Interventional MRI of the breast: lesion localisation and biopsy

With the growing use of breast MRI an increasing need exists for reliable M R-guided preoperative localisation or even MR-guided needle biopsy. In this article an overview is given of the different ap approaches and the presen t state of the art. With closed magnets the following approaches have been made: freeband localisation (similar to CT-guided freehand localisation), a nd freehand localisation combined with a frameless stereotaxic system opera ting with support by ultrasound. One localisation device for supine localis ation and a thermoplastic mesh for breast stabilisation have been reported. Most investigators ve used compression devices to immobilise the east and prevent shift during needle insertion. Thus far, one immobilisation and aim ing device has een designed for open magnets. A small number of experiences exist with interventions on open MR units using a navigation system. Wire localisations are presently a well-established procedure. Magnetic-resonanc e-guided needle biopsy has been accomplished in closed systems as well as b y the use of breast immobilisation devices. However, problems still exist d ue to severe needle artefacts, tissue shift during the intervention and fas t equalisation of contrast enhancement in lesions with surrounding tissue. Therefore, needle biopsy is not recommended for lesions < 10 mm. Magnetic-r esonance-guided vacuum biopsy is somewhat more invasive but promises to sol ve most of these problems.