Dual-time-point FDG-PET for evaluation of lymph node metastasis in patients with non-small-cell lung cancer.
OBJECTIVE
The objective of this study was to retrospectively evaluate whether delayed additional F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging can improve the certainty of this modality in evaluating lymph node metastasis in patients with non-small-cell lung cancer (NSCLC).


METHODS
Eighty-three patients with NSCLC were examined. FDG-PET imaging (whole body) was performed at 1-h (early) post-FDG injection and repeated 2 h (delayed) after injection only in the thoracic area. The PET images were evaluated qualitatively for regions of focally increased metabolism. If a lymph node was visible on the PET image, the semi-quantitative analysis using the standardized uptake value (SUV) was determined for both early and delayed images (SUV(early) and SUV(delayed), respectively). Retention index (RI) was then calculated on the basis of the following equation: (SUV(delayed) - SUV(early)) x 100/SUV(early). The RI value of more than 0% was taken to be the PET criterion for malignancy.


RESULTS
For early and delayed PET, sensitivities for lymph node staging were 54% and 62%, respectively, specificities were 89% for both, and accuracies were 78% and 81%, respectively. The results of combined delayed PET and RI showed a sensitivity of 62%, specificity of 96%, and accuracy of 86%.


CONCLUSIONS
Dual-time-point FDG-PET (combined delayed PET and RI) showed better (although not statistically significant) specificity, positive predictive value, and accuracy than early or delayed PET alone for lymph node staging in NSCLC.
Department of Radiology, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, Japan. nisiyosi@kms.ac.jp
Yoshihiro
Y
Nishiyama
Yuka
Y
Yamamoto
Naruhide
N
Kimura
Shinya
S
Ishikawa
Yasuhiro
Y
Sasakawa
Motoomi
M
Ohkawa
D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000556:secondary*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D013995:Time
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18