Influence of Statistical Fluctuation on Reproducibility and Accuracy of SUVmax and SUVpeak: A Phantom Study.
Standardized uptake values (SUVs) have been widely used in the diagnosis of malignant tumors and in clinical trials of tumor therapies as semiquantitative metrics of tumor (18)F-FDG uptake. However, SUVs for small lesions are liable to errors due to partial-volume effect and statistical noise. The purpose of this study was to evaluate the reproducibility and accuracy of maximum and peak SUV (SUVmax and SUVpeak, respectively) of small lesions in phantom experiments.


METHODS
We used a body phantom with 6 spheres in a quarter warm background. The PET data were acquired for 1,800 s in list-mode, from which data were extracted to generate 15 PET images for each of the 60-, 90-, 120-, 150-, and 180-s scanning times. The SUVmax and SUVpeak of the hot spheres in the 1,800-s scan were used as a reference (SUVref,max and SUVref,peak). Coefficients of variation for both SUVmax and SUVpeak in hot spheres (CVmax and CVpeak) were calculated to evaluate the variability of the SUVs. On the other hand, percentage differences between SUVmax and SUVref,max and between SUVpeak and SUVref,peak were calculated for evaluation of the accuracy of SUV. We additionally examined the coefficients of variation of background activity and the percentage background variability as parameters for the physical assessment of image quality.


RESULTS
Visibility of a 10-mm-diameter hot sphere was considerably different among scan frames. The CVmax and CVpeak increased as the sphere size became smaller and as the acquisition time became shorter. SUVmax was generally overestimated as the scan time shortened and the sphere size increased. The SUVmax and SUVpeak of a 37-mm-diameter sphere for 60-s scans had average positive biases of 28.3% and 4.4%, compared with the reference.


CONCLUSIONS
SUVmax was variable and overestimated as the scan time decreased and the sphere size increased. In contrast, SUVpeak was a more robust and accurate metric than SUVmax. The measurements of SUVpeak (or SUVpeak normalized to lean body mass) in addition to SUVmax are desirable for reproducible and accurate quantification in clinical situations.
Division of Molecular Imaging, Institute of Biomedical Research and Innovation, Kobe, Japan; and Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Go
G
Akamatsu
Division of Molecular Imaging, Institute of Biomedical Research and Innovation, Kobe, Japan; and.
Yasuhiko
Y
Ikari
Division of Molecular Imaging, Institute of Biomedical Research and Innovation, Kobe, Japan; and.
Hiroyuki
H
Nishida
Division of Molecular Imaging, Institute of Biomedical Research and Innovation, Kobe, Japan; and.
Tomoyuki
T
Nishio
Division of Molecular Imaging, Institute of Biomedical Research and Innovation, Kobe, Japan; and.
Akihito
A
Ohnishi
Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Akira
A
Maebatake
Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Masayuki
M
Sasaki
Division of Molecular Imaging, Institute of Biomedical Research and Innovation, Kobe, Japan; and senda@fbri.org.
Michio
M
Senda
D003198:Computer Simulation; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008954:Models, Biological; D015233:Models, Statistical; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D051598:Whole Body Imaging / Q000295:instrumentation / Q000379:methods*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
FDG PET; SUVmax; SUVpeak; reproducibility; statistical fluctuation