Abstract P3-01-17: Mri study of a novel paramagnetic seed for clinically occult breast tumor localization
Authors: Thiruchelvam Paul , Leff Daniel , Upadhyay Neil 
Published: March 2022

IntroductionWire localisation (WL) has been the standard of care for clinically occult breast tumorlocalisation since the 1970s. Whilst WL remained reliable, well tolerated and cost effectivethey were often painful and required close coordination of radiological and theatrescheduling. As a result, alternative localization techniques have been developed and arenow widely adopted. Neoadjuvant Chemotherapy (NACT) has enabled de-escalation inaxillary management (Targeted Axillary Dissection) and may facilitate increased breastconserving surgery. This requires localization prior to commencement of NACT. Magseed® isa small (1mm x 5mm) paramagnetic seed that has been used in both the breast and axillarylesion localization setting. It is however MRI conditional, and has a notable MRI artifact(4cm).AimA single institution study aiming to quantify the MRI artifact of a novel paramagnetic seed,the Magseed Biopsy®, which may be used prior to NACT enabling MRI follow-up.Materials and MethodMRI was performed using 1.5 and 3T MRI machines for T1, T2 and VIBE Dixon sequences.For each MRI sequence, the degree of susceptibility artifact was determined. Artifactdimensions were annotated and recorded.ResultsTable 1: Magseed Biopsy Max artifact at 3TVIBE DIXONT1 Non contrast, non fat T2 Non contrast nonsaturatedfat saturatedAxialSagittalAxialSagittalAxialSagittalMagsee 12mm6mm13mm7mm14mm6mmd BiopsyTable 2: Magseed Biopsy Max artifact at 1.5TVIBE DIXONT1 Non contrast, non fat T2 non contrast nonsaturatedfat saturatedAxialSagittalAxialSagittalAxialSagittal. Magseed 12mm7mm12mm6mm13mm7mmBiopsyImage: Magseed Biopsy 1.5T T2 Weighted MRIDiscussionNACT is increasingly utilised to downstage both the breast and the axilla. In some healthcareinstitutions, MRI is a preferred method to follow the progress of NACT treatment. Usingnon-wire guided technology it is sometimes preferable to place a seed at the time of biopsyand the significant artifact from historical Magnetic seed technology has, until now,precluded this option. This review of the MRI data from a novel iteration of magnetictechnology, Magseed Biopsy®, shows a maximum artifact of 14mm in the axial plane on 3TMRI, with less signal void still using 1.5T and other parameters.Based on this data we feel it is possible to use Magseed Biopsy® at the time of biopsy inpatients having NACT patients. This is the first description of this novel paramagnetic seed inan MRI setting, and we will be undertaking further research comparing imaging with othernon-wire guided technologies available.ConclusionThis novel paramagnetic technology produces a significantly reduced MRI artifact comparedto previous Magseeds, enabling placement at time of biopsy in those patients undergoingNACT.

Citation Format: Paul Thiruchelvam, Daniel Leff, Neil Upadhyay. Mri study of a novel paramagnetic seed for clinically occult breast tumor localization [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-01-17.