Fig. 2
From: Intra-articular osteoid osteoma as a differential diagnosis of diffuse mono-articular joint pain
Imaging of iaOO. a Case 1: Coronal reformat of a CT scan showing a subchondral OO with central calcification (nidus) in the talar neck adjacent to the distal tibia (red box). In proton density (PD)-weighted fat-suppressed (FS) turbo spin echo (TSE) images, the nidus was not as apparent as in CT scans. b Case 2: iaOO in the lateral tibia plateau, coronal CT reconstruction (red box). In PD FS TSE MRI, the nidus is only pictured as ill-defined signal attenuation in the subchondral bone of the lateral tibia. c Case 3: X-Ray does not show any pathological findings. Gadolinium-enhanced (GE) MR imaging (FS, T1-weighted, TSE) shows circular enhancement of the subchondral bone of the femoral head (red box). For more MRI sequences see Additional file 1: Figure S1