PET/CT is a medical imaging technique that combines a positron emission tomography (PET) scanner and an x-ray computed tomography (CT) scanner into a single gantry system. This allows it to obtain both functional metabolic information from PET and anatomic information from CT in a single imaging session. The PET data provides physiological functional imaging while the CT data provides accurate structural information. By combining the PET and CT images, diagnostic accuracy and localization of lesions is improved for conditions like cancer, infections, and inflammation. The PET/CT scan involves intravenous injection of FDG, a CT scan, a PET scan, and generation of thousands of fused PET/CT images which are reconstructed, reformatted and analyzed.
3. is a medical imaging technique using a device
which combines in a single gantry system both a
positron emission computed (PET) scanner and an
x- ray computed tomography (CT) scanner.
4. 1-Brain Tumor
2-Head and Neck Cancer
3-Thyroid Cancer
4-Lung Cancer
5-Lymphoma
6-Infection and Inflammation
*And many other applications
5. PET has incomparable abilities to determine the
metabolic activity of tissues but needs the
assistance of higher-resolution, anatomic
information that it cannot provide. CT is the
easiest and highest-resolution tomographic
modality to integrate into PET imaging. The
combination of the two offers the best of both
worlds in an integrated data set and thus improves
diagnostic accuracy and localization of many
lesions.
6. CT scan gives accurate diagnostic information
about the distribution of structures inside the
body.
9. Patients should be questioned independently for
allergies to iodine-based CT contrast agents if these are
to be administered intravenously during the course of
a PET/CT study. Oral contrast agents, on the other
hand typically do not require special premedication or
testing. Depending on whether and which oral CT
contrast agents are given, patients are asked to drink
up to 1,500 mL of oral contrast solution during the
18F-FDG uptake phase. The injected dose of 18F-FDG
may vary between 300 and 700MBq depending on
scanner characteristics, such as PET detector material
and acquisition mode
10. Sixty to ninety minutes after the FDG has been
injected, the patient is placed supine on the
imaging table. Then, just as with a diagnostic CT,
the CT tube and detector are used to obtain a
topogram (scout), which is essentially a digital x-
ray of the entire field of interest.
*FDG (Fludeoxyglucose)
11. The topogram is used to map out the precise
portion of the body to be scanned, and those
coordinates are entered into the system. The
scanner software then automatically realigns the
table, and a spiral CT is performed of the area of
interest (usually the base of the skull through the
mid-thigh for most oncology studies), generating
literally hundreds of transaxial images through the
body.
12. Next, the table indexes back to the PET scanner
part of the machine, which then begins detecting
the radiation being emitted from the patient,
performing the âemissionâ part of the PET scan.
The patient is âsteppedâ through the scanner; each
bed-step requires 2 to 5 minutes, images a swath of
about 14 to 15 cm through the patient, and
generates about 30 to 45 contiguous transaxial
images.
13. For the typical oncology study, the whole
scanning process takes about 30 minutes. If it is
necessary to scan the entire body, such as with
melanoma patients, scan times are increased
accordingly.
14. The volume of data generated is enormous.
Hundreds of transaxial PET and CT images are
first reconstructed. These are then reformatted into
coronal and sagittal images to facilitate image
interpretation. For each of these sets of PET and
CT images, corresponding âfusionâ images,
combining the two types of data, also are
generated.
15.
16.
17. The average oncologic PET/CT scan can generate
as many as 4000 to 8000 images. This places
obvious burdens on the interpreting physicians, as
well as on data archival and retrieval resources.
18. 1- Better identification of inflammatory lesions.
2- Confirmation of unusual or abnormal sites.
3- Improved localization for biopsy or
radiotherapy.
4- Tumor stages can be defined more exactly.
19. 1- The PET/CT scanner is more like a tunnel than a
doughnut, so claustrophobia is a problem for some
patients.
2- Technical difficulties also are more prevalent in
PET/CT, because the scanner comprises two very
complicated machines instead of one.
3- Radiation doses to the patient are relatively high.
4- High â cost
20. 1- Higher- frequency filter: sharper images.
2- Low- frequency filter: smoother images .
*These types of filters controlling the resolution of
the images.
22. 2- Q.CLEAR
*Since the image noise is controlled inside the
iterative reconstruction as part of regularization,
post filters are not necessary.
* These methods of reconstruction the images
managing the contrast of the images.
24. 1- Use the screen splitting tool to open CT and
PET series in two panels.
2- Activate the panel with CT series by clicking
the image it contains or its title bar.
25. 3- Click the "Fusion" button on the toolbar or use
the CTRL + ALT + F shortcut.
26. The color scale used for rendering a fused image
can be changed by clicking a bar with a color scale
to the left side of the image.
27. The range of values represented on a color scale is
adjusted by using the windowing tool in the
panel with the series used as overlay (PET).
28. The opacity of fused images is adjusted by
pressing the left mouse button over a color scale
bar and dragging the mouse up to increase
opacity or down to make the fused image more
transparent.
29. Use the ellipse tool in the panel with fused images
to measure maximum, minimum and average
values of SUVbw (Standardized Uptake Value
calculated using body weight) for a specified area.
