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3 techniques to evaluate ventricular
function
- Gated equilibrium radionuclide angiography
- first pass
- gated tomographic MI imaging
-
Other names for MUGA
- gated equilibrium radionuclide angiography (ERNA)
- radionuclide ventriculography (RVG)
-
Tooo few frames
- results in crap temporal resolution,
- image flicker during image display because of large change in counts from one frame to the next.
-
Too many frames
- results in statistical noise
- too few counts per image, causing poor image res
-
Improper gating of ECG signal can result in
- loss of counts in first several frames of
- data
- if acquisition begins after maximum
- filling (end diastole)
-
MUGA views
- anterior
- LAO (used for EF)
- left lateral
-
for accurate manual or
automatic edge detection.
- There must be adequate
- contrast (count differential) between anatomic structures
-
Contrast is a function of:
- spatial resolution (matrix size)
- RBC labeling integrity
- soft tissue attenuation
- patient positioning
- counting statistics
-
Quality Assurance
Checks for ROIs
- Are LV edges correct? Does ROI include all
- of LV?
- Is left atrium excluded from LV systolic
- frames?
Is bkg ROI correct? Does it exclude excessive extracardiac activity?
-
if ROI does not include all of LV?
EF will be lower
-
If LA is included in ROI
EF lower, says you havent ejected anything.
-
LV ef formula normalized
=bkg cts * heart pixels / bkg pixels
-
LV ef formula
Net ED cts - Net ES cts/ net ED cts
-
without normalizing
ef can be underestimated.
-
Too big of backround subtraction (bkg over spleen or aorta)
Overestimation of EF
-
underestimation of ef can be caused by
- LA in LV ROI
- poor seperation of RV and LV
- too little bkg subtraction w/o normalizaiton
- variable gating.
-
Functional
(parametric) images
- Show changes in counts in each pixel
- related to a physiologic parameter
Formed using matrix arithmetic
-
Stroke volume
- produced by subtracting ED-ES
- The amount of blood ejected from the ventricles with each beat of the heart
-
Paradox image
- subtract ES-ES
- Results in negative values in pixels in normal areas and positive values in areas of dyskinesis.
- useful in demonstation of aneurysm
-
aneurysm
An aneurysm is an abnormal widening or ballooning of a portion of an artery due to weakness in the wall of the blood vessel.
-
“Hotter”
septal wall (than surrounding myocardium) in BOTH rest and stress images should
alert the NMT to
-
true
with regard to volume curves involving shorter-than- average or
longer-than-average beats
low counts
-
temporal
smoothing of MUGA frames
-
- last fame may have fewer counts if there is arrhythmia
-
Statistical noise for counts can be a problem
with
- increasing
- the number of frames
-
A cardiac first pass study can be used to
assess all of the following
- cardiac shunts
- left and right ventricular function.
-
Buffered beat acquisition involves data
acquired in
list mode
-
All of the following can yield information on
dyskinesia
- phase image
- stroke image
- paradox image
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Which type of collimator is best for acquiring
a cardiac first-pass study?
LEHS
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Early tracer return to the lungs signify
left to right shunt
-
Lack of background normalization leads to what
results in the LVEF?
underestimation
-
Subtracting end-diastolic frame from the
end-systolic frame yields?
Paradox image
-
Image flicker as a result of large fluctuations
in counts between frames can be cause by
too few frames, poor temporal resolution
-
Stroke volume image is used to check:
regional wall motion
-
Time to peak filling rate represents the time
required for the ventricle to achieve:
fastest relaxation
-
Brain, kidney & bladder activity in the
Tc-MAA injected patient signifies
right to left shunt
-
All of the following can underestimate left
ventricular ejection fraction except
- -not all left ventricle is included in end
- systolic ROI
-
Subtracting end-systolic frame from the
end-diastolic frame yields
stroke vol
-
Qp/Qs over 1 signifies
left to right cardiac shunt
-
The time-activity curve of the background ROI
in an ERNA study will normally be
flat
-
Image flicker in a gated cardiac cine display
can be reduced by which image processing protocol:
temporal smoothing
-
The reason for the early LV peak is:
right to left shunt
-
Effects of misalignments in COR can be assessed by reconstructing a line source in
transverse plane
-
A common method for plotting COR is
projection angle vs pixel number
-
Large misalignments in COR will cause:
doughnut artifact
-
A sinusoidal plot represents COR measurements in which camera axis?
x
-
Subtle detector tilt can be assessed using a COR plot in which axis?
y
-
A “bull’s eye artifact” can be seen with all of the following, EXCEPT:
COR misalignment
-
small cor shift causes
blurring
-
large cor shift
causes doughnut artifact
-
variation of COR, 64*64 and 128*128
.5 and 1 pixel
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What would you do if you find a bull’s eye defect when reconstructing a SPECT phantom?
acquire new flood correction tables
-
RANGE of the differences in pixel counts in the entire FOV is referred to as
integral uniformity
-
RATE OF CHANGE of the pixel count differences across FOV:
differental uniformity
-
What type of a source(s) is/are used for intrinsic uniformity testing?
point and sheet sources
-
What would you do first if you find image blurring when reconstructing a SPECT phantom?
acquire new COR correction then case FSE
-
What type of a source(s) is/are used for extrinsic uniformity testing?
sheet source
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What would you do if you find a doughnut defect when reconstructing a SPECT phantom?
call FSE
-
The background ROI used to in determining % GE reflux is placed over the
lower left lung
-
A semi-log plot is used to calculate stomach half-emptying time of which of the following?
liquid
-
Slices from which tomographic plane is used to create transaxial slices in the cardiac plane?
transverse
-
In dual phase gastric emptying study the liquid phase is labeled with:
In-111 dtpa
-
The “star” artifact during image reconstruction can be minimized by:
decreasing number of projections
-
The background ROI to calculate GBEF is ideally placed where?
in the liver
-
Normal gall bladder ejection fraction range
>35%
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