Usefulness of breast-specific gamma imaging as an adjunct modality in breast cancer patients with dense breast: a comparative study with MRI.

OBJECTIVE: The aim of this study was to evaluate the adjunctive benefits of breast-specific gamma imaging (BSGI) versus magnetic resonance imaging (MRI) in breast cancer patients with dense breasts.

METHODS: This study included a total of 66 patients (44.1 ± 8.2 years) with dense breasts (breast density >50%) and already biopsy-confirmed breast cancer. All of the patients underwent BSGI and MRI as part of an adjunct modality before the initial therapy. Of 66 patients, the 97 undetermined breast lesions were newly detected and correlated with the biopsy results.

RESULTS: Twenty-six of the 97 breast lesions proved to be malignant tumors (invasive ductal cancer, n = 16; ductal carcinoma in situ, n = 6; mixed or other malignancies, n = 4); the remaining 71 lesions were diagnosed as benign tumors. The sensitivity and specificity of BSGI were 88.8% (confidence interval (CI), 69.8-97.6%) and 90.1% (CI, 80.7-95.9%), respectively, while the sensitivity and specificity of MRI were 92.3% (CI, 74.9-99.1%) and 39.4% (CI, 28.0-51.7%), respectively (p < 0.0001). MRI detected 43 false-positive breast lesions, 37 (86.0%) of which were correctly diagnosed as benign lesions using BSGI. In 12 malignant lesions <1 cm, the sensitivities of BSGI and MR imaging were 83.3% (CI, 51.6-97.9%) and 91.7% (CI, 61.5-99.8%), respectively.

CONCLUSION: BSGI showed an equivocal sensitivity and a high specificity compared to MRI in the diagnosis of breast lesions. In addition, BSGI had a good sensitivity in discriminating breast cancers ≤1 cm. The results of this study suggest that BSGI could play a crucial role as an adjunctive imaging modality which can be used to evaluate breast cancer patients with dense breasts.