Evaluation of Cartilaginous Endplate Degeneration Based on Magnetic Resonance Imaging.

In order to carry out the evaluation of cartilaginous endplate degeneration based on magnetic resonance imaging (MRI), this paper retrospectively analyzed the MRI data from 120 cases of patients who were diagnosed as lumbar intervertebral disc degeneration and underwent MRI examinations in the designated hospital of this study from June 2018 to June 2020. All cases underwent conventional sagittal and transverse T1WI and T2WI scans, and some cases were added with sagittal fat-suppression T2WI scans; then, the number of degenerative cartilaginous endplates and its ratio to degenerative lumbar intervertebral discs were counted and calculated, and the T1WI and T2WI signal characteristics of each degenerative cartilage endplate and its correlation with cartilaginous endplate degeneration were summarized, compared, and analyzed to evaluate the cartilaginous endplate degeneration by those magnetic resonance information. The study results show that there were 33 cases of cartilaginous endplate degeneration, accounting for 27.50% of all those 120 patients with lumbar intervertebral disc degeneration (54 degenerative endplates in total), including 9 cases with low T1WI and high T2WI signals, 5 cases with high T1WI and low T2WI signals, 12 cases with high and low mixed T1WI and high or mixed T2WI signals, and 4 cases with both low T1WI and T2WI signals. Therefore, MRI scanning can clearly present the abnormal signals of lumbar intervertebral disc and cartilaginous endplate degeneration, accurately identity their lesion locations, and type their degenerative characteristics, which may be best inspection method for the evaluation of cartilaginous endplate degeneration in the early diagnosis of intervertebral disc degeneration. The study results of this paper provide a reference for further researches on the evaluation of cartilaginous endplate degeneration based on magnetic resonance imaging.

1. Introduction

Cartilaginous endplate of lumbar intervertebral disc is the cartilages that cover the edge of lumbar intervertebral disc, which serves as the junction between intervertebral disc and bony vertebra and forms intervertebral disc structure together with nucleus pulposus and fibrous annulus. Previous studies have suggested that cartilaginous endplate is the main nutritional pathway of intervertebral disc with its shape and thickness all affecting the intervertebral disc' nutrient supply; therefore, cartilaginous endplate degeneration accelerates the degeneration of intervertebral disc, which may be caused by many factors such as age, local inflammation, chondrocyte apoptosis, cartilaginous matrix degeneration, and other biomechanical and physicochemical factors [1]. The cartilaginous endplate is a multicomponent tissue system that plays the role of preventing nucleus pulposus from entering vertebral body, controlling the nutrient penetration of intervertebral disc and undertaking buffer load, being not only responsible for spine's movement and bearing function together with intervertebral disc but also for maintaining the normal shape and physiological function of the intervertebral disc and being closely related to the degeneration of intervertebral disc [2]. The blood vessels of the vertebral endplate decrease with age, and the ossification and local calcification of the cartilaginous endplate layer due to damage and other factors can obviously hinder the permeability of vertebral endplate, which will cause the reduction of fluid exchange and lead to insufficient nutrient supply and possible intervertebral disc dehydration [3]. The cartilaginous endplate degeneration often leads to accelerated cell death, decreased proteoglycan synthesis, decreased blood supply under the endplate, obstructed nutritional pathway of nucleus pulposus, excessive endplate calcification, and altered endplate collagen structure, ultimately affecting the structure and function of intervertebral disc [4].

Magnetic resonance imaging (MRI) is a tomographic imaging technique; the signal display of cartilaginous endplate, nucleus pulposus, and annulus fibrosus on MRI is significantly different due to different components of intervertebral disc, therefore, compared with the limited capabilities of traditional CT and X-rays, MRI has high tissue resolution and multiparameter and multislice imaging and has become the preferred diagnostic technique for degenerative disc changes [5]. The cartilaginous endplate can undergo a series of degenerative changes with age, and these changes can cause its permeability to decrease and its nucleus pulposus water to decreases, which leads to the occurrence of degeneration [6]. The cartilage endplate also can undergo corresponding histological changes, including endplate cells' varying degrees of degeneration and reduction, endplate' thinning and even interruption or disappearance. The degenerated intervertebral disc can cause significant proliferation of the cartilage endplate and its adjacent vertebral blood vessels, so that it can be shown as thinning, blurring, and presenting or band-like abnormal signals of the cartilage endplate on MRI images [7]. MRI T2WI is more sensitive to water volume change and has great significance and potential clinical value for detecting the water volume information of intervertebral disc; the intervertebral disc degeneration is manifested as signal weakening in MRI T2WI, so MRI can reduce the shape and signal intensity of the nucleus pulposus to judge the degree of intervertebral disc degeneration [8].

