You are in: eMedicine Specialties > Radiology > BREAST Breast, Needle LocalizationArticle Last Updated: Feb 29, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 9
  Author: William Teh, MB, ChB, FRCR, Clinical Director, Department of Radiology, Northwick Park Hospital, UK William Teh is a member of the following medical societies: British Institute of Radiology, British Medical Association, and Royal College of Radiologists Coauthor(s): Hemant Singhal, MD, MBBS, FRCSE, FRCS(C), Senior Lecturer, Department of Surgery, Imperial College School of Medicine, UK; Consultant Surgeon, Northwick Park and St Marks Hospitals, UK Editors: John M Lewin, MD, Section Chief, Breast Imaging, Diversified Radiology of Colorado, PC; Associate Clinical Professor, Department of Preventative Medicine and Biometrics, University of Colorado Denver; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Edward Azavedo, MD, PhD, Director of Clinical Breast Imaging Services, Associate Professor, Department of Radiology, Karolinska University Hospital, Sweden; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Lawrence M Davis, MD, Assistant Professor of Diagnostic Imaging (Clinical), Department of Diagnostic Imaging, Warren Alpert Medical School at Brown University Author and Editor Disclosure Synonyms and related keywords: wire localization, guidewire localization, localization biopsy, hookwire breast localization, hook-wire breast localization INTRODUCTIONSection 2 of 9
  BackgroundThis article discusses the techniques applicable to the localization of breast lesions. As breast cancer screening with mammography increases, many impalpable breast lesions are being detected. These lesions should first and foremost be definitively diagnosed by using image-guided needle biopsy. After needle biopsy, some of these lesions may require diagnostic or therapeutic surgical biopsy. If a malignant or indefinite diagnosis is obtained, surgical excision is indicated. This, in turn, requires accurate localization of the lesion. Good accuracy of such localizations is required to ensure correct and adequate removal of the lesions and to minimize the degree of cosmetic disfigurement.1 For excellent patient education resources, visit eMedicine's Cancer and Tumors Center. Also, see eMedicine's patient education articles Mammogram and Breast Cancer. Preferred ExaminationThe modality of choice depends on operator expertise and the type of lesion. Most palpable lesions do not require image-guided localization. Breast lesions that are visible with ultrasonography can be adequately localized by using a skin marker if the lesion lies fairly superficially within the breast.2 In addition, a surgeon can easily perform ultrasonographic localization in the operating room to identify the lesion and to confirm its adequate removal.3, 4 Other localization techniques include magnetic resonance imaging (MRI) and mammography (by using a grid, a holey plate, or a stereotactic method).5, 6 Although a number of techniques are used to localize nonpalpable breast lesions, needle localization is the most common.7, 8, 9 After successful placement, the patient is then taken to the operating room, where the surgeon commonly makes an incision at the site of the wire insertion and excises the wire and the lesion. Some surgeons place a stiff outer cannula along the wire down to the wire tip and excise the tip along with the lesion. Impalpable lesions may also be marked by using an injection of methylene blue,10, 11 charcoal suspension,12 or radioisotopes.13 It is essential to obtain a diagnosis with a core biopsy under ultrasonographic or stereotactic guidance before surgery so that a definitive, 1-step surgical procedure can be planned. Once malignancy is diagnosed, any of the following procedures can be used to localize the lesion:
See also the following related eMedicine topics: Limitations of TechniquesAll methods are subject to potential inaccuracies.14 It is important to confirm the correct placement of the guidewire. Ultrasonographic and mammographic wire localizations can be followed by mammography performed in 2 planes (eg, lateromedial and craniocaudal projections) to confirm that the correct lesion has been accurately targeted. Ideally, the guidewire should transfix the lesion on both projections (see Image 1). The tip of the guidewire should ideally be placed within 1 cm of the target lesion. Guidewires may be dislodged or may migrate prior to surgery. Complications, including pneumothoraces, have been described. Wire fragments may also be retained following surgery. Published literature show that the rate of needle-localization failure is in the range of 0-20%. Factors associated with failure include the following15, 16, 17:
RADIOGRAPHSection 3 of 9
