Q: What are the causes of low back pain? How to check and confirm the diagnosis? A: Low back pain is one of the common conditions, but low back pain is only as a symptom, it can have many causes. Once low back pain occurs, it is natural for people to want to figure out what is causing it so they can get treatment early. We have found that some patients have found out the cause and received treatment; some have not found the cause; and some have received unrealistic misinterpretation or even mis-treatment. Here we talk about the relationship between low back pain and related medical imaging examinations to avoid blind examinations or misinterpretation and mistreatment. First of all, we divide low back pain into the following types according to whether there is a relationship with medical imaging: 1. There are no abnormal findings or only minor and unimportant abnormal findings in the imaging examination. This type of condition can be seen in simple lumbar muscle strain, rheumatism, sprain, weakness, i.e., lack of kidney qi as talked about in Chinese medicine. These patients are basically unrelated to imaging examinations, and even if MR examinations are done, it is possible to find mild disc herniation (which is an incidental finding and does not necessarily have any relationship with lumbar pain) or no abnormal findings. 2, lumbar spine osteoarthropathy: mostly seen in the elderly, these patients are generally not only lumbar pain, some can also be accompanied by leg pain, but also more lumbar muscle strain. Imaging of lumbar spine osteoarthropathy: X-ray lumbar spine frontal and lateral can only see lumbar spine osteophytes, vertebral body alignment, ligament ossification, etc., other information can not be reflected (for example, whether there is disc herniation, the degree of spinal stenosis?) . CT examination: osteophytes, ligament ossification, and accompanying spinal stenosis can be seen; obvious disc herniation can be seen, while inconspicuous disc herniation or fine evaluation of the degree of herniation and compression of nerve roots is less reliable than MR. MR examination: It is more sensitive and reliable than CT. In particular, it is more accurate in evaluating the cause of spinal stenosis (i.e., disc herniation, or hypertrophy of the ligamentum flavum, destruction or hypertrophy of the small vertebral joints, osteophytes, or a combination of factors that together lead to spinal stenosis, etc.) Recommendation: From the perspective of not receiving radiation as well as addressing the sensitivity and reliability of disease diagnosis, the disease should be directly selected for MR examination. 3, lumbar disc protrusion: divided into bulging, protrusion, prolapse; according to the location of the protrusion is also divided into central or left-sided, right-sided type. Most of these patients have lower extremity pain (except for those with bulging discs, which only belong to disc degeneration) Imaging of lumbar disc herniation: X-ray plain film, which is meaningless because the disc cannot be seen. Before CT and MR techniques were available, the use of radiographs was only an indirect speculation about the possibility of disc herniation. It is no longer used as a method to examine and diagnose herniated discs. CT examination, before MR was widely used, most of the herniated discs relied on CT examination. Currently, MR examination is widely used, and the use of low-grade MR equipment is not much more expensive than CT, but the overall effect is better than CT, and there is no need to receive radiation. If the protruding disc is observed to have no calcification (old disc herniation is mostly accompanied by calcification, which is not possible with ozone therapy) CT must be clarified. MR examination, except for the observation of calcification is not as sensitive as CT, is significantly better than CT in the examination of herniated discs. Note: The use of 3D or 2D reorganization techniques of a large spinal sagittal to obtain what appears to be a beautiful overall image of the vertebral body of the spine to evaluate disc herniation is not advocated. This is because it comes at the cost of receiving a certain amount of radiation, not to mention that it provides only information about the vertebrae mainly. 4, traumatic vertebral fracture, injury: when there is a history of obvious trauma and low back pain, it is necessary to check whether there is a fracture or injury of the spine. The advantages of MR examination are: 1) to detect bone injury, i.e., bone injury without fracture, i.e., microfracture, which only shows bone marrow edema, which is not seen in X-ray plain film or CT. 2) to distinguish whether it is a fresh or old fracture, for which X-ray plain film or CT sometimes has difficulty in identifying. 3. the presence of localized spinal stenosis or spinal cord compression or even spinal cord injury. MR is not as good as CT in evaluating fractures of vertebral attachments such as the vertebral plates, transverse processes, and spinous processes. 