Phytate technetium-99m versus dextran 500 technetium-99m in the sentinel lymph node biopsy

To study which of the two most used radiopharmaceutical drugs for the sentinel lymph node (SLN) biopsy procedure (dextran 500 99mTc and phytate 99mTc) best defines the SLN and migrates less to other lymph nodes.

Thirty-two rats, separated into two groups, underwent lymphoscintigraphy examination with either dextran or phytate followed by sentinel (popliteal), lumbar, and inguinal lymph node biopsy. Radiation was detected with a gamma probe.

The statistical study indicated count rates significantly higher in the SLN than in the other basins for both the dextran (P<0.01) and phytate groups (P<0.001). There was no statistically significant difference concerning SLN absorption in either group (P=0.2981). In the dextran group, migration occurred to 1.5 lymphatic basins with counting higher than 10% of that found in the SLN versus 0.8 in the phytate group (P=0.0023). Migration was thus higher in the dextran group (P=0.0207).

There was no statistically significant difference between dextran and phytate in the SLN identification, but the phytate migrated to fewer lymphatic basins beyond the SLN and with less intensity.