welcome to another MedCram lecture I want to give you a little bit
of insight on CT scans of the chest and this brings up a point about high
resolution versus just a regular CT scan of the chest when do you order one
versus the other let's talk about that so if there was
only one type of CT scan that you could get and you were concerned that you had
a lung nodule what kind of CT scan would you get would you get a regular CT scan
or would you get a high-resolution CT scan let's talk about those two types of
scans now let's pretend this is your lung kind of looks like a pacman ghosts
but nonetheless and here's our little nodule right here in the lung and you've
got a choice you can do a regular CT scan or we can do a high-res CT scan
otherwise known as an h r CT okay so which one is gonna be the best way to go
well first of all we got to know about how they do these things so a regular CT
scan basically does slices just like all CT scans do and they put it up onto the
screen so there's basically what they do but regular CT scans do something
specifically as they take all of the data between those scans okay so all
this data here gets plastered onto that film and all of this information gets
plastered onto this film all of this information gets plastered onto that
film and so forth and so forth and so what you get is something called volume
averaging where you take the average signal in that entire space there and
that image gets put onto that screen that you're seeing okay and so the point
here is that every square millimeter of the lung
is imaged in some way and has some sort of representation on the film below it
now that's different than a high-resolution CT scan here
you still get cuts
okay but these cuts don't volume average you're actually getting the image from
that area and all of the space in between those cuts are never really
imaged and so what's the advantage of doing this the advantage of doing this
is you get a very very detailed look at the architecture of that slice of the
lung so here we're looking for architecture so if I'm looking for what
am I looking for here I'm looking for fibrosis I'm looking for emphysema I'm
looking for bronchiectasis I'm not looking for nodules if I were looking
for nodules I would want to go over here and what's the reason I just sort of
demonstrated that here you could theoretically have a nodule in between
those two slices and completely miss it if it were small enough to fit in
between the distance between these slices because you're getting a
high-resolution image whereas here everything gets volume average so it's
not gonna be as clear it's not gonna be as distinct but you will pick up
everything here it will be distinct but you may miss stuff you will miss stuff
in between so when do you order one versus the other I would order a regular
CT scan if you're looking for nodules or if you want to follow the size of
nodules to see if they're growing if on the other hand you're looking for
architecture for instance you're looking for emphysema you're looking for
fibrosis you're looking for bronchiectasis you're looking for ground
glass of pacification you're looking for a specific way something might look in
terms of an infection or micro nodule or pattern then you need to get a
high-resolution CT scan usually this is done without contrast okay so now you
know how to order your CT scans thanks for joining us
you