Relationship between intraprostatic tracer deposits and sentinel lymph node mapping in prostate cancer patients.
Intraprostatic injection of the hybrid tracer indocyanine green (ICG)-(99m)Tc-nanocolloid enables both preoperative sentinel node (SN) identification and intraoperative visualization of the SN. Relating the fluorescence deposits in embedded prostate tissue specimens to the preoperatively detected SNs also provides the opportunity to study the influence of their placement on lymphatic drainage pattern.


METHODS
Nineteen patients with prostate carcinoma scheduled for robot-assisted laparoscopic prostatectomy and lymph node (LN) dissection were included. ICG-(99m)Tc-nanocolloid was injected intraprostatically, guided by ultrasound. SN biopsy was performed using a combination of radioguidance and fluorescence guidance. Tracer distribution was visualized in paraffin-embedded prostate samples using ex vivo fluorescence imaging. This distribution was correlated to the number and location of the SNs identified on preoperative lymphoscintigraphy and SPECT/CT.


RESULTS
ICG-(99m)Tc-nanocolloid helped guide surgical excision of the SNs. Ex vivo fluorescence imaging revealed a large variation in the locations of intraprostatic tracer deposits among patients. Tracer deposits in the peripheral zone correlated with a higher number of visualized LNs than deposits in the central zone (on average, 4.7 vs. 2.4 LNs per patient). Furthermore, tracer deposits in the mid gland correlated with a higher number of visualized LNs than deposits near the base or apex of the prostate (on average, 6 vs. 3.5 LNs per patient).


CONCLUSIONS
The hybrid nature of the tracer not only enables surgical guidance but also provides an opportunity to study the correlation between the location of tracer deposits within the prostate and the number and location of preoperatively visualized SNs. These data suggest that the location at which a tracer deposit is placed influences the lymphatic drainage pattern.
Department of Nuclear Medicine, Netherlands Cancer Institute, Amsterdam, The Netherlands.
Tessa
T
Buckle
Oscar R
OR
Brouwer
Renato A
RA
Valdés Olmos
Henk G
HG
van der Poel
Fijs W B
FW
van Leeuwen
D004396:Coloring Agents; D005456:Fluorescent Dyes; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007208:Indocyanine Green; D010535:Laparoscopy; D008198:Lymph Nodes / Q000000981:diagnostic imaging; D008297:Male; D016612:Paraffin Embedding; D011300:Preoperative Care; D011467:Prostate / Q000000981:diagnostic imaging* / Q000473:pathology*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D019275:Radiopharmaceuticals / Q000138:chemical synthesis; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*; D013668:Technetium Tc 99m Aggregated Albumin / Q000138:chemical synthesis; D015899:Tomography, Emission-Computed, Single-Photon
D004396:Coloring Agents; D005456:Fluorescent Dyes; D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin; C083602:technetium Tc 99m nanocolloid; D007208:Indocyanine Green