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L Lateral Anten or LAO

Figure 3. Sentinel node imaging in a patient with breast cancer. The peritumoral injection site of 99mTc-sulfur colloid is seen as an area of intense activity. Sentinel nodes are seen in the internal mammary chain (arrow) and axilla (arrowhead). (Courtesy of Dr. R. Kloiber, Foothills Hospital, Calgary, Canada.)

sentinel nodes has been as high as 90% (up to 100% in one series of 34 patients). Experience appears to be important to successful imaging.

The technique is now becoming standard of care in many breast centers allowing a decrease in the axillary node dissection rate; the effectiveness of this technique in improving survival or disease free interval is not established.

FDG Imaging

Although the role of FDG imaging in breast cancer is still being defined, indications will probably include detection of recurrence and monitoring treatment response. It may also have a role in the initial staging. Although sensitivities as high as 80-100% have been reported in the visualization of primary breast cancer, the effectiveness of morphological techniques, scintimammography and fine needle aspiration mean that PET is less likely to have a major role in this setting.

Staging

For staging, PET imaging offers the ability to detect involvement of both the axillary and internal mammary chains. While axillary node dissection—perhaps in conjunction with sentinel node imaging—remains the standard for staging the axilla, there are no effective tests for evaluating the internal mammary chains. Sensitivities of 85-100% have been reported in most large series for detecting nodal metastases (Fig. 4); specificity is somewhat lower, typically 65-90%. Although some authors have suggested that a negative PET scan of the axilla can be used to exclude axillary lymph node dissection, microscopic disease and lesions less than 7-10 mm will be missed. Distant metastases in the small percentage of patients who present with Stage IV disease will be accurately demonstrated.

Recurrence

Several studies have shown PET to be more accurate than CT or MRI in detecting local recurrence, locoregional lymph node metastases and distant metastases; a high sensitivity in detecting osteolytic metastases has also been claimed. In a patient with

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