Optical imaging for early detection of cervical cancer: state of the art and perspectives

Abstract

Significance: Cervical cancer is one of the major causes of death in females worldwide. HPV infection is the key cause of uncontrolled cell growth leading to cervical cancer. About 90% of cervical cancer is preventable because of the slow progression of the disease, giving a window of about 10 years for the precancerous lesion to be recognized and treated.

Aim: The present challenges for cervical cancer diagnosis are interobserver variation in clinicians' interpretation of visual inspection with acetic acid/visual inspection with Lugol's iodine, cost of cytology-based screening, and lack of skilled clinicians. The optical modalities can assist in qualitatively and quantitatively analyzing the tissue to differentiate between cancerous and surrounding normal tissues.

Approach: This work is on the recent advances in optical techniques for cervical cancer diagnosis, which promise to overcome the above-listed challenges faced by present screening techniques.

Results: The optical modalities provide substantial measurable information in addition to the conventional colposcopy and Pap smear test to clinically aid the diagnosis.

Conclusions: Recent optical modalities on fluorescence, multispectral imaging, polarization-sensitive imaging, microendoscopy, Raman spectroscopy, especially with the portable design and assisted by artificial intelligence, have a significant scope in the diagnosis of premalignant cervical cancer in future.

Keywords: Raman spectroscopy; cervical cancer diagnosis; fluorescence imaging; multimodal imaging; optical imaging; point-of-care; polarization-sensitive; white light imaging.

Fig. 1

(a) Uterus (frontal plane) with diseased cervix (yellow), (b) diseased cervix (transverse plane) with the lesion in yellow and the transformation zone represented by the gray shaded area.

Fig. 2

Schematic of various optical modalities for cervical cancer diagnosis.

Fig. 3

(a) Schematic of cervix imaging using a Pocket colposcope. (b) Steps of image analysis of cervical lesions with the help of visual inspection by acetic acid and Lugol’s iodine. (Reprinted from Ref.  with permission of IEEE © 2018). (b) Cervix image of a patient who tested positive for HPV: (c.1) before acetic acid, (c.2) after acetic acid, (c.3) treatment-thermal coagulation. (Reprinted from Ref.  with permission of ecancer © 2021.)

Fig. 4

In-vivo fluorescence endomicroscopy. (a) Image of the fluorescence-based endomicroscope. (b) Endomicroscopic images of normal squamous epithelium compared with the histological images. (c) Endomicroscopic images of precancerous squamous epithelium compared with histological images. (Reprinted from Ref.  with permission of SPIE © 2016.)

Fig. 5

(a)–(c) Intrinsic fluorescence-based portable device for cervical cancer detection. (a) Design of the instrument, (b) comparison of intrinsic fluorescence intensity of normal and CIN-1 lesions obtained from whole uterus samples, and (c) comparison of intrinsic fluorescence intensity of CIN1 and CIN2 lesions. (Reprinted from Ref.  with permission of SPIE © 2018.)

Fig. 6

(a) Cancerous site of cervix, (b) normal cervical tissues, and (c) normal vaginal sites. (Reprinted from Ref.  with permission of Wiley © 2017.) (d) Spectral differences between cervicitis, LSIL, HSIL, cervical squamous cell carcinoma, and cervical adenocarcinoma. (Reprinted from Ref.  with permission of Wiley © 2021.) (LSIL, low-grade squamous intraepithelial lesion; HSIL, high-grade squamous intraepithelial lesion.)

Fig. 7

Radiance images (550 nm) of 24 patients labeled in red and green to represent high-grade CIN and healthy tissues, respectively, in accordance with histopathological studies. (Reprinted from Ref.  with permission of SPIE © 2018.)

Fig. 8

(a) Computer-aided narrow-band snapshot MSI system, (b) fused image of NBI snapshot processed with Euclidean classification algorithm in which green, gray, pink, and red regions indicate normal, CIN2, CIN3, carcinoma in situ, respectively. (Reprinted from Ref.  with permission of Springer © 2020.) (c) ME-NBI system, (d) NBI imaging showing thin white epithelium (yellow box) and CIN1 confirmed by biopsy (red box). (Reprinted from Ref.  with permission of MDPI © 2021.)

Fig. 9

(a) MMC image of cervix of patient with low grade and high grade cervical lesions showing acetowhiteness. (b) Images of low grade lesion. (c) Images of normal cervical region. (d) Images of high grade lesion. (Reprinted from Ref.  with permission of OPTICA © 2022.)