Non-palpable breast lesions are not easy to resect without prior localisation. With the increased uptake of breast screening, there are more impalpable lesions detected that requires surgical excision – indeterminate and biopsy proven malignant lesions.
The traditional, and only available approach for many years, has been image-guided hookwire localisation. This is a fine wire with a thickened portion inserted into the breast on the morning of surgery by the radiologist, under ultrasound or mammographic guidance. After it is inserted, a mammogram is performed with the hookwire in situ to provide a visual guide for the surgeon during surgical resection.
The patient is told not to move her arm for fear of dislodging the wire. Breast movement is also painful unless she is wearing a bra. The hookwire protrudes out the breast until it is removed at the time of the lesion resection. The patient would have come into hospital early on the morning of surgery to have the hookwire inserted, and then wait for many hours until her operation time. Scheduling for the radiologist is also stressful as multiple hookwires are sometimes required in many women in one day.
The Magseed and Sentimag system is a new localisation technique, which is now available to women in WA. Essentially, a tiny (5 x 1mm) metal marker is inserted into the breast by the radiologist. A ‘metal detector’ through magnetic technology (Fig. 3) is used by the surgeon in theatre to localise the impalpable lesion. The Magseed is made of surgical grade stainless steel and has no expiry date.
Radiologists are already familiar with placing markers into breasts at the time of biopsy of indeterminate lesions. The Magseed insertion technique is no different. It can be placed into the breast days in advance and women are not even aware of it. It is also an easy technique to learn for the surgeon.
Women can still have MRI breast with Magseed in situ, but there will be a small void artefact in their MRI scan. However, we are currently only using Magseed as a surgical localisation tool and all Magseeds will be removed.
The Magseed and Sentimag system has already been widely used internationally and interstate. COVID delayed its introduction to more women in Western Australia.
Radioactive seeds
There are other seed/marker technology available, and we have assessed them and found Magseed to be the most user and patient friendly.
For instance, radio-guided occult lesion localisation using Iodine-125 seeds (ROLLIS), is available as a hookwire alternative. However, it is a radioactive product that will decay and differing regulatory bodies have variable restriction to the number of days it can remain in situ. Radioactive seeds are also labour intensive to order and track and need to be disposed of safely by medical physics.
It is a major problem if a ROLLIS seed is lost and not retrieved in surgery. Whereas losing a Magseed is not an issue as long as the surgeon has resected the lesion in question.
Future developments
Magtrace is a suspension of magnetic particles. It is non-toxic, non-radioactive (unlike traditional Tc-99) and is without anaphylaxis risk of Patent Blue dye. Magtrace now has NICE recommendation and FDA approval for sentinel node localisation, an important part of breast cancer staging.
It allows the surgeon to inject up to seven days before surgery, improving scheduling efficiency, especially for cases booked on Monday mornings. We hope to start offering Magtrace in early 2023.
Key messages
- Screening has led to an increase in non-palpable lesions being detected
- Magseed and Magtrace represents the biggest shift in breast surgery for many years and will transform the operative day.
– References available on request
Author competing interests – nil