Sentinel Lymph Node Identification in Breast Cancer - Comparison of Planar Scintigraphy and SPECT/CT

Aim: Assess the role of planar lymphoscintigraphy and fusion imaging of SPECT/CT in sentinel lymph node (SLN) identification in patients with breast cancer. Methods: Planar scintigraphy and hybrid modality SPECT/CT were performed in 223 consecutive women with breast cancer (mean age 59,5 yrs with range 25 - 82 years). In 190 women with a palpable mass radiocolloid was injected in four peritumoral sites and one subdermal injection above the tumour (GROUP A), in 33 women with nonpalpable tumour radiotracer was injected in four subareolar sites (GROUP B). Planar and SPECT/CT images were interpreted separately by two nuclear medicine physicians. Ability of these two techniques to image SLN was compared. Results: In GROUP A the overall hot LN detection rate by planar and SPECT-CT lymphoscintigraphy was 87,9 % (167 patients). In 10 patients (5,3 %), hot LNs were detected only by SPECT-CT. 18 (5,3 %) foci of uptake in 13 (6,8 %) patients interpreted on planar images as hot LNs were found to be false positive non-nodal sites of uptake when further assessed on SPECT/CT. In GROUP B the overall hot LN detection rate on planar and SPECT-CT was 97 % (32 patients). In one (3,0 %) patient hot LNs were identified only on SPECT/CT. Four (6,6 %) foci of uptake in four (12,1 %) patients were found to be false positive when further correlated with SPECT/CT. Differences in detection of SLNs between planar and SPECT/CT imaging in all 223 patients were statistically significant (P< 0.001). Conclusion: In some patients with breast cancer SPECT/CT improves the detection of sentinel lymph nodes. It can image nodes not visible on planar scintigrams, exclude false positive uptake and exactly localize axillary and non-axillary SLN.