Point-of-care and point-of-procedure optical imaging technologies for primary care and global health

Abstract

Leveraging advances in consumer electronics and wireless telecommunications, low-cost, portable optical imaging devices have the potential to improve screening and detection of disease at the point of care in primary health care settings in both low- and high-resource countries. Similarly, real-time optical imaging technologies can improve diagnosis and treatment at the point of procedure by circumventing the need for biopsy and analysis by expert pathologists, who are scarce in developing countries. Although many optical imaging technologies have been translated from bench to bedside, industry support is needed to commercialize and broadly disseminate these from the patient level to the population level to transform the standard of care. This review provides an overview of promising optical imaging technologies, the infrastructure needed to integrate them into widespread clinical use, and the challenges that must be addressed to harness the potential of these technologies to improve health care systems around the world.

Fig. 1. Gaps in PoC and PoP that may be addressed by imaging

The outer ring illustrates current gaps at the frontline primary care, referral care, and health care system levels. The inner ring illustrates how optical imaging technologies designed to be used at the PoC/PoP can fill these gaps.

Fig. 2. PoC microscopes and flow cytometers

(A) A cell phone–based microscope. Four different cell phones were used to obtain images of a Wright-stained blood smear (14), illustrating the resulting differences in image resolution, color, and brightness. For global health care, these images can be viewed locally and transmitted remotely for storage or further analysis. [IMAGE: Visible Earth, NASA.] (B) Foldscope components, tools, and instructions used in its assembly. The cross-section view shows sample mount and translation mechanism, LED illumination, and imaging optics. The sample is inserted from the side. Images were acquired from 1-μm polystyrene beads in bright field, 2-μm fluorescent beads in fluorescence, a Giemsa-stained blood smear in lens array, and 6-μm polystyrene beads in dark field modes (15). (C) Schematic diagram and photo of a cell phone–based flow cytometer. The spatial resolution of the system is about 2 μm, and images acquired with the system show that it can resolve 2- and 4-μm-diameter fluorescent beads (18). Images reproduced from (14, 15, 18) with permission.

Fig. 3. PoC and PoP imaging systems

(A) Handheld OCT scanner for primary care imaging. The handheld unit with a built-in screen shows both the surface video image and the depth-resolved OCT images in real time. Interchangeable tips are used for imaging various tissue sites. Reproduced from (24, 25) with permission. (B) A handheld diffuse optical spectroscopy scanner generates images based on water, deoxyhemoglobin, and fat content in the human breast for early identification of treatment response during chemotherapy. When compared to breast MRI, the low-cost and portable optical imaging system data strongly correlate with breast density and provide additional functional information. Reproduced from (37) with permission. (C) A tethered imaging capsule coupled to a portable OCT system enables rapid high-resolution 3D imaging of the human esophagus for screening and surveillance of premalignant changes in Barrett’s esophagus patients. The tethered imaging capsule is swallowed, then pulled back during image acquisition to collect the 3D image data. Reproduced from (41) with permission.

Fig. 4. Translational research and transformational changes to health care

Driven by health care needs, PoC and PoP imaging technologies are increasingly being translated from the bench to the patient bedside via technology development and initial clinical application studies. However, these initial translational efforts frequently stall without advancing toward commercialization and wider dissemination for larger populations of patients unless supported and funded by industry, government, and/or private foundations. With such support, transformational changes can occur by first validating the imaging technology against the current standard of care, followed by successfully overcoming the challenges associated with the integration and adoption of the imaging technology as the new standard of care.