Can Intraoperative Fluorescence Imaging Identify All Lesions While the Road Map Created by Preoperative Nuclear Imaging Is Masked?

Abstract

Tracers can help visualize the lymphatic drainage patterns and sentinel nodes (SNs) of individual prostate cancer patients. To determine the role of nuclear medicine in surgical guidance, in particular the positional guidance of a SPECT/CT-based 3dimensional imaging road map, in this process we studied to what extent fluorescence guidance underestimated the number of target lesions relative to radioguidance. Methods: SPECT/CT imaging was performed after intraprostatic tracer administration of either indocyanine green (ICG)-99m Tc-nanocolloid (hybrid-tracer group) or 99m Tc-nanocolloid to create a road map that depicted all SNs. Patients who received 99m Tc-nanocolloid were injected with "free" ICG immediately before surgery. Before unmasking, fluorescence guidance was used for intraoperative SN identification. This was followed by extended pelvic lymph node dissection (ePLND). After unmasking of the SPECT/CT images, the number of missed SNs was recorded and their resection was pursued when there was no risk of intraoperative complications. Results: Preoperative SPECT/ CT revealed no differences in the SN identification rate between ICG-99m Tc-nanocolloid and 99m Tc-nanocolloid. However, fluorescence guidance allowed intraoperative removal of all SNs in only 40% of patients in the hybrid-tracer group and 20% of patients in the free-ICG group. Overall, 75.9% of the intraoperatively resected SNs in the hybrid-tracer group and 51.8% of the SNs in the free-ICG group were removed solely under fluorescence guidance. During ePLND, 22 additional SNs were resected (7 in the hybrid-tracer group and 15 in the free-ICG group). After unmasking, 18 remaining SNs were identified (6 in the hybrid group and 12 in the free-ICG group). In the free-ICG group, ex vivo evaluation of the excised specimens revealed that 14 SNs removed under ePLND or after unmasking contained radioactivity but no fluorescence. Conclusion: The preoperative imaging road map provided by SPECT/CT enhanced the detection of prostate SNs in more ectopic locations in 17 of the 25 patients, and the hybrid tracer ICG-99m Tc-nanocolloid was shown to outperform free ICG. Overall, fluorescenceguided pelvic nodal surgery underestimated the number of SNs in 60%-80% of patients.

Robotic surgery using a DROP-IN beta probe – feasibility study with 68Ga-PSMA in prostate cancer specimens

“…Furthermore, the confirmation of tracer uptake reduces the probability of false negatives (i.e. lesions missed) during surgery (2) and thus supports the exploration of tumor-receptor targeted excisions. Applications of this approach include the localization of local lymphatic metastases or primary tumor margins (3).…”

Advancing intraoperative magnetic tracing using 3D freehand magnetic particle imaging

“…Limiting in this study was the lack of porcine preoperative imaging, making it possible that not all stained SLNs were localized during surgery. When the concept is evaluated in clinical routine, however, preoperative SLN mapping can be realized using MRI, providing a roadmap for surgery, something that has proven critical in the radioactive SLN approach [ 13 ].…”

“…Use of the hybrid tracer indocyanine green [ICG]-99m Tc-nanocolloid, a tracer that has proven its potential in a.o. melanoma and penile cancer [11,12], has helped complement the abovementioned radioguidance concepts with real-time fluorescence imaging [13][14][15]. In parallel to these efforts, the use of magnetic tracers [e.g.…”

Laparoscopic Probe for Sentinel Lymph Node Harvesting Using Magnetic Nanoparticles

“…Therefore, advanced fluorescent tracers, including human serum albumin (HSA), HSA800 and quantum dots (QDs), are being developed to increase retention and potential accumulation in SLNs [13]. By using the dedicated filter (wavelength setting) on the laparoscopic camera, the fluorescent tracer is directly visible and can be used for LN identification during surgery [14]. Nevertheless, drawbacks of a fluorescent tracer are still pertinent: leakage during surgery contaminating the view [15], no pre-operative imaging, and limited intra-operative penetration depth.…”