1. PET In Osteosarcoma: The Correlation Between Percent Necrosis and Response as Seen by PET
Valerae O. Lewis
HA Macapinlac
Kevin Raymond
Patrick Lin
Alan Yasko
Haesun Choi
Robert Benjamin 1

2. Osteosarcoma Most common primary malignancy of bone
Current treatment regimen: neoadjuvant chemotherapy and surgical resection
Role of imaging:
To evaluate the degree of local extension (preoperative planning)
Assess the response to chemotherapy

3. Monitoring the Response to Neoadjuvant Chemotherapy
Tumor measurements performed during chemotherapy have
limited prognostic value

4. Purpose
To evaluate whether PET can function as a non-invasive assessment of response to chemotherapy and thus provide preoperative prognostic/survival information.

5. Evaluation of PET 14 patients diagnosed with high grade osteosarcoma
Age: median 25 (range, years)
5 female: 9 male
Chemotherapy regimen: Intra-arterial cisplatin (120 mg/m2) and adriamycin (90 mg/m2)
Baseline and Preoperative imaging
Radiographs
MRI
PET

6. PET Evaluation
Each patient underwent PET scan before initiating chemotherapy, and prior to the definitive surgical procedure.
Percent change or SUV decrease is expressed by a ratio of post-treatment to pretreatment SUV.
PET data were analyzed based on percent change in SUV and final SUV, and were correlated with tumor necrosis.

7. A Poor PET Response
Pre-chemo
Post-chemo

8. A Good PET Response
Post-chemo
Pre-chemo

9. Resection and Necrosis Mapping

10. Response by PET By Percent Necrosis

11. Response by PET By Percent Change in SUV

12. Response by PET By Final SUV

13. PET Measured Response
A measured response (necrosis > 95%) by PET was considered an SUV decrease by >50% to a value of < 2.5 (p<0.003) .

14. Response by PET By Final SUV and Percent Change
All patientswith >95% necrosis had a final SUV <2.5 with at least 50% decrease in the SUV

15. Response by PET
A significant response by PET identified 5/5 of patients who had > 95% necrosis of their tumor.
The eight patients whose pathology revealed < 95% necrosis did not have a response by PET

16. PET
May prove to be a valuable non-invasive preoperative diagnostic tool that provides the clinician with tumor response to chemotherapy and prognostic information.
May be a important pre-operative/surgical planning tool.