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 scintigr aphy and subsequent gamma probe localization. The aim of the present study was to evaluate an adjustment in the colloid particle concentration and tra cer dosage to optimize mammary lymphoscintigraphy. Scintigraphy was perform ed in 151 patients with a palpable breast carcinoma and clinically negative axilla: for the first 75 patients (group A) a standard labelling of 0.5 mg nanocolloid with Tc-99(m) was performed, for the subsequent 76 patients (g roup 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 cou nt 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 up-take 3+ was significantly higher (P = 0.001) in group B (51% vs 35% in group A). SN counts were significantly hi gher for group B (P<0.001). The percentage of patients with less than 2000 counts/node diminished from 45% in group A to 9% in group B (P = 0.001). In group B (P = 0.033) more lymph channels (53% vs 35% in group A) were visua lized and for a longer time (26% vs 4% at 4 h). Axillary drainage was seen in 96% in group A and 98% in group B whereas non-axillary drainage was obse rved in 19% and 25%, respectively. Intraoperative SN identification rate wa s 97% in group A and 100% in group B. SN metastases were found in 41% of gr oup A and 47% of group B. It is concluded that enhancement of colloid parti cle concentration and adjustment of tracer dosage led to improved SN identi fication by substantial increase in lymph node uptake and lymph vessel depi ction. A significant reduction of cases with faint SN uptake enables better surgical efficacy. ((C) 2001 Lippincott Williams & Wilkins).