Etil

Figure 4-11. Local anesthetic injection, skin incision with an 11-blade scalpel followed by insertion of vacuum-assisted probe into the skin, in preparation for biopsy.

depth (Figure 4-11). Prefire stereo images assess the alignment of the probe with the microcalcifications. The driver is designed with a spring-loaded mechanism to permit automated advancement of the probe through the breast tissue. The sampling notch may be positioned within the breast by the automated forward movement of the probe, or it can be manually aligned with the lesion by taking the driver to the appropriate depth with the probe already in its full excursion. The alignment of the sampling notch with

Figure 4-12. The vacuum assisted probe may be used for directional sampling. In this example, the majority of samples will be taken between 3:00 and 9:00 through the 6:00 position.

the lesion is confirmed with postfire (alignment) stereo images (Figure 4-12). A vacuum pulls breast tissue into the sampling notch, and the cutter is advanced across the sampling notch, cutting the tissue free from inside the breast. The tissue sample is removed from the specimen retrieval chamber. The entire process is then repeated. The number of biopsy samples taken is based on the size of the lesion and the volume of tissue desired. On average, approximately 12 to 16 tissue samples are obtained for a small cluster of microcalcifications, frequently resulting in removal of the entire mammographie evidence of the lesion. The vacuum assistance provides several advantages. It eliminates the need for pinpoint accuracy required with automated Tru-cut biopsy instruments and facilitates removal of multiple tissue samples without removal of the biopsy probe.42 In addition, the notch may be positioned for specific directional sampling, on the basis of the alignment of the probe notch with the lesion. The larger tissue samples provide a greater chance

Figure 4-12. The vacuum assisted probe may be used for directional sampling. In this example, the majority of samples will be taken between 3:00 and 9:00 through the 6:00 position.

of lesion removal and a greater percentage of positive specimen radiographs (Figure 4-13). Burbank and Jackman have demonstrated that the improved accuracy with the directional vacuum-assisted biopsy device decreases the upgrading of diagnosis seen with core-needle biopsy.44,45 Burbank showed that the 14-gauge device provided no upgrading of atypical ductal hyperplasia to carcinoma at open biopsy. Jack-man compared 14-gauge vacuum-assisted device to 14-gauge core-needle biopsy and illustrated a reduction of upgrading of atypical ductal hyperplasia from 48 to 18 percent. Post-procedure imaging yields a well-defined air-contrast cavity in the majority of cases. The 11-gauge core probe also allows a marker clip to be placed in the wall of the biopsy cavity to assist in the localization of the area in the future when all evidence of the lesion has been eliminated.46 This marker clip and/or the residual cavity may be localized if the diagnosis requires further surgical management. The complication rate for the device is less than 1 percent, which is comparable to core-needle biopsy.7,42 Ecchymosis of the skin at the insertion site is common as well as intraparenchymal hemorrhage localized to the biopsy cavity, but clinically significant hematomas that interfere or complicate subsequent surgery or follow-up are rare.

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