PET probe-guided surgery: applications and clinical protocol

Abstract

Introduction: Parallel to the advances in diagnostic imaging using positron emission tomography (PET), and availability of new systemic treatment options, the treatment paradigm in oncology has shifted towards more aggressive therapeutic interventions to include cytoreductive techniques and metastasectomies. Intraoperative localization of PET positive recurrent/metastatic lesions can be facilitated using a hand-held PET probe.

Materials and methods: Records of patients who underwent PET probe-guided surgery were reviewed. Surgical indications and operative targets were determined based on diagnostic PET/PET-CT images performed prior to probe-guided surgical planning. PET probe-guided surgery was performed on a separate day using a high-energy gamma probe (PET probe, Care Wise Medical, Morgan Hills CA) 2-6 hours post-injection of 5-15 mCi FDG. Probe count rates, target-to-background ratios, and lesion detection success were analyzed.

Results: Twenty-four patients underwent PET probe-guided surgery; one patient had two PET-probe guided surgeries resulting in a total of 25 cases (5 colorectal cancer cases, 4 thyroid cancer cases, 6 lymphoma cancer cases, and 10 other cancer cases). Surgical indication was diagnostic exploration in 6 cases with lymphoma and 1 case with head and neck cancer (28%). The remaining 18 cases (72%) underwent PET probe-guided surgery with a therapeutic intent in a recurrent or metastatic disease setting. All the lesions identified and targeted on a preoperative FDG-PET scan were detected by the PET probe with satisfactory in-vivo lesion count rates and a TBR of >/= 1.5. PET probe allowed localization of lesions that were non-palpable and non-obvious at surgical exploration in 8 patients.

Conclusion: The use of the PET probe improves the success of surgical exploration in selected indications. Separate day protocol is clinically feasible allowing for flexible operating room scheduling.

Figure 1

FDG-PET/CT scan of a patient with nasopharyngeal cancer. Transverse slice demonstrating FDG-positive primary site

Figure 2

Transverse slice demonstrating FDG-positive lymph node. An US-guided FNA of this node was non-diagnostic.

Figure 3

PET-probe guided excision of FDG-positive lymph node in the neck. Final pathology confirmed metastatic squamous cell cancer.