Antibody-positive paraneoplastic neurologic syndromes - Value of CT and PET for tumor diagnosis

Objective: To assess use of whole-body F-18 fluoro-2-deoxy-glucose (FDG)-PET and CT for diagnosing tumor in patients with antibody-positive paraneoplastic neurologic syndromes (PNS). Methods: In order to directly compare CT and FDG-PET imaging in patients with various antineuronal antibodies, the authors performed in parallel CT scanning and FDG-PET in a series of 13 consecutive patients ( 9 women, 4 men, aged 59 +/- 14 years) with positive antineuronal antibodies (anti-Hu: 8, anti-Yo: 4, anti-Tr: 1) in whom the authors were searching for a tumor or tumor recurrence. Results: A new tumor or tumor recurrence was found in 10/13 patients ( 5 small cell lung cancer, 2 ovarian cancer, and 1 each neuroblastoma, Hodgkin's lymphoma, and lymph node metastasis of adenocarcinoma). All tumors except one with good clinical evidence for small cell lung cancer were confirmed histologically. For detection of tumor or tumor recurrence, CT was positive in 3/10 patients ( sensitivity of 30%), and FDG-PET in 9/10 ( sensitivity of 90%, difference between methods p < 0.01), but the combination of both methods showed a sensitivity of 100%. Conclusions: FDG-PET imaging is useful in tumor screening of patients with antineuronal antibodies, but should be complemented by CT scanning to increase sensitivity and accuracy of tumor diagnosis.