[Diagnosis of Perthes disease using magnetic resonance tomography]

Lateral displacement of the femoral head and slight flattening are typical radiological signs of early Legg-Calvé-Perthes disease. There is the value of magnetic resonance imaging (MRI) in demonstrating the congruity of the acetabular and femoral articular surfaces, the cartilage, the femoral head containment, intracapsular joint effusion, and hypertrophy synovium without using any ionizing radiation. Loss of containment because of lateralisation seems to be the result of medial hypertrophy of the femoral head cartilage. The hips show a characteristic low-intensity signal in T1-weighted images representative of necrotic areas of the capital epiphysis. The extent of involvement and revascularisation can be identified in Legg-Calvé-Perthes disease.