In order to carry out the evaluation of cartilaginous endplate degeneration based on MRI, this paper retrospectively analyzed the MRI data from 120 cases of patients who were diagnosed as lumbar intervertebral disc degeneration and underwent MRI examinations. All cases underwent conventional sagittal and transverse T1WI and T2WI scans, and some cases were added with sagittal fat-suppression T2WI scans; then the number of degenerative cartilaginous endplates and its ratio to degenerative lumbar intervertebral discs were counted and calculated, and the T1WI and T2WI signal characteristics of each degenerative cartilage endplate and its correlation with cartilaginous endplate degeneration were summarized, compared, and analyzed to evaluate the cartilaginous endplate degeneration by those magnetic resonance information. The detailed chapters of this paper are arranged as follows: Section 2 introduces the materials and methods; Section 3 counts and calculates the number of degenerative cartilaginous endplates and its ratio to degenerative lumbar intervertebral discs; Section 4 summarizes, compares, and analyzes the correlation between cartilaginous endplate degenerations and their magnetic resonance signals and then use the MRI information to assess the degree of cartilaginous endplate degeneration; Section 5 discusses the impact of cartilaginous endplate degeneration on intervertebral disc degeneration and its clinical significance; and Section 6 is the conclusion.

2. Materials and Methods

2.1. General Information

This study selected a total of 120 cases of MRI data from the patients who were diagnosed as lumbar intervertebral disc degeneration and underwent MRI examinations in the designated hospital of this study from June 2018 to June 2020. Those cases of patients include 56 males and 64 females; their ages range from 36 to 77 years old with an average age of 51.34 years old. The patient's clinical manifestations include intermittent lumbar pain, dull or radiating pain in the lower limbs, numbness, and limited mobility.

Inclusion criteria: (1) patients with body mass index <27 kg/m2; (2) patients who have been approved by the ethics committee of this hospital and signed an informed consent form after this study.

Exclusion criteria: (1) patients with scoliosis, acute or chronic trauma; (2) patients with benign and malignant tumors of the vertebral body, blood system diseases, and other systemic diseases; (3) patients with diabetes or a history of surgery or radiotherapy.

2.2. Examination Parameters

All cases underwent conventional sagittal and transverse T1WI and T2WI scans, and some cases were added with sagittal fat-suppression T2WI scans The scanning parameters are as follows: T1WI: spin echo sequence, 525 ms TR, 22 ms TE, 5 excitation times, 7 echo chain length, 4.0 mm layer thickness, 8.0 mm layer distance, 32 cm × 32 cm field of view, 256 × 256 scanning matrix; T2WI: fast recovery fast spin echo sequence, 3000 ms TR, 100 ms TE, 5 excitation times, 11 echo chain length; fat-suppression T2WI: short-term reaction sequence, 2400 ms TR, 49.5 ms TE, 75 ms TI, 4 excitation times, 7 echo chain length, 4.0 mm layer thickness, 8.0 mm layer interval, 32 cm × 32 cm field of view, 256 × 256 scanning matrix.

2.3. Image Analysis

The image analysis steps are as follows: (1) assess the display of cartilaginous endplate degeneration by conventional MRI sequence images of each segment; (2) group the subjects and divide them into cartilaginous endplate degeneration injury group and cartilaginous endplate degeneration non-injury group based on whether the high signal continuity of cartilaginous endplate degeneration was interrupted as an indicator; (3) assess the type of vertebral body change, which is divided into types I, II, and III as normal and types I, II, and III are classified as positive; (4) assess the grade of intervertebral disc degeneration, which is divided into 1 to 5. It is supposed that a time series has signal characteristics, and the vector sequence is obtained by image analysis set {x1, x2,…, x}, then the calculation dimension f(x) can be obtained by the following formula: where a is a constant and b (x) is associated integral; when the probability density distribution function of i-th cell divided by scale projection method is specified as e (x), it depends on interval i and scale x:where t(x) is the signal strength obtained from the projection of i-th scale as the interval of x and t(x) is the sum of the signal duration measured at the scale.

2.4. Identification Diagnosis

Cartilaginous endplate degeneration often occurs on the basis of intervertebral disc degeneration, and completely degenerated intervertebral discs have low signal on T1WI and T2WI. The abnormal signal area of the endplate and adjacent vertebral bodies is clearly separated from the normal vertebral body, and there is no vertebral body. Bone destruction and the lesions of intervertebral disc infection are mostly from vertebral body or intervertebral disc surgery; the intervertebral disc shows high signal on T2WI, accompanied by cortex and vertebral endplate erosion or destruction and epidural inflammation. Spinal tuberculosis manifests intervertebral disc destruction narrowing of intervertebral space and bone destruction of adjacent vertebrae, often accompanied by the formation of cold vertebral abscesses. The clinical manifestations are rapid onset, often severe pain, fever, extensive bone marrow invasion, intervertebral discs, and vertebrae, and the body boundary is unclear, which is usually not difficult to distinguish. The evaluation framework of cartilaginous endplate degeneration in intervertebral disc based on MRI is shown in Figure 1.

