SPECT-CT VISUALIZATION OF SENTINEL LYMPH NODES AND LYMPH FLOW FROM TONGUE CANCER

The main purpose of the study was to determine distribution of sentinel lymph nodes in patients with tongue cancer. SPECT-CT visualization of sentinel lymph nodes was performed in 19 primary patients with clinically T1-2N0M0 tongue cancer. SPECT-CT acquisition started 60-120 min after peritumoral injections of 99mTc-nannocolloids (100-150MBq in 0.3-0.4ml). Finally we analyzed lymph flow patterns and localization of lymph nodes with radiocolloids uptake. Bilateral lymph flow from the tongue cancer was detected in 9 (47%) of 19 patients. In 6 cases bilateral pattern was associated with tumors less than 5mm from medial sulcus of the tongue. On the contrary, in 9 of 10 patients with lesions more than 4mm from medial sulcus we detected monolateral lymph-flow. In 4 (21%) of 19 patients SPECT-CT visualized sentinel lymph nodes only in groups Ib-IIa. Modeling of radiotherapy with with standard and lymph-flow guided radiation fields was performed on Eclips treatment planning station. It demonstrated that with lymph-flow guided strategy irradiated volumes can be reduced from 1224 cm3 to 367 cm3, dose to spinal cord can be reduced from 24,7Gy to 14.3Gy, medial dose to contralateral parotid gland - from 24,6Gy to 12,4 Gy. SPECT-CT with radiocolloids can be successfully used for visualization of lymph flow from the primary tumour and subsequent radiotherapy planning.