Noninvasive Assessment of Response to Neoadjuvant Chemotherapy in Osteosarcoma of Long Bones with Diffusion-Weighted Imaging: An Initial In Vivo Study

Objectives: The purpose of our study is to investigate whether diffusion-weighted imaging (DWI) is useful for monitoring the therapeutic response after neoadjuvant chemotherapy in osteosarcoma of long bones. Materials and methods: Conventional magnetic resonance imaging (MRI) and DWI were obtained from 35 patients with histologically proven osteosarcomas. MR examinations were performed in all patients before and after 4 courses of preoperative neoadjuvant chemotherapy. Apparent diffusion coefficients (ADC) were measured. The degree of tumor necrosis was assessed macroscopically and histologically by two experienced pathologists after operation. Student’s t test was performed for testing changes in ADC value. Pearson’s correlation coefficient was used to estimate the correlation between necrosis rate and post- neoadjuvant chemotherapy ADC values. P,0.05 was considered to denote a significant difference. Results: The difference of the whole osteosarcoma between pre- neoadjuvant chemotherapy ADC value (1.2460.1761023 mm2/s) and post- (1.9360.3961023 mm2/s) was significant difference (P,0.01). Regarding in patients with good response, the post- neoadjuvant chemotherapy values were significantly higher than the pre- neoadjuvant chemotherapy values (P,0.01). The post- neoadjuvant chemotherapy ADC value in patients with good response was higher than that of poor response (t = 8.995, P,0.01). The differences in post- neoadjuvant chemotherapy ADC between viabl