Relationship of uptake of 99mTc-MIBI in bone metastases to efficiency of strontium-89 therapy in prostate cancer patients
Nuclear Medicine Review
BACKGROUND: Although the pharmacokinetic profiles and clinical efficiency of 89 SrCl 2 as an agent of choice in extensive metastatic bone disease have been studied widely, the relationship of its efficiency to perfusion of metastases remains unresolved. Hence we aimed to compare the clinical and radiological manifestations of regression of metastatic bone disease in prostate cancer with results of pre-treatment scanning with 99m Tc-MIBI as a blood flow marker. MATERIALS AND METHODS: Sixteen
... ETHODS: Sixteen patients with bone metastatic spread of prostate cancer (on average 9 s.d. 3 bone metastases on 99m Tc-MDP scan) were treated with 89 SrCl 2 (Metastron, Amersham plc) and studied during post-injection followup. In each patient whole-body 99m Tc-MDP (3-4h post-injection of 510 MBq) and 99m Tc-MIBI (10 min post-injection of 510 MBq) scans were performed before injection of 150 MBq of 89 SrCl 2 and 3 and 6 months after. Mean count ratio (metastasis/normal bone) was calculated for 99m Tc-MDP scans for all metastases. 99m Tc-MIBI uptake was employed as a marker of local neoplastic blood flow in metastases, and quantified in a manner similar to 99m Tc-MDP study as (metastasis/ normal bone) pixel count ratio. MRI T1 and T2 scanning were used for anatomic followup of metastases. RESULTS: All patients demonstrated substantial improvement in severity of pain syndrome with full release from pain in ten. The 99m Tc-MDP follow-up revealed a decrease in the number of «hot» metastatic uptake sites from 9 s.d. 3 to 5 s.d. 3 (p<0.01) with a simultaneous decrease of normal bone ratio in remaining hot spots on 99m Tc-MDP scans from 2.79 s.d. 0.45 to 1.83 s.d. 0.18 (p<0.05) after 3 months and further to 1.44 s.d. 0.43 (p<0.05) after 6 months. Metastases with 99m Tc-MIBI pre-treatment (metastasis/background) index over 1.5 and anatomic cross-dimensions below 19 mm demonstrated near-full regression when studied using 99m Tc-MDP and MRI 3 and 6 months after injection of 89 SrCl 2 . A significant correlation was observed between pre-treatment 99m Tc-MIBI (Mts/Bg) ratio and decrease in 99m Tc-MDP metastatic uptake (r=0.84, p<0.005). CONCLUSION: Metastases with anatomic dimensions smaller than 20 mm and persistent blood supply can be effectively cured with 89 Sr. The 99m Tc-MIBI scan of bone metastases is of predictive value for prognosis of success of systemic 89 Sr therapy in prostate cancer.