Website of Prof. Pascal Tyrrell
A traditional holiday – originating from the native peoples of the Americas – to celebrate the completion and bounty of the harvest.
This year I am off to Algonquin park for a canoe portage trip with the kids! I will take the time to appreciate some of the successes of our MiVIP program and this blog over the long weekend.
Thanks for being a part of it!
Listen to Dem Bones by the famous Delta Rhythm Boys…
… and I’ll see you in the blogosphere.
Pascal Tyrrell
A what scan? I am actually a cat guy myself. Not to say I don’t love dogs but if I had to make a choice…
I just finished reading a fantastic book by David Dosa entitled “Making Rounds With Oscar”. The premise of the book is a story about an extraordinary cat but the subject matter is very serious – dementia and end-of-life care in the elderly. Have a gander.
So what the heck is a cat scan and what does it have to do with medical imaging?
CT scans – also referred to as computerized axial tomography (CAT) – are special X-ray tests that produce cross-sectional images of the body using X-rays and a computer. CT was developed independently by a British engineer named Sir Godfrey Hounsfield and Dr. Alan Cormack and were jointly awarded the Nobel Prize in 1979. Yes, more Nobel prize winners…
In a nutshell, x-ray computed tomography:
– uses data from several X-ray images of structures inside the body and converts them into 3D pictures – especially useful for soft tissues.
– emits a series of narrow beams through the human body, producing more detail than standard single beam X-rays.
– is able to distinguish tissues inside a solid organ. A CT scan is able to illustrate organ tear and organ injury quickly and so is often used for accident victims.
– is analyzed by radiologists.
Unfortunately, unlike MRI scans, a CT scan uses X-rays and therefore are a source of ionizing radiation.
Now for the fun part (see the rules here), using CAT Scan in a sentence by the end of the day:
Serious: Hey Bob, did you know that the recorded image of a CAT Scan is called a tomogram?
Less serious: My GP suggested that howling at the moon at night is not normal behavior and he wants to send me for a CAT scan. What? No way, I’m allergic to cats…
OK, listen to Cat Stevens to decompress and I’ll see you in the blogosphere…
MiWord, a post on Sunday?!!! Well, I have been very busy lately and fell behind on my blog so I am now playing a little catch-up…
I was waiting in Logan airport for my flight back from a presentation in Boston – what unbelievably crazy traffic in that city – and I was texting my kids with my laptop open and my tablet next to me on the seat when I thought: I feel a little like Jimmy Neutron! I enjoyed watching that show with my kids. Lots of fun. Anyway, that idea of crazy science and the internal structure of the atom as displayed on Jimmy’s t-shirt may be the premise for a great kids show but it also led to the development of MRI. What?!!! You say.
MRI is an imaging technique. Maybe so, but it is particular in that it does not use any classic photographic equipment (film or lenses) or use x-rays as Roentgen did. It simply numerically measures how hydrogen nuclei absorb and release energy in response to particular frequencies. Need a refresher on the structure of an atom? See this post.
Don’t get it? OK, how about you think of this process as a crazy huge tuning fork. If you were to flick a tuning fork of a certain frequency (pitch) other tuning forks of the same frequency close by will pick up energy from the humming tuning fork and emit a sound in turn. Cool.
The nucleus of an atom can absorb energy and then relax by emitting energy in a similar way. Different atoms (or the same atom in different environments) will have different relaxation rates allowing for the identification of the composition of molecules. Ya, maybe a little complicated.
MRI measures how hydrogen nuclei absorb and release energy. Dependent on the location and the environment of the hydrogen atoms the MRI process is able to provide knowledge about the placement of hydrogen atoms in the body and in turn knowledge about the anatomy.
Now for the fun part (see the rules here), using Atom in a sentence by the end of the day:
Serious: Hey Bob, did you know that the atom is the smallest unit that defines the chemical elements and their isotopes?
Less serious: I thought that splitting atoms would produce a large explosion but when I tried using my mom’s perfume “atomizer” it just produced a fine spray and nice smell…
Yes, it is Halloween today and my kids could barely contain themselves getting ready for school. I suspect today will not be very productive as they count down the minutes before heading out to terrorize my neighbors.
Anyway, how about this for a scary thought: cinemaradiology! In the late 1800’s John MacIntyre at the Gasgow Royal Infirmary experimented with producing X-ray motion pictures. What!!!? He tried exposing film by passing it between the screen of the fluoroscope and the x-ray tube and by simply filming the fluoroscopic screen. This latter method was very difficult because, as all of you budding radiologists know, the images viewed on the fluoroscope screen were dim and of poor resolution at the time.
For years researchers worked on perfecting cinemaradiology. However, during those early years of discovery they lost interest when they realized that sharper images were possible when BOTH patients and investigators were exposed together AND that excessive radiation was a bad thing – duh!
It would only be many many years later that fluoroscope screen technology would be improved to allow for brighter and higher resolution images (and without frying the patient and everyone around!).
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| Fluoroscopy is a study of moving body structures – similar to an x-ray “movie.” A continuous x-ray beam is passed through the body part being examined, and is transmitted to a TV-like monitor so that the body part and its motion can be seen in detail. As an imaging tool, Fluoroscopy is used in many types of examinations and procedures. |
To my knowledge, no actors from the cinemaradiology era ever became successful stars in Hollywood…
No need to use the MiWord of the day in a sentence today (see rules here) as I realize you are busy getting ready for Halloween and need a break!
