2. FLUROSCOPY
Fluoroscopy is a method of obtaining real
time images that is especially useful for
guiding a variety of diagnostic and
interventional procedures.
The ability of fluoroscopy to display motion
is provided by a continuous series of
images.
4. MR FLUOROSCOPY
Magnetic resonance fluoroscopy is a
method for high speed MR image
acquisition.
Short acquisition time per image(500
msec or less).
High image rate ( 10 or more per sec ).
High speed image reconstruction (150
msec 0r less).
5. MR fluoroscopic image were acquired with a
limited flip angle pulse sequence with reduced
repetition times(TRs) and fewer phase encodings
used per image.
The sequence is applied continuously.
Images are formed by updating one set of data
with data from the most recently taken.
Artifacts from the motion become less evident on
images as progressively shorter acquisition time
is used.
6. In the MR fluoroscopy, high rate imaging,
reconstruction and display are performed
sequentially, periodically for a slice of a
subject.
Real time images of the slice are displayed.
7. The image reconstructing time for a
slice is substantially adjusted to the
imaging time for the slice.
So that images if slice can be
displayed in real time.
8. The acquisition is a modification of the basic
sequence FLASH.
But with a restricted number of phase encodings.
The encodings are applied continuously.
Images are formed by sliding a window of width
encodings along the acquired data and
reconstructing an image for each position of the
window
9. MR fluoroscopy offers guidance and monitoring
advantages that enable one to perform biopsy
and cross-sectional imaging in near real time.
The advent of MR fluoroscopy has made it
possible to obtain images at a rate that can be
considered real time in terms of effectiveness
10. Image rates can be as low as 1 second,
which is fast enough to facilitate MR
imaging guidance of biopsy procedures.
Such procedures include the localization of
biopsy needles within a tumor and the
localization of surgical tools for
administering therapeutic drugs
11. The advantages of MR fluoroscopy are
near-real-time imaging and the absence of
radiation hazards.
A potential disadvantage of MR fluoroscopy
is that the image feedback with this system
is not as immediate as that with US, CT
fluoroscopy, or x-ray fluoroscopy.
12. With CT imaging, it is possible to identify fissures, focal
areas of emphysema and thereby avoid these areas
during biopsy.
MR imaging does not offer this advantage.
MR imaging is not routinely used for evaluation of the
lungs, mediastinum, or pleura in practice, but it is an
established tool for evaluation of the thoracic vasculature
and chest wall.
And is used as an alternative to CT for evaluation of the
mediastinum in patients who are allergic to intravenous
contrast agents.
13.
14.
15. Contrast-enhanced coronal T1-weighted image shows a left temporal abscess and
infection of the temporal bone (A). Image of the drainage seen during MR
fluoroscopy image (B).
16. Contrast-enhanced coronal image demonstrates a subdural emphysema
in occipital localization (A). The needle has ruptured the capsule and is
seen in the abscess cavity (B). The interhemispheric fissure is seen very
close to tip of the needle, but it is intact. After the drainage, no pus is
seen in the abscess localization (C).
