PET Imaging with Millennium VG
PET Overview
PET is a medical imaging
technology that generates high
resolution images of human
physiology. Unlike traditional
nuclear medicine that relies on
single photon emitting isotopes,
PET uses radionuclides (tracers)
like carbon, oxygen, nitrogen,
fluorine and rubidium, which
are the basic elements of (or used as analogs to) biological
substances. PET produces images of physiological
function, such as glucose metabolism, blood flow, organ
perfusion, receptor-ligand binding rates, and oxygen
utilization. With PET, normal and abnormal biological
functions of cells and organs can be determined.
The Millennium VG Acquisition
System makes it as easy to switch from SPECT to CoDe5
mode as changing collimators and selecting a different
acquisition.Operation modes are selected as photopeak
only or increased sensitivity, which includes Compton
interactions. It has standard and customizable brain
and whole body proto-cols with
variable numbers of
projections,be determined.
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Coincidence Detection on Gamma Cameras
When PET technology is applied to the gamma camera,
traditional nuclear medicine can take advantage of the
positrons emitted from biological tracers. Positron
imaging is currently being performed by both 511 keV
SPECT imaging and coincidence detection methods. The
CoDe5 option transforms the Millennium VG into a dual-purpose
system that can detect either single photons or
positron emissions. The Millennium VG Acquisition
System makes it as easy to switch from SPECT to CoDe5
mode as changing collimators and selecting a different
acquisition. Operation modes are selected as photopeak
only or increased sensitivity, which includes Compton
interactions. It has standard and customizable brain and
whole body proto-cols with variable numbers of
projections, matrix size, acceptance angle, zoom and
speed of rotation. Single Slice Rebinning (SSRB) is
performed for 2D acquisitions. Finally, the projection
data is sent via
DICOM to the
GENIE
Processing &
Review workstation
to be reconstructed
using either Filtered
Back Projection or
Iterative
Reconstruction.
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Nuclear Cardiology
Myocardial Perfusion Scanning
An Overview
NUCLEAR MEDICINE HAS ESTABLISHED a major role
in the evaluation and management of Coronary
artery disease. Cardiac SPECT had its clinical
beginnings in the early 1980s with initial commercial
availability of tomographic imaging systems. Since the
advent of cardiac SPECT, perfusion imaging with Tl-201
has dominated this aspect of cardiovascular nuclear
medicine. Introduction of Technetium labeled
radiopharmaceticals (99mTc-Sestamibi and 99mTc-Tetrafosmin)
and Dual detector SPECT systems have
significantly improved image quality permitting Gated
SPECT imaging in clinically realistic time frames. On the
other hand the improved computer technology now
permits complicated and computationally intensive
operations, such as iterative reconstruction, Bulls-eye
processing and three-dimensional quantification to be
performed routinely.
Myocardial perfusion scanning is currently accepted
by the Cardiology fraternity as a valuable technique for
evaluation of degree of myocardial ischemia and
myocardial viability as well as in the process of decision
making in management of Coronary Arter y Disease. The
property of differentiating between ischemic but viable
and infarcted nonviable tissues is helpful in decision
making for revascularisation in Coronary Artery disease.
An infarcted myocardium does not show any
improvement in function even after revascularisation
while an ischemic but viable myocardium recovers its
function and contractility with improvement in symptoms
like angina following revascularisation like CABG or
Coronary angioplasty.Clinical usage – Major indications of Myocardial
perfusion scanning
are as follows:
- As noninvasive evaluation in patients with high pretest
probability of having Coronary artery disease (family
history, diabetes, hypertension, hypercholesterolemia) etc.
- In-patients with atypical and non-diagnostic Treadmill
stress tests - for diagnosis of CAD (Case 1)
- In-patients with atypical angina - for diagnosis of CAD.
- In-patients with angiographically documented Coronary
artery disease - to evaluate myocardial viability - to facilitate
decision making for revascularisation procedures. (Case 3)
- In-patients with history of myocardial infarction -evaluation
of extent of infarction and extent of viable
myocardium for management planning. (Case 2)
- As risk stratification in-patients with recent myocardial
infarction.
In the field of diagnosis of Coronary artery disease a
well-defined defect in a patient with high pretest
probability of CAD is strongly diagnostic. The sensitivity
varies: Defects in LAD territory have highest sensitivity
and specificity (90-95%) while Lt.Circumflex territory
lesions have the lowest sensitivity (70-80%). SPECT
imaging gives much better sensitivity since the entire LV
myocardium can be imaged in slices.
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Contact our Marketing Team for more information on the complete range of GE PET products and services
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