Heterogeneity analysis of Gd-DTPA uptake: Improvement in breast lesion differentiation

Purpose: The aim of this study was to assess whether lesion heterogeneity t hrough pixel-by-pixel analysis of contrast-enhanced MR parameter maps would improve breast lesion differentiation. Method: Forty-nine female patients with primary tumors of the breast were i maged using contrast-enhanced MRI. The rate of transfer of contrast medium between the lesion and plasma was calculated via compartmental modeling ove r semiautomatically delineated regions of interest. The distributions of tr ansfer rate values were subdivided into 10 segments for each lesion. The ra te of change of the statistical moments of the transfer rate measured over the 10 segments allowed a quantitative measure of heterogeneity. Results: In this patient group of 25 malignant and 25 benign lesions, impro ved differentiation was achieved by using a measure of lesion heterogeneity . The sensitivity and specificity obtained were 88 and 88%. respectively, c ompared with 84 and 76% when using the mean value of the transfer rate coef ficient. Conclusion: Pixel-by-pixel analysis of contrast medium transfer rate maps a llows the examination of lesion heterogeneity and offers improved lesion di fferentiation. The new method used to quantify lesion heterogeneity relies on the manner in which the exchange rate parameter varies when calculated o ver different segments of the distribution.