Confocal microscopy (CM) is an optical imaging technique that enables real-time high resolution imaging of tissue at the cellular level. Confocal imaging can be performed with either reflectance or fluorescence contrast.
Reflectance confocal microscopy (RCM) images tissue in its native state, i.e. without the use of exogenous contrast agent/dye. Thus RCM is used to visualize patient’s skin non-invasively in vivo. En face images are acquired approximately up to a depth of 100-150 microns below the skin surface, i.e. from superficial skin layer (epidermis) down to the reticular dermis (deeper layer of skin). RCM has shown to have a high sensitivity and specificity for detection of melanocytic skin lesions as well as non-melanocytic skin lesions such as basal cell carcinomas. Furthermore, RCM is being used to evaluate dermoscopically equivocal lesions, especially for lightly-pigmented and amelanotic (non-pigmented) lesions.
Dermoscopy combined with RCM is being implemented to guide noninvasive diagnosis to rule out malignancy of melanocytic and non-melanocytic skin lesions in vivo. It is is being explored to guide treatment such as tracing the margins of a lentigo maligna (LM) prior to resection. A confocal map of LM can be confirmed by scouting biopsies, however, it is tremendously helpful to map the entire extent of the lesion to plan the repair.
Fluorescence confocal microscopy (FCM) requires exogenous contrast agent/dye and is used for the evaluation of ex vivo tissues. FCM confocal is being implemented for the detection of residual basal cell carcinomas in Mohs surgically excised fresh tissue, to guide surgery.
Commercial confocal microscopes for in vivo imaging:
The VivaScope 1500 makes it possible to capture confocal images that depict cellular structures of living tissue (skin) in real-time. The same area of interest can be captured by the integrated dermatoscopic camera and may be imaged repeatedly over time to access both clinical and sub-clinical changes. It is being used for the bed-side evaluation of the lesion to guide patient management.
The VivaScope 3000 is a hand-held reflectance confocal microscope device for in vivo skin imaging. This imaging tool simplifies examination of difficult-to-access regions of the skin, and is particularly useful for imaging difficult locations such as lips and ears; all the while delivering the stable, repeatable, high quality cellular-resolution images.
Commercial confocal microscope for ex vivo imaging:
RS-G4: RS-G4 is a confocal microscope that is exclusively for the research purposes. But can also be used in Mohs surgery for margin assessment of the ex vivo tissue for basal cell and squamous cell carcinoma. It features a uniquely flexible scan head, innovative high-speed strip mosaic capabilities and large scale image stitching.
US Centers for Medicare and Medicaid Services:
On January 1st, 2016, following more than two decades of research and development, commercialization, translational studies and clinical trials, reflectance confocal microscopy (RCM) imaging of skin was granted category I current procedural terminology (CPT) reimbursement codes (96931-96936) by the US Centers for Medicare and Medicaid Services (CMS). These codes are only applicable for in vivo reflectance confocal microscopy of skin when the examination includes mosaics at multiple levels of the epidermis and superficial dermis. Link.