MRI of the breast at 3.0 T with SENSE and Flip Angle Sweep

Purpose: Even with current state-of-the-art 1.5T systems, breast MRI imaging protocols will always constitute a compromise between the diverging demands of high spatial and temporal resolution. Whole body magnets operating at higher magnetic fields (e.g. 3.0T) become increasingly available in clinical settings. We report on our first experiences with bilateral contrast-enhanced dynamic breast MRI at 3.0T.

Methods: Ongoing intra-individual comparative study on so far 24 patients (mean age, 49.5) with a total 30 contrast enhancing lesions (11 breast cancers, 15 fibroadenomas, 1 focal chronic mastitis, 3 intramammary lymph nodes) who underwent contrast enhanced dynamic bilateral breast MRI twice, once with the our standard breast MRI technique at 1.5T, and, on another day, at a clinical whole-body system operating at 3.0T. At 1.5T, a 2D-GE dynamic series with TR/TE/FA 290/4.6/90; FoV 330mm, 512×400 imaging matrix, 3mm section thickness, acquisition time 1:50min per dynamic was obtained with regular phase encoding. At 3.0T, a SENSE-compatible bilateral receive-only breast coil was used (MRIDevices). A 2D-GE pulse sequence with TR/TE/FA 320/2.3/70, full 512 imaging matrix, FOV 340 mms, 2mm sections, and a SENSE-factor of 2 was chosen to accelerate image acquisition time to 80 seconds per dynamic scan. In all patients, unilateral very-high-resolution imaging was performed with 3D-GE, TR/TE/FA 10/2.6/10, active fat suppression (SPAIR), 1mm section thickness, 250mm FOV Image quality, full 512 matrix, yielding a pixel size of 0.25mm, 100 sections, with only 2min. acquisition time. Features of enhancing lesions were compared to the same patients' MRI study at 1.5T.

Results: Bilateral SENSE breast MR imaging at 3.0T yielded homogeneous image quality over the entire FOV. All lesions were prospectively identified on both studies. The higher in- and through-plane spatial resolution and the higher temporal resolution of the dynamic series at 3.0T improved the delineation of lesion morphologic details compared to 1.5T imaging. Enhancement kinetics were comparable. Best image quality was achieved with uni-lateral high-resolution imaging with active fat suppression.

Conclusion: Our initial experiences with contrast-enhanced breast MRI with SENSE at 3.0T are encouraging. It allowed high spatial and temporal resolution imaging over a large Field of View (for bilateral dynamic subtraction imaging), or very high resolution uni-lateral fat-suppressed approaches. 3.0T breast imaging with SENSE allow us to acquire breast MR images with unprecedented spatial resolution.