Differential diagnosis between (18)F-FDG-avid metastatic lymph nodes in non-small cell lung cancer and benign nodes on dual-time point PET/CT scan.
OBJECTIVE
To clarify the difference of (18)F-FDG uptake kinetics between FDG-avid metastatic lymph nodes (LNs) in patients with non-small-cell lung cancer (NSCLC) and FDG-avid benign LNs associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation.


METHODS
The subjects were 134 FDG-avid metastatic LNs in 67 patients with NSCLC and 62 FDG-avid benign LNs in 61 patients with various lung disorders including NSCLC. PET/CT scan was performed at 2 time points (at 60 min and at 120 min) after intravenous injection of 4.4 MBq/kg (18)F-FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) were measured at each FDG-avid LN. The optimal parameter for differentiation was determined by the receiver-operating characteristic analysis.


RESULTS
Delayed SUVmax was increased compared with early SUVmax in 114 (85.0%) FDG-avid metastatic LNs and 42 (67.7%) FDG-avid benign LNs, with significant higher delayed SUVmax than early values (7.0 +/- 5.0 vs. 5.9 +/- 3.4; P < 0.0001, and 3.0 +/- 1.3 vs. 2.8 +/- 1.0; P < 0.05, respectively). Early and delayed SUVmax and %DeltaSUVmax in metastatic LNs were significantly higher than those in benign LNs (P < 0.0001). The optimal parameter for the differentiation was the combined use of early SUVmax > 3.0 or delayed SUVmax > 4.0, yielding sensitivity of 88.8%, specificity of 80.6%, accuracy of 86.2%, negative predictive value of 76.9%, and positive predictive value of 90.6%. It provided better results than the use of early SUVmax > 3.0 alone (P = 0.019) or the optimal parameter for %DeltaSUVmax (>5%) (P = 0.012). However, 12 (19.3%) benign LNs were indistinguishable from metastatic LNs.


CONCLUSIONS
Although dual-time point PET/CT scan enhances the difference of FDG uptake between FDG-avid metastatic and benign LNs and improves the differentiation when compared with a single scan, biopsy procedure may be still required for accurate assessment of LN status in patients with NSCLC and possible etiologies showing intensive FDG uptake in benign LNs.
Suga
Kazuyoshi
K
Department of Radiology, St. Hill Hospital, 1462-3 Nishikiwa, Ube, Yamaguchi 755-0151, Japan. sugar@sthill-hp.or.jp
Kawakami
Yasuhiko
Y
Hiyama
Atsuto
A
Sugi
Kazurou
K
Okabe
Kazutomo
K
Matsumoto
Tsuneo
T
Ueda
Kazuhiro
K
Tanaka
Nobuyuki
N
Matsunaga
Naofumi
N
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D008207:Lymphatic Metastasis; 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