The Clinical Application Of CT-guided ¹²⁵I Seed Brachytherapy In Treating Vertebral Metastasis

Background and purposeBone metastases are most commonly seen in vertebral metastases.Due to vertebral destruction and/or pathological fractures of the spinal cord and nerve compression,severe pain,paralysis,hypercalcemia can occur in patients with vertebral body metastases,which seriously reduces their life quality and survival rate,and brings heavy burden to their families and society.The principle of the treatment of vertebral metastases is to alleviate the symptoms of patients,and to improve the mobility and life quality of patients.For vertebral metastases,surgery and external radiotherapy can be performed;however,the surgical access standards are high,which makes it difficult to completely remove the tumor,while due to the human and spinal cord tolerance dose limit,it can be hard to achieve tumor lethal dose in the conventional external radiotherapy,which thereby easily leads to tumor relapse in the future.In this study,we investigated the clinical and radiographic changes in patients with vertebral metastases after implantation of ¹²⁵I radioactive particles,and evaluated the safety and efficacy of ¹²⁵I in the treatment of vertebral metastases.Materials and MethodsThe clinical and imaging data of 68 patients undergoing CT-guided spinal metastatic tumor from August 2012 to October 2016 in the Department of Radiology,Third Military Medical University were collected.The clinical data included the gender,age,pathological type of primary tumor,the number and location of the affected vertebrae,with epidural spinal cord compression or not,pain score and neurological score.The imaging data included preoperative and postoperative computed tomography（CT）,magnetic resonance imaging（MRI）,emission computed tomography（ECT）,etc.Among them,22 cases of（metastatic epidural spinal cord compression）MESCC were investigated for the first part of the study,46 cases of intra-compartmental lesion were included in the second part of the study.The preoperative thin-layer CT images were input into the TPS system for reconstruction.The needle flow,the number of implanted particles and the dose curve were simulated.After the CT-guided implantation of ¹²⁵I particles,for the first part of the patients,American Society of spinal cord injury standards（ASIA）was used to assess preoperative and postoperative neurological status,and grading evaluation of tumor treatment was made using the MRI-based epidural spinal cord compression（ESCC）.For the second part of the patients,the University of Texas MD Anderson Cancer Center（MDA）criteria for tumor responses was applied to assess the effect of tumor therapy.Preoperative and postoperative pain of the two parts of patients were evaluated by numerical rating scale（NRS）,and the survival time was recorded and compared with the prognosis of the Tokuhashi spinal metastases.The number of postoperative use of seeds and the treatment of target and spinal cord dose was also recorded,and D90（delivered to 90% of the target volume）and V90（at least 90% of the target volume received the prescribed dose）was calculated.ResultsPart One1.A total of 36 vertebral bodies in 22 MESCC cases were implanted.The dose was 12,000 c Gy,the particle spacing was 0.5-1 cm,the particle activity was 0.8 m Ci,¹²⁵I particles were 48.17 ± 23.96,and the target D90 was 11,072 c Gy.Spinal cord D90 was 4189.32 ± 1740.06 cGy.2.The preoperative ESCC 0-V levels were respectively 0,2.8%,36.1%,16.7%,30.5%,13.9%;postoperative ESCC 0-V levels were 19.5%,30.5%,25%,22.2%,2.8% and 0,respectively.Nonparametric test showed a significant increase in postoperative ESCC score（P <0.05）.3,The number of patients with neurological impairment reduced from 11 cases to 8 cases after operation,among which due to secondary compression fractures two patients were found neurological damage.There was no significant difference in AISA score during follow-up（P> 0.05）.The neurological retention,recovery and descent rates were 63.7%（14/22）,27.3%（6/22）,and 9%（2/22）,respectively.4.The overall remission rate of pain was 95.2%.The preoperative NRS score of patients was 3（3,4.25）,and the postoperative 3-month NRS score was 1.5（0.75,3）.The scores were statistically significant（P <0.05）.5.The median survival time was 10 months.The 6,12,24-month survival rates were 80%,50.0%,and 21.9%.No complications occurred during the follow-up period.Part Two1.A total of 87 vertebral bodies in 46 cases were implanted.The dose was 12,000 c Gy,the number of particles was 35.46 ± 22.42,and the particle spacing was 0.5-1cm.The particle activity was 0.8mCi.The postoperative D90 was 11232.35 ± 1815.02 cGy and the spinal cord D90 was 3510.38 ± 1755.83.2.By the end of the follow-up,87 vertebrae were evaluated according to the MDA standard: among them,complete response（CR）34 cases,partial response（PR）31 cases,progressive disease（SD）17 cases,stable disease（PD）5 cases.The local control rate is 94.2%.3.The overall remission rate of pain was 95.0%.The preoperative NRS score of patients was 3（2,4）,and the postoperative 3-month NRS score was 1（0,2.25）.The scores were statistically significant（P <0.05）.4.The median survival time was 10 months.The survival rates of 6,12,24 months were 69.6%,38.7%,15.5%.No serious complications occurred during the follow-up period.Conclusion CT-guided ¹²⁵I seed implantation is an effective and safe palliative care for the vertebral metastasis patients,which can effectively relieve the pain,maintain and improve the neurological status,improve the life quality of patients and extend their survival time.