An analysis of the utility of handheld PET probes for the intraoperative localization of malignant tissue.

Introduction: The intraoperative localization of suspicious lesions detected by positron emission tomography (PET) scan remains a challenge. To solve this, two novel probes have been created to accurately detect the (18)F-FDG radiotracer intraoperatively.

Methods: Nude rats were inoculated with mesothelioma. When PET scans detected 10-mm tumors, animals were dissected and the PET probes analyzed the intraoperative radiotracer uptake of these lesions as tumor to background ratio (TBR).

Results: The 17 suspicious lesions seen on PET scan were localized intraoperatively (by their high TBR) using the PET probes and found malignant on pathology. Interestingly, smaller tumors not visualized on PET scan were detected intraoperatively by their high TBR and found malignant on pathology. Furthermore, using a TBR threshold as low as 2.0, both gamma (sensitivity, 100%; specificity, 80%; positive predictive value (PPV), 96%; and negative predictive value (NPV), 100%) and beta (sensitivity, 100%; specificity, 60%; PPV, 93%; and NPV, 100%) probes reliably detected suspicious lesions on PET scan imaging. They also showed an excellent area under the curve of 0.9 and 0.97 (95% CI of 0.81-0.99 and 0.93-1.0) for gamma and beta probes, respectively, in the receiver operating characteristic analysis for detecting malignancy.

Conclusion: This novel tool could be used synergistically with a PET scan imaging to maximize tissue selection intraoperatively.