5. Spontaneous osteoporotic fractures: also known as failure fractures, which have three causes: senile osteoporosis; metabolic osteoporosis (such as hyperparathyroidism); and pharmacological osteoporosis (long-term hormone use). All can lack a clear history of trauma and present with vertebral fractures and more pronounced back pain. It is advisable to choose MR examination, which can observe the degree of freshness and compression and clarify the presence of concomitant spinal stenosis with injury to the spinal cord end. 6, vertebral endplate inflammation: a special type of degenerative spinal disease, it is accompanied by significant back pain, is a sterile inflammatory lesion, the lesion often occurs at the edge of the vertebral body and adjacent to the lesioned intervertebral disc. Vertebral endplate inflammation is self-limiting, with pain disappearing after a few months and fatty deposits evolving in the lesioned area. The disease can only be detected and diagnosed by MR in both the endplate and fatty deposit stages, and cannot be diagnosed by radiographs or CT. Nuclear bone scan or PET-CT examinations are sometimes indistinguishable from tumors because of the uptake of the lesion area. 7, lumbar spine inflammatory or infectious diseases: various infections of the spine (septic infection, Borrelia burgdorferi infection, tuberculosis infection, etc.) can be seen on X-ray plain film in the severe or late stage of bone destruction; CT can also see paravertebral abscesses or severe intraspinal invasion in addition to looking at the destruction of bone more finely; MR can be detected in the early stage of infection, that is, the bone marrow edema stage before the destruction of vertebrae occurs, and MR is more sensitive than CT to peripheral soft tissue edema, abscesses, and early intradiscal invasion. 8. Ankylosing spondylitis: It is an immune inflammatory lesion that is most likely to invade the sacroiliac joint. In early or active lesions, the pathological change is bone marrow edema on the sacroiliac joint surface, therefore, imaging should be selected for MR (diagnosis needs to be combined with the determination of B-27), and the examination site should focus on bilateral sacroiliac joints. x-ray plain film and CT examination are only applicable to advanced lesions. 9, vertebral malignant tumor: tumors occurring in vertebrae, most commonly metastases, or lymphoma, myeloma, etc., often have severe back pain, X-ray plain film is not sensitive, and CT is not as good as MR examination in terms of localization, quantification or characterization; after MR examination, PET-CT can be chosen as further examination according to whether the situation requires it or not. When there is a suspicion of bone metastases, the method of nuclear bone scan can be used as a screening, and those who are found to be abnormal or suspicious should do MR examination directly (bone scan of nuclear is sensitive to the detection of lesions, but it is not easy to distinguish their nature; cancer foci, inflammatory foci, hemangioma, injury, etc. will all appear similar abnormal uptake foci). 10.Vertebral canal tumor: In addition to back pain, patients usually have corresponding symptoms due to tumor compression of spinal cord and nerves. MR should be the first choice. 11, congenital anomalies of the spine: spina bifida, lumbar sacralization, spinal cord embolism, scoliosis, hemivertebrae or cleft vertebrae, etc. also often cause low back pain, and may aggravate low back pain due to increased degeneration as age increases. In addition to the need to understand the presence of accompanying spinal cord or dural sac deformities, MR examination is generally not required. 12, no direct causal relationship with low back pain abnormal findings: vertebral hemangioma, healthy people are very common, no symptoms, generally do not need treatment, the larger should be prevented from external forces that lead to fracture, some injected “bone cement” treatment. Fatty deposits in the vertebral body are uneven and do not require treatment, but can only be detected by MR examination. 13, other diseases that may cause low back pain: gynecological diseases, urinary tract infection, nephritis, urinary stones, pseudoaneurysm, abdominal aortic coarctation, pancreatic cancer, retroperitoneal tumor, etc. …… In addition to low back pain and discomfort, most of them also have other corresponding symptoms and manifestations. Each of them needs to be diagnosed in combination with appropriate imaging examinations. The above mentioned diseases that can cause low back pain are only a general summary based on clinical practice in terms of correlation with imaging examinations, the specific clinical manifestations should be based on seeing a doctor, do not put yourself in the right place, because, the symptoms and signs identified by the doctor and the patient’s personal understanding are different.