Generation of 4-dimensional CT images based on 4-dimensional PET-derived motion fields

H. J. Fayad, F. Lamare, C. C. Le Rest, V. Bettinardi, D. Visvikis
Journal of Nuclear Medicine. 2013-03-07; 54(4): 631-638
DOI: 10.2967/jnumed.112.110809

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1. J Nucl Med. 2013 Apr;54(4):631-8. doi: 10.2967/jnumed.112.110809. Epub 2013 Mar

Generation of 4-dimensional CT images based on 4-dimensional PET-derived motion

Fayad HJ(1), Lamare F, Le Rest CC, Bettinardi V, Visvikis D.

Author information:
(1)INSERM, UMR1101, LaTIM, CHRU Morvan, Brest, France.

Respiratory motion can potentially reduce accuracy in anatomic and functional
image fusion from multimodality systems. It can blur the uptake of small lesions
and lead to significant activity underestimation. Solutions presented to date
include respiration-synchronized anatomic and functional acquisitions. To
increase the signal-to-noise ratio of the synchronized PET images, methods using
nonrigid transformations during the reconstruction process have been proposed. In
most of these methods, 4-dimensional (4D) CT images were used to derive the
required deformation matrices. However, variations between acquired 4D PET and
corresponding CT image series due to differences in respiratory conditions during
PET and CT acquisitions have been reported. In addition, the radiation dose
burden resulting from a 4D CT acquisition may not be justifiable for every
patient.METHODS: In this paper, we present a method for the generation of dynamic
CT images from the combination of one reference CT image and deformation matrices
obtained from the elastic registration of 4D PET images not corrected for
attenuation. On the one hand, our approach eliminates the need for the
acquisition of dynamic CT. On the other hand, it also ensures a good match
between CT and PET images, allowing accurate attenuation correction to be
performed for respiration-synchronized PET acquisitions.
RESULTS: The proposed method was first validated on Monte Carlo-simulated
datasets, and then on patient datasets (n = 4) by comparing generated 4D CT
images with the corresponding acquired original CT images. Different levels of
PET image statistical quality were considered in order to investigate the impact
of image noise in the derivation of the 4D CT series.
CONCLUSION: Our results suggest that clinically relevant PET acquisition times
can be used for the implementation of such an approach, making this an even more
attractive solution considering the absence of the extra dose given by a standard
4D CT acquisition. Finally, this approach may be applicable to other
multimodality devices such as PET/MR.

DOI: 10.2967/jnumed.112.110809
PMID: 23471313 [Indexed for MEDLINE]

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