Dual-time point 18F-FDG PET/CT scan for differentiation between 18F-FDG-avid non-small cell lung cancer and benign lesions.
OBJECTIVE
The aim of this study is to clarify the difference of F-18 FDG uptake kinetics between FDG-avid non-small-cell lung cancer (NSCLC) and benign lesions associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation.


METHODS
The materials were 76 FDG-avid solitary NSCLC in 76 patients and 57 FDG-avid solitary benign lesions associated with various etiologies in 61 patients. FDG PET/CT scan was performed at 60 and 120 min after intravenous injection of 4.4 MBq/kg F-18 FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) between the two time points were measured. The optimal differential parameter was determined by receiver-operating characteristic curve analysis and evaluation of diagnostic accuracy.


RESULTS
The mean +/- SD of early SUV max, delayed SUVmax and %DeltaSUVmax were 8.3 +/- 5.2, and 10.2 +/- 6.5, and 21.9% +/- 18.9 in FDG-avid NSCLC, and 3.8 +/- 3.2, 4.0 +/- 3.7, and 11.3% +/- 26.0 in FDG-avid benign lesions, respectively. Delayed SUVmax in NSCLC was significantly higher than early SUVmax (P < 0.0001); while not different in benign lesions. Percent change of SUVmax in NSCLC was also significantly higher than that in benign lesions (P < 0.01). The optimal parameter for the differentiation was delayed SUVmax > 5.5 and yielded sensitivity of 77.6%, specificity of 80.7% and accuracy of 78.9%, which provided better differentiation than the use of %DeltaSUVmax or the traditional parameter of early SUVmax > 2.5. However, 11 (19.2%) benign lesions were indistinguishable from NSCLC.


CONCLUSIONS
Although delayed PET/CT scan enhances the difference of FDG uptake between FDG-avid NSCLC and benign lesions, and the use of delayed SUVmax > 5.5 appears to improve the differentiation of these hypermetabolic lesions compared with an early scan, careful interpretation and management for correct differentiation are still required.
Department of Radiology, St. Hill Hospital, 1462-3 Nishikiwa, Ube, Yamaguchi, Japan. sugar@sthill-hp.or.jp
Kazuyoshi
K
Suga
Yasuhiko
Y
Kawakami
Atsuto
A
Hiyama
Kazurou
K
Sugi
Kazutomo
K
Okabe
Tsuneo
T
Matsumoto
Kazuhiro
K
Ueda
Nobuyuki
N
Tanaka
Naofumi
N
Matsunaga
D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D012372:ROC Curve; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed
D019788:Fluorodeoxyglucose F18