Sentinel lymph nodes and planar scintigraphy and SPECT/CT in various types of tumours. Estimation of some factors influencing detection success.

BACKGROUND Aim ot the study was to assess the role of planar lymphoscintigraphy and fusion imaging of SPECT/CT in sentinel lymph node (SLN) detection in patients with various types of tumours and to estimate some factors influencing detection success - age and body mass index. MATERIAL AND METHODS Planar scintigraphy and hybrid modality SPECT/CT were performed in 550 consecutive patients (mean age 58.1 ± 13.1 years): 69 pts with gynaecological tumours (37 pts with cervical cancer, 25 pts with endometrial cancer, 7 pts with vulvar carcinoma; mean age 54.4 ± 13.2 years), 161 consecutive patients with melanomas (mean age 57.1 ± 14.8 years), and 320 consecutive women with breast cancer (mean age 59.4 ± 12.0 years). The radiopharmaceutical was injected around the tumour (gynaecologic and breast cancers, melanomas), subareolarly (in some breast cancers), or around the scar (in melanomas after their removal). Planar and SPECT/CT images were interpreted separately by two nuclear medicine physicians. RESULTS Planar scintigraphy did not show SLN in 77 patients (14.0%): in 8 pts with gynaecologic tumours, in 23 pts with melanomas and in 46 pts with breast cancer. SPECT/CT was negative in 49 patients (8.9%): in 4 pts with gynaecologic tumours, in 12 pts with melanomas and in 33 pts with breast cancer. In 199 (36.2%) patients the number of SLNs captured on SPECT/CT was higher than on planar imaging. 35 foci of uptake (3.1% from totally visible 1134 foci on planar images) interpreted on planar images as hot LNs were found to be false positive non-nodal sites of uptake when further assessed on SPECT/CT. SPECT/CT showed the exact anatomical location of all visualized sentinel nodes. Influence of the age and BMI: The group of patients with higher number of detected SLN on SPECT/CT than on planar scintigraphy had lower average age than the group of patients with the same number of detected SLN on SPECT/CT and on planar scintigraphy, the difference was statistically significant (P=0.008). BMI did not differ between the two groups. CONCLUSION In some patients with gynaecologic and breast cancers and melanomas, SPECT/CT improves detection of sentinel lymph nodes. It can image nodes not visible on planar scintigrams, exclude false positive uptake and exactly localize axillary, inguinal, pelvic and paraaortic SLNs. It improves anatomical localization of SLNs. We have found the influence of the age on the difference in the number of SLNs detected by the fusion of SPECT/CT and planar lymphoscintigraphy. On the other hand, this difference was not influenced by BMI.