What is a fault examination?

Tomography can show the overlapping structure of plain films layer by layer. In order to make the image of the developing layer clear, the shadows of the upper and lower parts of the developing layer should be blurred to improve the imaging ability of the developing layer.

Spinal tomography is mainly used in the following aspects: (1) showing the bone condition of overlapping parts; Display the ossification range and shape of the posterior longitudinal ligament and the degree of hyperosteogeny at the posterior edge of vertebral body; Understand the sagittal diameter of central spinal canal and lateral recess; Conducive to the discovery of minor lesions.

For patients with sciatica, lateral recess stenosis is a very important factor, but lumbar plain film can not show this structure. Tomography provides us with a better perspective and directly measures the sagittal diameter of the lateral recess. Measured from the upper edge of pedicle, its anterior edge is the posterior edge of vertebral body, and the posterior edge is the anterior edge of superior articular process. If the measurement result is less than 5mm, it means that there is lateral recess stenosis.

At present, CT has been widely used in the examination and diagnosis of various parts of the body in large and medium-sized cities. Because of its high resolution, it can scan images in cross-section, sagittal plane and coronal plane, so CT examination of spine can accurately observe the shape and size of spinal canal, the relative position of articular process and soft tissues such as ligamentum flavum and nerve root, which has a good auxiliary effect on intraspinal diseases. It is suitable for the diagnosis of spinal stenosis, disc herniation, space occupying lesions in spinal canal, primary spinal tumor or metastatic cancer, congenital spinal dysplasia and other diseases caused by various reasons.

However, because CT equipment is expensive, it cannot be popularized in some small and medium-sized cities. And due to technical reasons, CT examination is still not the first choice for spinal examination, and its limitations are:

The scanning range is limited, and it is difficult to diagnose multi-segmental lesions: it is difficult to diagnose lumbar disc herniation if there is too little fat in epidural space; It is difficult to judge the thickness of intervertebral disc and the size of intervertebral foramen in cross section.