Thank you for email@example.comAndrew ScottPhD Student (in Physics)Cardiovascular Magnetic Resonance UnitRoyal Brompton and Harefield NHS Trust.National Heart and Lung Institute, Imperial College.
Insert a cardiac MRI cine here. To impress.**This is the heart. Its a particularly interesting organ and Clinicians (Drs) and researchers like to look at and study it. To see it, obviously we can remove it from someone who has died and consented to use of their body for medical research but what about if we want to see a live heart?
Well get back to this, but first well look at the heart a bit more. This is a simplified diagram of what it does. Right atrium, right ventricle, left atrium, left ventricle.
What does it do?
The atria contract, then the tricuspid or mitral valves close to stop blood flowing backward. The ventricles contract and the pulmonary and aortic valves close and the tricuspid and mitral valves open again.
The valves have no muscle and are just flaps moved by the blood flow. The lubdup sound you hear through a stethoscope is the sound of the valves closing.
The blood from the body comes into the right atrium and out of the right ventricle to the lungs, where it collects oxygen molecules (turning deoxyheamoglobin into oxyheamoglobin) and then flows into the left atrium and out of the left ventricle, where it delivers oxygen to the rest of your organs.
A diagram where the blood flowsFrom http://en.wikipedia.org/wiki/Image:Humhrt2.jpg imageFrom http://www.fi.edu/learn/heart/enrichment/gallery.html diagram
From http://www.imcpl.org/kids/guides/health/circulatorysystem.html Circulatory system. **Play this movie in a new window.
Explain briefly why we have valves.**What can go wrong with the heart?
Lots heart disease kills around 238,000 people/year. The UKs biggest killer.
The most common thing is coronary artery disease. This is where the saturated fats you eat in burgers, crisps, cheese, butter, bacon sandwiches, chocolate, fried chips, gets stuck in the blood vessels that feed the heart. If you smoke, do little exercise or drink lots of alcohol this becomes more likely.
The heart, like any other muscle needs a supply of oxygen and it has its own set of blood vessels, called the coronary arteries and coronary veins, which supply and return the blood.
This is what happens to parts of your blood vessels after years of eating these saturated fats! Bits of these plaques as we call them, can break off and get stuck in your tiny coronary arteries and cause a heart attack. Alternatively, they can get stuck in your brain and cause a stroke or in your lungs and cause a pulmonary embolism. Either way its pretty bad news.
In a heart attack, the blood cant get to the heart and the bit of heart muscle supplied by the blocked artery can stop working or even die!
If you get really big plaques in your coronary arteries that stop some of the blood from reaching the heart, it can cause really bad chest pains, known as angina.
Other problems with the heart include birth defects, known as congenital heart disease. This might be a bit of the heart that didnt grow or a something that grew in slightly the wrong place or shape.
There are other diseases that can affect the heart including Thalassemia, a problem with the oxygen carrying heamoglobin in the blood, the treatment for which can cause Iron to collect in the heart and also some cancers affect the heart.Different heart diseases, including: congenital, cardiomyopathy, tumours, coronary heart disease.***You can also have a problem in your genes a birth defect congenital heart disease.
And some other diseases can affect the heart.*****Dilated cardiomyopathy means that the heart has dilated (expanded is too fat, but not from eating to much).*Can anyone tell me how we can see someone's heart without ripping open their chest? This might be to study how it works or to see if something is wrong with it.
We can use an x-ray, but if we do it like we would for broken bones all we would see would be the bones around the body. So we inject some dye made of Iodine into the blood vessels. If we want to look for blockages in the coronary arteries we put a wire into a vein in the leg and push it up through the body and the heart to the coronary arteries. We inject the iodine and look for a narrowed artery.
We can use a special x-ray known as a CT or CAT scan which produces slices through the body. Again we need to use the iodine dye.
Alternatively we can use ultrasound like we would for babies in the womb. We would use this to look for mis-shapen hearts or broken valves.
We can inject a different kind of dye which is radioactive and we can trace with a special camera called a gamma camera in a field of techniques known as nuclear medicine.
Alternatively we can use an MRI scan which well talk about more.
The problem with nuclear medicine is that it uses potentially unhealthy radiation which can increase your risk of developing cancer as do the first two techniques which use x-rays. The iodine dye used with the x-ray techniques can also be harmful to the kidneys in some cases.
Ultrasound doesnt use harmful dyes or radiation but the images can often be a bit crap..., and we cant see through the ribs with it so we have to look between them.