FindingsTechniques that involve mammography usually require the upright mammographic attachment on a normal mammographic unit, although localizations with stereotactic prone tables also have been described. Before stereotaxy came into use, a grid (see Image 2) or holey plate was used to calculate the position of needle placement in the X and Y planes. The depth was calculated from the lateromedial projection. The position was then checked according to the superimposition of target, hub, and shaft of the needle, and the required depth was verified on the orthogonal view (see Image 3). Stereotaxy enables the exact position to be located. The needle is then placed 1 cm beyond the lesion to ensure that it is adequately transfixed. Because of the accordion effect (the thickness of the breast expands when compression is released), the needle tip may migrate, causing the needle to be placed short of the lesion.18 The final depth of the needle is therefore checked on the orthogonal view to ensure that the lesion is adequately transfixed. Different needles exist, and most are introduced by using a stiffer, co-axial needle. Some needles are then removed, leaving the wire in situ. The wires commonly have a barb or hook that is deployed in the final position to anchor the wire in place. Some needles require the outer cannula to be retained in situ. The choice of needles and wires used are dictated by the preference of the radiologist and the surgeons. After surgical removal of the lesion, specimen radiography must be performed to ensure that the lesion was adequately excised (see Image 4). MRISection 4 of 9
FindingsThe use of MRI localization reflects the increasing use of magnetic resonance mammography. Although a portion of MRI-depicted lesions can subsequently be localized with ultrasonography, some of them are mammographically and ultrasonographically occult, which means that they require MRI-guided needle biopsy or localization.5, 19 All of the major manufacturers of MRI units have made biopsy attachments available; these require the patient to be kept in a semiprone position. MRI is then performed with the intravenous administration of a gadolinium-based contrast agent, and the lesion is localized by using MRI-compatible localization needles. The correct placement of the needle can be confirmed by obtaining a T2-weighted MRI to verify the signal void to transfix the lesion. Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or magnetic resonance angiography (MRA) scans. Technical difficulties and challenges include the tendency of the MRI-visible lesion to fade over time (because enhancement with contrast material is transient).5 In addition, because of the amount of time required to perform the procedure (30-60 min), the patient may begin to move, which could cause an error in needle placement. Nevertheless, MRI localizations have generally been as accurate as mammographic localizations, with miss rates of 2-9%. Some have suggested that postoperative MRI should be performed to verify complete excision of the lesion. ULTRASOUNDSection 5 of 9
FindingsWhen the lesion is visible, ultrasonography is the modality of choice for needle placement. It provides the advantage of real-time imaging, allowing accurate placement of the needle. Being able to directly visualize the lesion and needle position results in a quicker procedure, reducing the risk of patient morbidity. As in mammographic techniques, the lesion must be transfixed, and orthogonal mammography can be used to confirm that the correct lesion has been localized. The use of intraoperative ultrasonography by the surgeon in the operating theatre, as well as the employment of skin marking, is described in Preferred Examination. NUCLEAR MEDICINESection 6 of 9
FindingsNuclear medicine study was originally used for sentinel lymph node biopsy. Colloidal albumin labeled with technetium-99m (99mTc) is injected directly into the lesion under stereotactic or ultrasonographic guidance.13 The accuracy of isotope placement is checked with scintigraphy. Excision biopsy is then performed by using a gamma probe. After excision, the excised lesion and the cavity are checked for radioactivity, and the specimen is radiographed to ensure the radiographic adequacy of the excision. Measured doses to the breast and to the surgeon's hand appear to be negligible (0.03 ± 0.02 mGy/MBq and 7.5 ± 5.0 µSv/h, respectively). Degree of ConfidenceResults from a study of 67 consecutive patients showed complete removal of the lesion in 99.5% of them. Thus, this technique is accurate and at least comparable to conventional wire localization.20 INTERVENTIONSection 7 of 9
The amount of tissue that is excised is dependent on the nature of the surgical procedure. If a diagnostic procedure is performed, a small volume of tissue is removed so that histologic diagnosis can be achieved with minimal scarring. When surgery is performed to treat malignant disease, the aim is to excise the lesion with a clear margin in order to minimize the risk of local recurrence.13 MULTIMEDIASection 8 of 9
REFERENCESSection 9 of 9
Breast, Needle Localization excerpt Article Last Updated: Feb 29, 2008 | ||||||||||||||||||||||||||||||||||||||||||
