EJNMMI Research (Aug 2020)

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

  • Francesco Collamati,
  • Matthias N. van Oosterom,
  • Micol De Simoni,
  • Riccardo Faccini,
  • Marta Fischetti,
  • Carlo Mancini Terracciano,
  • Riccardo Mirabelli,
  • Roberto Moretti,
  • Judith olde Heuvel,
  • Elena Solfaroli Camillocci,
  • Florian van Beurden,
  • Henk G. van der Poel,
  • Renato A. Valdes Olmos,
  • Pim J. van Leeuwen,
  • Fijs W. B. van Leeuwen,
  • Silvio Morganti

DOI
https://doi.org/10.1186/s13550-020-00682-6
Journal volume & issue
Vol. 10, no. 1
pp. 1 – 10

Abstract

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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 have engineered and validated the performance of a novel DROP-IN beta particle (DROP-INβ) 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-INβ 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-INβ 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 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-INβ 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.

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