F-18 FDG PET/CT, breast MRI and mammography: Can breast cancer be reliably detected?

Abstract

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Objectives: F-18 FDG PET/CT is a powerful imaging modality for cancer diagnosis, staging and establishing response to therapy, including breast cancer (BC). Breast MRI (BMRI) is gaining a major role in the management of high risk BC patients, adding information when mammography findings are equivocal. The role of PET/CT in addition to mammography and BMRI in BC diagnosis is not completely elucidated. Therefore, we were prompted to review our experience with mammography, BMRI and PET/CT in BC.

Methods: This is a retrospective study of 101 women with BC, 30-82 years-old (average: 56.1±12.1), who had F-18 FDG PET/CT at our institution from Jan 2003 to Jun 2005. Of these, 27 patients also had mammography and BMRI. Reinterpretation of the studies for accuracy and data analysis from medical records were performed. Sensitivity and specificity were calculated using a 2 x 2 table with pathology results (84.1% of the patients) or clinical follow-up (15.9% of the cases) as the gold standard.

Results: The tumor types in the 85 patients with available pathology reports were: 68 ductal (41 infiltrative, 22 invasive, 5 in situ), 11 lobular (5 infiltrative, 6 invasive), 4 adenocarcinomas and 2 mucinous carcinomas. Tumor size at cancer presentation ranged 0.8-10.0 cm (average: 2.8±1.9) for all the patients and 1.9-9.0 cm (average: 3.72±1.8) for the patients that had PET/CT at initial presentation. PET/CT sensitivity was 79.2 % (95% CI: 59.5-90.7) for breast disease, 68.2% (95% CI: 47.3-83.6) for axilla and 94.1% (95% CI: 80.9-93.3) for distant metastases. Specificities were 98.7% (95% CI: 93-99.8), 100% (95% CI: 95.3-100) and 91% (95% CI: 81.8-95.8), respectively. For the 27 patients with all 3 exams, sensitivities and specificities for BC detection were 69.2% (95% CI: 42.3-87.3) and 77.8% (95% CI: 45.3-93.7) for mammography, 80% (95% CI: 54.8-92.9) and 91.7% (95% CI: 64.6-98.5) for BMRI, and 71.4% (95% CI: 45.3-88.3) and 92.3% (95% CI: 66.7-98.6) for PET/CT.

Conclusions: Our results suggest a good performance for PET/CT in identification of BC and distant metastases in this patient population. However, the sensitivity of PET/CT for axillary staging is limited, despite excellent specificity. BMRI appears more sensitive than PET/CT and mammography in the detection of breast lesions, probably due to higher resolution. The specificities of BMRI and PET/CT are similar, outperforming mammography. In addition, PET/CT as a whole body examination detected axillary and distant metastases in 9 (33.3%) of the 27 patients. Thus, PET/CT should be used as a complimentary imaging tool in the evaluation of patients with locally advanced BC, since a whole body staging can be achieved in a single exam.