Hybrid SPECT-CT: an additional technique for sentinel node detection of patients with invasive bladder cancer

OBJECTIVES: To explore the feasibility of performing lymphoscintigraphy combined with computed tomography (CT) for preoperative detection of sentinel lymph nodes in patients with invasive bladder cancer. MATERIALS: Six consecutive patients scheduled for radical cystectomy underwent lymphoscintigraphy after transurethral injection of Albures-technetium 99m in the detrusor muscle peritumourally both with planar imaging and with single-photon emission computed tomography/CT (SPECT/CT). CT for anatomic fusion was performed directly after the SPECT/CT and both investigations were combined to a fused image. Radical cystectomy started with extended lymphadenectomy and intraoperative detection of sentinel nodes with both Geiger probe and dye marker. The conventional planar lymphoscintigraphies and the fused SPECT/CT were compared with each other and with the outcome of intraoperative sentinel node detection and final histopathologic analyses. RESULTS: The method allowed anatomically detailed preoperative visualisation of 21 sentinel nodes in five of the six patients, whereas planar pictures only visualised two sentinel nodes in two of six patients. Two patients had lymph node metastases and in the other four the nodes were negative. The combined method visualised all metastatic sentinel nodes, whereas planar lymphoscintigraphy detected only one of six node metastases. CONCLUSIONS: The combination of lymphoscintigraphy with CT enhanced preoperative anatomic localisation of sentinel nodes in bladder cancer and aided in the identification of sentinel nodes during surgery. The yield of detected sentinel nodes, both metastatic and nonmetastatic, was markedly increased using the combined method compared to conventional planar lymphoscintigraphy.