Prediction of early response to radiotherapy of uterine carcinoma with dynamic contrast-enhanced MR imaging using pixel analysis of MR perfusion imaging

Purpose: To assess the predictability of the response to radiotherapy of uterine carcinoma, this study retrospectively analyzed dynamic contrast-enhanced magnetic resonance images (DCE-MRI) taken before radiotherapy. Materials and Methods: Forty-two patients with uterine carcinoma were studied, of whom 22 had adenocarcinoma and 20 had squamous cell carcinoma (SCC). In DCE-MRI analysis, two parameters, SIe and R_down, were measured. SIe is a median value for the degree of signal intensity change in all selected pixels in the tumor at 1-2 min after contrast agent injection. R_down is the ratio of the number of down-sloped pixels to that of all selected pixels 3-7 min after injection. The tumor volume reduction rate (TVRR) was measured by MRI-based volumetry in pre- and post-radiotherapy transverse T2-weighted images. Results: Overall, TVRR was significantly correlated to both SIe (r=0.37, P=.015) and R_down (r=0.73, P<.0001). In the separate patient groups, SIe but not R_down was significantly different between the adenocarcinoma and SCC patients (t=3.64, P<.001). TVRR was not correlated to SIe in any group. TVRR was significantly correlated to R_down in adenocarcinoma patients (r=0.78, P<.001) but not in SCC patients. Conclusion: SIe may reflect differences in histological characteristics. R_down may be useful for predicting the response to radiotherapy of uterine carcinoma.