Mobile Phone Based Clinical Microscopy for Global Health Applications

1. Mobile Phone Based Clinical Microscopy for Global Health Applications Breslauer, Maamari, Switz, Lam, Fletcher

2. Authors • David N. Breslauer • Bioengineering Grad Student • Robi N. Maamari • Bioengineering Grad Student • Neil A. Switz • Biophysics Grad Student • Wilbur A. Lam • Assistant Professor of Pediatrics& Bioengineering • Daniel A. Fletcher • Professor of Bioengineering

3. Introduction: Initial Concerns about Feasibility & Impact • “…we have built a mobile phone-mounted light microscope and demonstrated its potential for clinical use by imaging P. falciparum-infected and sickle red blood cells in brightfield and M. tuberculosis-infected sputum samples in fluorescence with LED excitation.” • Marli: Do camera phones have high enough resolution to take light microscope pictures? • Marli: Does anyone actually have tuberculosis anymore? • Marli: I know LEDs are bright, but are they THAT BRIGHT?

4. Introduction: Advantages of This Method • LEDs are inexpensive • Rob: Not sure how well the device would cut down equipment costs; you still have to buy their device, plus the relevant dyes. The training costs are an obvious savings, however. • Cost breakdown in a few slides! • Mobile phone networks are prevalent; useful for image transmission • Marli: So like picture messages? • Marli: This means they don't have to pay to fly out specialists for a consult. • Are phone data plans cheaper/faster than wifi in other countries?

5. Introduction: Advantages of This Method Cont’d • Mobile phones today almost always have cameras • Erin: That phone doesn't look very smart, I bet we could do even better with an iPhone (8MP vs 3.2MP). • Sunitha: Not sure if there were iPhones in 2009 :-). But the gadget looks neat - like a prize-winning science-fair project... • Digital image processing available on phones • Rob: Hadn't thought about this advantage. Interesting! • More on this later… but keep in mind, how much did they actually process the images using phones vs computers?

6. Brightfield Imaging of Malaria and Sickle Cell Anemia • “…malaria can be effectively diagnosed from e-mailed smear images.” • Sunitha: This proves that in a hospital with minimal lab facility (like a microscope and internet connection), the same can be achieved without having to use the special hardware with the cell phones. The cell-phone technology described here is probably suitable for places with absolutely no lab or internet facility. • How common is it for a hospital to have no lab/internet facility whatsoever? Is that the main scenario of usefulness?

7. The Malaria Game • Marli: Wouldn't it be SO much more difficult with the thicker blood smears? • Erin: How do you tell if malaria is present in a thick smear such as this? I certainly can't!

8. The Malaria Game Cont’d • Erin: This is a lot better. What do you think, class, could we play the Malaria game with this image? • Erin: Seems like their “automated bacillus counting of the fluorescent TB images” could be useful for that time-intensive cell photo cropping we were talking about for the Malaria game.

9. Fluorescence Imaging of Tuberculosis and Automated Image Analysis • Sunitha: This means there are two versions of the hardware needed with the mobile phone: One for fluorescence microscopy technique and another for brightfield imaging technique. The former is expensive than the latter. • Just how much more expensive? Let’s find out…

10. Materials and Methods

11. Traditional Methods Cost comparison

12. Other Materials and Methods • Free water drop method • http://blogs.scientificamerican.com/compound-eye/2012/03/12/transform-your-iphone-into-a-microscope-just-add-water/ • $5 mini-microscope method • http://crabfuartworks.blogspot.com/2010/09/crabfu-5-iphone-microscope-mod.html • $20 tiny lens method • http://www.wired.com/wiredscience/2011/03/diy-cellphone-microscope/?pid=1112&viewall=true

13. $20 Tiny Lens Method Mini-Lab • Find some thin, dark, rubbery material and poke a small hole in it (less than 1 millimeter in diameter). This can be done using a pin or needle. • Carefully mount the lens to this “iris,” covering as little of the lens as possible. • Center the iris with the ball lens tucked in the middle over the camera of the cellphone (above). • Mount the iris to the phone with electrical tape. Our rubbery material is sticky, so we don’t need to. • As with a standard microscope, use plenty of light to illuminate your sample. Liquid samples should be placed between a glass slide and coverslip.

