anatomic." This view can be weighted during the acquisition of the image so as to produce a TI image, in which the CSF is dark (this illustration), or a T2 image, in which the CSF is bright (see Figure 28B). With MRI, the bones of the skull are dark, while fatty tissue (including the bone marrow) is bright. Other settings are now available to visualize the brain, such as FLAIR.
As imaging and technology improve, we are able to visualize the brain during functional activity — functional MRIs are becoming more widely available; this allows us to "see" which areas of the brain are particularly active during a certain task, based upon the increased blood supply to that area during the active period.
Other techniques are also used to visualize the living brain and its activity, such as positron emission tomography (PET scan); this technique utilizes a very short-acting radioactive compound, which is injected into the venous system. Its use is usually restricted to specialized neurological centers involved in research on the human brain.
Sphenoid sinus Nasopharynx
Subarachnoid space (CSF)
Sphenoid sinus Nasopharynx
Subarachnoid space (CSF)
Cerebellum
Skull Medulla
Cisterna magna
Spinal cord
Subcutaneous fat
Spinous processes
Ligamentum flavum
Cerebellum
Skull Medulla
Cisterna magna
Spinal cord
Subcutaneous fat
Spinous processes
Ligamentum flavum
Vertebral bodies
Aorta
Intervertebral disc
Conus medullaris
Epidural fat
Lumbar cistern
FIGURE 3: Spinal Cord 5 — MRI: Longitudinal View (radiograph)
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