**2.3.2 Region Of Interest (ROI)**

The ROI of the tumors or ROI1 was selected from the scanning section with the maximum tumor diameter and the contrast-enhanced area of the solid part (> 0.1 cm2). The control or ROI2 was selected from the adjacent unaffected myometrial tissue, and its size and shape were kept same to those of ROI1. Necrosis, hemorrhage, and other areas with heterogeneous signal were avoided on the basis of the characteristics of conventional MRI.

#### **2.3.3 Quantitative measurements**

The DCE TIC was obtained directly from the GE functool 4.3 workstation. The signal intensity in the different DCE phases was measured in the ROI1 and ROI2, respectively. The enhanced rate in each phase was calculated as enhanced rate = (SIpost-SIpre)/SIpre×100%. SIpost was the enhanced signal intensity in the ROI and SIpre was the corresponding signal intensity before the enhancement. The enhanced rate at 16 s was recorded as the arterial phase relative signal increase (ARSI%) and the enhanced rate at the curve peak was recorded as the maximal relative signal increase (MRSI%). The signal enhancement ratio (SER%) was calculated as SER% = (SImax-SIprior)/(SIe-SIprior) × 100%. SImax was the maximum signal intensity from the DCE TIC, and SIe was the signal intensity during the delayed period.

#### **2.3.4 TIC types**

The time period of enhancement to 32 s after injection of contrast agent was set to the early phase; the time period from 32 s to 64 s was set to the middle phase; the time period from 64 s was set to the late phase; and the time period from 300 s was set to the delayed phase. Thus the TIC of endometrial cancer could be divided into four types【6】: type I: early and rapid enhancement to the peak in the early phase with the ARSI% ≥ 60%; type II: similar enhancement pattern in the early phase to type I, but with the ARSI% <60%; type III: significant enhancement in the early phase with the ARSI% ≥ 60%, but showing continued enhancement in the middle and late phases; and type IV: lack of rapid enhancement in the early phase with ARSI% < 60%, but showing continued enhancement.

#### **2.3.5 Endometrial cancer staging based on pathology**

The pathological information of 15 postoperative cases was collected by two physicians. The general type, differentiation degree, and invasion depth on MRI were compared with the corresponding findings in pathology which was used as the gold standard. The other 9 cases without operative treatment were staged comprehensively based on the clinical information, mainly the gynecological specialized examination, B-mode ultrasound, cystoscopy, and colonoscopy【7】.
