Fig. 1
Flow chart of the study design showing grouping, treatment and imaging time points. a DWI and DKI were performed for all rats on day 0 after which they were randomly assigned to the treatment and control groups. The rats in the treatment group received 12 mg/kg of DTX. Before (day 0) and 3, 7,14, 21 days after DTX therapy, all rats underwent MRI scanning. Twenty-one days after DTX therapy, the tumors were categorized into the sensitive group and the insensitive group. Youden’s index was obtained using retrospective logistic regression analysis of the DWI and DKI parameters at different time points. b Another 93 rats received the same DTX, DWI and DKI as those in a. According to the above cutoff value at the optimal time point, the treatment rats were categorized into the sensitive or insensitive groups. Several rats in the control group on day 0 and in every group at different time points were killed, and the tumors were excised for histology (“black up-pointing triangle” indicated DWI, DKI and histology). Δ% DWI/DKI parameter = (DWI/DKI parameterafter − DWI/DKI parameterday 0)/DWI/DKI parameterday 0 × 100%. Δ% tumor size = (tumor sizeafter − tumor sizeday 0)/tumor sizeday 0 × 100%. Δ% Ki-67/Bcl-2/apoptosis rate/necrosis rate = (Ki-67/Bcl-2/apoptosis rate/necrosis rate after − Ki-67/Bcl-2/apoptosis rate/necrosis rateday 0)/Ki-67/Bcl-2/apoptosis rate/necrosis rateday 0 × 100%. (Note: The tumor size indicated the longest diameter of the tumor; Ki-67day 0, Bcl-2day 0, apoptosis rateday 0 and necrosisday 0 represented the average expression of corresponding biomarkers in the control group on day 0)