SPECT imaging technique – Imaging in medicine (11/13)

This patient is being prepared to
undergo a SPECT procedure to look at myocardial profusion, that is,
blood supply to the heart muscle. It’s usual to scan the patient to look at
the profusion when the heart is being stressed
and also when the heart is rested. There can be several days between
these two image acquisitions. Stressing of the heart is achieved
in two ways, first by a pharmaceutical which has
a similar effect on the heart to taking exercise. And also by squeezing a dumbbell. The heart needs to monitored
carefully during this period, so an ECG is recorded. This is the bit that allows us to see – take some pictures
and see what’s going on. Once the heart has been stressed,
the radiopharmaceutical is injected. In this case, the pharmaceutical being used
is Technetium-labelled Tetrofosmin. Okay? That’s that part of the test finished now,
Mr Park, so I’m just going to disconnect you
from all of the machinery and then I’m going to ask you to wait
in the waiting room, because it takes this isotope
up to an hour to reach your heart. And then I’ll come and collect you
and escort you through for your scan, okay? Hello, Geoff, this is Mr Park. Mr Park, this is Geoff,
and Geoff will be doing your scan, – so I’ll hand you over, okay?
– Thank you very much. If you’d like to lie on this bed,
on your back, for me, with your feet up this end and your
head on the pillow just up there. Alright? I need you to put your arms just above
your head for me now, just on either side of you,
and that one as well. In order to obtain thermographic images, two gamma cameras must be rotated
around the patient, as close as possible to the heart, and the cameras are now trained to
move around the patient as closely as possible
without touching him. The computer will now calculate… and teach this camera head
just to move in. Keep very still… I’ll go and start the positioning. The images are reconstructed
from the data, using the same back projection
techniques that are used in CT scanning. They’re shown as slices through the
heart in different directions, with the white part of the image
corresponding to high take-up of the radiopharmaceutical, and the blue part representing
low take-up. Right, that’s it,
we’re all finished now, you can relax. We will be doing some pictures
of your heart when it’s at rest, and that will be later on. We’ll give you all the details about when
we’re going to do that in about ten minutes or so, but first of all I’m going to check
the data. Have a seat in the waiting room
where you were before. Right. And I’ll come and let you know. Thank you. – bye bye for now.
– Bye. Right, here we have some
processed images, and we’re looking at the stress
and rest in the short axis, stress and rest in the
horizontal long axis, and stress and rest in
the vertical long axis. And what we’re now going to do is compare isotope distribution in the
stress images and the rest images, looking for reversible
or irreversible defects.

5 comments

  1. Surely the one hour delay between injecting and imaging is to allow liver clearance of the tetrofosmin so that the inferior wall of the heart is better visualised. Prone imaging +/- full cream milk is useful in this instance if a one hour delay is impractical

  2. I LOOOOOOOOOOOOOOOOOOOOOOOOOOOVE these videos. Now when they were talking about ECg, That was NOT an ECG machine on the scren. it was a Nellcor pulse oximeter.

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