European Nuclear Medicine Guide
Patients selection criteria are similar for all the above radiopharmaceuticals:
Inclusion criteria
Absolute contraindications:
Relative contraindications:
Radiographs of the joints to be treated should be obtained and reviewed prior to undertaking radiosynoviorthesis. Weightbearing views of lower limb joints should be requested specifically. Symptoms largely or exclusively attributable to cartilage damage are unlikely to benefit from radiosynoviorthesis.
Joint puncture for radiosynovectomy carries the same risk as any joint puncture and should follow the rules of strict asepsis.
Local skin anaesthesia is advisable.
Correct deposition and homogeneous distribution of the radiopharmaceutical agent in the joint space is essential. Puncture of all joints should be performed under fluoroscopic (X-ray screening) or ultrasound guidance.
A particle size of at least 5-10 nm is essential to avoid leakage.
Absolute immobilization of the treated joint(s) for 48 h using splints or bed rest is recommended as this will reduce transport of particles through the lymphatics to the regional lymph nodes.
Where possible, simultaneous administration of intraarticular long-acting glucocorticoids (e.g. methylprednisolone or triamcinolone) is recommended to reduce the risk/severity of acute synovitis and to improve treatment response.
For Erbium-169 10 mg of triamcinolone acetonide can be administered if there is enough joint space for a pressure-free injection.
The needle through which the radiopharmaceutical has been injected should be flushed before and during withdrawal with 0.9% saline or directly through the glucorticoids administration.
The importance of joint immobilization following treatment should be emphasized.
The radiation absorbed dose about 100 Gy leads to a synovectomy similar to surgical synovectomy [86,87].
According to MIRD scheme the estimated reported absorbed dose for Erbium-169 to finger joints is 132.3+/-34.3 Gy, to the synovia (at 40% leakage) is of 73.10+/-25.25 Gy. The reported whole body absorbed dose evaluated in 7 patients is 0.4±0.3 cGy, the estimated blood dose 15 +/- 29 microGy and to lymph nodes 2.3 Gy [88,89].
The absorbed dose calculated at the injected joints of the shoulder with Rhenium-186 is 120.5+/-32.2 Gy, hand 130.0+/-12.6 Gy, elbow 83.6+/-38.7 Gy, and talar/subtalar joint 84.1+/-30.7 Gy. The reduced doses to the synovia (at 40% leakage) were for [186Re]Rhenium-sulphide 65.40+/-32.55 Gy The mean radiation absorbed dose of [186Re]Rhenium-sulphide to the whole body is 5.3+/-2.7 cGy, liver 10.0+/-8.1 cGy, spleen 20.3+/-22.9 cGy, kidneys 9.4+/-11.4 cGy [88].
After intra-articular administration of 185 MBq of Yttrium-90, the MIRD system can be used to calculate an absorbed dose of 92 Gy for a 100 gram spherical volume. The radiation dose caused by 1% leakage from the knee joint after administration of 185 MBq of Yttrium-90 can lead to 10 Gy in the lymph nodes.
The joint knee joint absorbed dose evaluated in 6 patients was 130.1 Gy. The reduced doses to the synovia (at 40% leakage) was 59.25+/-46.45 Gy. The whole body dose reported was 15.5 cGy, liver dose 26.5 cGy, splenic dose 11.9 cGy, kidney dose 67 cGy [88].
The ambient dose-equivalent rate due to the presence of pure β-emitters in a joint is very low. Assuming that Yttrium-90 causes 1% Bremsstrahlung in tissue, the environmental dose-equivalent rate 1 m away from the knee after the administration of 185 MBq of Yttrium-90 colloid is 0.04 µSv/h.
There are other treatments that can be employed for synovitis:
A disadvantage of radiosynoviorthesis is the potential leakage of the radiopharmaceutical to the lymph nodes and liver. However, this is normally below 5% of the injected activity [90].
Extra-articular tissue radiation may be caused by:
Acute side effects are rare. Joint inflammation might worsen and could last for several days and sometimes accompanied by fever. ESR could increase and leukocytosis could occur. Long term side effects have not been described in the literature, even though this treatment has been in use for more than 60 years.
[169Er]Erbium-citrate 186Re]Rhenium-sulphide [90Y]Yttrium-citrate are approved in a few European countries for the treatment of a range of refractory painful arthropathies. National rules concerning the different approvals of all radionuclides used for radiosynoviorthesis must be strictly considered.