Purpose
This study aimed to explore the diagnostic performance of single photon emission computed tomography / computerized tomography (SPECT/CT) using a new radiotracer Tc-99m-RGD-BBN for breast malignant tumor compared with Tc-99m-3P4-RGD(2).
Methods
6 female patients with breast malignant tumors diagnosed by fine needle aspiration cytology biopsy (FNAB) who were scheduled to undergo surgery were included in the study. Tc-99m-3P4-RGD(2) and 99mTc-RGD-BBN were performed with single photon emission computed tomography (SPECT) at 1 hour after intravenous injection of 299 +/- 30 MBq and 293 +/- 32 MBq of radiotracers respectively at separate day. The results were evaluated by the Tumor to non-Tumor ratios (T/NT). Tc-99m-RGD-BBN and Tc-99m-3P4-RGD(2) SPECT/CT images were interpreted independently by 3 experienced nuclear medicine physicians using a 3-point scale system. All of the samples were analyzed immunohistochemically to evaluate the integrin alpha v beta 3 and gastrin-releasing peptide receptor (GRPR) expression. The safety, biodistribution and radiation dosimetry of Tc-99m-RGD-BBN were also evaluated in the healthy volunteers.
Results
No serious adverse events were reported in any of the patients during the study. The effective radiation dose entirely conformed to the relevant standards. A total of 6 palpable malignant lesions were detected using Tc-99m-RGD-BBN SPECT/CT with clear uptake. All malignant lesions were also detected using Tc-99m-3P4-RGD(2) SPECT/CT. The results showed that five malignant lesions were with clear uptake and the other one with barely an uptake. 4 malignant cases were found with both alpha v beta 3 and GRPR expression, 1 case with only GRPR positive expression (integrin alpha v beta 3 negative) and 1 case with only integrin alpha nu beta 3 positive expression (GRPR negative).
Conclusion
Tc-99m-RGD-BBN is a safe agent for detecting breast cancer. Tc-99m-RGD-BBN may have the potential to make up for the deficiency of Tc-99m-3P4-RGD(2) in the detection of breast cancer with only GRPR positive expression (integrin alpha(v)beta(3) negative). The preliminary application of Tc-99m-RGD-BBN has demonstrated its powerful potential in breast cancer diagnosis and therapy.