Emerging Minimally Invasive Technologies for the Detection of Skin Cancer

Abstract

With the increasing incidence of skin cancer, many noninvasive technologies to detect its presence have been developed. This review focuses on reflectance confocal microscopy (RCM), optical coherence tomography (OCT), high-frequency ultrasound (HFUS), electrical impedance spectroscopy (EIS), pigmented lesion assay (PLA), and Raman spectroscopy (RS) and discusses the basic principle, clinical applications, advantages, and disadvantages of each technology. RCM provides high cellular resolution and has high sensitivity and specificity for the diagnosis of skin cancer. OCT provides lower resolution than RCM, although its evaluable depth is deeper than that of RCM. RCM and OCT may be useful in reducing the number of unnecessary biopsies, evaluating the tumor margin, and monitoring treatment response. HFUS can be mainly used to delineate tumor depths or margins and monitor the treatment response. EIS provides high sensitivity but low specificity for the diagnosis of skin malignancies. PLA, which is based on the genetic information of lesions, is applicable for the detection of melanoma with high sensitivity and moderate-to-high specificity. RS showed high accuracy for the diagnosis of skin cancer, although more clinical studies are required. Advances in these technologies for the diagnosis of skin cancer can lead to the realization of optimized and individualized treatments.

Skin Cancer Pathobiology at a Glance: A Focus on Imaging Techniques and Their Potential for Improved Diagnosis and Surveillance in Clinical Cohorts

“…In contrast, HFUS, OCT, and MRI can precisely acquire the entire lesion thickness, being ideal for cross-sectional tissue imaging; however, they lack cellular resolution, causing the identification of malignant lesions to be extremely difficult [ 17 ]. RCM and OCT remain the most promising alternatives to invasive tissue biopsies, being ideal for delineating the tumor margins and monitoring therapeutic responses [ 16 ]. HFUS may also evaluate tumor margins or depth and monitor patients after exposure to specific therapeutic algorithms [ 28 ].…”

“…In contrast, handled RCM does not require fixation on the skin and can examine lesions located on curved areas such as the ears. Handled RCM covers an 0.75 × 0.75-mm 2 -sized area and has a shorter imaging time than the wide-probe RCM version [ 16 ]. Due to its high resolution, RCM may be applied to all types of skin cancers with increased specificity and sensitivity; nonetheless, it presents a limited depth of penetration of about 200 µm, which may lead to false-negative results for tumors located below the papillary dermis [ 16 ].…”

“…A clinical trial on 250 patients also confirmed that melanoma cells fluoresce much more brightly than surrounding cells in MPM, and morphological differences could also be seen in pathological tissues versus normal ones [ 15 ]. In addition, in a clinical cohort of 115 patients, MPM showed a sensitivity of 95% and a specificity of 97% for the diagnosis of melanoma tumors [ 16 ]. Logistic regression analysis was performed to identify the most significant diagnostic criteria.…”

“…Consequently, many anatomical and molecular imaging techniques have been developed and employed to interrogate different types of malignant lesions [ 15 ]. Overall, the use of non-invasive, high-resolution techniques for the anatomical imaging of skin cancers or related cutaneous lesions significantly increased the diagnostic accuracy for these highly problematic pathologies [ 16 ]. The most frequently used techniques with anatomical precision include confocal laser scanning microscopy (CLSM), optical coherence tomography (OCT), multiphoton microscopy (MPM), high-frequency ultrasound (HFUS), terahertz pulsed imaging (TPI), and magnetic resonance imaging (MRI).…”

“…Therefore, radiologists need to be knowledgeable about these issues to educate patients and inform colleagues about the harms and appropriate use of imaging-based screening. Finally, image interpretation has large inter-observer and intra-observer variability, which may significantly influence measurements in cancer patients, resulting in erroneous interpretations [ 16 ]. Ongoing efforts to standardize the terminology, technique, interpretation, reporting, and data collection in functional imaging are expected to help solve these limitations in the future.…”