The diagnostic role of 99mTc-dual receptor targeted probe and targeted peptide bombesin (RGD-BBN) SPET/CT in the detection of malignant and benign breast tumors and axillary lymph nodes compared to ultrasound.

OBJECTIVE: This study aimed to explore the diagnostic role of a new dual receptor-targeted probe, integrin ανβ3 and gastrin releasing peptide receptor (GRPR) targeted peptide Glu-c(RGDyK)-bombesin (RGD-BBN) labeled with technetium-99m ((99m)Tc-RGD-BBN), using single photon emission tomography/computed tomography (SPET/CT) in the detection of breast tumor in comparison to ultrasound (US).

SUBJECTS AND METHODS: One hundred and twenty six female patients with suspicious breast lesions who had already been scheduled for biopsy or surgery were enrolled in this study. All patients had previously underwent breast US and (99m)Tc-RGD-BBN SPET/CT. The US findings were evaluated according to the breast imaging report and the data system (BI-RADS). Technetium-99m-RGD-BBN SPET/CT images were interpreted independently by two experienced nuclear medicine physicians. A final diagnosis was made by histopathology of the specimens. A total of 130 lesions, 77 malignant and 53 benign lesions were ascertained. One hundred and twelve breast lesions, 69 malignant and 43 benign lesions were above 10mm in diameter and 18 breast lesions (8 malignant lesions and 10 benign lesions) were below 10mm. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of (99m)Tc-RGD-BBN SPET/CT and US for breast lesions were 93.5% vs. 81.8% (P<0.05), 79.2% vs. 75.5% (P>0.05), 86.7% vs. 82.9% (P>0.05), 89.4% vs. 74.1% (P<0.05) and 87.7% vs. 79.2% (P>0.05). Technetium-99m-RGD-BBN SPET/CT detected all lesions ≥10mm and US only detected 57 (P<0.05). In malignant lesions <10mm, US was superior than (99m)Tc-RGD-BBN SPET/CT (75.0% vs. 37.5%, P<0.05). There was no significant difference between the two methods no matter the size of the benign lesions. The overall sensitivity and specificity of (99m)Tc-RGD-BBN SPET/CT and US for axillae lymph nodes were 87.5% vs. 71.9% (P<0.05) and 77.6% vs. 68.9% (P>0.05), respectively. For the metastatic lymph nodes of <10mm, the sensitivity of (99m)Tc-RGD-BBN SPET/CT and of US was 88.5% and 72.1% respectively (P<0.05). Statistical analysis was not performed due to the small number of metastatic lesions of <10mm. The specificity of (99m)Tc-RGD-BBN SPET/CT and of US was not different, no matter the size of the axilla lymph nodes that had no metastases (P>0.05). Technetium-99m-RGD-BBN SPET/CT had higher sensitivity and NPV than US in detecting primary breast tumors and axilla lymph nodes and it also showed an advantage in distance metastatic lesions detection. On the contrary, specificity and PPV of the two methods were not different.

CONCLUSION: Technetium-99m-RGD-BBN SPET/CT cannot totally replace US in the detection of primary breast cancer and axillary lymph nodes metastases. It can be used as an additional imaging tool of eliminating the necessity of surgical biopsy and histopathologic examination because of its high NPV.