Improved sentinel node visualization in breast cancer by optimizing the colloid particle concentration and tracer dosage

Faint lymph uptake may hamper sentinel node (SN) identification by scintigraphy and subsequent gamma probe localization. The aim of the present study was to evaluate an adjustment in the colloid particle concentration and tracer dosage to optimize mammary lymphoscintigraphy. Scintigraphy was performed in 151 patients with a palpable breast carcinoma and clinically negative axillafor the first 75 patients (group A) a standard labelling of 0.5 mg nanocolloid with Tc was performed, for the subsequent 76 patients (group B) the labelling dilution volume was reduced from 4 to 2 ml. For both groups the volume of injection was 0.2 ml. Lymph node uptake was evaluated by a 4-step visual score (from 0 = absent to 3+ = very intense), and by count quantification of at 4 h in the first draining SN. The SN visualization rate increased from 93% (70/75) in group A (mean dosage 93.4 MBq, range 57-130 MBq) to 99% (75/76) in group B (mean dosage 106.5 MBq, range 74-139 MBq). The percentage of patients with uptake 3+ was significantly higher (P = 0.001) in group B (51% vs 35% in group A). SN counts were significantly higher for group B (P