A DROP-IN beta probe for robot-assisted 68Ga-PSMA radioguided surgery: first ex vivo technology evaluation using prostate cancer specimens

Abstract

Background: Recently, a flexible DROP-IN gamma-probe was introduced for robot-assisted radioguided surgery, using traditional low-energy SPECT-isotopes. In parallel, a novel approach to achieve sensitive radioguidance using beta-emitting PET-isotopes has been proposed. Integration of these two concepts would allow to exploit the use of PET-tracers during robot-assisted tumor-receptor-targeted. In this study, we’ve engineered and validated the performance of a novel DROP-IN beta-particle (DROP-INb) detector.Methods: Seven prostate cancer patients with PSMA-PET positive tumors received an additional intraoperative injection of ~70 MBq 68Ga-PSMA-11, followed by robot-assisted prostatectomy and extended pelvic lymph node dissection. The surgical specimens from these procedures were used to validate the performance of our DROP-INb probe prototype, which merged a scintillating detector with a housing optimized for a 12 mm trocar and prograsp instruments. Results: After optimization of the detector and probe housing via Monte Carlo simulations, the resulting DROP-INb probe prototype was tested in a robotic setting. In the ex vivo setting, the probe – positioned by the robot- was able to identify 68Ga-PSMA-11 containing hot-spots in the surgical specimens: signal-to-background (S/B) was > 5 when pathology confirmed that the tumor was located <1 mm below the specimen surface. 68Ga-PSMA-11 containing (and PET positive) lymph nodes, as found in two patients, were also confirmed with the DROP-INb probe (S/B>3). The rotational freedom of the DROP-IN design and the ability to manipulate the probe with the prograsp tool allowed the surgeon to perform autonomous beta tracing. Conclusions: This study demonstrates the feasibility of beta-radioguided surgery in a robotic context by means of a DROP-INb detector. When translated to an in vivo setting in the future, this technique could provide a valuable tool in detecting tumor remnants on the prostate surface and in confirmation of PSMA-PET positive lymph nodes.

First Ex Vivo Results of β−-Radioguided Surgery in Small Intestine Neuroendocrine Tumors with 90Y-DOTATOC

“…These in vivo tests will also confirm the authors' assumption, based on physical principles, that, due to the reduced penetration of beta particles, the blood pool will not affect the sensitivity and specificity of the technique. 18 The results of this pilot study demonstrate that the collaboration between different specialties is fundamental for the best management of patients, especially in NET patients where the association of CT scan and 68 Ga-DOTATOC PET/CT are mandatory for a correct surgical approach and the basis for RGS with 90 Y-DOTATOC. FIG.…”

Diagnostic Value, Oncologic Outcomes, and Safety Profile of Image-Guided Surgery Technologies During Robot-Assisted Lymph Node Dissection with Sentinel Node Biopsy for Prostate Cancer

“…Recently, a new gamma-probe for image-guided robotic surgery was developed (i.e. DROP-IN probe) and implanted into clinical practice (24)(25)(26)(27). Its increased manoeuvrability yielded higher in vivo SNs detection rate compared to laparoscopic rigid gamma probe (25), suggesting that the impact of Hybrid SNB might be further improved in future studies that rely on DROP-IN probe as radio guidance in the robotic setting.…”