Angiogenesis of Ovarian Cancer: Characterization by 3.0t Diffusion Weighted MRI

Background and aims: Prognosis of ovarian cancer (OC) remains poor. Recently, diffusion weighted MRI (DW-MRI) has shown promise in characterization of OC. We aimed to study whether DWI-MRI is associated with angiogenic growth factors and whether it predicts the clinical course of patients. Methods: We enrolled 20 patients with primary OC treated at Kuopio University Hospital in 2011–2013 in this prospective study. DW-MRI (3.0 T, Philips Achieva TX) was performed before the surgical treatment. Apparent diffusion coefficient (ADC) maps were automatically generated for b-values of 0 and 600. Two observers measured ADC-values from (1) the whole primary lesion region of interest (W-ROI) and (2) five small subregions (S-ROIs) with lowest ADC values. Tissue samples from tumors were collected in surgery. Immunohistochemistry and qRT-PCR analyses were used to measure expression of several angiogenic growth factors and receptors of VEGF and angiopoietin families. Results: Interobserver reproducibility of ADC measurements was acceptable (Intra-class correlation coefficient (0.577–0.650). ADC values in W-ROIs were significantly correlated with high relative mRNA expressions of VEGFR-2 (r = 0.818, p = 0.003), VEGFR-3 (r = 0.818, p = 0.001) and Tie1 (r = 0.762, p = 0.004) in qRT-PCR analyses. Correlation coefficients were even higher using mean ADC values of S-ROIs (r = 0.928, p = 0.000; r = 0.886, p = 0.000 and r = 0.879, p = 0.000, respectively). There was no correlation between ADC values and Caspase-3 or Ki-67 expression. Higher mean ADC value of S-ROIs was associated with advanced stage of disease (p = 0.042). Conclusions: Measurement of ADC values is a valuable tool in tumor characterization of ovarian cancer. Specifically, ADC values are associated with angiogenesis of tumors.