Is (99m)Tc-MIBI scintigraphy a predictor of response to pre-operative neoadjuvant chemotherapy in Osteosarcoma?
Mohammad Gharehdaghi1, Vahid Reza Dabbagh Kakhki2, Alireza Khooei3
1Department of Orthopedic surgery, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran.
Objectives:
Multidrug resistance (MDR), which may be due to the over expression of P-glycoprotein (Pgp) and/or MRP, is a major problem in neoadjuvant chemotherapy of osteosarcoma. The aim of this study was to investigate the role of Tc-99m MIBI scan for predicting the response to pre-operative chemotherapy.
Methods:
Twenty-five patients (12 males and 13 females, aged between 8 and 52y) with osteosarcoma were studied. Before the chemotherapy, planar (99m)Tc-MIBI anterior and posterior images were obtained 10-min [tumor-to-background ratio: (T1/B1)10min] and 3-hr after tracer injection. After completion of chemotherapy, again (99m)Tc-MIBI scan was performed at 10-min after tracer injection. In addition to calculation of decay corrected tumor to background (T/B) ratios, using the 10-min and 3-hr images of the pre-chemotherapy scintigraphy, percent wash-out rate (WR%) of (99m)Tc-MIBI was calculated. Using the 10-min images of the pre- and post-chemotherapy scans, the percent reduction in uptake at the tumor site after treatment (Red%) was also calculated. Then after surgical resection, tumor response was assessed by percentage of necrosis.
Results:
All patients showed significant (99m)Tc-MIBI uptake in early images. Only 9 patients showed good response to chemotherapy (necrosis≥90%) while 16 patients were considered as non-responder (necrosis<90%). There was no statistical significant difference between non-responders and responders in (T1/B1)10min.There was a significant negative correlation between WR% and percentage of necrosis (P=0.001). On the other hand, there was a significant correlation between Red% and percentage of necrosis (P<0.001).There was also statistical significant difference in WR% and Red% between non-responders and responders (both P< 0.001).
Conclusion:
Washout rate of (99m)Tc-MIBI in pre-chemotherapy scintigraphy as well as Red% using pre- and post-chemotherapy MIBI scintigraphy are useful methods for predicting response to neoadjuvant chemotherapy.
Insights
Technetium-99m MIBI scans can predict osteosarcoma chemotherapy response. Washout rate and uptake reduction effectively indicate treatment success in patients receiving neoadjuvant chemotherapy.
Area of Science:
- Nuclear Medicine
- Oncology
- Radiopharmaceuticals
Background:
- Multidrug resistance (MDR) is a significant challenge in osteosarcoma neoadjuvant chemotherapy, often linked to P-glycoprotein (Pgp) and MRP overexpression.
- Predicting patient response to pre-operative chemotherapy is crucial for effective treatment planning.
Purpose of the Study:
- To evaluate the utility of Technetium-99m MIBI ([(99m)]Tc-MIBI) scans in predicting the response to neoadjuvant chemotherapy in osteosarcoma patients.
- To assess the correlation between [(99m)]Tc-MIBI uptake, washout rate, and reduction in uptake with tumor necrosis after chemotherapy.
Main Methods:
- Twenty-five osteosarcoma patients underwent [(99m)]Tc-MIBI planar scintigraphy before and after neoadjuvant chemotherapy.
- Pre-chemotherapy scans measured initial tumor-to-background ratios (T/B) at 10 minutes and 3 hours, calculating the washout rate (WR%).
- Post-chemotherapy scans measured the reduction in tumor uptake (Red%) compared to pre-chemotherapy scans. Tumor response was histopathologically assessed by necrosis percentage.
Main Results:
- All patients exhibited significant initial [(99m)]Tc-MIBI uptake.
- A significant negative correlation was found between WR% and tumor necrosis (P=0.001).
- A significant positive correlation was observed between Red% and tumor necrosis (P<0.001). Both WR% and Red% showed significant differences between responders and non-responders (P<0.001).
Conclusions:
- The washout rate (WR%) of [(99m)]Tc-MIBI during pre-chemotherapy scintigraphy is a valuable predictor of treatment response.
- The percentage reduction in [(99m)]Tc-MIBI uptake (Red%) using pre- and post-chemotherapy scans effectively predicts neoadjuvant chemotherapy response in osteosarcoma.
