Background and objective Vascularity evaluation on breast dynamic contrast enhanced magnetic resonance imaging has a potential diagnostic value but it represents a time consuming procedure affected by intra and inter observer variability . This study tests the application of a recently published method to reproducibly quantify breast vascularity and evaluates if the vascular volume of cancer bearing breast calculated from automatic vascular maps may correlate with pathologic tumor response after neoadjuvant chemotherapy . Methods Twenty four patients with unilateral locally advanced breast cancer underwent DCE MRI before and after NAC 8 responders and 16 non responders . A validated algorithm based on multiscale 3D Hessian matrix analysis provided AVMs and allowed the calculation of vessel volume before the initiation and after the last NAC cycle for each breast . For cancer bearing breast the difference in vascular volume before and after NAC was compared in responders and non responders using the Wilcoxon two sample test . A radiologist evaluated the vascularity on the subtracted images before and after treatment assigning a vascular score for each breast according to the number of vessels with length 30mm and maximal transverse diameter 2mm . The same evaluation was repeated with the support of the simultaneous visualization of the AVMs . The two evaluations were compared in terms of mean number of vessels and mean vascular score per breast in responders and non responders by use of Wilcoxon two sample test . For all the analysis the statistical significance level was set at 0.05 . Results For breasts harboring the cancer evidence of a difference in vascular volume before and after NAC for responders and non responders was found . A significant difference was also found in the number of vessels and vascular score before or after NAC according to the evaluation supported by the AVMs . Conclusions The encouraging although preliminary results of this study suggest the use of AVMs as new biomarker to evaluate the pathologic response after NAC but also support their application in other breast DCE MRI vessel analysis that are waiting for a reliable quantification method . Solid tumors rely on blood vessels to obtain necessary nutrient and oxygen and new vessels also offer path way for tumor expansion . Therefore the assessment of tumor vascularity may provide useful information to characterize underlying malignancy and monitor vascular abnormalities . In the past decade microvessel density represented the most commonly used prognostic indicator for tumor vascularization in a wide range of cancers although its quantification remained unreliable because of the lack of sufficient morphological and functional information of blood vessels and it could be only assessed after the surgical resection of the primary tumor . A better alternative to study tumor vasculature may be derived from non invasive imaging techniques such as contrast enhanced computed tomography magnetic resonance imaging and dynamic contrast enhanced magnetic resonance imaging positron emission tomography and more recently B mode and Doppler ultrasound . With varied types of cancer there is no general agreement as to which. 


Summary: A validated algorithm quantifies breast vascularity through vascular maps AVM . Breast DCE MR exams are analyzed before and after neoadjuvant chemotherapy NAC . Responders and non responders show difference in vascularity before and after NAC. AVMs may represent a reliable method to evaluate pathologic response after NAC.