The AIM of this study was to determine the additional value of SPECT/CT in sentinel node scintigraphy in breast cancer. Furthermore, it was our question to determine, whether the low-dose computed tomography component (LD-CT) can be used for axillary lymph node staging of clinically negative patients.
Patients, methods: 51 patients with invasive breast cancer <3 cm in diameter were included in our prospective investigation. SPECT/CT was performed on a dedicated scanner 30 minutes after subareolar injection of (99m)Tc-Nanocoll. Axillary staging with CT(LD) was performed using standard CT-criteria. SLN were allocated to an axillary level using SPECT alone and SPECT/CT. Additionally, the number of SLN on CT(LD) corresponding to the scintigraphic hot node was notified for each patient and compared to the number of SLN found with the gamma probe.
Results: In 45/51 evaluable patients SLN could be localised in level I in 43 patients and in level II in two patients (all positive) using SPECT-CT, whereas a clear allocation could not be obtained by SPECT alone. The number of SLN was discrepant between SPECT and CT(LD) in 13/45 patients. The number of SLN detected with the gamma probe (n = 68) not significantly differed from the number of SLN detected by CT(LD) (n = 65) but was significantly higher than with SPECT (n = 51). CT(LD) yielded a sensitivity of 35.7%, a specificity of 83.9%, a positive predictive value (PPT) of 50%, a negative predictive value (NPV) of 74.3% and a diagnostic accuracy of 68.9% for axillary staging with CT(LD).
Conclusion: The additional information of SPECT/CT allows a more accurate characterization of the SN concerning size, depth and anatomical location. CT(LD) when performed during (99m)Tc-Nanocoll sentinel-SPECT/CT is not suitable for axillary staging in breast cancer patients with clinical negative axilla due to its low sensitivity and moderate specificity. Therefore, it does not influence the decision for SNB or ALND. The limited resolution of SPECT leads to an underestimation of the number of SLN compared to CT(LD) and the gamma probe.