Application of an exogenous hyperoxic contrast agent in MR mammography: initial results

There is interest in applying novel methods to dynamic MR mammography (MRM). One such possibility is to administer an exogenous hyperoxic contrast agent, such as carbogen (95-98% O2 and 2-5% CO2) or pure oxygen (100% O2). We report our first experiences with these agents in a patient with an invasive lobular carcinoma. Fourteen dynamic series were acquired with an rf-spoiled 2D multislice gradient echo sequence, including three measurements while breathing air, four measurements with 100% oxygen, three measurements with air and four measurements with carbogen. Afterwards, 0.1 mmol/kg bw of Gd-DTPA was administered to obtain dynamic T1-weighted double-echo 3D axial gradient echo images (TR/TE1/TE2/alpha=7.8 ms/2 ms/4.76 ms/15 degrees) every 90 s up to 4.5 min after injection. The lesion was well delineated on the contrast-enhanced images, contrary to magnitude images reconstructed from the raw data sets acquired during air/oxygen/carbogen breathing. A ROI-based median-filtered signal-time course revealed a tumor signal increase of roughly 15% between scans acquired during air and oxygen breathing. Though preliminary, these first results are encouraging concerning the exploration of these alternative contrast agents in MRM in greater detail.