Combining wide-field imaging and reflectance confocal microscopy in a single handheld device

Reflectance Confocal Microscopy (RCM) imaging shows cellular-level morphology of skin in vivo, noninvasively detecting skin lesions with high sensitivity (80-95%) and specificity (70-90%) that is 2-3X higher than that of dermoscopy. The higher specificity helps reduce false positives in dermoscopically indeterminate lesions and thus reduces biopsies of benign skin lesions by 50-70%. RCM imaging is advancing into routine use at the bedside to guide patient care in clinical settings worldwide. However, a significant challenge faced by clinicians when performing RCM imaging is knowing unambiguously the location of the small RCM field-of-view (FOV) within the context of a larger lesion. The objective lens, which has a large numerical aperture (NA) and very short working distance, obscures the skin surface surrounding the location of RCM imaging. This problem can be addressed by combining a wide-field (WF) surface imaging approach with RCM imaging within a single device. We demonstrate feasibility of WF surface imaging combined with RCM imaging by integrating a micro-camera within the objective lens of a handheld confocal microscope. We report a novel objective lens design that introduces an air gap before the final hemisphere lens element, creating space for a small WF micro-camera. The micro-camera provides long depth of field and wide FOV and is integrated inside the objective lens without significantly increasing its size or decreasing optical sectioning and resolution of RCM imaging. Preliminary clinical testing on human volunteer subjects demonstrates the new handheld microscope’s ability to display a WF view surrounding the location of RCM imaging on melanocytic and non-melanocytic skin lesions.