Sacral cyst is a kind of dural cyst located in the sacral canal, which is filled with watery and clear cerebrospinal fluid, as the sacral cyst communicates with the subarachnoid space through a valve-like neck of the cyst. The cyst gradually expands and then compresses the nerve roots in the sacral canal, causing lumbosacral pain, tingling in the perineum of the buttocks, radiating pain in the lower limbs and intermittent claudication; in severe cases, sexual dysfunction and incontinence even occur. According to the relationship between sacral cysts and nerve roots, they can be divided into two types: (1) if the cyst is a simple hydatid cyst with no nerve roots inside, this type is called Nabors IB type sacral cyst and the surgical treatment is simple (simple ligation is sufficient) and the surgical risk is minimal; (2) if the cyst contains nerve root fibers (Nabors II type), the symptoms will be more severe and persistent. Since the sacral nerve roots cannot be damaged, surgical treatment cannot be done by ligation, and endoscopic cyst neck sealing surgery is required. Since the interrelationship between the nerve root and the cyst directly determines the treatment strategy, surgical efficacy and surgical risk, it is very important to clarify the interrelationship between the nerve root and the cyst through preoperative imaging. Because the sacral nerve roots are relatively slender and have low signal contrast with surrounding structures, it is difficult to show the sacral nerve roots with conventional magnetic resonance imaging techniques. Recently, the lumbar spinal sacral canal group of neurosurgery and the radiology department have worked together to establish a nerve root imaging technique for sacral cysts by absorbing and introducing the latest foreign technology (DTI + fiber imaging), which can clearly show the whole picture of nerve roots in the lower lumbar segment and sacral canal, and at the same time, combined with the three-dimensional reconstruction and superposition technology of cysts, help neurosurgeons to preoperatively judge the relationship between sacral cysts and nerve roots. It can also help the neurosurgeon to determine the relationship between the sacral cyst and the nerve root before surgery, thus further improving the safety of surgery.