Statistical analysis of 18F-fluorodeoxyglucose positron-emission tomography/computed tomography ground-glass nodule findings.

Abstract

18F-fluorodeoxyglucose positron-emission tomography/computed tomography (18F-FDG-PET/CT) is important in lung cancer diagnosis; false negatives are often caused by ground-glass nodules (GGNs). PET/CT utility in GGN diagnosis is unknown. The associations between GGN CT findings (size, properties), the pathological diagnosis and maximum standardized uptake value (SUVmax) were explored. Sixty-six patients with pathological stage IA1-IIA lung adenocarcinoma underwent surgical resection and PET/CT between January 2010 and December 2014. Clinical characteristics, CT findings, pathological diagnoses and PET/CT findings were retrospectively examined. The age range was 47-86 years (median, 69 years), the female/male ratio was 38:28 and the pathological stage was IA1, IA2, IA3, IB and IIA in 5, 30, 21, 9 and 1, respectively. Total and solid-part lesion diameters ranged from 7.00-41.13 mm (median, 19.43 mm) and 0.00-23.23 mm (median, 4.55 mm), respectively; the solid-part ratio (solid-part diameter/total diameter) was 0-77% (median, 20%). SUVmax ranged from a value too low for evaluation to 3.9 (median, 1.0). Pathological diagnoses were adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), lepidic-predominant adenocarcinoma (LPA) and papillary predominant adenocarcinoma (PPA) in 17, 15, 32 and 2, respectively. Correlation coefficients for each factor and SUVmax for total and solid-part diameters were 0.513 (p<0.0001) and 0.461 (p<0.0001), respectively. All pure GGNs showed clinically unimportant SUVmax<2.5, even though some large GGNs were included (maximum, 40.0 mm). A total diameter ≥20 mm was significantly associated with FDG uptake (p<0.0001). SUVmax were <2.5 when the solid-part diameter was <4.55 mm. The AIS-MIA group showed significantly lower SUVmax than the LPA-PPA group (p=0.0008). There was no clinically important SUVmax with diagnostic value for pure or small part-solid GGNs. There were medium correlations for GGN total diameter, solid-part diameter, and SUVmax. We should note PET/CT's limitations in GGN diagnosis.