Trester, Pamela S.

When a breast lesion is seen on only magnetic resonance imaging (MRI) and needs to be excised, pre-operative MRI-guided radioactive seed localization (RSL) is preferred. However, MRI safety and radiation safety issues associated with the inability to recover a potentially lost seed in the MRI scanner room (Zone IV) have precluded this in the past. This manuscript provides a protocol for MRI-guided RSLs that meets MRI safety and radiation safety criteria established by the American College of Radiology and the Nuclear Regulatory Commission. To the authors’ best knowledge, this has never been published in the literature. The complete protocol is provided.

AbstractWe present the development of a two‐component magnetic resonance (MR) fiducial system, that is, a fiducial marker device combined with an auto‐segmentation algorithm, designed to be paired with existing ultrasound probe tracking and image fusion technology to automatically fuse MR and ultrasound (US) images. The fiducial device consisted of four ~6.4 mL cylindrical wells filled with 1 g/L copper sulfate solution. The algorithm was designed to automatically segment the device in clinical abdominal MR images. The algorithm's detection rate and repeatability were investigated through a phantom study and in human volunteers. The detection rate was 100% in all phantom and human images. The center‐of‐mass of the fiducial device was robustly identified with maximum variations of 2.9 mm in position and 0.9° in angular orientation. In volunteer images, average differences between algorithm‐measured inter‐marker spacings and actual separation distances were 0.53 ± 0.36 mm. “Proof‐of‐concept” automatic MR‐US fusions were conducted with sets of images from both a phantom and volunteer using a commercial prototype system, which was built based on the above findings. Image fusion accuracy was measured to be within 5 mm for breath‐hold scanning. These results demonstrate the capability of this approach to automatically fuse US and MR images acquired across a wide range of clinical abdominal pulse sequences.