European Journal of Radiology 79 (2011) e98–e102 Contents lists available at ScienceDirect European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad Fusion of dynamic contrast-enhanced magnetic resonance mammography at 3.0 T with X-ray mammograms: Pilot study evaluation using dedicated semi-automatic registration software Matthias Dietzel a,∗ , Torsten Hopp b , Nicole Ruiter b , Ramy Zoubi a , Ingo B. Runnebaum d , Werner A. Kaiser a,c , Pascal A.T. Baltzer a a Institute of Diagnostic and Interventional Radiology, Friedrich-Schiller-University Jena, Erlanger Allee 101, D-07740 Jena, Germany b Karlsruhe Institute of Technology (KIT), Institute for Data Processing and Electronics, Postfach 3640, D-76021 Karlsruhe, Germany c Medical School; University of Harvard, 25 Shattuck Street, Boston, MA 02115, USA d Clinic of Gynecology and Obstetrics, Friedrich-Schiller-University Jena, Bachstraße 18, D-07743 Jena, Germany article info Article history: Received 14 February 2011 Accepted 6 April 2011 Keywords: Mammography Magnetic resonance imaging Breast neoplasms Radiographic image interpretation Computer-assisted Image interpretation Computer-assisted Imaging Three-dimensional Humans Female Contrast media Gadolinium DTPA abstract Rationale and objectives: To evaluate the semi-automatic image registration accuracy of X-ray- mammography (XR-M) with high-resolution high-field (3.0 T) MR-mammography (MR-M) in an initial pilot study. Material and methods: MR-M was acquired on a high-field clinical scanner at 3.0 T (T1-weighted 3D VIBE ± Gd). XR-M was obtained with state-of-the-art full-field digital systems. Seven patients with clearly delineable mass lesions >10 mm both in XR-M and MR-M were enrolled (exclusion criteria: previous breast surgery; surgical intervention between XR-M and MR-M). XR-M and MR-M were matched using a dedicated image-registration algorithm allowing semi- automatic non-linear deformation of MR-M based on finite-element modeling. To identify registration errors (RE) a virtual craniocaudal 2D mammogram was calculated by the software from MR-M (with and w/o Gadodiamide/Gd) and matched with corresponding XR-M. To quantify REs the geometric center of the lesions in the virtual vs. conventional mammogram were subtracted. The robustness of registration was quantified by registration of X-MRs to both MR-Ms with and w/o Gadodiamide. Results: Image registration was performed successfully for all patients. Overall RE was 8.2 mm (1 min after Gd; confidence interval/CI: 2.0–14.4 mm, standard deviation/SD: 6.7 mm) vs. 8.9 mm (no Gd; CI: 4.0–13.9 mm, SD: 5.4 mm). The mean difference between pre- vs. post-contrast was 0.7 mm (SD: 1.9 mm). Conclusion: Image registration of high-field 3.0 T MR-mammography with X-ray-mammography is feasi- ble. For this study applying a high-resolution protocol at 3.0 T, the registration was robust and the overall registration error was sufficient for clinical application. © 2011 Elsevier Ireland Ltd. All rights reserved. 1. Introduction X-ray-mammography (XR-M) is the most common and most widely available breast imaging technique [1]. It is used in almost all senological scenarios. Image contrast is based on electron density. Thus, XR-M is able to detect microcalcification. Today, full-field dig- ital mammography has become the standard technique to perform XR-M [1]. Magnetic resonance mammography (MR-M) plays an increas- ing role as a breast imaging modality. After more than 25 years of clinical evaluation [2,3], numerous primary investigations and meta-analyses have accumulated evidence for its application in dif- ∗ Corresponding author. Tel.: +49 3641 9324801; fax: +49 3641 9324802. E-mail address: dietzelmatthias2@hotmail.com (M. Dietzel). ferent clinical scenarios [4]. The physical basis of image contrast of MR-M is entirely different compared to XR-M, as it is based on mag- netic tissue properties. Most important in MR-M is the visualization of tissue vasculature by intravenous injection of a T1 shortening contrast agent. Due to a characteristically increased vasculature [5], malignant tumors regularly show a stronger and faster con- trast agent uptake compared to benign lesions or healthy breast tissue [6]. Although 1.5 T is by far the most common field strength in clinical breast imaging, commercial 3.0 T MR units are increas- ingly used for magnetic resonance mammography [7]. Basically, higher magnetic field strengths provide higher signal to noise ratio (SNR). This increase in SNR can be invested either in faster image acquisition and/or higher in-plane resolution [6–8]. Accordingly, 3.0 T MR units are getting increasingly popular in the radiologi- cal community. However, number of studies on high-field MR-M 0720-048X/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2011.04.017