44 vocal folds in 22 patients were imaged with the MEMS scanning catheter. Benign vocal fold lesions included scar tissue (N = 2), polyp (N = 2), nodule (N = 2), papilloma (N = 4) and other rare benign lesions (N = 5). In addition, seven patients with malignant vocal fold lesions (N = 7) were imaged. When clinically indicated, biopsy or complete removal of the lesion established histological diagnosis. Representative large sectional 3D PS-OCT images of individual lesions are presented in
. Video clips of reconstructed 3D vocal fold images with the progression of cross-sectional surfaces in two orthogonal directions are presented together along with an intra-operative wide field image of the vocal fold lesion.
Wide field image (a), 3D PS-OCT image of polyp (b, intensity: left, PS: right), and cross-sectional images (c-e).
Fig. 10 (
Media 5) Video clip of 3D PS-OCT image of the carcinoma-in situ case.
The wide field image and 3D reconstructed PS-OCT image of a right vocal fold polyp are shown in , and a video clip of the 3D PS-OCT image is shown in
. The PS-OCT image shows 3D intensity and PS images side by side, and three cross-sectional images at selected regions. The video clip shows internal structures of the vocal fold with moving cross-sections. In the wide field image, the polyp appears on the mid-portion of the right vocal fold as a local swelling. In the PS-OCT image, the polyp appears as a small surface irregularity [, intensity image], because most of the polyp was compressed by the catheter during manual scanning. The polyp appears as a fluid filled sac covered with an outer tissue layer and has little or no banding pattern (birefringence) as shown in the cross-sectional image of polyp section in .
Wide-field, 3D reconstructed PS-OCT still images of a vocal fold nodule and a 3D PS-OCT video clip are shown in
respectively. The nodules appear in the mid-portion of the vocal folds bilaterally as symmetric swellings in the wide-field image . The PS-OCT image of the left vocal fold shows irregular tissue structures in the nodule region [arrows in , intensity image], and the boundary between the epithelium and SLP is not clear. The irregular structures could be either the thickened epithelium or loose fibrous structure in the SLP. The nodule shows a relatively weak banding pattern, especially in the section showing loose tissue structures in the PS image.
Wide-field image (a) and 3D PS-OCT image of nodule (b, intensity: right, PS: left), and cross-sectional images (c-e).
Wide-field, 3D reconstructed PS-OCT still images of vocal fold papilloma and a 3D PS-OCT video clip are shown in
respectively. The papilloma appears in the wide-field image as an exophytic fibrovascular growth on the right anterior vocal fold -P—papilloma in . The PS-OCT image of the right side also shows a clear boundary between normal tissue posteriorly and papilloma anteriorly [arrow in , intensity image]. The normal tissue posteriorly shows layered tissue structures with the basement membrane in the intensity image , and a horizontal black and white banding pattern in the PS image [bracket labeled H in , PS image]. However, the papilloma anteriorly shows homogeneous vertically aligned structures rather than layered tissue structure in the intensity image . Also, the black-white banding pattern of the PS image of papilloma is irregular and aligned in the vertical direction rather than in the horizontal [bracket labeled V in , PS image]. The boundary between normal tissue and papilloma is clear in the PS-OCT image [* at boundary between brackets of , PS image].
Wide-field image (a) and 3D PS-OCT image of papilloma (b, intensity: left, PS: right), and cross-sectional images (c-e).
3.4 Cancer and carcinoma-in situ
The images from two representative cancer cases are presented here. The first case is a deeply invasive cancer which extends beyond the 1.5 mm imaging depth of the current PS-OCT system. Wide-field, 3D reconstructed PS-OCT still images of the thick cancer and a 3D PS-OCT video clip for this case are shown in
respectively. In the wide-field image, the cancer is seen bilaterally as a combination of raised irregular white and red areas. The intensity image shows homogeneous structures posteriorly and layered structures anteriorly. In addition, the intensity image posteriorly turns white quickly with depth due to the fast signal decay, compared to the images obtained more anteriorly. This is because the cancer tissue is usually highly scattering and suggests deeper cancer invasion posteriorly. In the PS image, almost no or irregular banding patterns are seen posteriorly, but clear horizontal banding patterns (indicative of normal vocal fold microstructure) are seen anteriorly. Three cross-sectional images show the transition from cancer to normal tissue as the cross-section goes from posterior to anterior [: cancer, : transition, : normal]. This 3D PS-OCT image shows a clear distinction between the cancer side (posterior) and normal side (anterior) in both the intensity and PS images, but the PS image shows the difference with better contrast [* marks this boundary in , PS image].
Wide-field image (a) and 3D PS-OCT image of a deeply invasive cancer case (b, intensity: right, PS: left), and cross-sectional images (c-e).
Fig. 8 (
Media 4) Video clip of 3D PS-OCT image of the deeply invasive cancer case.
The second case is carcinoma-in situ originating on the left vocal fold as shown in the wide-field image (
). These lesions contain malignant cells but are confined to the epithelium with no invasion through the epithelial basement membrane. The 3D PS-OCT image of the left vocal fold in shows the lesion confined superficially within the epithelium in both the intensity [arrows in ] and PS images [bracket showing loss of banding pattern in ], and the corresponding video clip () shows internal structures in various cross-sections. The intensity image shows some boundary structures between cancerous and normal tissue [, ]. The PS image shows little horizontal banding pattern on the superficial layer and a white band occurs in the lower layer indicating birefringence . There is a clear boundary between the carcinoma-in situ lesion and normal tissue.
Wide-field image (a) and 3D PS-OCT image of a carcinoma-in situ case (b, intensity: right, PS: left), and cross-sectional images (c-e).