I. Osteomyositis is classified according to the imaging diagnosis: 1. acute edema stage (early stage): the initial 2-6 weeks of onset, the edema area boundary is vague, clinical pain is obvious; 2. proliferative mass stage (middle stage): 6 weeks-6 months, boundary between acute edema and calcification repair; 3. calcification repair stage: after 6 months of onset, the lesion is limited, clear boundary, visible ossified tissue, calcification, clinically painless. The first is that the patient’s body is not a part of the body. In the proliferating mass phase, X-rays and CT show stratified “eggshell”-like calcifications (visible from 3-6 weeks), with soft tissue density around the lesion. CT enhancement is a good method to assess the relationship between bone and blood vessels and to perform preoperative evaluation, and can be used for preoperative scope assessment and guidance. MRI has good soft tissue contrast and can well reflect the pathological evolution of ossifying myositis, which is the best means for early diagnosis. early T1WI on MRI is moderately high signal T2WI high signal is predominant, edema at the edge of the lesion is obvious, increasing to the mass stage T1WI and T2WI signal can be reduced compared to the early stage. The calcification at the edge of the lesion shows as a marginal low signal ring on MRI, and the iron-containing heme deposition after hemorrhage and fibrosis also shows as a low signal ring, and this low signal ring becomes more and more clear during the maturation of the lesion, which is a typical manifestation of ossifying myositis, and it is an important basis for diagnosis and differential diagnosis especially in dynamic observation. In the stage of calcification repair, there are high signal changes on both T1WI and T2WI, and the morphology of the lesion may change to oblong and shuttle shape. Because MRI lacks sensitivity and specificity for early calcification or ossification, early diagnosis still requires a combination of X-ray and CT examination. 3. Ultrasound Lasry et al. concluded that ultrasound can be effective in detecting early recurrent ossifying myositis and distinguishing malignant tumors. In the early stage of ossifying myositis, high-frequency ultrasound shows a heterogeneous hypoechoic mass with clear margins; in the mass and calcification stages, it shows irregular punctate strong echogenicity or discontinuous shell-like strong echogenicity with smooth or bumpy surface, and its posterior side is visible as an acoustic shadow, and the posterior border shows unclear, and a hypoechoic band is visible around the incomplete ossification. 4.Blood test Alkaline phosphatase, blood sedimentation, etc. are mostly normal. However, the blood sedimentation, AKP and leukocytes may be increased in the acute and subacute stages. In addition, nuclear bone imaging can be applied, but the advantage of nuclear bone imaging is not to diagnose the disease, but to judge the maturity of ossification and provide objective guidance basis for reasonable treatment. MRI has advantages for patients with benign soft tissue lesions in the early and middle stages, and is more sensitive to early lesions but less sensitive to ossification and calcification; CT and X-ray are better for ossification and “eggshell” signs with annular ossification and accurate preoperative localization. Ultrasound also has advantages in terms of price, less damage to the body and early diagnosis.