Fig. 2

A case of D-TGCT demonstrating pre and post synovectomy findings on MRI. a Sagittal T2 weighted image shows multilobular posterior tumour with low signal intensity, and adjacent cyst-like components present within tumour in the popliteal cyst. Anterior, in the medial gutter of the suprapatellar recess smaller synovial proliferations are present. b Sagittal T1 SPIR post contrast performed 3 months after anterior and posterior synovectomy shows surgical clips with metal artefact anterior and posterior in the soft tissues, thickening of the quadriceps tendon, subcutaneous oedema and marked enhancement in Hoffa’s fatpad (asterisk) and along the posterior cortex of the tibia (subpopliteal recess). This mass-like enhancement can be post operative but residual tumour cannot be excluded at this time. MRI performed 3 years post synovectomy: c Sagittal T1 shows a bone erosion centrally in the tibial plateau (arrow). Furthermore, soft tissue masses posteriorly in the knee are present containing foci of low signal intensity. d Axial PD SPAIR shows a typical location of a lesion containing cystic components at the medial retrocondylar recess (arrow). e Sagittal T1 SPIR post contrast demonstrates enhancement of tumour within the tibia plateau erosion and of the posterior mass lesions. Note that Hoffa’s fat pad shows normalisation of fatty signal intensity except for a rim of tumour enhancement in the central synovial recess and inferior infrapatellar recess. f, g Time intensity curve of the tumour based on the region of interest (orange line) of the lesion demonstrated in d, showing early enhancement within 10 s after the artery (blue line) followed by a plateau phase (type III curve suggestive of a benign lesion)