Patterns of positron emission mammography uptake by benign and malignant breast lesions: radiopathological correlation with malignant histopathological subtypes, histological grades, and molecular subtypes.

purposeIn the new era of nuclear breast imaging, differentiating benign from malignant uptake in the breast is essential in guiding clinical management. Accordingly, we aimed to assess the pattern of PEM uptake in benign and malignant breast lesions and to investigate its correlation with different histopathological subtypes, histological tumor grades, and molecular subtypes.

methodsThis was a prospective study comprised of 337 women with 465 breast lesions, of whom 128 patients had bilateral breast lesions. All patients performed Positron Emission Mammography (PEM) from March 2022 to February 2024. Any abnormality was evaluated qualitatively (mass and non-mass enhancement ) and quantitatively ( PUVmax and LTB ratio). The PEM readings were correlated with final pathology to differentiate benign from malignant lesions, and receiver operating characteristic (ROC) curve analysis was performed to assess the discriminant ability of PUVmax and LTB ratio in distinguishing histopathological groups, histological grades, and molecular subtypes.

resultsAccording to the final pathology, 330 (71%) lesions were malignant, and 135 (29%) were benign. The ROC curve analysis showed cutoff values of 1.92 and 3.145 for PUVmax and the LTB ratio, respectively, to discriminate between benign and malignant breast lesions. Significant differences in PUVmax and LTB ratio were detected between benign lesions and histopathological types, grades, and molecular malignant subtypes. The cutoff values for PUVmax and LTB ratio from benign were 1.81 and 3.165 for Ductal carcinoma in situ, 2.09 and 3.55 for invasive duct carcinoma (IDC) 1.62 and 2.8 for invasive lobular carcinoma,1.92 & 3.165 for grade I, 1.935 & 3.145 for grade II & III tumors, 1.92 and 3.145 for luminal molecular subtype, 1.95 and 3.45 for HER 2 subtype, and 2.28 and 4.27 for the triple-negative subtype respectively. The lesions with irregular shapes, uncircumscribed margins, and segmental non-mass distribution have higher PUVmax and LTB ratios.

conclusionsPEM is a valuable imaging modality for distinguishing between benign and malignant breast lesions. PEM may enable stratification of malignant lesions by histopathological subtype, tumour grade, and molecular subtypes. The highest metabolic activity was observed in invasive duct carcinoma, grade III, and the triple-negative molecular subtype. Overall, PEM can provide in vivo evaluation of breast lesion metabolic activity, leading to better lesion characterization and individualized patient management. However, due to methodological constraints, subgroup sample size, and radiation exposure, PEM should be regarded as an adjunct to sonomammography rather than a primary screening imaging modality.