Posts with the tag: microscopy
Many diseases, including cancer, can be diagnosed by extracting tissue samples from the patient’s body and studying them under a microscope. This is called histopathology. An alternative technique called endomicroscopy has recently been developed. It allows tissue to be imaged at the microscopic level without removing it from the patient. This post introduces the topic of endomicroscopy – sometimes known as ‘confocal laser endomicroscopey’ or CLE – to the non-specialist.
I’ve recently co-authored a perspective called Robotics and Smart Instruments for Translating Endomicroscopy to In situ, In vivo Applications in the journal Computerized Medical Imaging and Graphics. The editorial discusses some of the challenges of in vivo confocal laser endomicroscopy (CLE), and how robotics technology may help to overcome them. This forms the basis for quite a lot of my current research so I would be interested to hear any comments or ideas people may have.
Microscopes are great tools – they make modern biology possible, and are essential for the diagnosis of many diseases. But they have one big disadvantage when it comes to medicine: they can’t be used directly on patients. Or at least they couldn’t, because now a new technology has emerged that allows us to perform ‘endomicroscopy’ – microscopy inside of the patient. This in vivo microscopy has lots of potential applications and is a pretty exciting area to be working in. The technology still has a few problems, but it’s shaping up to be one of the key new imaging techniques of the twenty-first century. And it has become practical because of the use of optical fibre bundles.
There’s a stark contrast between the elegant simplicity of a conventional widefield microscope and the much more complex apparatus need for point-by-point scanning in confocal microscopy. It’s this point-by-point scanning, together with a pinhole, which gives the confocal microscope its optical sectioning ability. By removing the out of focus blur which would degrade a conventional microscope image, confocal microscopes obtain crisp, clean images of thick samples, or even of in vivo tissue. The additional complexity involved with confocal operation, which includes the requirement to use a laser rather than a thermal light source, is accepted as the price that has to be paid if we want to obtain these kinds of images. But now, HiLo microscopy is offering an alternative approach which could have a number of niche applications, particularly where space or cost preclude the use of a full confocal microscopy setup.
Optical Coherence Tomography (OCT) has a lot of advantages over confocal microscopy, especially for applications where it’s useful to have a large working distance between the probe and the tissue. But a big limitation is that it can only detect reflected light, and so can’t be used with fluorescent stains. Fluorescence is often preferred in conventional microscopy because it allows us to visualise structures that we can’t easily identify in reflectance images. So the race is on to find a way to make OCT work with fluorescent emission as well as reflected light.