Assessment of multifocality and axillary nodal involvement in early-stage breast cancer patients using 18F-FDG PET/CT compared to contrast-enhanced and diffusion-weighted magnetic resonance imaging and sentinel node biopsy

Background: Non-invasive evaluation of the extent of axillary nodal involvement in early-stage breast cancer (ESBC) patients and accurate assessment of multifocality are both challenging. Few reports have explored whether 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) might be more useful than other diagnostic methods in these contexts. Purpose: To prospectively evaluate the diagnostic utility of FDG PET/CT, contrast-enhanced, and diffusion-weighted magnetic resonance imaging (DCE-MRI and DWI), and sentinel lymph node biopsy (SNB), in detection of axillary metastatic lymph nodes in ESBC patients; and to explore the utilities of FDG PET/CT and DCE-MRI for identification of multifocality. Material and Methods: Twenty-four female patients (mean age, 47 +/- 9.9 years; range, 24-68 years) with ESBC underwent whole-body FDG PET/CT and breast MRI prior to operation. SNB and axillary lymph node dissection (ALND) were performed on all patients, as was mastectomy or wide local tumor excision. Histopathological findings served as the gold standard when evaluating either multifocality or axillary nodal involvement. Results: The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy, of PET/ CTand DCE-MRI, used to detect multifocality, were as follows: 67% versus 78%, 100% versus 53%, 100% versus 50%, 83% versus 80%, and 88% versus 63%. SNB afforded the highest sensitivity (93%) in terms of detection of axillary metastasis. The sensitivity, NPV, and accuracy of PET/CT were 67%, 62%, and 75% respectively, thus higher than the equivalent values of either DCE-MRI or DWI. Conclusion: For assessment of multifocality in ESBC patients, highly specific results of PET/CT should be taken into account along with DCE-MRI findings. For evaluation of axillary nodal involvement, PET/CT has higher sensitivity, NPV, and accuracy values than DCE-MRI and DWI and may guide a surgical decision to proceed or not to SNB or ALND.