Breast imaging with positron emission tomography and fluorine-18 fluorodeoxyglucose: Use and limitations

Purpose: To evaluate the diagnostic value of positron emission tomography ( PET) using fluorine-18 fluorodeaxyglucose (FDG) for the diagnosis of primar y breast cancer. Patients and Methods: Preoperatively, 144 patients with masses suggestive o f breast cancer underwent PET imaging of the breast. To identify breast can cer by increased metabolic activity, parametric FDG-PET images were analyze d for increased tracer uptake applying conventional image reading (CIR) and sensitive image reading (SIR). One hundred eighty-five breast tumors were evaluated by histology, revealing 132 breast carcinomas and 53 benign masse s. Results: breast carcinomas were identified with an overall sensitivity of 6 4.4% (CIR) and 80.3% (SIR). The increase in sensitivity (SIR) resulted in c t noticeable decrease in specificity, from 94.3% (CIR) to 75.5% (SIR). At s tage pT1, only 30 (68.2%) of 44 breast carcinomas were detected, compared w ith 57 (91.9%) of 62 at stage pT2. A higher percentage of invasive lobular carcinomas were false-negative (65.2%) compared with invasive ductal carcin omas (23.7%). Nevertheless, positive PET scans provided a high positive-pre dictive value (96.6%) for breast cancer. Conclusion: Partial volume effects and varying metabolic activity (dependen t on tumor type) seem to represent the most significant limitations for the routine diagnostic application of PET. The number of invasive procedures i s therefore unlikely to be significantly reduced by PET imaging in patients presenting with abnormal mammagraphy. However, the high positive-predictiv e value, resulting from the increased metabolic activity of malignant tissu e, may be used with carefully selected subsets of patients as well as to de termine the extent of disease or to assess therapy response. (C) 2000 by Am erican Society of Clinical Oncology.