Improved attenuation correction via appropriate selection of respiratory-correlated PET data.
OBJECTIVE
We propose a respiratory-correlated PET data processing method (called "BH-CT-based") based on breath-hold CT acquisition to reduce the smearing effect and improve the attenuation correction. The resulting images are compared with the ungated PET images acquired using a standard, free-breathing clinical protocol.


METHODS
The BH-CT-based method consisted of a list-mode acquisition with simultaneous respiratory signal recording. An additional breath-hold CT acquisition was also performed in order to define a tissue position from which PET events can be selected. A phantom study featured a 0.5-ml sphere (filled with 18F-fluorodeoxyglucose ((18)F-FDG) solution) pushed onto a rubber balloon (filled with (18)F-FDG solution and iodinated contrast agent). The feasibility of the BH-CT-based method was also assessed in two patients.


RESULTS
In the phantom study, the contrast-to-noise ratios (CNRs) were -1.6 for the Ungated volume and 5.1 for the BH-CT-based volume. For patients, CNRs were higher for BH-CT-based volumes than those for Ungated volumes (17.3 vs. 6.3 and 7.3 vs. 3.8, for patients 1 and 2, respectively). Bias-variance measurements were performed and yielded bias reduction of 40% with BH-CT-based.


CONCLUSIONS
The application of a BH-CT-based method decreases motion bias in PET images. This method resolves issues related to both PET-to-CT misregistration and erroneous attenuation correction and increases lesion detectability.
Daouk
Joël
J
Nuclear Medicine Department, Amiens University Medical Center, Amiens, France.
Fin
Loïc
L
Bailly
Pascal
P
Meyer
Marc-Etienne
ME
D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D009369:Neoplasms / Q000175:diagnosis*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D055425:Respiratory-Gated Imaging Techniques / Q000295:instrumentation / Q000379:methods*; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*