Hu 2011.

Study characteristics
Patient sampling	Patient series
Patient characteristics and setting	102 participants, mean age = 56 (SD = 14) years, 79 males/23 females, China Histology of primary tumour Adenocarcinoma: N = 41; squamous cell: N = 52; NSCLC not otherwise specified: N = 9; comorbidities: pulmonary (diagnosed on the basis of chest CT or PET/CT images): N = 53, including obstructive pneumonia (N = 24), unspecified acute or chronic infection pneumonia (N = 16), interstitial pneumonitis (N = 3), previous pulmonary tuberculosis (N = 4), active pulmonary tuberculosis (N = 1), atelectasis (N = 2), aspergillosis (N = 1), pneumoconiosis (N = 1), and bronchiectasis (N = 3) Inclusion criteria From March 2004 to March 2009, participants with pathologically proven NSCLC who received dual‐time‐point FDG PET‐CT scanning before radical surgery were included in this study. It is unclear if enrolment was prospective or retrospective or of consecutive participants Exclusion criteria None listed Previous/all reported tests All participants underwent conventional lung cancer staging on the basis of clinical information and FDG PET‐CT studies Clinical setting Departments of Thoracic Surgery, Radiation Oncology, Oncology, and Nuclear Medicine The inclusion of only participants who received surgery narrows the range of patients who would receive PET‐CT in practice, namely, patients (clinically) with suspected resectable non‐small cell lung cancer, a proportion of whom would have N2 or N3 disease already on PET‐CT
Index tests	All participants were fasted for at least 6 hours before the examination. PET images were acquired using an integrated PET‐CT scanner (Discovery LS; GE Healthcare, Milwaukee, WI, USA). The dosage of the FDG injection was 370 MBq. Immediately after unenhanced CT, a PET emission scan was performed that covered the identical transverse field of view. Images were acquired twice: an early scan that included the head, thorax, abdomen, pelvis, and thigh approximately 60 minutes after FDG injection (range = 50 to 65 minutes); and a delayed scan that included the chest approximately 120 minutes after injection (range = 110 to 140 minutes). The acquisition parameters for these 2 scans were the same. 2 experienced nuclear medicine physicians who were unaware of the participant's clinical history and the results of previous conventional imaging tests reviewed the PET‐CT images. On a transaxial slice of attenuation corrected PET, standardised uptake value (SUV) was obtained by placing regions of interest on the primary tumours and the LNs in each station that had been identified by visual analysis. To minimise partial volume effects, the maximum SUV (SUVmax) within an region of interest that had been automatically calculated by the Xeleris software was used. The SUVmax of the early and delayed image were defined as SUVe and SUVd, respectively Covariates Type of PET‐CT scanner: Discovery LS (GE Healthcare, Milwaukee, WI, USA) FDG dose: 370 MBq Injection‐to‐scan time: 60 min Attenuation correction: yes Cut‐off values for test positivity (malignancy): The retention index (RI) was the percentage change of SUV in the respective lesions between early and delay images: RI = (SUVd ‐ SUVe)/SUVe X 100%. SUVmax ≥ 2.5 were considered to be positive metastatic LNs on single‐time‐point imaging; a RI of 10% is the criterion for metastatic LNs on dual‐time‐point imaging
Target condition and reference standard(s)	All participants received radical surgery with system mediastinal LN dissection within 4 days (range = 3 to 7 days) following the PET‐CT scanning. A pathologist examined all lymph nodes for the presence/absence of malignancy
Flow and timing	All participants were accounted for in the results. All participants received the reference standard. There were no uninterpretable results
Comparative
Notes	Suported by the National High Technology Research and Development Program of China Adverse events: not reported Single‐time‐point data Participants with a comorbidity: TP = 14, FP = 15, FN = 2, TN = 22 Participants without a comorbidity: TP = 15, FP = 10, FN = 3, TN = 21 Dual time‐point data Participants with a comorbidity: TP = 15, FP = 12, FN = 1, TN = 25 Participants without a comorbidity: TP = 15, FP = 9, FN = 3, TN = 22
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Unclear
		Unclear	High
DOMAIN 2: Index Test All tests
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
Was there a pre‐specified cut‐off value?	Yes
Was a positive result defined?	Yes
		Low	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
		Low	Low
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Yes
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
		Low