Derechos:
Atribución-NoComercial-SinDerivadas 3.0 España
Resumen:
Positron emission tomography (PET) is a functional medical imaging modality that
is acquired after the administration of a radiotracer. PET imaging technique is
based on the coincident detection of gamma photons of 511 keV. If any of the
antiparallel gamma Positron emission tomography (PET) is a functional medical imaging modality that
is acquired after the administration of a radiotracer. PET imaging technique is
based on the coincident detection of gamma photons of 511 keV. If any of the
antiparallel gamma photons does not reach the PET detectors due to attenuation
(scatter or absorption), a coincidence is not recorded, which means missing
information. Attenuation is the largest correction that is applied to PET images in
order to obtain an accurate quantification of radiotracer activity concentration.
One approach to perform that correction is based on creating an attenuation map
using a computed tomography (CT) image in which its Hounsfield units are
transformed into attenuation coefficients at 511 keV by applying a bilinear
approximation. Then, the attenuation map is used to correct PET data in the
reconstruction process.
There are no studies that compare non‐attenuation corrected PET images and
attenuation corrected PET images acquired with the Argus PET/CT scanner with
different energy windows and reconstruction methods from a practical point of
view (quantification results). The aim of this study was to perform that
comparison by means of three different experiments.
Our results showed that attenuation correction has an impact on the image data
and results are different depending on the Argus PET/CT reconstruction method
and energy window used. For filtered back projection (FBP) and ordered –subset
expectation maximization (OSEM) 2D reconstruction methods, image activity
(counts per second) increases when applying the attenuation correction
independently of the attenuation medium and the energy window. However, for
OSEM 3D, the activity decreases. The absolute relative error between the
estimated and real activity concentration either for non‐attenuation corrected PET
images or attenuation corrected PET images was smaller than 5%. Finally,
recovery coefficients for non‐attenuation corrected PET images are similar than
the ones for attenuation corrected PET images. The segmentation rule does not
affect the recovery coefficient calculation. However, when segmenting small
objects, VOI mean value does not provide an accurate activity concentration.[+][-]