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PET resources located at MGH combine state-of-the-art conventional
PET technology with a first-in-the-world μPET camera to study
metabolism in burn patients. This noninvasive, high-resolution molecular
imaging technology is currently being applied to explore noninvasive
measurement of apoptosis, measurement of cell proliferation and detection
of gene expression.
Cyclotron and Radiochemistry
The MGH Cyclotron and Radiochemistry Facility includes a Scanditronix
MC17F Cyclotron providing 17.5 MeV protons and 8.5 MeV deuterons
at 50 μamp beam current. Seven automated targets and chemical
precursor processing systems routinely provide the following radioisotopes
for the PET study protocols: 11C, 13N, 150 and 18F. The Cyclotron
and Radiochemistry Lab consists of a cyclotron vault, a high radioactivity
laboratory with 3 hot cells, a quality control laboratory electronics
area, and a maintenance shop.
PET and μPET Camera Data Analysis
The MGH PET and μPET (microPET) Camera Data Analysis facility
is located within the MGH clinical nuclear medicine department and
consists of 2 Siemens HR+ whole body tomographs and a FE4096 whole-body
PET tomography. The camera facility also contains a radioactivity
dispensing and counting area fully equipped to handle and count
blood samples from PET studies and ancillary support equipment for
the studies.
A Bedside PET Imaging System
A Concorde Microsystems P4 μPET system, adapted from use in
model systems, has been developed for high-resolution studies of
human extremities, such as arms and legs (see Figure 1). The basic
properties of the μPET include ability to obtain 63 slices
simultaneously at resolutions of 1 mm or less.
The μPET unit is mobile on a wheeled cart and therefore can
be transported to a hospital room or Intensive Care Unit bed to
study a burn patient. It is currently designed and constructed to
allow imaging of the forearm (see Figure 2). There are two parts
to the system: a positioning component to retain the arm in the
center of the field of view and a patient stretcher, which can be
raised to 38 inches and “docked” to the μPET unit.
An example of recently acquired images of a human forearm are shown
in Figure 3. These images are μPET images of the forearm of
a healthy volunteer acquired at 15 minutes after injection of 15
mCI 18FDG. Note the excellent definition of the vascular structures
and clear delineation of muscle and bone.
Figure 1
The Concorde Microsystems "primate" system with modifications
to allow imaging of the extremities of human subjects.
(A) The plexiglass housing has been added to ensure that the rotating
transmission source and its mechanism are isolated during operation.
(B) A welded iron frame carries large casters, allowing easy transport
of the μPET from one location to another.
(C) A cradle has been added to support and position the limb during
imaging.
Figure 2
A model lying on the imaging bed with the arm positioned in the μPET
unit.
Figure 3
μPET images of a forearm from a healthy volunteer.
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