Legg-Calve-Perthes disease, referred to as Perthes disease, is an idiopathic ischemic necrosis of the femoral head of boys aged 4 to 9 years whose cause is not yet known. 50 years of age or older, suggesting that repair of the femoral head may lead to irreversible, permanent femoral deformity and early onset of secondary osteoarthritis in approximately 50% of adults. The goal of Perthes disease treatment is to promote spherical repair of the femoral head and avoid early onset of osteoarthritis. The concept of treatment through good “inclusion” of the femoral head, which protrudes outside the acetabulum and is the main cause of femoral deformity, has been widely accepted. The prognosis for surgical inclusion after the stage of fragmentation is poor. Based on radiographs, Catterall proposed that the greater the extent of femoral head involvement, the worse the prognosis; Herring divided the femoral head into medial, middle, and lateral columns, and classified them into types A, B, and C according to the degree of collapse of the lateral column of the femoral head, with types A and B having a good prognosis and type C having a poor prognosis. The prognosis of children with Perthes’ disease who are seen in the necrotic phase needs to wait until the disease progresses to the fragmentation phase before prognosis assessment and treatment decisions can be made. or prevent femoral deformity. Non-enhanced magnetic resonance imaging (MRI) is commonly used to detect fatty (lipid degradation) signal changes in the femoral epiphysis and protrusion of the cartilaginous portion of the femoral head earlier than X-rays. However, in the initial stages of Perthes disease, fatty signal changes in the femoral epiphysis take several weeks to months after fat necrosis to present on MRI, and ElsigJP reported that non-enhanced MRI did not accurately reflect the true involvement of the femoral head when performed within 3 to 6 months after the first symptoms. In contrast, enhanced MRI combined with subtraction techniques (hereafter referred to as enhanced MRI) more accurately reflects information about the blood supply flowing to the femoral head. It has been proposed that enhancement MRI does not differ significantly from subtraction MRI images in assessing femoral head perfusion, but subtraction MRI is more beneficial to the measurer in identifying perfusion boundaries during measurement. Using enhancement MRI subtraction technique can detect changes in femoral head blood supply early to predict the regression of the lateral column of the femoral head after entering the fragmentation phase, thus providing a therapeutic basis for early intervention.