14. But how useful is it? • Sunitha: I wonder where this technology could be applicable. There are millions of under-equipped hospitals throughout the world, but the question is: who will they send the images to? Will a medical professional sitting in a bigger hospital do the diagnosis of the images? Who will pay them? May be, there is an affiliation of all the under-equipped hospitals with a more sophisticated medical facility. I guess I am thinking out loud :)

15. Discussion - Viability • “Microscope-enabled mobile phones have the potential to significantly contribute to the technology available for global healthcare, particularly in the developing world and rural areas where mobile phone infrastructure is already ubiquitous but trained medical personnel, clinical laboratory facilities, and clinical expertise are scarce.” • Sunitha: I guess we still need trained medical personnel to use the equipment - especially to handle the blood smear, etc. I can visualize the use of this equipment in rural hospitals where there are one or two doctors covering a fairly big low income population. • Erin: True. Technology like this might be very helpful for community health initiatives, though (info on community health initiatives in India)

16. Discussion – Viability Cont’d • “Combining the mobile phone microscopy system with automated sample preparation systems…” • Sunitha: This seems to be part of an answer to my previous question, but it is mentioned here for the first time. Not sure what it really means and how they automate the process so personnel not trained to prepare the sample can manage it. Probably this is part of the "future field study" they mentioned at the end of this section. • Something like this? That’s got to be expensive, though, right?

17. Discussion – Post-processing Issues • Post-processing of images • Sunitha: This article doesn't give sufficient examples of specifically what kinds of post-processing a mobile phone can do! Wonder how one can do automated particle counting on a mobile phone! It must be a super advanced cell phone! Are they talking about special apps running on smartphones? • They said they used ImageJon a desktop for simplicity, could they also be using it because current photo editing apps aren’t up to the task? How valid is this concept, then?

18. Discussion – Acceptance • “Since we are developing a technology that makes the current and long-standing internationally accepted standards for disease screening in developing countries more portable – rather than creating an entirely new diagnostic assay – we anticipate that a relatively fast time to adoption by clinicians and health workers may be possible.” • Erin: Would there be a difference between this method and the malaria game in terms of quickness of acceptance, then? What do you guys think? • Sunitha: I guess there is a difference between the two, especially in the purpose each of the two serves. This gadget is intended for getting the smear readings out to a professional quicker, where as the game is for diagnosis. I guess a combination of the two could be something quite new and possibly quick and cheap. • Rob: Once you get the product approved, initiate mass-production of the microscope attachment, deal with the programming issues, and set up a network of people who can do the diagnoses (you still need an expert (or at least a sufficiently programmed computer) to analyze the images) Still promising.

19. Discussion – Proprietary Camera Software; Privacy • Proprietary camera software leads to lack of information on several fronts (e.g., sensor integration time unknown) • Erin: Seems like they should look into this. • Rob: This would seem like an area where either a more open-source platform or manufacturer collaboration would be useful to actually control these settings. • Rob: Might some of these be proprietary? • Location-tagging patient data • Rob: Privacy concerns?

20. System Design & Characterization • “Both the brightfield and fluorescence instruments are designed to work with a typical camera-enabled mobile phone.” • Rob: Phones have a variety of shapes/sizes; are they going to try a one-size fits all approach, or produce different models for different phones? • “~50,000 hour lifetimes of LEDs make them particularly suitable for use in portable systems and systems designed for use in developing areas where replacement parts may be unavailable or unaffordable.” • Erin: Always good to factor in maintenance costs. I have a fancy newer HP printer that I never use because the ink is 4x as expensive as my old printer's ink.

21. BrightfieldMicroscopy • Erin: Brightfield is traditional microscopy (a bright light shines through the cell) • Sunitha: To understand brightfield, the following linkhelped

22. Fluorescence Microscopy • Erin: Fluorescence method stains the cells so they can be seen glowing • Erin: Have been around since at least the 1950's • Sunitha: I found a nice article to understand the details on fluorescent imaging here

23. Sensor Integration Time • Sunitha: Not sure what this means. Is this the time needed to focus before taking the picture? • Same thing as exposure time/shutter speed in photography – the time during which a sensor acquires ambient light

24. Epi-Illumination Geometry • Rob: Microscope geometries - • trans-illuminated=light source (here the LED) behind the sample(as in picture) • epi-illuminated=light source coming from same direction as viewer.

25. Full Width at Half Maximum • Rob: Full Width at Half Maximum (FWHM) - a frequently used heuristic. Basically, if you have some plotted distribution with peak height H, you measure the distance between where it drops to H/2 on either side of the peak. This provides a simple, easy way to characterize the distribution, without worrying about noise, etc. You guys may already know this; I'm not sure how commonly used it is outside the natural sciences, but given the talk about statistical measures a couple weeks back, I thought it might be worth addressing.

26. Nominal Rayleigh Resolution Limit • Rob: Nominal Rayleigh resolution limit - Basically, assuming normal Rayleigh diffraction, a light source will give you a bright inner spot, surrounded by a dark region, then a bright ring, then another dark region, etc. The Rayleigh resolution limit is the point at which the bright inner spot from one object would fall in the first dark ring from the other object.