MRI detects and shows prostate cancer mainly by T2-weighted images, which mainly show a low-signal defect area within the peripheral zone, which is distinctly different from the normal high-signal peripheral zone and helps in the diagnosis. When the tumor is confined to the prostate, the outer edge of the prostate is intact and clearly delineated from the surrounding venous plexus. The envelope of the prostate is linear and low signal on T2-weighted images. When the side of the lesion shows a blurred or interrupted, discontinuous envelope, it is indicative of envelope invasion. The periprostatic venous plexus is located at the periphery of the envelope and is a thin structure, which is more obvious at 4-5 and 7-8 o’clock. Tumor invasion of the periprostatic fat is manifested by the appearance of a low signal area within the high signal fat, especially on the lateral side of the prostate, in the area called the prostatic rectal angle, and the loss of this structure is a typical sign of periprostatic fat invasion. If the seminal vesicles are normal and basically symmetrical bilaterally, but show reduced signal in both seminal vesicles or part of the seminal vesicles are replaced by low signal, they may have been invaded by tumor. MRI staging: MRI is very helpful for prostate cancer staging, especially for the differentiation of T2 and T3 stages: (1) MRI can directly observe whether the prostate cancer penetrates the envelope, MRI indications of prostate cancer invasion of the envelope; (1) irregular expansion of the outer edge of the prostate on the side of the lesion, the edges are not smooth; (2) tumor protrudes posteriorly and laterally or becomes angular signs, bilateral neurovascular plexus is asymmetric; (3) shows that the tumor (2) signs of tumor protrusion or angulation to the posterior side and asymmetry of bilateral neurovascular plexus; (3) signs of tumor directly penetrating the envelope and entering the surrounding high-signal fat, and disappearance of fat in the neurovascular plexus or prostatic rectal fossa. MRI is sensitive to show the invasion of the seminal vesicles, reaching more than 97%, and the indications of prostate cancer invading the seminal vesicles are: (1) showing low-signal tumor entering and encircling the seminal vesicle gland from the base of the prostate, resulting in low-signal foci in the normal T2 high-signal seminal vesicle gland and the disappearance of the prostatic seminal vesicle angle; (2) showing tumor invading the seminal vesicle gland along the ejaculatory duct and the disappearance of the seminal vesicle wall; (3) focal low-signal areas in the seminal vesicle. (3) focal low-signal areas in the seminal vesicles. MRI is sensitive to detect metastases in the lymph nodes in the pelvis, and its accuracy is similar to that of CT; 4. MRI can also detect metastases in other areas because of its large display field. In recent years, various multi-parametric MRI and MRI-guided prostate puncture have developed rapidly, providing more accurate information for the diagnosis, staging and postoperative follow-up of prostate cancer.