Characterization of solitary pulmonary nodules with 18F-FDG PET/CT relative activity distribution analysis

To compare the capability of relative activity distribution (RAD), a new index of fluorodeoxyglucose F18 ((18)F-FDG) uptake, with those of the typical markers for differentiating benign and malignant solitary pulmonary nodules (SPNs) by integrated positron emission tomography (PET)/computed tomography (CT).

RAD, maximal standardised uptake value (SUV(max)), partial volume corrected SUV(max) (corrSUV(max)), and retention index (RI) were calculated prospectively for 115 malignant and 60 benign SPNs. Area under receiver operating characteristic curve (AUC), sensitivity, specificity, and accuracy were compared (P < 0.05).

Malignant lesions (0.98 ± 0.03) had significantly lower RAD than benign lesions (1.01 ± 0.02). AUC (0.935) was significantly larger and specificity (96.67%) was significantly higher for RAD than for SUV(max) (P ≤ 0.0001), corrSUV(max) (P < 0.0001), RI (P < 0.0001), and visual assessment (P = 0.01 and 0.002, respectively). Further, RAD had significantly higher sensitivity (92.17%) than SUV(max) (P = 0.0007) and higher accuracy (93.71%) than SUV(max) (P < 0.0001), corrSUV(max) (P < 0.0001), and RI (P = 0.002).

RAD seems to be more specific and accurate than the typical markers for differentiating malignant and benign SPNs by (18)F-FDG PET/CT.

• Relative activity distribution index is assessable by (18)F-FDG PET/CT • The index effectively characterises solitary pulmonary nodules • RAD is more specific and accurate than the typical markers in (18)F-FDG PET/CT • RAD provides additional options for small solitary pulmonary nodules.