Cell phone as medical device

Tuesday, 06 January 2009 08:22 |

A recurring theme in medical imaging at the moment is an evolution towards smaller, often handheld devices that use more common technologies. Many of them share the property of being potentially cheap to produce and have specific diagnostic use rather than being a general imaging tool like MRI. An exciting development announced by UCLA uses lens free photonic based around a mobile telephone.

mobilephone UCLA electrical engineering professor Aydogan Ozcan has constructed a prototype cell phone that is capable of monitoring the condition of HIV and malaria patients, as well as testing water quality in undeveloped areas or disaster sites. The imaging technology was invented by Ozcan, a member of the California NanoSystems Institute at UCLA, and has been miniaturized by researchers in his lab to the point that it can fit in standard cell phones and webcams.

The imaging platform is known as LUCAS (Lensless Ultra-wide-field Cell monitoring Array platform based on Shadow imaging), acquires an image using a short wavelength blue light to illuminate a blood, saliva or other fluid sample. LUCAS captures an image of the microparticles in the solution using a sensor array.

As red blood cells and other microparticles have a distinct diffraction pattern, or shadow image, they can be identified and counted virtually instantaneously by LUCAS using custom-developed "decision algorithm" software that compares the captured shadow images to a library of training images. Data collected by LUCAS can then be sent to a hospital for analysis and diagnosis using the cell phone, or transferred via USB to a computer for transmission to a hospital. This characteristic opens exciting opportunities for remote diagnostic for use in field situations where bulky equipment is not appropriate. Likewise if costs allows, it might allow patients to use the equipment at home or remote from clinicians where the images can then be analysed by human or computers. Since first demonstrating the technology in 2007 the UCLA researchers have now improved the LUCAS technique to the point that it can classify a significantly larger sample volume than previously shown — up to 5 milliliters, from an earlier volume of less than 0.1 ml — representing a major step toward portable medical diagnostic applications.

Ozcan envisions people one day being able to draw a blood sample into a chip the size of a quarter, which could then be inserted into a LUCAS-equipped cell phone that would quickly identify and count the cells within the sample. The read-out could be sent wirelessly to a hospital for further analysis.

"This on-chip imaging platform may have a significant impact, especially for medical diagnostic applications related to global health problems such as HIV or malaria monitoring," Ozcan said.

LUCAS functions as an imaging scheme in which the shadow of each cell in an entire sample volume is detected in less than a second. The acquired shadow image is then digitally processed using a custom-developed "decision algorithm" to enable both the identification of the cell/bacteria location in 3-D and the classification of each microparticle type within the sample volume.

Various cell types — such as red blood cells, fibroblasts and hepatocytes — or other microparticles, such as bacteria, all exhibit uniquely different shadow patterns and therefore can be rapidly identified using the decision algorithm.

The new study demonstrates that the use of narrowband, short-wavelength illumination significantly improves the detection of cell shadow images. Furthermore, by varying the wavelength, the two-dimensional pattern of the recorded cell signatures can be tuned to enable automated identification and counting of a target cell type within a mixed cell solution.

"This is the first demonstration of automated, lens-free counting and characterization of a mixed, or heterogeneous, cell solution on a chip and holds significant promise for telemedicine applications," Ozcan said.

Another improvement detailed in the UCLA research is the creation of a hybrid imaging scheme that combines two different wavelengths to further improve the digital quality of shadow images. This new cell classification scheme has been termed "multicolor LUCAS." As the team illustrated, further improvement in image quality can also be achieved through the use of adaptive digital filtering. As result of these upgrades, the volume of the sample solution that can be imaged has been increased, as mentioned, from less than 0.1 ml to 5 ml.

"This is a significant advance in the quest to bring advanced medical care to all reaches of the planet," said Leonard H. Rome, interim director of the CNSI and senior associate dean for research at the David Geffen School of Medicine at UCLA. "The implications for medical diagnostic applications are in keeping with CNSI initiatives for new advances toward improving global health."

LUCAS is not a substitute for a microscope but rather a complement. While microscopes can produce detailed images, images produced by LUCAS are grainy and pixelated. The LUCAS platform's advantage lies in its ability to nearly instantaneously identify and count microparticles, something that is time consuming and difficult to do with a microscope in resource-limited settings. Also, because LUCAS does not use a lens, the only constraint on size is the size of the chip it is built on.

Benefits:

Small scale implies lost cost
Enables the hospital to come to the patient - critical in locations where access to healthcare is limited
Enables to transmission of data wirelessly to centres for analysis
Potential portability would enable this tecnhology to be available to patients
Tuning the scheme enables different outcomes to be observed.