PURPOSE: To define MR imaging characteristics of primary aneurysmal bone cyst. MATERIALS AND METHODS: MR imaging studies of 38 patients with histologically proven primary aneurysmal bone cyst were reviewed with reference to morphological features, signal characteristics, and patterns of contrast-enhancement. RESULT: Most lesions were well marginated towards bone and soft tissues (95%), either surrounded by a complete (84%) or incomplete (16%) rim of low signal intensity on images of all pulse sequences. Frequent features were polycyclic margins (84%), cortical expansion (87%), cystic spaces (100%), contrast-enhancing cyst walls (100%), internal septations (89%), fluid levels (71%) and diverticula-like projections of cyst walls (68%). Solid tissue components could be identified by MR imaging in all lesions which, on pathological examination, contained larger portions of solid material (18%). Edema of surrounding soft-tissues was observed in 29% of the cases. CONCLUSIONS: Primary aneurysmal bone cysts demonstrate a relatively uniform MR imaging appearance, which reflects the patho-anatomic composition of the lesion.
PURPOSE: To define MR imaging characteristics of primary aneurysmal bone cyst. MATERIALS AND METHODS: MR imaging studies of 38 patients with histologically proven primary aneurysmal bone cyst were reviewed with reference to morphological features, signal characteristics, and patterns of contrast-enhancement. RESULT: Most lesions were well marginated towards bone and soft tissues (95%), either surrounded by a complete (84%) or incomplete (16%) rim of low signal intensity on images of all pulse sequences. Frequent features were polycyclic margins (84%), cortical expansion (87%), cystic spaces (100%), contrast-enhancing cyst walls (100%), internal septations (89%), fluid levels (71%) and diverticula-like projections of cyst walls (68%). Solid tissue components could be identified by MR imaging in all lesions which, on pathological examination, contained larger portions of solid material (18%). Edema of surrounding soft-tissues was observed in 29% of the cases. CONCLUSIONS:Primary aneurysmal bone cysts demonstrate a relatively uniform MR imaging appearance, which reflects the patho-anatomic composition of the lesion.