Dynamic contrast-enhanced magnetic resonance imaging: a non-invasive method to evaluate significant differences between malignant and normal tissue.

PURPOSE An ever recurring challenge in diagnostic radiology is the differentiation between non-malignant and malignant tissue. Based on evidence that microcirculation of normal, non-malignant tissue differs from that of malignant tissue, the goal of this study was to assess the reliability of dynamic contrast-enhanced Magnetic Resonance Imaging (dcMRI) for differentiating these two entities. MATERIALS AND METHODS DcMRI data of rectum carcinoma and gluteus maximus muscles were acquired in 41 patients. Using an fast T1-mapping sequence on a 1.5-T whole body scanner, T1-maps were dynamically retrieved before, during and after constant rate i.v. infusion of a contrast medium (CM). On the basis of the acquired data sets, PI-values were calculated on a pixel-by-pixel basis. The relevance of spatial heterogeneities of microcirculation was investigated by relative frequency histograms of the PI-values. RESULTS A statistically significant difference between malignant and normal tissue was found for the mean PI-value (P < 0.001; 8.95 ml/min/100 g +/- 2.45 versus 3.56 ml/min/100 g +/- 1.20). Additionally relative frequency distributions of PI-values with equal class intervals of 2.5 ml/min/100 g revealed significant differences between the histograms of muscles and rectum carcinoma. CONCLUSION We could show that microcirculation differences between malignant and normal, non-malignant tissue can be reliably assessed by non-invasive dcMRI. Therefore, dcMRI holds great promise in the aid of cancer assessment, especially in patients where biopsy is contraindicated.