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 (¹⁸F-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 ¹⁸F-FDG PET/CT. (orig.)