CTR - the dodgiest health test in the world

Recently I have had to re-submit a full health check for my latest adoption. It has been over 5 years since I did my last one and the adoption agency requires that you have a full medical check up every five years to stay on the register.

Part of the health check is a chest x-ray ( I am not going to go into the arguments against chest x-rays here but lets just say my doctor agrees that they are the worst idea ever) . So I went down to my local X-ray clinic and got a chest X-ray. The radiologists report said that I had cardiomegaly . Freaking out about this I checked the net and found that this meant that I had an enlarged heart ( this sounds bad ). The basic diagnosis for this is something called "Cardiothorasic Ratio"(CTR) which basic means that ratio of the width of your heart compared to the width of your chest. If it is over 50% then you are supposedly in trouble. So I start to panic , given that the usual diagnosis for cardiomegaly is something wrong with your heart valves or vascular system. So I ring me doctor to make an urgent appointment. The appointment goes something like this:

Me: Hi, yeah I got that chest x-ray you gave me the referral for. The report says I have cardiomegaly. What usually causes that.

Doc: Mmm. High blood pressure.. But you don't have that. Did you breathe in ??

Me: Breath in ?? What do you mean??

Doc: Well the CTR is a measurement of the width of your lungs compared to your heart. If you don't breathe in when you get an x-ray then its total rubbish.

Me: wtf? So this whole cardiomegaly thing is based on whether I bothered to breathe in when the x-ray was taken.

Doc: Yeah !! So did you breathe in ??

Me: No

Doc: Well you better get back to the x-ray place and do it again.

Me: AAAHHH!!!!

So if you every have to get a chest x-ray , make sure you breathe in until your blue in the face to save yourself alot of worry.