Comparison of BSGI and MRI as Approaches to Evaluating Residual Tumor Status after Neoadjuvant Chemotherapy in Chinese Women with Breast Cancer

Abstract

Background: The present retrospective study was designed to evaluate the relative diagnostic utility of breast-specific gamma imaging (BSGI) and breast magnetic resonance imaging (MRI) as means of evaluating female breast cancer patients in China.

Methods: A total of 229 malignant breast cancer patients underwent ultrasound, mammography, BSGI, and MRI between January 2015 and December 2018 for initial tumor staging. Of these patients, 73 were subsequently treated via definitive breast surgery following neoadjuvant chemotherapy (NAC), of whom 17 exhibited a complete pathologic response (pCR) to NAC.

Results: BSGI and MRI were associated with 76.8% (43/56) and 83.9% (47/56) sensitivity (BSGI vs. MRI, p = 0.341) values, respectively, as a means of detecting residual tumors following NAC, while both these approaches exhibited comparable specificity in this diagnostic context. The specificity of BSGI for detecting residual tumors following NAC was 70.6% (12/17), and that of MRI was 58.8% (10/17) (BSGI vs. MRI, p = 0.473).

Conclusion: These results demonstrate that BSGI is a useful auxiliary approach to evaluating pCR to NAC treatment.

Keywords: breast cancer; breast-specific gamma imaging (BSGI); magnetic resonance imaging (MRI); neoadjuvant chemotherapy (NAC); residual tumor size.

Figure 1

Bland–Altman plots compare maximal residual diameter between BSGI and MRI exhibited following NAC. (A) Before NAC. Dashed line indicates the mean difference between two methods, solid lines indicate the limits of the agreements (1.96 standard deviations of the mean difference). (B) After NAC. Dashed line indicates the mean difference between two methods, solid lines indicate the limits of the agreements (1.96 standard deviations of the mean difference).

Figure 2

Breast scans from a 53-year-old woman. (A) Pathologic findings revealing DCIS (×100), necrotic tumor cells, and interstitial fibrosis (Miller-Payne grade 5, pCR). (B) MRI scans revealed non-mass enhancement in the left breast; efficacy evaluation was PD. (C) BSGI revealed clear evidence of abnormal radiotracer uptake in the left breast (maximum T/N = 1.67). (D) BSGI revealed a significant increase in abnormal ^99mTc-sestamibi foci in the left breast, consistent with metabolic disease progression (maximum T/N = 2.41; PD).