Angiogenic activity of cervical carcinoma: assessment by functional magnetic resonance imaging-based parameters and a histomorphological approach in correlation with disease outcome.

ABSTRACT

Angiogenesis plays a fundamental role in tumor growth and metastasis. What is needed is a quantitative, noninvasive, and repeatable assay to estimate functional angiogenic activity of the entire tumor. The aims of the present study were to (a) examine the relationship between functional magnetic resonance imaging (MRI)-based parameters with established histomorphological markers of tumor angiogenesis [histological microvessel density (HMVD) and vascular endothelial growth factor expression (VEGF)]; and (b) determine the ultimate value of both approaches to assess functional angiogenic active hotspots as markers of disease outcome in patients with cancer of the uterine cervix. Pharmacokinetic parameters (amplitude A, tissue exchange rate constant k21) were calculated from contrast-enhanced dynamic MRI series in 57 patients (mean age, 49 +/- 14 years) with biopsy proven uterine cervical cancer. Both pharmacokinetic parameters were correlated to histomorphologically determined areas of high HMVD and VEGF expression obtained from the operative specimens after radical surgery. In addition, the functional MRI and histomorphological data were used to assess disease outcome. A significant association was found between HMVD and the amplitude A (P < 0.001) and a less pronounced association with k21, (P < 0.05), respectively. No significant associations were found between the pharmacokinetic parameters (A, k21) and VEGF expression. When stratified into high and low median k21 groups, median k21 values >5.4 min(-1) were the only significant (P < 0.05) factors in predicting poor patient survival. None of the histomorphological markers of angiogenesis (HMVD or VEGF expression) showed any predictive power. We have found that (a) focal hotspots of HMVD are the pathophysiological basis for differences in functional MRI; (b) areas of high microvessel density and microvessel permeability do not necessarily coincide, as demonstrated by the histomorphological and functional MRI findings; (c) the functional angiogenic activity of a tumor may not be sufficiently characterized by a histomorphological approach but rather by a functional MRI-based approach; and (d) functional MRI-based analysis may assess tumor angiogenic activity in terms of disease outcome more comprehensively than the histomorphological approach.