Evaluation of lung lesions using FDG γ-camera PET equipped with a one-inch crystal

The aim of this study was to evaluate the clinical value of 18-fluorodeoxyglucose (FDG) imaging with γ-camera positron emission tomography (GCPET) equipped with a one-inch crystal for diagnosing lung lesions and determining the stage of non-small cell lung cancer (NSCLC) in regions with a high prevalence of inflammatory disease and tuberculosis. FDG-GCPET was used to examine 103 patients with suspected malignant lesions in the lung. The results of FDG-GCPET and conventional workup (CWU) including computed tomography (CT), ultrasonography and radionuclide bone scintigraphy were compared. The final diagnosis was based on the results of a histological analysis or follow-up of at least six months. The results showed 82 patients with malignant and 21 patients with benign lesions. If a lesion to background ratio ≥2.0 was used as the threshold, then the diagnostic sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of FDG-GCPET for NSCLC were 93.9, 57.1, 86.4, 89.5 and 70.6%, respectively. In 36 patients who underwent open-chest surgery, the diagnostic positive values of FDG-GCPET and CT for lymph-node involvement were 85% (17/20) and 65% (13/20), respectively. The diagnostic sensitivity, specificity, accuracy, PPV and NPV of FDG imaging were 85, 81.3, 83.3, 85 and 81.3%, respectively compared to the CT values of 65, 75, 69.4, 76.5 and 63.2%, respectively (NS). For the evaluation of distant metastases, 31 true-positive patients were identified during the follow-up. FDG imaging correctly identified 28 patients compared to 25 by CWU. In conclusion, FDG imaging with GCPET equipped with a one-inch crystal revealed a high lesion detection capability but a low level of clinical effectiveness for differentiating between malignant and benign lesions in the lung in regions with a high prevalence of inflammatory disease and tuberculosis. For N and M staging of NSCLC, this method may provide additional data that are not available from the CWU.