Optical coherence tomography imaging during thyroid and parathyroid surgery: a novel system of tissue identification and differentiation to obviate tissue resection and frozen section

Abstract

Background: Optical coherence tomography (OCT) allows tissue histologic-like evaluation, but without tissue fixation or staining. We investigated OCT images from tissues obtained at thyroid and parathyroid surgeries to provide a preliminary assessment as to whether these images contain sufficient information for recognition and differentiation of normal neck tissues.

Methods: Normal tissues were obtained from patients undergoing surgical treatment. Two new-generation OCT systems, including optical frequency domain imaging (OFDI) and μOCT, were compared to representative hematoxylin-eosin histology.

Results: Thyroid, fat, muscle, lymph nodes, and parathyroid tissues were evaluated. Histologic-like microscopic characteristics sufficient for tissue type identification was realized using both systems for all tissue types examined.

Conclusion: This pilot study demonstrated that new-generation OCT systems are capable of recognizing and differentiating neck tissues encountered during thyroid and parathyroid surgeries. Further advances in OCT miniaturization and development of sterile intraoperative probe formats may allow OCT to offer an intraoperative "optical biopsy" without fixation, staining, or tissue resection.

Keywords: hyperparathyroidism; parathyroid adenoma; parathyroidectomy; thyroid cancer; thyroidectomy.

FIGURE 1

Comparison between (A) hematoxylin-eosin slides (original magnification ×40), (B) en face optical frequency domain imaging (OFDI), and (C) cross-sectional μ-optical coherence tomography (μOCT) images of normal thyroid gland. The thyroid gland shows spherical structural units – thyroid follicles (F), which include simple cuboidal epithelium that lines these structures (arrows). OFDI and μOCT images show multiple thyroid follicles (F′ and F″, respectively). A capsule of connective tissue with some small vessels can be observed in a cross-sectional μOCT view (C).

FIGURE 2

Comparison between (A) hematoxylin-eosin slides (original magnification ×100), (B) en face optical frequency domain imaging (OFDI), and (C) cross-sectional μ-optical coherence tomography (μOCT) images of the normal parathyroid gland. The gland is covered by a delicate capsule (C); its parenchyma is composed by chief cells, oncocyte cells, and adipose cells (A). Adipocytes are easily recognized in OFDI (arrows) and μOCT as a large dark ovoid or round shaped structures (A′). A thin but bright capsule covers the glandular parenchyma (C′).

FIGURE 3

Comparison between (A) hematoxylin-eosin slides (original magnification ×100), (B) en face optical frequency domain imaging (OFDI), and (C) cross-sectional μ-optical coherence tomography (μOCT) images of adipose tissue. Adipose tissue demonstrates a dense collection of adipocytes (A) with flattened nuclei (arrows), surrounded by a fine network of reticular fibers. Both OFDI and μOCT show areas of low reflectance representing lipid inclusions (A′ and A″, respectively). The area between lipid inclusions comprise thin and highly reflecting lines that are consistent with reticular fibers or cell walls.

FIGURE 4

Comparison between (A) transverse and (B) longitudinal section hematoxylin-eosin slides (original magnification ×100), (C) en face optical frequency domain imaging (OFDI), and cross-sectional μ-optical coherence tomography (μOCT) images of (D) transverse and (E) longitudinal view of muscle tissue. Skeletal muscle fibers occur in bundles (F), separated by endomysium (E). The myocyte nuclei are located peripherally within the bundle (arrows). In the OFDI image, the myocytes appear in the longitudinal view as elongated gray bands against a black background (F′). μOCT image demonstrates fascicles (F″) surrounded by endomysium. Bright dots that possibly represent nuclei (white arrows) can be recognized in the μOCT image.

FIGURE 5

Comparison between (A) hematoxylin-eosin slides (original magnification ×100) and (B) cross-sectional μ-optical coherence tomography (μOCT) images of lymph nodes. A clear capsule (C) has a high μOCT signal (C′). A large well-delineated (F) and less dense round subcapsular structure (arrows) corresponding to a lymphoid follicle can be recognized in the μOCT image (F′).