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Author(s): D. Faria
J. Patrina
A. Sevilla
J. Tavares
L. Ribeiro
D. Sousa
J. Oliveira
J. Vale
D. C. Costa
Title: Respiratory movements cause significant misregistration and altered SUVs in thoracic PET-CT studies with 18F-DG
Issue Date: 2008
Abstract: PET-CT with 18F-DG studies are frequently used in the management of patients with lung malignancies. Unfortunately respiratory movements may influence significantly disease evaluation, particularly during longitudinal follow-up. Our aim is to investigate the influence of forced inspiration (I) and expiration (E) on shallow breathing (S) results (anatomic registration and SUV calculation).We included 18 patients, 15 male and 3 female, with ages between 40 and 78 years, with pulmonary and hepatic lesions. Data was acquired on a GE Discovery LS/4 PET-CT Scanner starting 60 to 90 minutes after the i.v. administration of 18F-DG (5 MBq/Kg of patient weight). CT acquisition used 120 kV, 80 mA and 1.5 pitch and PET acquisition on 2D mode included 5 to 6 AFOV (4 minutes per bed position). A further 1 to 2 late AFOV (> 2 hours p.i.) acquisition was routinely undertaken on S and complemented by 2 other attenuation maps with CT, 120 kV, 60 mA and 1.5 pitch, in I and E. PET images (always on S) were acquired in 2D mode, 1 or 2 AFOV/6 minutes. Three emission image sets were then reconstructed with OSEM and MAC using the 3 attenuation maps. Each lung was divided in 3 segments - Superior, Medial and Inferior, and the liver lesions classified in Superior and Deep. Images were then analysed according to lesion anatomic registration, and lesion SUV calculated on I, E and S.Our preliminary results show significant difference between SUV values (p=0.0154) of hepatic lesions located in superior segments in I and E. Lung lesions in the superior segment were better registered in S than in I or E. The worst misregistrations were observed in the inferior segments of the lung, with deviations up to 1,5 cm between I and E.Conclusion: respiratory movements impact significantly in image registration and SUV calculation of lung and hepatic lesions, depending on their regional localization. Failure to correct adequately for respiratory movements in follow-up longitudinal studies may cause significant evaluation errors. A well defined and "rigid" protocol must be used for longitudinal studies.
Subject: Engenharia
Document Type: Artigo em Revista Científica Internacional
Rights: restrictedAccess
Appears in Collections:FEUP - Artigo em Revista Científica Internacional

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