In my daily work, many patients around me with lumbar disc herniation have this question. Why do patients need so many different kinds of imaging tests during diagnosis and treatment, including the most common ones: X-rays, CT, MRI (magnetic resonance imaging). The most common thought they have is: MRI is too expensive, so can we just take X-rays or CT? Or if they hear that MRI is the best, then they don’t need to take any other MRI, right?
For these questions, I would like to first tell you what role different imaging tests have in the diagnosis and treatment of lumbar disc herniation, and their differences.
I. Lumbar spine X-ray.
Plain X-ray examination, as a traditional means of imaging diagnosis, is the imaging examination with the highest public acceptance at this stage. In the diagnosis of lumbar disc herniation, plain radiographs of the lumbar spine are indispensable, and the most common X-ray examination is the front and side, hyperextension and hyperflexion position of the lumbar spine. It can play an auxiliary reference role in the diagnosis of the disease. Direct signs of lumbar disc herniation are seldom seen on lumbar spine X-rays, which mostly show negative results, but most of them can show a series of non-specific signs.
Lumbar spine frontal and lateral views.
Features.
①Lateral lumbar spine films can see the lesion-induced physiological curvature of the lumbar spine become smaller or disappear; changes in the degree of anterior and posterior width of the intervertebral space and generalized narrowing of the intervertebral space can be seen, which can be symmetrical or asymmetrical; lip-like hypertrophy and hyperplasia of the posterior edge of the vertebral body, osteophytes of the small vertebral joints, calcification of the intervertebral disc, Schmorl
The presence of Schmorl’s nodules; structural abnormalities of the lumbar spine (e.g., collapse of the vertebral arch, spondylolisthesis, etc.) can also be seen in the hyperextension and hyperflexion films;
(ii) Inflammation of the lumbar spine, lumbar tuberculosis, primary or secondary tumors of the lumbar spine, and ankylosing spondylitis can be excluded;
③ On the lumbar spine plain film, lumbar scoliosis can be found, which is a protective postural reflex that can relieve the compression of the nerve roots by the protruding discs.
Disadvantages: Lumbar spine plain films are not diagnostic of whether there is a herniated disc, the degree of the herniated disc, and the degree of nerve root spinal cord compression, all of which need to rely on other methods to confirm the diagnosis.
Narrowing of the lumbar spinal space.
Schmorl nodules.
II. CT
CT (Computed Tomography), i.e., electronic computed tomography, is a cross-sectional scan using precisely collimated X-ray beams, γ-rays, ultrasound, etc., together with a highly sensitive detector around a part of the body one after another.CT has many advantages as a common diagnostic method for lumbar disc herniation in clinical practice.
Features.
①Short scanning time, no obvious contraindications to examination, higher density resolution, etc.;
②It can clearly show the specific situation of the patient’s lumbar disc, including the site and degree of disc herniation, in addition to visualizing the patient’s nerve root compression; it can more clearly show the bony and soft tissue structures of each vertebral axis, such as changes in the articular eminence and lateral fossa;
③Higher sensitivity to signs such as lumbar disc pneumatization, calcification of lumbar discs and ligaments.
Disadvantages.
①There is a certain amount of radiation damage;
② Disadvantage in dynamic scanning.
Normal lumbar spine CT performance.
CT of herniated disc.
Third, MRI (magnetic resonance imaging)
Magnetic resonance imaging is a kind of tomographic imaging, which uses the magnetic resonance phenomenon to obtain electromagnetic signals from the human body and reconstruct information about the human body. MRI is performed by applying a specific frequency of radiofrequency pulse to the human body in a static magnetic field, so that the hydrogen protons in the human body are excited and the magnetic resonance phenomenon occurs. After stopping the pulse, the protons produce MR signals during the relaxation process. The MR signal is generated through the processing of MR signal reception, spatial encoding and image reconstruction.MRI has an irreplaceable role in the diagnosis of lumbar disc herniation.
Features.
①Non-invasive, no radiation damage ;
②The anatomy of the spine and spinal cord is clearly displayed, especially for soft tissues with high resolution, and its sagittal imaging is one-time imaging, which helps to accurately and comprehensively observe the morphology, location and degree of protrusion of the herniated nucleus pulposus, and has a unique level of examination of the free intervertebral disc, and is also very valuable for the detection of Schmorl nodules;
③ To a certain extent, it can reflect the pathological changes of the interstitial disc and be used for the early detection of degeneration.
Disadvantages.
①The examination time is longer and the examination cost is higher;
②The examination cannot be performed if there are magnetic metal objects in the body;
(③) The observation of disc and ligament calcification, joint osteophytes and other changes in the transverse axis position is not as clear as CT.
MRI of herniated discs.
There are many diagnostic methods for lumbar disc herniation, and each of the three types of imaging examinations – X-ray, CT and MRI – plays a role in the diagnosis of lumbar disc herniation. X-ray plain films are easy to perform, inexpensive and provide direct or indirect signs for the diagnosis of the disease; CT and MRI have a diagnostic accuracy rate of over 90%. “MRI is gradually gaining popularity in the application of lumbar disc herniation diagnosis. When medical conditions allow, combining the above imaging examinations can provide a comprehensive guarantee for the diagnosis and treatment of specific conditions.