title: Is (99m)Tc-MIBI scintigraphy a predictor of response to pre-operative neoadjuvant chemotherapy in Osteosarcoma?
abstract: OBJECTIVE
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Orthopedic surgery, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Gharehdaghi
authors.affiliation: Nuclear Medicine Research Center, Ghaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Vahid Reza
authors.initials: VR
authors.lastname: Dabbagh Kakhki
authors.affiliation: Department of Pathology, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Khooei
authors.affiliation: Department of Oncology, Omid Hospital, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Gholamhosein
authors.initials: G
authors.lastname: Novferesti
authors.affiliation: Department of Orthopedic surgery, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Hootkani
authors.affiliation: Department of Pathology, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Farzadnia
authors.affiliation: Nuclear Medicine Research Center, Ghaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Ramin
authors.initials: R
authors.lastname: Sadeghi
keywords: 99mTc-MIBI; Neoadjuvant chemotherapy; Osteosarcoma; Therapy response