Positron emission mammography (PEM) in newly diagnosed breast cancer patients: Can it detect other occult breast lesions and tumor size accurately

Objective: To evaluate the added value of preoperative positron emission mammography (PEM) in detecting tumor multiplicity and size. Methods: Seventy-seven patients (80 pathologically proven malignant breast lesions) were included in this cross-sectional, single-site study. All cases underwent PEM in addition to standard diagnostic sono-mammography, core biopsy, and surgery. PUV max and lesion-to-background ratio (LTB) values were calculated for each lesion. Results: All patients had at least one breast mass detected during clinical examination or screening mammography. Three out of 77 patients had bilateral breast masses. One out of 77 patients presented with a mass post-conservative breast surgery (CBS). Five out of 77 patients had renal impairment. Histopathological assessment of the lesions revealed that 4/80 (5%) were DCIS, 64/80 (80%) were IDC, and 11/80 (13.8%) were ILC. One case out of the 80 (1.3%) presented with metastatic axillary adenocarcinoma with no detectable pre- or post-operative breast cancer. Regarding tumor multiplicity, there was almost perfect agreement (Kappa value = 0.827, P value < 0.001) between the results of PEM and the post-operative pathology results, while there was fair agreement (Kappa value = 0.401, P value < 0.001) between sono-mammography (SM) and the post-operative pathology results. Ten cases were diagnosed by SM as single or multifocal malignant lesions. PEM was performed and revealed multicentric malignant lesions. The surgical management was modified accordingly, and they underwent modified radical mastectomy (MRM). The post-operative pathology results confirmed multicentric disease. Six cases were diagnosed by SM as multifocal or multicentric disease. PEM was performed and revealed a single malignant mass only. MRM could be avoided, and CBS was performed. The post-operative pathology results confirmed a single mass. One case was diagnosed by SM as a single malignant mass. PEM was performed and revealed multifocal malignant masses. The surgical management was modified accordingly, and CBS was performed. The post-operative pathology results confirmed multifocal malignant masses. One case was diagnosed by SM as multicentric malignant masses. PEM was performed and revealed multifocal malignant masses. The surgical management was modified accordingly, and CBS was performed instead of MRM. The post-operative pathology results confirmed multifocal malignant masses. Regarding lesion size, PEM also showed substantial agreement with the post-operative pathology results (single-measure intra-class correlation = 0.724, P value < 0.001). SM revealed fair agreement (intra-class correlation = 0.275, P value < 0.006). Conclusion: PEM is a sensitive and specific imaging modality for diagnosing breast cancer. It also demonstrates great accuracy in detecting tumor multiplicity and estimating precise tumor size; therefore, its use prior to surgery should be considered. Clinical Relevance/Application: PEM is a problem-solving tool in the pre-operative local staging of breast cancer in patients with contraindications to undergo MRI.