ABSTRACTS XVI ALASBIMN CONGRESS  NUCLEAR MEDICINE 1999.

9. LUNG

R. P.Baum¹, K. Plichta¹, M.Schmücking², R.Bonnet¹, N.Presselt¹, A. Niesen¹, J. Leonhardi¹

Zentralklinik Bad Berka¹ (PET Center, Dept. of Diagnostic Radiology, Dept. of Pneumology, and Dept. of Thoracic Surgery) Bad Berka, Germany

University of Jena Medical School², Dept. of Radiotherapy, Jena, Germany

baum@em.uni-frankfurt.de

Objective. Current noninvasive morphological imaging methods are not sufficiently reliable for accurate detection of malignancy in most solitary pulmonary nodules (SPN). To determine the role of F-18 FDG-PET for differentiating malignant SPN from benign SPN, findings in 46 patients, receiving a PET between July 1998 to May 1999, were analyzed prospectively in a routine setting (highly specialized, non-university based center).

Methods. Based on histopathological findings or a median follow-up of 9 months, diagnostic efficacy of PET (whole-body ECAT Exact 47, Siemens/CTI) was determined by calculating sensitivity, specificity, positive (PPV) and negative predictive value (NPV) and overall predictive accuracy for PET. All patients were studied by helical CT before PET with indeterminate results (most were small lesions under 2 cm). 6 MBq per kg bodyweight (350-600 MBq) F-18 FDG (produced by the radiopharmaceutical laboratory in Bad Berka) were injected one hour (45 to 90 min.) before a transmission corrected whole-body study was started. The data were iteratively reconstructed into 3D images and image fusion with CT data was routinely applied (Nuclear Diagnostics software run on a Hermes computer).

Results. There were 23 benign and 23 malignant nodules. Sensitivity and specificity of PET in differentiating benign from malignant lesions were 100% and 83% (19 out of 23), respectively (accuracy 89%, PPV 85% (23 out of 27) and NPV 100%, respectively). There were four false-positive cases with a moderate increase in FDG uptake due to postprimary tuberculosis, anthracosilicotic nodules and nonspecific inflammation.

Conclusions. Our results demonstrate that F-18 FDG-PET imaging can differentiate highly accurately as a noninvasive technique malignant SPN from benign SPN. FDG PET reduces the need for invasive tissue biopsy and can save patients from unnecessary operations.

Key Words. PET, FDG, solitary pulmonary nodules

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