18F-FDG PET/CT Diagnosis of Bronchopulmonary Carcinoids Versus Pulmonary Hamartomas

Radiological characterization of pulmonary tumors may be difficult and invasive. Needle biopsy may produce false-negative results. 18F-FDG PET/CT is an established noninvasive procedure for lung tumor characterization and staging. This study was aimed at differentiating bronchopulmonary carcinoids from hamartomas and typical from atypical bronchopulmonary carcinoids by means of 18F-FDG PET/CT.

In a retrospective analysis of 118 patients, with surgically resected pulmonary carcinoid tumors and hamartomas, 87 of those selected had also undergone 18F-FDG PET/CT preoperatively and constituted the study population. To better assess the tracer accumulation, especially in small lesions, the 18F-FDG uptake (SUV) in the tumors was corrected for partial volume effect by applying recovery coefficients corresponding to the respective various specific tumor volumes, as extrapolated from those obtained from experiments in a NEMA phantom.

The SUVmax was higher in the pulmonary carcinoids (mean, 3.9) than in the hamartomas (mean, 1.4; P ≤ 0.00001) and higher in the subgroup of peripheral carcinoids than in hamartomas (P ≤ 0.00001). The SUVmax was similar for the atypical and typical carcinoids, 5.0 and 3.8, respectively, because of the large variation in the data (P = 0.11).

Using PET measurements of the 18F-FDG uptake (SUVmax) in the tumors, corrected for partial volume effects, it was possible to differentiate the carcinoids from the hamartomas, but the clinically more aggressive atypical carcinoids could not be differentiated from the typical carcinoids.