Detection of surgical margins in oral cavity cancer: the role of dynamic optical contrast imaging

Abstract

Purpose of review: The quantity of tissue removed during an oncologic surgical procedure is not standardized and there are numerous reports of local recurrence despite histologically adequate resection margins. The oral cavity is one of the sites in the head and neck with high chances of recurrence following negative margins. To address this need, this article reviews the recent applications of Dynamic Optical Contrast Imaging (DOCI) towards both oral screening and the intraoperative evaluation of tumor margins in head and neck surgery.

Recent findings: Human ex-vivo and in-vivo trials suggest DOCI is well tolerated, low-cost, and sensitive for differentiating cancerous from normal tissues throughout the head and neck, in addition to the oral cavity. Ex-vivo imaging of OSCC specimens generated histologically verified image contrast. Furthermore, in-vivo intraoperative results demonstrate significant potential for image-guided detection and resection of oral cavity squamous cell carcinoma (OSCC).

Summary: DOCI augments tissue contrast and may enable surgeons to clinically screen patients for oral cancer, make histologic evaluations in vivo with fewer unnecessary biopsies, delineate clinical margins for tumor resection, provide guidance in the choice of biopsy sites, and preserve healthy tissue to increase the postoperative functionality and quality of life of the patient.

Figure 1. Sampling error associated with biopsy

“C,” “P,” and “N” denote cancerous, pre-cancerous, and normal tissue in the oral cavity. The site biopsied may not be representative of neighboring tissue in the field of evaluation (dotted green region), and therefore measured sensitivity and sensitivity is often incomparable. Original.

Figure 2. DOCI permits differentiation of pre-cancer from inflammation

(a) visible image of precancerous lesion and (b) inflammation of the lip. (c) visible image and DOCI overlay of pre-cancerous lesion and (d) inflammation of the lip. Original.

Figure 3. In vivo imaging of tongue cancer

(a-b) visible image of cancer, (c-f) in vivo DOCI images at corresponding wavelengths (g) Histology (h) visible image of biopsy (i-l) DOCI images of ex vivo biopsy. DOCI contrast is displayed using an absolute color map scale where shorter relative lifetimes are mapped to blue and longer lifetimes are mapped to red. The in vivo DOCI image of the tumor tissue has a substantially shorter relative lifetime than the surrounding normal tissue and the tissues are thus displayed in bluer shades and redder shades, respectively. Similar contrast is observed in ex vivo DOCI images at all emission wavelengths. Original.

Figure 4. DOCI permits optical evaluation of OSCC histology

(a) Gross visible images. (b) DOCI data with (c) accompanying co-registered histologic section. Regions of interest have been drawn by a physician blinded to the DOCI images and then superimposed upon the DOCI images and histology. The absolute color map associated with DOCI imagery transforms blue to the global minimum relative decay lifetime and yellow to the maximum relative decay lifetime. Malignant OSCC (red contour) is associated with lower relative decay lifetimes than normal, fat tissue (black contour). (d) Statistical analysis is performed on the pooled DOCI data grouped by tissue type. Original.