Figure 1

Evaluation framework of cartilaginous endplate degeneration in intervertebral disc based on MRI.

2.5. Statistical Methods

SPSS 19.0 software is used for statistical analysis of experimental results; χ2 test is applied for categorical data comparison, and measurement data are expressed as . Measurement data are normally distributed between the two groups and means are compared by independent sample t test, and the two groups of indicators were compared by paired t test, α = 0.05 was the test level; the difference between the parameters was compared by analysis of variance; the difference was statistically significant with P < 0.05.

3. Result Analysis

3.1. Analytical Results of Cartilaginous Endplate Degeneration

Among 120 patients with lumbar intervertebral disc degeneration, there were 33 cases of cartilaginous endplate degeneration, accounting for 27.50% (54 degenerative endplates in total), of which 22 cases were accompanied by single or multiple disc herniation or herniation, and 11 cases only saw disc degeneration and dehydration, or mild bulging, and no clear disc herniation. These 33 patients include 9 cases with low T1WI and high T2WI signals, 5 cases with high T1WI and low T2WI signals, 12 cases with high and low mixed T1WI and high or mixed T2WI signals, and 4 cases with both low T1WI and T2WI signals. If the structural integrity of the cartilaginous endplate is impaired or the diffusion is limited, the nutrient transport of the endplate diffusion pathway is blocked, which will cause or aggravate the degeneration of the lumbar intervertebral disc. Previous studies have shown that the apoptotic rate of cartilaginous endplate cells is much higher than that of nucleus pulposus cells, which is speculated that cartilaginous endplate degeneration is earlier than nucleus pulposus, and cartilaginous endplate degeneration will lead to lumbar intervertebral disc degeneration. As already presented in the Section 2.3, the type of vertebral body change is assessed, which is divided into types I, II, and III as normal, and types I, II, and III are classified as positive. Therefore, early intervention for the defective cartilaginous endplate may be a potential basic treatment direction for lumbar intervertebral disc degeneration. The changing types of cartilaginous endplates in different vertebrae are shown in Table 1 and Figure 2.

Table 1

Changing types of cartilaginous endplates in different vertebrae (n (%)).

Changing type	n	L1-2	L2-3	L3-4	L4-5	L5-S1
Normal	n = 43	6 (13.95)	10 (23.26)	7 (16.28)	9 (20.93)	11 (25.58)
Type I	n = 37	10 (27.03)	6 (16.22)	8 (21.62)	6 (16.22)	7 (18.92)
Type II	n = 45	12 (26.67)	9 (20.00)	6 (13.33)	10 (22.22)	8 (17.78)
Type III	n = 35	8 (22.86)	9 (25.71)	5 (14.29)	6 (17.14)	7 (20.00)
χ 2		14.37	15.21	11.77	10.65	12.43
P		＜0.05	＜0.05	＜0.05	＜0.05	＜0.05

Figure 2

Changing types of cartilaginous endplates in different vertebrae. (a) Normal. (b) Type I. (c) Type II. (d) Type III.

The cartilaginous endplate undergoes natural degeneration, damage degeneration, stress, and other factors that have a greater impact on the weight bearing and biochemical metabolism of the cartilaginous endplate. Abnormal high stress often leads to accelerated cartilaginous endplate cell death, chondrocyte degeneration, proteoglycan synthesis, decreased blood supply under endplate, obstructed nutritional pathway of nucleus pulposus, excessive calcification of endplate, and changes in the collagen structure of the endplate, ultimately affecting the structure and function of the intervertebral disc [9]. The secondary disc degeneration aggravates the instability of the vertebral body after the intervertebral disc degeneration; the protective effect of the endplate is weakened or lost, causing bone edema of the adjacent vertebral body, fatty infiltration, fibrosis, and calcification. After diagnosis, patients should rest more appropriately, avoid heavy physical activity, and relieve symptoms after waist physiotherapy, which may be related to the reduction of injury degeneration after rest, and may also be related to the stable development of some cases. Infections usually include vertebral body destruction, intervertebral disc destruction, narrowing of the intervertebral space and clinical symptoms such as redness, heat, and pain; laboratory checks such as erythrocyte sedimentation rate are also helpful for identification.

