MR signal intensity characteristics in LEgg-Calve-Perthes disease. Value of fat-suppressed (STIR) images and contrast-enhanced T1-weighted images

Abstract

Purpose: To evaluate the MR signal intensity characteristics in Legg-Calve-Perthes disease on fat-suppressed (STIR) images and contrast-enhanced T1-weighted spin-echo images, and to develop criteria for the administration of contrast material. Material and Methods: Twenty children with Legg-Calve-Perthes disease underwent conventional radiography and MR imaging of the hip utilizing fat-suppressed (STIR) sequences and T1-weighted spin-echo sequences before and after i.v. contrast administration. The signal intensity characteristics of the femoral head and the proximal femoral metaphysis were assessed retrospectively by two pediatric radiologists. Results: Evaluation of the MR images revealed six different signal patterns within the femoral head: 1) isointense signal on all images; 2) complete signal void on all images; 3) hyperintense signal on STIR images with; or 4) without contrast enhancement on T1-weighted spin-echo images; 5) isointense signal on STIR images with; or 6) without contrast enhancement on T1-weighted images. Within the metaphysis three different signal patterns were differentiated. Conclusion: Combination of fat-suppressed (STIR) sequences and T1-weighted pre- and post-contrast sequences allows an accurate evaluation of Legg-Calve-Perthes disease. In patients without signal alterations or complete signal loss on fat-suppressed and T1-weighted spin-echo images, administration of i.v. contrast is not necessary. In case of bone marrow edema on fat-supressed images, contrast-enhanced T1-weighted images are required to identify viable osseous fragments.