Decompress listening to the classic song Thriller by the King of Pop Michael Jackson and I’ll see you in the blogosphere…
Pascal Tyrrell
This week and I had the pleasure of presenting to the Division of Rheumatology Research Rounds – University of Toronto. They were a fantastic audience who asked questions and appeared to be very engaged. Shout out to the Rheumatology gang!
So, I was asked to talk about a statistical methodology called Cluster Analysis. I thought I would start a short series on the topic for you guys. Don’t worry I will keep the stats to a minimum as I always do!
Complex information can always be best recognized as patterns. The first picture below on the left certainly helps you realize that it is not a simple task to know someone at a glance.
Now, I guess it doesn’t help that many of you have never met me either! However, you can appreciate that things get a little easier when the same portrait is presented in the usual manner – upright!
This is an interesting example where the information is identical, however, our ability to intuitively recognize a pattern (me!) appears to be restricted to situations that we are familiar with.
This intuition often fails miserably when abstract magnitudes (numbers!) are involved. I am certain most of us can relate to that.
The good news is that with the advent of crazy powerful personal computers we can benefit from complex and resource intensive mathematical procedures to help us make sense of large scary looking data sets.
So, when would you use this kind of methodology you ask? I’ll tell you…
1 – Detection of subgroups/ clusters of entities (ie: items, subjects, users…) within your data set.
2 – Discovery of useful, possibly unexpected, patterns in data.
OK, time for some homework. Try to think of times when you could apply this kind of analysis.
I’ll start you off with an example that you can relate to. Every time you go to YouTube and search for your favorite movie trailer you get a long list of other items on the right that YouTube thinks may be of interest to you. How do you think they do that? By taking into account things like keywords, popularity, and user browser history (and many, many more variables) and using cluster analysis of course! You and your interests belong to a cluster. Cool!
In this series, we will delve into this fun world of working with patterns in data.
Now that you have peace of mind, listen to The Grapes of Wrath…
See you in the blogosphere,
Pascal Tyrrell
One of my favorite more serious films is One Flew Over the Cuckoo’s Nest. What does Jack Nicholson’s portrayal of a bad guy hoping for easy served time in a mental institution have to do with medical imaging? Well it all starts with the lobotomy. Not to spoil the story, suffice it to say that the movie broaches the topic of lobotomies and how ridiculous they were. Lobotomy was a form of neurosurgery that involved damaging the prefrontal cortex in order to “calm” certain mentally ill patients. Needless to say the procedure was controversial from the beginning (1935 to the early 1970’s) but the author of the discovery, Egas Moniz, was awarded the Nobel Prize in 1949. Maybe not the most sound of decisions by the committee. However, for the time, it was considered progress in a very challenging area of medicine – mental illness.
OK, medical imaging? Well as it turns out Moniz (do not confuse with St-Moriz, ahhh skiing…) is also known for developing cerebral angiography – a technique allowing the visualization of blood vessels in and around the brain.
Moniz was interested in finding a non-toxic substance that would be eliminated from the body, but would not be diluted by the flow of blood before the x-ray could be taken. Another requirement is that the substance could not cause an emboli or clot as this would be a bad thing. Moniz played with salts of iodine and bromine and settled on iodine because of its greater radiographic density. And voila, birth of iodinated radiocontrast agents still in use today. Cool.
Supposedly it took him 9 patients to perfect his angiogram technique. Don’t ask about the first 8…
Moral of the story is: lobotomy bad and cerebral angiography good.
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| For more info see Free Birds… |
Happy Canadian Thanksgiving!!!
A traditional holiday – originating from the native peoples of the Americas – to celebrate the completion and bounty of the harvest. Well, no harvest for me but I will take the time to appreciate some of the successes of our MiVIP program and this blog over the long weekend.
Well, OK maybe think Zotero. The Mask of Zorro was such a great movie I could not resist. Having said that, when starting a new research project it may be helpful for you to think of yourself as Zorro. It may give you that extra zip required to get you through the inevitable research project doldrums…
So what is this Zotero thing anyway? Well Zotero is an open source reference management software that can act as your personal research assistant – helping you to organize and cite the numerous articles that you will be reviewing.
I was talking to Ori the other day – who is in the Radiation Therapy program at the Michener Institute – and he is in the process of planning a research project. As it turns out he has been a member of the MiVIP family since the beginning so he is well aware of my earlier posts that will help him along:
1- Thoughts on how to become a researcher
2- What is in a research question?
3- What makes up a good research question with the F.I.N.E.R. series.
Now how about the reference management software thing? Well, I give you an easy, fun, and instructional e-learning module to help you along. Our group has just finished our first kick at the can (so to speak) and so I invite you to have a look. Here is the link:
MiEducation Zotero e-learning module
Tell us what you think by posting comments and suggestions to this post.
Maybe listen to Ylvis in What Does the Zorro Say? while you go through the module. Fox in spanish is zorro…
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| Timeline of my ROP experience |
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| Helena Lan Summer 2014 ROP |
What is research like? If you had asked me this
question several months ago, I would have answered, “You wear a lab coat and
goggles while mixing chemicals or observing organisms. Hopefully something
interesting will happen, so that you get to publish your findings!” Well, after
participating in the Research Opportunity Program (ROP) at the University of
Toronto, I discovered that medical imaging research is more than just
pipetting, and is all the more exciting!