The characteristic of MRI in endplate cartilaginous degeneration is that the upper and lower edges of the patient's vertebral body will appear blurred in the endplate structure and the endplate and the interior of the vertebrae that are close to it will show horizontal strips. It is patchy, and the signal is abnormal; the boundary between the area with abnormal signal and the area with normal signal is often blurred, and only part of it can be relatively clearly observed. When it develops into intervertebral disc degeneration, the protective ability of the endplate cartilaginous will gradually weaken and disappear, the vertebral body close to it will experience bone edema and be infiltrated by vertebral fat, and fibrosis and calcification will also appear. In the MRI examination of patients with low back pain, attention is often focused on spinal degenerative diseases, which are often ignored in MRI examination. The MRI is the best examination method for this disease, which pays attention to the existence and significance of lumbar cartilaginous endplate degeneration in clinical work and will definitely help the diagnosis and treatment of patients with low back pain [10].

3.2. Analytical Results of Intervertebral Disc Degeneration

Among 120 cases of lumbar intervertebral disc degeneration, there were 41 cases of nodules, accounting for 34.17% (78 endplates in total), of which 11 cases with low T1WI and high T2WI signals around the nodules, 8 cases with high T1WI and low T2WI signals around the nodules, 16 cases with high and low mixed T1WI and high or mixed T2WI signals around the nodules, and 6 cases with both low T1WI and T2WI signals around the nodules. Some studies believe that compared with other diagnostic techniques, MRI diagnosis clearly shows the location of cartilaginous endplate degeneration and abnormal signal in lumbar intervertebral disc degeneration. In current clinical studies, it is believed that the pathology leading to bone degeneration of the endplate cartilaginous is the damage and remodeling of the endplate cartilaginous and the lower bones. The degeneration is also fully displayed, and spinal tuberculosis has obvious destruction of intervertebral discs and vertebral bodies, narrowing of the intervertebral discs, often accompanied by abscesses. MRI can clearly show the signal characteristics of the cartilaginous endplate degeneration in lumbar intervertebral disc degeneration and the image signal-to-noise ratio is high, and there are fewer artifacts; satisfactory results, accurate classification, and early diagnosis can be made, which is conducive to clinical development of a reasonable treatment plan. The degeneration levels of cartilaginous endplates in different vertebra are shown in Table 2 and Figure 3.

Table 2

Degeneration levels of cartilaginous endplates in different vertebrae (n (%)).

Degeneration level	n	L1-2	L2-3	L3-4	L4-5	L5-S1
Level 1	n = 23	5 (21.74)	3 (13.04)	7 (30.43)	5 (21.74)	3 (13.04)
Level 2	n = 36	10 (27.78)	6 (16.67)	7 (19.45)	9 (25.00)	4 (11.11)
Level 3	n = 29	5 (17.24)	7 (24.14)	5 (17.24)	4 (13.79)	8 (27.59)
Level 4	n = 21	4 (19.05)	5 (23.81)	3 (14.28)	5 (23.81)	5 (23.81)
Level 5	n = 11	1 (9.09)	3 (27.27)	1 (9.09)	4 (36.36)	2 (18.18)
χ 2		11.46	15.38	13.11	17.24	15.51
P		＜0.05	＜0.05	＜0.05	＜0.05	＜0.05

Figure 3

Degeneration levels of cartilaginous endplates in different vertebra. (a) Normal. (b) Type I. (c) Type II. (d) Type III.

Under normal circumstances, the instantaneous center of rotation of the lumbar spine is located in the nucleus pulposus of the intervertebral disc, which changes with the flexion and extension of the lumbar spine. If the repeated cumulative fatigue stress reaches or exceeds the stress point of the annulus fibrosus tissue, it will cause the annulus fibrosus to break, nucleus pulposus, and intervertebral disc degeneration. The bone and endplate of the vertebral body will be structurally damaged under the action of greater longitudinal pressure, leading to micro-fractures or other forms of injury, and endplate changes [11]. Under physiological load, in order to maintain the normal positional relationship between the vertebral bodies, the lumbar spine must rely on the complete vertebral arch annulus, intervertebral disc fibrous annulus, peripheral ligament and muscle contraction strength, and normal spine line of force. Metastases are characterized by expansive destruction of the vertebrae, and the bone changes can be round or diffuse, rarely close to the endplate, and can invade the appendages and spinal canal. Among them, the vertebral arch ring and fiber, ring, and surrounding ligaments and muscles are three ways to resist shear stress and the weakening or loss of any one of the tissue mechanisms can lead to lumbar spine instability. MRI is more helpful to determine the degree of intervertebral disc degeneration and cartilaginous endplate degeneration.

