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3 techniques to evaluate ventricular
- 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
- if acquisition begins after maximum
- filling (end diastole)
- 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
Checks for ROIs
- Are LV edges correct? Does ROI include all
- of LV?
Is bkg ROI correct? Does it exclude excessive extracardiac activity?
- Is left atrium excluded from LV systolic
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
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.
Formed using matrix arithmetic
- Show changes in counts in each pixel
- related to a physiologic parameter
- produced by subtracting ED-ES
- The amount of blood ejected from the ventricles with each beat of the heart
- subtract ES-ES
- Results in negative values in pixels in normal areas and positive values in areas of dyskinesis.
- useful in demonstation of 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.
septal wall (than surrounding myocardium) in BOTH rest and stress images should
alert the NMT to
with regard to volume curves involving shorter-than- average or
smoothing of MUGA frames
- last fame may have fewer counts if there is arrhythmia
Statistical noise for counts can be a problem
- 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
All of the following can yield information on
- phase image
- stroke image
- paradox image
Which type of collimator is best for acquiring
a cardiac first-pass study?
Early tracer return to the lungs signify
left to right shunt
Lack of background normalization leads to what
results in the LVEF?
Subtracting end-diastolic frame from the
end-systolic frame yields?
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:
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
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
Image flicker in a gated cardiac cine display
can be reduced by which image processing protocol:
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
A common method for plotting COR is
projection angle vs pixel number
Large misalignments in COR will cause:
A sinusoidal plot represents COR measurements in which camera axis?
Subtle detector tilt can be assessed using a COR plot in which axis?
A “bull’s eye artifact” can be seen with all of the following, EXCEPT:
small cor shift causes
large cor shift
causes doughnut artifact
variation of COR, 64*64 and 128*128
.5 and 1 pixel
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
RATE OF CHANGE of the pixel count differences across FOV:
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?
What would you do if you find a doughnut defect when reconstructing a SPECT phantom?
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?
Slices from which tomographic plane is used to create transaxial slices in the cardiac plane?
In dual phase gastric emptying study the liquid phase is labeled with:
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