The various modalities and what they are used for.European Journal of Cardio-Thoracic Surgery Volume 32, Issue 3, September 2007, Page 532
*What it is very briefly and why it is so good.
This is an MRI scanner, we have 2 of these at the Royal Brompton and one in a trailer so we can tow it to other places if need be.
They also use them in other hospitals for looking at other parts of the body, often the brain.
You lie on the bed and you have a thing like a mat strapped around your chest for a heart scan. You are inside the narrow tunnel for around an hour for most scans. If you are very claustrophobic you cant have the scan or if you are too fat! In America they have larger scanners for really fat people. Here we have to use scanners designed for horses.
The scanner is very noisy, and you need to wear earplugs or special headphones while you are in their. The scan doesnt hurt at all, you can listen to music in the headphones and you and the person doing the scan can talk to each other.
The most important thing is not to take anything metal into the room where the scanner is. The doughnut shaped scanner is a huge magnet and anything with any iron in it will be dragged into the middle of the scanner at a huge speed and force. This means if you have metal plates in your arms, you might have problems, or any other metal implants.
A child died in the USA in 2001 because someone took the wrong type of oxygen cylinder into the magnet room and it hit the boy lying in the scanner on the head.
Video from http://www.mri-planning.com/videos/video_dl.html
*MRI is often used to look at tumours, in the breast, prostate, liver, as shown here, in muscles, in the spinal cord and in the brain, as shown here.
Insert image from portfolio of multiple brain tumours.*Remember the coronary arteries?*This is similar to what we saw with the x-ray contrast angiography. But the images are nicer.
Some things we can do with MRI.Make movies of the heart to see how it moves and how the volume of blood changes.*Measure how fast blood moves in arteries and in the heart. Including diagnosing faulty valves. **Look for ischemic muscle, where blood is not flowing. Look for infarcted tissue, which has died.
Movie of a perfusion sequence maybe with and without stress?*High resolution still 3D images of parts of the heart, imaged during free breathing.
The coronary arteries can I get a rendering?*****Contrast agent.
If we change the rate at which the protons magnetic moment goes from pointing like this, to pointing like this, we can change how the scan looks. By injecting a special dye into the patient called contrast agent (Gd-DTPA) we can make the magnetic field change in some places (sometimes we use Iron based ones, which we know have an effect on the magnetic field). This changes how bright we see the blood or wherver weve injected this contrast agent. ***So, we can see the water inside people. We can do tomography!
Tomography comes from tomo a section or cutting and graph like imaging.
So it is images in slices. Like slicing the body and in mri we can take slices in any direction we like.
MRI is most commonly used to get pictures of the brain! - examples of brain images transversal, sagittal and coronal. We can also look at where the information travels in the brain and which bits of the brain are used to for different tasks for example i was a volunteer in a study where we had pain inflicted on us during a special type of scan and the researchers looked for the bits of the brain which were active.
MRI is also used to look for cancer often breast cancer. It can also be used to examine joint injuries broken ligaments... Sports players often have them!
But here we are going to talk more about using MRI to get pictures of the heart and blood vessels.*http://www.open2.net/open2static/source/file/root/58/47/240596/boldeffect.jpg?forceFilename*Functional MRI.
When you use a part of your brain to think about something, for example, moving your arm more blood flows to this area of the brain. Blood without oxygen has special properties in a magnetic field and changes the strength of the field. This reduces the time that the radio wave takes to come back out of the proton. It slows the relaxation of the magnetic moment. So when blood with oxygen flows to the part of the brain you are using to think about moving your arm the magnetic field at this point changes and we can see this on the scan.
So we can tell in this type of scan whether you are moving your arm. Can you think of anything else we might be able to use this for?
We can almost tell what you are thinking aboutWe can detect lying. Your brain has to work harder to lie as there is more to think about than when you are telling the truth.
Imaging the premotor areasNathalie Picard* and Peter L StrickCurrent Opinion in Neurobiology 2001, 11:663672
*3D rendering with highlighted activation regions showing where the blood flows when someone moves their finger in and out.*The green areas show the regions of the brain used when the subject is telling the truth and the red ones when the person is lying. Although when the subject is having the scan they cant talk because this would move their head to much and ruin the scan, so they have to think about the lies (or the truth) in their head.
*Physicist designs and programs the sequenceDr and physicist test the sequence in a trial scientific paper in Journal.Radiographer does the scan (with Dr?) (processes the images in programs written by physicists)Dr reports the scan (decides what it does show or what it does not show)**