In order to observe the relationship between cartilaginous endplate degeneration injury and lumbar degeneration in a targeted manner, this study excluded those with organic diseases other than lumbar degeneration, aiming to eliminate the influence of other lumbar diseases on cartilaginous endplate degeneration. In view of the possibility of false positive or false negative results in MRI sequence imaging due to scanning, equipment artifacts, etc., this study adopts methods of repeating scans or increasing the number of excitations to ensure clear and accurate images. In order to include more information about lumbar degeneration in different age groups, the age span of subjects included in this study is relatively large to study the imaging conditions of MRI sequences in different populations, but there is a gap in the amount of data between each age group. In the future, groups will be grouped by age to reveal the changing trend of age-related cartilaginous endplate degeneration; in addition, the grouping of cartilaginous endplate degeneration damage shown by MRI sequence imaging will be further refined. This study found that the positive rate of cartilaginous endplate damage and the severity of the two degenerative types tended to be more serious as the closer the foot is. The reason is that the stress caused by the spine shape is mainly distributed in a certain segment, which is manifested as severe degeneration of the lumbar vertebral body and a higher positive rate of cartilaginous endplate damage.

4. Evaluation of Cartilaginous Endplate Degeneration Based on MRI

4.1. Correlation between Cartilaginous Endplate Degeneration and MRI Signals

The hydrodynamic characteristics of the intervertebral disc are determined by the high water content of the nucleus pulposus. With the aging and intervertebral disc degeneration, the nucleus pulposus changes from a viscous hydrodynamic state to a dry fibrous material inelastic and its height is gradually lost. The bony endplate is depressed in the center and most of it is covered by the cartilaginous endplate, while the surrounding cortical bone is thicker and becomes the epiphyseal ring, which is covered by the fibrous ring attachment. Structures of degenerative cartilaginous endplate combined with typical MRI findings and other clinical manifestations can directly perform multidirectional imaging such as sagittal, coronal, and horizontal axis and can reflect a variety of tissue parameters, which is helpful to reflect the pathological characteristics of this disease and determine the correct choice of clinical diagnosis and treatment plan. The cartilaginous endplate is composed of hyaline cartilaginous and covers the top of the bony endplate, which is loosely combined with its central part. Because the scan can directly observe the central area of the endplate that shows the deepest depression, so the measurement of the depressed angle of the vertebral endplate is used to reflect the endplate in the vector (Figure 4). These may also be long-term degenerative lumbar spine diseases with one of the causes of low back pain, fixed on the upper and lower vertebral bodies [12].

Figure 4

Structures of degenerative cartilaginous endplate in lumbar intervertebral disc.

The cartilaginous endplate not only plays an important role in the nutrient metabolism of the intervertebral disc but also plays an important role in maintaining the biomechanical conduction of the spine and dispersing the stress load. At the same time, the endplate is also a site that is easily damaged during spinal movement. When the endplate of the vertebral body and subchondral bone are damaged, not only the nutrient pathway is destroyed and the material transportation is blocked but also some enzymes that destroy the intervertebral disc matrix enter the intervertebral disc through the endplate, causing the extracellular matrix is destroyed and the internal pressure of the intervertebral disc is reduced, leading to intervertebral disc degeneration. It has the function of maintaining the normal morphology and structure of the intervertebral disc, controlling the exchange of nutrients and metabolites of the intervertebral disc and undertaking the role of buffering external load, and the intervertebral disc together maintains the normal shape and physiological function of the spine. MRI shows that the cartilaginous endplate is rough, fuzziness, thinning, and abnormal signal and can further involve the subchondral bone marrow to form horizontal band, small flocculent or arc-shaped patchy abnormal signal.

The classification and staging of cartilaginous endplate degeneration are helpful for a detailed clinical understanding of the disease. The degeneration of the lumbar cartilaginous endplate has a typical MRI appearance; combined with the clinical history, the diagnosis is not difficult, but it still needs to be differentiated from spinal tuberculosis and purulent inflammation. The more severe the cartilaginous endplate is damaged, the higher the grade of the lumbar intervertebral disc, that is, the shape of the cartilaginous endplate is closely related to the degree of lumbar intervertebral disc degeneration [13]. As the degree of cartilaginous endplate degeneration intensifies, the lumbar intervertebral disc is in a state of continuous nutrient shortage, which causes the corresponding intervertebral disc cell apoptosis, which intensifies the degree of lumbar intervertebral disc degeneration in patients, and the higher the grade of the intervertebral disc. In addition, the magnetic resonance imaging sequence shows the completeness of the endplate cartilaginous, and the obtained images are clear and easy to judge, which reduces the misjudgment rate of the defect degree. It not only prompts the degeneration of the lumbar cartilaginous endplate but also prompts the associated lumbar spine osteoporosis, bone hyperplasia, herniated disc degeneration, spinal stenosis, vertebral body instability, and other signs of degeneration.

