Smartphone Technology Will Extend Low-Cost Molecular Diagnostic Testing to Developing Countries

This method utilizes molecular-specific microbeads to generate unique diffraction patterns of “blurry beads” which can be recorded and decoded by digital processing.

Investigators at Massachusetts General Hospital (Boston, USA) developed a smartphone imaging module, which they called the D3 (digital diffraction diagnosis) system. This platform consisted of a battery-powered LED light clipped onto a standard smartphone that recorded high-resolution imaging data with its camera. Since the telephone camera had a much greater field of view than a traditional microscope, the D3 system was capable of recording data on more than 100,000 cells from a blood or tissue sample in a single image. The data was transmitted for analysis by the smartphone to a remote graphic-processing server via a secure, encrypted cloud service. A numerical algorithm developed for the D3 platform distinguished cells from microbeads and was capable of analyzing up to 10 megabytes of data in less than 0.09 seconds. Results were then transmitted back to the testing device.

The investigators documented several applications of the D3 system in a paper published in the April 13, 2015, online edition of the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS). In one example, cervical biopsy samples from 25 women with abnormal PAP smears were labeled with microbeads coated with antibodies against three published markers of cervical cancer. Based on the number of antibody-tagged microbeads bound to cells, the D3 program categorized the biopsy samples as high-risk, low-risk, or benign, with results matching those of conventional pathologic analysis.

A second example described using the D3 system to analyze fine-needle lymph node biopsy samples. The system was able to differentiate accurately four patients whose lymphoma diagnosis was confirmed by conventional pathology from another four with benign lymph node enlargement.

“We expect that the D3 platform will enhance the breadth and depth of cancer screening in a way that is feasible and sustainable for resource limited-settings,” said contributing author Dr. Ralph Weissleder, director of the center for systems biology at Massachusetts General Hospital. “By taking advantage of the increased penetration of mobile phone technology worldwide, the system should allow the prompt triaging of suspicious or high-risk cases that could help to offset delays caused by limited pathology services in those regions and reduce the need for patients to return for follow-up care, which is often challenging for them.”

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