Myometrial invasion in trial cancer: Diagnostic accuracy of diffusion-weighted 3.0-T MR imaging-initial experience

Purpose: To assess the diagnostic accuracy of fused T2-weighted and high-b-value diffusion-weighted (DW) magnetic resonance (MR) images at 3 T for evaluation of myometrial invasion in patients with endometrial cancer. Materials and Methods: Institutional review board approval and informed consent were obtained. From May 2006 to October 2007, 48 consecutive patients aged 25-80 years (mean age, 57 years) who had endometrial cancer were prospectively enrolled for preoperative evaluation by using a 3-T MR unit. Two radiologists interpreted the depth of myometrial invasion on T2-weighted images, dynamic contrast material-enhanced MR images, and fused T2-weighted and DW MR images (b = 1000 sec/mm2). Statistical methods included k statistics for reader agreement, Pearson analysis for pathologic correlation, accuracy assessment, and receiver operating characteristic analysis for diagnostic performance comparison. Surgical pathologic findings were the reference standard. Results: Reader agreement was excellent for fused T2-weighted and DW images (weighted k, 0.79), with a significant pathologic correlation regarding the depth of myometrial invasion (r = 0.94, P < .0001). For assessing any myometrial involvement, addition of fused T2-weighted and DW imaging to dynamic contrast-enhanced or dynamic contrast-enhanced and T2-weighted imaging was significantly better compared with dynamic contrast-enhanced imaging alone (P < .001) or dynamic contrast-enhanced and T2- weighted (P = .001) imaging; T2-weighted imaging combined with fused T2-weighted and DW imaging also was better than dynamic contrast-enhanced and T2-weighted imaging (P = .001). Tumor apparent diffusion coefficients were 0.60-1.32 × 10^-3 mm2/sec (median, 0.75 × 10^-3 mm2/sec), with no significant correlation with the depth of myometrial invasion (P = .31, r = -0.15). Conclusion: Fused T2-weighted and high-b-value DW images at 3 T can provide accurate information for preoperative evaluation of myometrial invasion.