4.2. Evaluation of Cartilaginous Endplate Degeneration Based on MRI Signals

A large number of studies have shown that the intervertebral disc degeneration cartilaginous endplate is the initiating factor of the intervertebral disc degeneration. Therefore, the asymmetric distribution of stress is one of the main causes of cartilaginous endplate degeneration in the lumbar degeneration, which leads to the intervertebral disc degeneration at the stage of lumbar degeneration, and the degenerated intervertebral disc can accelerate the progress of the lumbar degeneration and promote each other. At the same time, the biochemical composition of subchondral bone tissue also undergoes quantitative and qualitative changes, such as stagnation and fibrosis of metabolites. There are different degrees of degenerative changes in the MRI of the patient's herniated and adjacent intervertebral discs, which are mainly manifested as low-intensity intervertebral disc signals in the weighted image, mild disc bulging, decreased intervertebral disc height, and cartilaginous endplate sclerosis (Figure 5). The degeneration of the herniated intervertebral disc significantly increases the stress and internal pressure load of the adjacent intervertebral disc, especially the adjacent segments that have undergone degeneration, which can further accelerate the degeneration process. When the pressure in the adjacent intervertebral disc increases, the stress of the annulus fibrosus and the lamina increases; it can cause joint deformation of the responsible segment to act on the adjacent segment, causing it to degenerate [14].

Figure 5

Sagittal T1WI and sagittal fat-suppression T2WI MRI images of degenerative cartilaginous endplate in a lumbar intervertebral disc based on MRI [15].

The scan images clearly show the location and signal abnormalities of the cartilaginous endplate degeneration in lumbar intervertebral disc degeneration and can be accurately classified. Multiple cartilaginous endplate degeneration has also been fully displayed, which provides important signals for early clinical diagnosis and selection of reasonable diagnosis and treatment plans. While suggesting the degeneration of the lumbar cartilaginous endplate, it also prompts the associated degenerative signs of lumbar spine osteoporosis, bone hyperplasia, herniated disc degeneration, spinal canal stenosis, and vertebral body instability. Previous studies on the intervertebral disc mainly focused on the nucleus pulposus and annulus fibrosus; there are few studies on the cartilaginous endplate. Due to insufficient understanding of its clinical significance, it is often ignored in imaging examinations, which affects the early diagnosis and targeting of clinicians and morphological changes include abnormal signals, thinning, fission, and loss. MRI is the best way to check this disease and can clearly show the signal characteristics of the cartilaginous endplate degeneration in lumbar intervertebral disc degeneration. They are satisfied with the display of the lesion, can be accurately classified, and can make early diagnosis, which is conducive to the clinical development of a reasonable treatment plan and provides beneficial help for the timely diagnosis and treatment of low back pain.

The cartilaginous endplate degeneration in lumbar intervertebral disc degeneration needs to be differentiated from lumbar tuberculosis and other diseases. Lumbar tuberculosis imaging shows intervertebral disc destruction, intervertebral space narrowing, and adjacent vertebral bone destruction, often accompanied by cold abscess [16]. The clinical manifestations of lumbar degeneration are rapid onset, often severe pain, fever, extensive range of vertebral bone marrow invasion, unclear boundaries between intervertebral discs, and vertebral bodies, and obvious uniform or uneven enhancement after enhancement. While these disease signs are mild and MRI shows that there are small patches or arc-shaped patch-like abnormal signals in the adjacent vertebral endplates and the bone under the endplates, which have certain characteristics and can be distinguished from them. Previous studies on intervertebral discs mainly focused on the nucleus pulposus and annulus fibrosus, there are few studies on cartilaginous endplates, and their clinical significance is insufficient. They are often ignored in imaging examinations, which affects clinicians' early diagnosis and treatment for the cause. The study believes that the low-field magnetic resonance machine scan image can clearly show the signal characteristics of the cartilaginous endplate degeneration in the lumbar intervertebral disc degeneration. The image has a high signal-to-noise ratio and fewer artifacts, which is satisfied with the display of the lesion and can accurately distinguish type and is conducive to clinical development of a reasonable treatment plan.

5. Discussions

5.1. Effect of Cartilaginous Endplate Degeneration on Intervertebral Disc Degeneration

As age increases, the blood vessels of the vertebral endplate begin to decrease, and the cartilaginous endplate ossification and local calcification due to inflammation, injury, and other factors can significantly hinder the permeability of the vertebral endplate, resulting in insufficient nutrient supply and possible intervertebral disc dehydration. The mechanism of low back pain caused by degeneration of lumbar intervertebral disc and vertebral cartilaginous endplate is believed to be caused by the increased synthesis of pain-causing factors, such as calcitonin gene-related peptide and activation of the vertebral endplate trauma and aseptic inflammation (Figure 6). More detailed explanations have been supplemented as follows: the degeneration type I affects intervertebral disc and adjacent vertebral bodies shows extensive fusion low signal and the boundary between the intervertebral disc and its vertebral body is obviously uniform or uneven strengthening after strengthening; degeneration type II usually has vertebral body destruction, intervertebral disc destruction, and local swelling, etc., and experiments laboratory tests such as erythrocyte sedimentation rate can also help identify; degeneration type III always shows the signal characteristics of each stage of vertebral cartilaginous endplate degeneration and can reflect its pathological changes. The former is often accompanied by intervertebral disc infection, the boundary between the intervertebral disc and the vertebral endplate is not clear, and the clinical symptoms are more obvious; the latter is often accompanied by narrowing or disappearing of the intervertebral space and abscess formation. Metastases are characterized by expansive destruction of the vertebrae and can invade the appendages and spinal canal.

