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UCLA School of Medicine Eisenberg Keefer Breast Center Santa Monica, CA 90404-2032
In their carefully reported experience, Morris et al. [1] introduce the rationale for their study by noting, "Few data address MR imaging—guided needle localization for surgical excision," and citing five references. Even fewer data will be reported when literature searches are not completely performed.
Although two of the five references are from European journals, the authors [1] omitted a consideration of a different approach, described in 1995 in the British Journal of Radiology [2], which may be of particular value to readers who require MR imaging—guided localization of lesions identified in their own practices. Institutions that do not use screening MR imaging to the extent that Morris's group does and that may not have special MR localizing equipment (even though commercially available) have the option of a simple freehand localization technique described in 1995—as did the group of patients reported by Lee et al. [3] in the AJR. Even those radiologists whose facilities have commercially available units may encounter difficulties with medial lesions, as described by Morris et al., and may find the freehand approach preferable.
Perhaps inadvertently, literature reviews sometimes fail to include important alternative approaches [4] to subjects of discussion. Like others, I appreciate the experience shared by Morris et al. but encourage readers to be cognizant of potential limitations inherent to any perspective, including this one.
References
Memorial Sloan-Kettering Cancer Center New York, NY 10021
We thank Dr. Brenner for his comments regarding our recent article [1] and for giving us the opportunity to discuss and elaborate on several points for readers. The purpose of our work was to evaluate a commercially available system and to show that it can be used successfully for breast MR imaging localization with good accuracy. Brenner's reference [2] was concerned with the use of a freehand technique and reported a single case. Our references included only those published reports of experience with using grid systems for localizations on multiple patients. Most series have reported using some type of grid system because a grid allows greater accuracy and requires less time repositioning the needle compared with freehand techniques.
However, we do not wish to leave the impression that there is only one way to perform MR imaging—guided needle localizations. As with mammographic needle localizations, the technique used is often at the preference of the radiologist and operating surgeon. For this reason, we referred to several approaches in our article. It is certainly possible to perform localizations using a freehand approach; however, the published experience with this method in closed systems is extremely limited. Most radiologists use the freehand approach as a last resort or when they first start performing MR imaging—guided procedures. Most of the institutions cited by Brenner now favor a grid-based system, reserving the use of freehand localization for lesions outside the margins of the localizing grid. In fact, Brenner states in his report [2] that "as special grids become available with adapted techniques, alternative approaches toward localization are likely to be introduced into clinical practice."
Brenner rightly points out that radiologists who do not perform a high volume of MR imaging examinations of the breast and do not have a commercially available biopsy system may want to consider the freehand approach. However, the approach he advocates is not without limitations. In Brenner's case report [2], the patient was placed in a shoulder coil, which may not provide resolution equivalent to that of the breast coil. Additionally, the patient was removed from the imaging coil and the bore of the magnet three times for repositioning of the needle while having to position herself on her elbows. This maneuvering increases the likelihood of motion as the patient and her nonstabilized breast move in and out of both the magnet and the breast coil. Furthermore, these types of maneuvers lengthen the duration of the needle localization procedure, which can complicate matters when contrast washout causes the lesion to become a vanishing target. For the novice, these are not insignificant considerations.
Brenner also rightly points out that literature searches often lack inclusion of alternative approaches, which is particularly true now that there are limits on bibliography size. For example, Daniel et al. [3] at Stanford University have had excellent results using a freehand approach with real-time imaging. This approach was not discussed in our article because it requires an open magnet with specialized real-time monitoring, whereas most radiologists in practice operate in a closed MR imaging environment. For these reasons, when imaging and localization are performed with a closed magnet, we advocate using a grid system with an open imaging coil to optimize the accuracy of needle placement.
References
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