Background ^99mTc-methoxyisobutylisonitrile uptake of breast-specific gamma imaging in relation to background parenchymal enhancement in magnetic resonance imaging

Results: Heterogeneous texture and high background uptake ratio on BSGI were significantly correlated with younger age (p < 0.001, respectively), premenopausal status (p < 0.001 and p = 0.003), dense breast (p < 0.001, respectively), and marked BPE (p < 0.001, respectively). On multivariate analysis, only BPE remained a significant factor for background MIBI uptake (p < 0.001).There was a significant reduction in positive predictive value (p = 0.024 and p = 0.002) as background MIBI uptake and BPE grade increased.

Objectives: This study investigated factors that could affect background uptake of ^99mTc- methoxyisobutylisonitrile (MIBI) on normal breast by breast-specific gamma imaging (BSGI). In addition, the impact of background ^99mTc-MIBI uptake on the diagnostic performance of BSGI was further investigated.

Methods: One hundred forty-five women with unilateral breast cancer who underwent BSGI, MRI, and mammography were retrospectively enrolled. Background uptake on BSGI was evaluated qualitatively and quantitatively. Patients were classified into non-dense and dense breast groups according to mammographic breast density. Background parenchymal enhancement (BPE) was rated according to BI-RADS classification. The relationship of age, menopausal status, mammographic breast density, and BPE with background ^99mTc-MIBI uptake was analyzed.

Conclusions: BPE on MRI was the most important factor for background MIBI uptake on BSGI. High background MIBI uptake or marked BPE can diminish the diagnostic performance of BSGI.