Figure 6

Three changing types of degenerative cartilaginous endplate in a lumbar intervertebral disc.

The clinical symptoms of lumbar intervertebral disc degeneration combined with vertebral cartilaginous endplate degeneration are often confused with each other. In the past, due to insufficient understanding of it, only attention was paid to intervertebral disc degeneration and the existence of cartilaginous endplate degeneration was ignored. Cartilaginous endplate degeneration can occur frequently, that is, the same patient can have multiple vertebral endplates at the same time, different endplates can be in different stages, and the survival time of cartilaginous endplate degeneration can be as long as several months or even several years; at different times check, the same vertebral endplate can evolve into different periods and types [17]. Diagnosis of cartilaginous endplate degeneration should be distinguished from spinal tuberculosis and other diseases and lumbar degeneration has a rapid clinical onset, high fever, and often severe pain. Spinal tuberculosis shows early intervertebral space narrowing, intervertebral disc destruction, adjacent vertebral bone destruction, and even signs behind the vertebral body compressing the spinal cord. The affected intervertebral disc and adjacent vertebral bodies show extensive fusion low signal, and the boundary between the intervertebral disc and the vertebral body is unclear, which is obviously uniform or uneven strengthening after strengthening and the bone marrow is invaded widely and diffusely. However, the symptoms and signs of this disease are mild. MRI shows that the abnormal signals of horizontal bands, small patches or arc-shaped patches along the vertebral endplate, and its adjacent vertebrae are characteristics which are different from the previous two manifestations and is often not difficult to identify combined with clinical. Figure 7 shows the evaluation accuracy and efficiency of cartilaginous endplate degeneration with different changing types based on MRI.

Figure 7

Evaluation accuracy (a) and efficiency (b) of cartilaginous endplate degeneration with different changing types based on MRI.

Cartilaginous endplate degeneration is manifested on MRI as the structure of the upper or lower edge of the vertebral body is blurred, and the vertebral endplate is adjacent to the vertebral body. There is a horizontal band or patchy abnormal signal, and the abnormal signal area is normal to the vertebral body. The boundaries between the signal areas are blurred, and some of them can be relatively clear. The abnormal area of cartilaginous endplate degeneration signal is more in the vertebral body near the bilateral margins, which seems to be consistent with the anatomical basis of the vertebral endplate being thin and thick around the center. Cartilaginous endplate degeneration can occur frequently, that is, the same patient can have multiple vertebral endplates at the same time, and different vertebral endplate inflammations can be in different periods. Cartilaginous endplate degeneration can last for several months or even years and examination at different times; the same vertebral endplate disease can evolve into different stages and types and vertebral cartilaginous endplate degeneration should be distinguished from intervertebral space infection [18]. Lumbar intervertebral disc degeneration with vertebral cartilaginous endplate degeneration combined with typical MRI findings and other clinical manifestations, the diagnosis is not difficult. The latter usually has vertebral body destruction, intervertebral disc destruction, narrowing of the intervertebral space, clinically often fever, local swelling, etc., and experiments laboratory tests such as erythrocyte sedimentation rate can also help identify. Magnetic resonance is an ideal examination method for this disease, and it can reflect the pathological characteristics of this disease. The timely and accurate diagnosis of this disease is helpful to the correct choice of clinical diagnosis and treatment plan.

5.2. Clinical Significance of Vertebral Endplate Degeneration Evaluation

Cartilaginous endplate degeneration is manifested on MRI as the structure of the upper or lower edge of the vertebral body is blurred and the endplate of the vertebral body is adjacent to the vertebral body. There is a horizontal band or patchy abnormal signal, the abnormal signal area is normal to the vertebral body, the boundaries between signal areas are often blurred, and some are relatively clear. The abnormal area of cartilaginous endplate degeneration signal is more in the vertebral body near the bilateral margins, which seems to be consistent with the anatomical basis of the vertebral endplate being thin and thick around the center [19]. Cartilaginous endplate degeneration can occur frequently, that is, the same patient can have multiple vertebral endplates at the same time, and different vertebral endplate inflammations can be in different periods. When it is destroyed, other substances such as some enzymes that destroy the intervertebral disc matrix enter the intervertebral disc through the endplate, resulting in the destruction of the extracellular matrix. In addition, the fracture of the endplate will reduce the pressure of the intervertebral disc and reduce the height of the motion segment and cause the laxity of the intervertebral disc ligament, and the resistance of the motion segment to bending will be weakened, which can cause secondary cell-mediated disc degeneration, and at the same time, cell-mediated intervertebral disc degeneration can aggravate this instability. MRI is an ideal examination method for the evaluation of cartilaginous endplate degeneration and can reflect the pathological characteristics of the disease; timely and accurate diagnosis of the disease can help the correct choice of clinical diagnosis and treatment. The evaluation accuracy and efficiency of cartilaginous endplate degeneration with different degeneration levels based on MRI are shown in Figure 8.

