Jacky Luiten

130 | Chapter 9 biopsy. Overall, only one third of all recalled microcalcifications proved (pre ‐ ) malignant, of which almost 70% consisted of DCIS [ this thesis, chapter 5 ]. Ongoing studies investigate the possibility of close surveillance of not only low grade but even intermediate grade DCIS. 22,23 A next step in de ‐ escalating treatment might be a better discrimination of microcalcifications based on radiologic features to prevent invasive biopsy for suspected low grade DCIS. MRI can improve the ability to detect DCIS and its local spread, especially high grade DCIS, and it can be useful for the diagnosis of a possible invasive component in patients initially diagnosed with pure DCIS. 24,25 MRI is a technique based on tissue contrast enhancement. In breast tissue, increased microvessel density or capillary permeability leads to contrast enhancement. 26 The vessel density is significantly higher in high grade DCIS compared to low grade DCIS which explains why MRI is more likely to detect high grade DCIS than low grade DCIS. 24,27,28 Kuhl et al . reported that 60% of the DCIS diagnosed by MRI only were high grade, suggesting that MRI helps to detect lesions that might more likely progress to high grade invasive carcinoma. 24 However, on the other hand, studies have shown that the use of MRI among DCIS patients increases the mastectomy rate and the use of routine MRI is therefore still controversial. 29 The aforementioned is in contrast to another recent study suggesting that preoperative MRI reduces positives surgical margins and repeat surgery for DCIS without a higher mastectomy rate. 30 At the moment MRI is not routinely implemented in the pre ‐ operative assessment of DCIS. Currently, it is not yet clear to which degree histologic features of DCIS can be estimated by the mammographic patterns of microcalcifications alone. Therefore, a minimally invasive SCNB is still considered mandatory in the workup of these lesions to date. 31 When DCIS is detected, and surgical excision is indicated, breast conserving surgery (BCS) rather than mastectomy may be the preferred surgical procedure. The goal of BCS is to perform a radical resection and thereby preserving the shape of the breast for a satisfactory cosmetic result. In order to perform an adequate resection intraoperative localization of small non ‐ palpable lesions is of utmost importance. Wire guided localization (WGL), introduced in 1965 by Dodd et al . 32 is worldwide still a frequently used localization technique. 33,34 In order to locate the lesion, a hook wire is placed under ultrasound or stereotactic guidance by a radiologist. An alternative localization technique is radioguided occult lesion localization (ROLL), which was first described by Luini et al . in 1998. 35 Prior to surgery (<24 hours) a small volume of radiolabeled technetium (Tc ‐ 99m) colloid is injected into the center of the lesion under stereotactic guidance. In 2001 Gray et al . described, a new technique using iodine ‐ 125 seed ‐ guided localization (I ‐ 125 GL). 36,37 This