The diagnostic role of dual-phase (18)F-FDG PET/CT in the characterization of solitary pulmonary nodules.
OBJECTIVE
Our objective was to evaluate the diagnostic role of dual-phase (18)F-fluorodeoxyglucose ((18)F-FDG) PET/computed tomography (CT) in the characterization of solitary pulmonary nodules (SPNs).


METHODS
A total of 48 SPNs in 48 patients were included in this retrospective study. The final diagnosis was confirmed histopathologically or by follow-up CT. Two PET/CT scans were performed: the first (early scan) was performed 1 h after injection and the second (delayed scan) was performed 2 h later. Standardized uptake values (SUVs) [early and delayed SUVmax and SUVmean adjusted to body weight, body surface area (BSA), lean body mass (LBM) and blood glucose level (Glc)], retention index and nodule-to-mediastinum (nodule activity/subcarinal region of interest activity) ratios were calculated, along with the receiver operating characteristic curve. Intraobserver and interobserver variabilities among nuclear medicine physicians were analysed for the two phases.


RESULTS
Eighteen patients had malignant tumour, whereas 30 had benign lesions. The median (min-max) SUVmax was 1.5 (0.5-4.1) in the benign group and 3.6 (1.3-38) in the malignant group. With the threshold value of early SUVmax as 2.5 and 2.75 using the receiver operating characteristic curve, a sensitivity of 94-75%, specificity of 75-80% and an accuracy of 83-78% were calculated. With the same threshold values for delayed images, 94-100% sensitivity, 77-80% specificity and 83-88% accuracy were obtained. BSA-SUVmax, LBM-SUVmax and Glc-SUVmax did not show any advantage over other quantitative parameters in the SPN characterization. There was no variability in the results obtained between the two nuclear medicine physicians.


CONCLUSIONS
Dual-phase PET/CT may increase the diagnostic potential of PET/CT in the characterization of SPNs. In this particular study group, a threshold value could not be determined for the retention index, but higher retention indices may show higher malignant potential in SPNs.
aDepartment of Nuclear Medicine, School of Medicine, Yuzuncuyil University, Van Departments of bNuclear Medicine cChest Disease dChest Surgery, School of Medicine, Dokuz Eylül University, Izmir, Turkey.
Yusuf
Y
Demir
Berna D
BD
Polack
Canan
C
Karaman
Ozhan
O
Ozdoğan
Erdem
E
Sürücü
Sadet
S
Ayhan
Atila
A
Akkoçlu
Nezih
N
Ozdemir
D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D015588:Observer Variation; D049268:Positron-Emission Tomography; D012372:ROC Curve; D012189:Retrospective Studies; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed
D019788:Fluorodeoxyglucose F18