Multicenter prospective study of dedicated breast positron emission tomography (dbPET) for breast cancer: examination in preoperative patients.

[BACKGROUND] Dedicated breast positron emission tomography (dbPET) was developed to detect breast cancers smaller than those detectable using whole-body PET (wbPET). Although several studies have explored the use of dbPET, clear criteria for identifying which patients would benefit most from this modality are lacking. Our objective was to determine which patient groups would benefit most from dbPET and how it should be utilized. We conducted a multicenter, prospective exploratory study to investigate how the dbPET maximum standardized uptake values (SUVmax) correlate with patients' clinical characteristics, other imaging modalities, and pathological findings of the lesions.

[METHODS] In total, 219 patients with breast cancer (median age [range], 58.0 [30-83] years) were included in this study. The enrolled patients were divided into three groups (primary care, neoadjuvant therapy, postoperative follow-up patients). In this research, we examined the primary care group (n = 92). To investigate which patient groups benefit from dbPET, we examined which factors influence and correlate with dbPET SUVmax. Depending on the items being compared, correlation analysis, Wilcoxon signed rank test was used to examine the following items. Which factors (physical factors, pathological characteristics, etc.) correlate with dbPET SUVmax, differences between dbPET and other imaging examination (detection rate, etc.), and whether dbPET SUVmax L/H ratio (Lesion-to-Healthy (normal) site dbPET SUVmax ratio) incorporating dbPET SUVmax from healthy (normal) mammary gland tissue are necessary for evaluating dbPET SUVmax in lesion areas.

[RESULTS] dbPET SUVmax in healthy(normal) mammary gland tissue were strongly associated with background mammary density observed on mammography (MMG) examination (positive correlation, p<0.05). Ki-67 showed the strongest positive correlation with both the lesion-site dbPET SUVmax (r=0.56, R=0.31, p<0.05) and the dbPET SUVmax L/H ratio (lesion-to-healthy (normal) -site ratio) (r=0.47, R=0.22, p<0.05). Additionally, the tissue grade, MMG and ultrasonography categories were positively correlated with dbPET SUVmax. Regarding the lesion detection rate, dbPET identified 100% of the lesions, including benign findings. The dbPET SUVmax L/H ratio showed a trend nearly identical to that of the dbPET SUVmax.

[CONCLUSIONS] dbPET demonstrated higher detection capabilities than other imaging tests and showed a strong correlation with tissue malignancy. Therefore, they were suggested to be potentially useful for distinguishing benign findings from malignant lesions that are difficult to differentiate using other imaging tests. The dbPET SUVmax of healthy mammary gland tissue were presumed to correlate with the amount of mammary gland tissue within the breast. However, no significant differences were observed in the correlations between the dbPET values and the L/H ratio and the individual parameters. In this study, it remained unclear whether the dbPET values of normal breast tissue should be taken into account when evaluating dbPET values.