Breast sentinel node imaging with low-dose SPECT/CT.

OBJECTIVE

The critical factors in quality control for breast sentinel lymph node (SLN) biopsy are the SLN identification rate and the false-negative rate. Earlier reports have not formalized indications for use of single-photon emission computed tomography/computed tomography (SPECT/CT) lymphscintigraphy. In view of the potential advantages of the dual nature of structural and functional imaging of SPECT/CT, this study reports the false-negative rate resulting from nonvisualization of SLNs on SPECT/CT.

METHODS

One hundred and eighty-seven consecutive female patients (age range: 30-87 years) with biopsy proved breast carcinoma (18 lobular, 159 ductal carcinomas, two mucinous carcinomas and eight ductal carcinoma in situ) were injected with 40 MBq of 99mTc sulphur colloid, and underwent SPECT/CT scanning 45 min later.

RESULTS

Tracer uptake in the largest SLNs could be assessed in 158 patients. Two patients had SLNs close to the site of periareolar injection; the remaining SLNs were located in the ipsilateral axillae. Five patients had two or more SLNs identified on SPECT/CT. Twenty-nine patients (15.5%) had no SLNs identified on SPECT/CT; of these, 10 patients had metastatic infiltration confirmed peroperatively. This equates to an overall false-negative rate for SPECT/CT of 5.3% (expressed by convention, as percentage of total patient number).

CONCLUSION

SPECT/CT lymphscintigraphy readily shows SLNs preoperatively and is practical in a clinical setting on patients without specific selection criteria. The false-negative rate may encourage more widespread use of this technique.