Detection of sentinel lymph nodes in patients of breast cancer by Technetium-99m-phytate lymphoscintigraphy and comparison of peri-tumor and subareolar injection

Objectives The purpose of this study was to assess the use of Technetium-99m-phytate for detection of sentinel lymph nodes (SLNs) and to compare peri-tumor and subareolar injection for identification of sentinel lymph nodes by lymphoscintigraphy.

Methods This study included 190 breast cancer patients who underwent surgery. Peri-tumor injection of Technetium-99m-phytate was carried out in 22 patients, and subareolar injection was carried out in 168 patients. Lymphoscintigraphy was performed in the supine position and sentinel node identification was performed by hand-held gamma probe and methyl blue during surgery. All SLNs were studied by hematoxylin and eosin staining and histopathological examination.

Results Positive imaging findings were found in 120 patients. The detection rate of SLNs is 63.15%. Among the 120 patients, frozen section revealed cancer cell in 20 patients. Negative imaging findings were found in 70 patients. Among the 70 patients, frozen section revealed cancer cells in 20 patients, negative in 50 patients. We found the relative high failure rate of SLNs detection by using Tc-99m-phytate lymphoscintigraphy. There was no significant difference between the peri-tumor and subareolar injection for the identification of the sentinel lymph nodes by lymphoscintigraphy.

Conclusions The results show low detection rate of SLNs by Tc-99m-phytate lymphoscintigraphy and no significant difference between the peri-tumor and subareolar injection for the identification of the sentinel lymph nodes by lymphoscintigraphy. We hypothesize that ralatively large or uncontrolable particle size may become trapped in the interstitial space and not easily enter the lymphatic system. The limited migration from the injection site may result in faint lymph node visualization or even non-visualization by Tc-99m-phytate lymphoscintigraphy and lead to an underestimation of sentinel nodes