Probe-based fluorescence dosimetry of an antibody-dye conjugate to identify head and neck cancer as a first step to fluorescence-guided tissue preselection for pathological assessment.

BACKGROUND: Despite the rapid growth of fluorescence imaging, accurate sampling of tissue sections remains challenging. Development of novel technologies to improve intraoperative assessment of tissue is needed. METHODS: A novel contact probe-based fluorescence dosimeter device, optimized for IRDye800CW quantification, was developed. After evaluation of the device in a phantom setup, its clinical value was defined ex vivo in patients with head and neck squamous cell carcinoma who received panitumumab-IRDye800CW. RESULTS: Ten patients were enrolled with a total of 216 data points obtained. Final histopathology showed tumor in 119 spots and normal tissue in 97 spots. Fluorescence-to-excitation ratios in tumor tissue were more than three times higher than those in normal tissue. The area under the curve was 0.86 (95% CI: 0.81-0.91) for tumor detection. CONCLUSIONS: Fluorescence-guided tissue preselection using a fluorescence dosimeter could have substantial impact on tissue sampling for frozen section analysis and potentially reduce sampling errors.

Intraoperative Tumor Assessment Using Real-Time Molecular Imaging in Head and Neck Cancer Patients.

BACKGROUND: In head and neck cancer, surgical resection using primarily visual and tactile feedback is considered the gold standard for solid tumors. Due to high numbers of tumor-involved surgical margins, which are directly correlated to poor clinical outcomes, intraoperative optical imaging trials have rapidly proliferated over the past 5 years. However, few studies report on intraoperative in situ imaging data that could support surgical resection. To demonstrate the clinical application of in situ surgical imaging, we report on the imaging data that are directly (ie in real-time) available to the surgeon. STUDY DESIGN: Fluorescence intensities and tumor-to-background ratios (TBRs) were determined from the intraoperative imaging data-the view as seen by the surgeon during tumor resection-of 20 patients, and correlated to patient and tumor characteristics including age, sex, tumor site, tumor size, histologic differentiation, and epidermal growth factor receptor (EGFR) expression. Furthermore, different lighting conditions in regard to surgical workflow were evaluated. RESULTS: Under these circumstances, intraoperative TBRs of the primary tumors averaged 2.2 ± 0.4 (range 1.5 to 2.9). Age, sex, tumor site, and tumor size did not have a significant effect on open-field intraoperative molecular imaging of the primary tumors (p > 0.05). In addition, variation in EGFR expression levels or the presence of ambient light did not seem to alter TBRs. CONCLUSIONS: We present the results of successful in situ intraoperative imaging of primary tumors alongside the optimal conditions with respect to both molecular image acquisition and surgical workflow. This study illuminates the potentials of open-field molecular imaging to assist the surgeon in achieving successful cancer removal.

Rapid, non-invasive fluorescence margin assessment: Optical specimen mapping in oral squamous cell carcinoma.

OBJECTIVE: Surgical resection remains the primary treatment for the majority of solid tumors. Despite efforts to obtain wide margins, close or positive surgical margins (<5 mm) are found in 15-30% of head and neck cancer patients. Obtaining negative margins requires immediate, intraoperative feedback of margin status. To this end, we propose optical specimen mapping of resected tumor specimens immediately after removal. MATERIALS AND METHODS: A first-in-human pilot study was performed in patients (n = 8) after infusion of fluorescently labeled antibody, panitumumab-IRDye800 to allow surgical mapping of the tumor specimen. Patients underwent standard of care surgical resection for head and neck squamous cell carcinoma (HNSCC). Optical specimen mapping was performed on the primary tumor specimen and correlated with pathological findings after tissue processing. RESULTS: Optical mapping of the specimen had a 95% sensitivity and 89% specificity to detect cancer within 5 mm (n = 160) of the cut surface. To detect tumor within 2 mm of the specimen surface, the sensitivity of optical specimen mapping was 100%. The maximal observed penetration depth of panitumumab-IRDye800 through human tissue in our study was 6.3 mm. CONCLUSION: Optical specimen mapping is a highly sensitive and specific method for evaluation of margins within <5 mm of the tumor mass in HNSCC specimens. This technology has potentially broad applications for ensuring adequate tumor resection and negative margins in head and neck cancers.

Intraoperative Molecular Imaging for ex vivo Assessment of Peripheral Margins in Oral Squamous Cell Carcinoma.

Objective: Complete surgical resection is the standard of care for treatment of oral cancer although the positive margin rate remains 15-30%. Tissue sampling from the resected specimen and from the wound bed for frozen section analysis (FSA) remains the mainstay for intraoperative margin assessment but is subject to sampling error and can require the processing of multiple samples. We sought to understand if an ex vivo imaging strategy using a tumor-targeted fluorescently labeled antibody could accurately identify the closest peripheral margin on the mucosal surface of resected tumor specimen, so that this "sentinel margin" could be used to guide pathological sampling. Materials and Methods: Twenty-nine patients with oral squamous cell carcinoma scheduled for surgical resection were consented for the study and received systemic administration of a tumor-targeted fluorescently labeled antibody (Panitumumab IRDye800CW). After surgical resection, the tumor specimen was imaged using a closed-field fluorescent imaging device. Relevant pathological data was available for five patients on retrospective review. For each of these five patients, two regions of highest fluorescence intensity at the peripheral margin and one region of lowest fluorescence intensity were identified, and results were correlated with histology to determine if the region of highest fluorescence intensity along the mucosal margin (i.e., the sentinel margin) was truly the closest margin. Results: Imaging acquisition of the mucosal surface of the specimen immediately after surgery took 30 s. In all of the specimens, the region of highest fluorescence at the specimen edge had a significantly smaller margin distance than other sampled regions. The average margin distance at the closest, "sentinel," margin was 3.2 mm compared to a margin distance of 8.0 mm at other regions (p < 0.0001). Conclusions: This proof-of-concept study suggests that, when combined with routine FSA, ex vivo fluorescent specimen imaging can be used to identify the closest surgical margin on the specimen. This approach may reduce sampling error of intraoperative evaluation, which should ultimately improve the ability of the surgeon to identify the sentinel margin. This rapid sentinel margin identification improves the surgeon's orientation to areas most likely to be positive in the surgical wound bed and may expedite pathology workflow.