Validation of the CT iterative reconstruction technique for low-dose CT attenuation correction for improving the quality of PET images in an obesity-simulating body phantom and clinical study.
OBJECTIVE
The aim of this study was to validate the efficacy of computed tomography (CT) iterative reconstruction (CT-IR) for low-dose CT attenuation correction in terms of the estimation of attenuation coefficient and quality of PET images.


METHODS
We used normal and obesity-simulating body phantoms. PET images were reconstructed using two attenuation correction maps obtained using filtered back projection (CT-FBP) and CT-IR. The CT numbers, attenuation coefficients, contrast-to-noise ratio (CNR10 mm), and coefficient of variation were evaluated. Fifty-two consecutive patients who underwent F-FDG PET/CT with low-dose CT scans were selected for the clinical study. Clinical PET images were reconstructed using CT-FBP and CT-IR, and the effects of CT-IR were examined according to the maximum standardized uptake value (SUVmax), contrast-to-noise ratio in the tumor (CNRtumor), and signal-to-noise ratio in the liver (SNRliver).


RESULTS
The CT number on the CT-IR was significantly lower than that of CT-FBP in the obesity-simulating body phantom. The decrease in attenuation coefficients obtained using CT-IR was smaller than that obtained using CT-FBP. The CNR10 mm and coefficient of variation obtained using CT-IR were superior to those obtained using CT-FBP. The SUVmax was not significantly different between the CT-FBP and CT-IR. Although the difference in the SNRliver between the CT-FBP and CT-IR was not significant, the CNRtumor of the CT-IR was significantly higher than that obtained using CT-FBP in obese patients.


CONCLUSIONS
We demonstrated that CT-IR improved the estimation of the attenuation coefficient and provided significant improvement in the CNR of the clinical PET images.
aDepartment of Radiological Technology, Kurashiki Central Hospital bDepartment of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Norikazu
N
Matsutomo
Akio
A
Nagaki
Masayuki
M
Sasaki
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D011829:Radiation Dosage; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*