Figure 8

Evaluation accuracy (a) and efficiency (b) of cartilaginous endplate degeneration with different degeneration levels based on MRI.

In different parts of the vertebral body, the thickness of the endplate is different; the middle position of the lumbar endplate is the weakest, and the endplate near the annulus fibrosus is thicker than the endplate near the nucleus pulposus. In the same intervertebral space, the lower endplate of the upper vertebra is thicker than the upper endplate of the lower vertebra. The cartilaginous endplate is a multicomponent tissue system that prevents the nucleus pulposus from protruding into the vertebral body, controls the nutrient penetration of the intervertebral disc, and accepts the buffer load. It not only shares the activities and bearing functions of the spine with the intervertebral disc but also maintains the normal shape and function of the intervertebral disc. A series of cartilaginous endplate degeneration can lead to decreased permeability and degeneration of the nucleus pulposus due to reduced water content. The MRI can directly perform multidirectional imaging such as sagittal, coronal, and horizontal axis and can reflect a variety of tissue parameters. In clinical practice, some patients have severe low back pain without obvious root symptoms such as radiation pain in the lower limbs, but only show pain and soreness in the buttocks, back of thighs, front of thighs, and other areas. However, after examination, it is found that the herniated disc is not obvious, and MRI shows such as the abovementioned changes in the vertebral body signal in the proximal endplate area, which is very important to determine the exact cause of low back pain and choose the treatment method [20].

As the role of MRI in evaluating the skeletal and muscle system is gradually being recognized, the superiority of MRI evaluation is gradually showing. Compared with traditional X-ray films and CT examinations, MRI has high tissue resolution, can perform multiparameter and multitomography, can accurately reflect the signal characteristics of different tissues, and can clearly show the degeneration of vertebral cartilaginous endplates. The signal characteristics of the period and can reflect its pathological changes. Satisfied with the display of the lesion, it can accurately type, and at the same time, it is significantly better than plain film for degenerative changes such as intervertebral disc herniation, degeneration, spinal stenosis, ligamentum flavum hypertrophy, and lumbar degeneration, providing early diagnosis for the clinic. The cartilaginous endplate degeneration of the lumbar vertebral body is one of the causes of clinical low back pain. In the past, due to insufficient understanding, previous study often only paid attention to the disease of the intervertebral disc and ignored the existence of the cartilaginous endplate degeneration [21]. MRI can clearly show the signal characteristics of each stage of vertebral cartilaginous endplate degeneration and can reflect its pathological changes, which is currently the most sensitive and specific imaging method for diagnosing cartilaginous endplate degeneration. The application of T2WI sequence to the diagnosis of vertebral cartilaginous endplate degeneration is conducive to the differential diagnosis of other diseases and provides timely and reliable basis for the selection of clinical treatment options.

6. Conclusions

This paper retrospectively analyzed the MRI data from 120 cases of patients who were diagnosed as lumbar intervertebral disc degeneration and underwent MRI examinations. The clinical symptoms they cause are often confused with each other, and doctors often focus on the lesions such as herniated disc and ignore the cartilaginous endplate and the clinical significance of degeneration. There are different degrees of degenerative changes in the MRI of the patient's herniated and adjacent intervertebral discs, which are mainly manifested as low-intensity intervertebral disc signals in the weighted image, mild disc bulging, decreased intervertebral disc height, and cartilaginous endplate sclerosis. The degeneration is also fully displayed, and spinal tuberculosis has obvious destruction of intervertebral discs and vertebral bodies and narrowing of the intervertebral discs, often accompanied by abscesses. When it develops into intervertebral disc degeneration, the protective ability of the endplate cartilaginous will gradually weaken and disappear, the vertebral body close to it will experience bone edema and be infiltrated by vertebral fat, and fibrosis, and calcification will also appear. The study results show that MRI scanning can clearly present the abnormal signals of lumbar intervertebral disc and cartilaginous endplate degeneration and accurately identity their lesion locations and type their degenerative characteristics, which may be best inspection method for the evaluation of cartilaginous endplate degeneration in the early diagnosis of intervertebral disc degeneration. The study results of this paper provide a reference for further researches on the evaluation of cartilaginous endplate degeneration based on magnetic resonance imaging.