Applied radioactivity in radiation synovectomy with [188Re]rhenium sulfide suspension

Early experience demonstrated absorbed dose in radiation synovectomy is about 100 Gy. For reaching this dose, the applied radioactivity should be calculated.

Twenty-nine synovitic models of rabbit were treated by intra-articular injection of [(188)Re]rhenium sulfide and histological changes of synovium and cartilage were examined. The applied radioactivity was calculated by method of absorbed dose factor. In clinical, eleven haemophilic patients with haemarthrosis were performed radiation synovectomy with treated [(188)Re]rhenium sulfide. The synovial thickness was evaluated by MR and its value was used to calculate the applied radioactivity. After radiation synovectomy, all patients were followed up by synovial thickness, regional inflammation, and clinical course including bleeding frequency.

In rabbit models, the synovitic membrane can be eliminated by calculated radioactivity as planed without damaging the joint cartilage. In patients study, all patients exhibited significant reductions in synovial thickness and inflammation after radiation synovectomy with the planed radioactivities of [(188)Re]rhenium sulfide. Post-procedure bleeding frequency reduction in excellent and good reached to 63.6% by 18 months. In the cases of joint bleeding, the need for antihaemophilic factor treatment decreased immensely. Most of the recurrent episodes of bleeding were mild, subsiding with local means.

The applied radioactivity in radiation synovectomy could be calculated according to thickness of inflamed synovium. Further study including comparison therapeutic results from calculated individual activities with results from fixed activities and long-term follow-up is warranted.