Research on the Application Value of ¹⁸F-FDG PET/CT Combined with Neuronal Antibody Detection in the Diagnosis and Treatment of PNS Patients

Objective: To explore the clinical value of whole-body <sup<18</sup<F-FDG PET/CT combined with neuroantibody detection in the diagnosis and treatment of paraneoplastic neurological syndromes  (PNS). Methods: Clinical, laboratory,  and imaging data of 56 hospitalized patients with suspected PNS who underwent systemic <sup<18</sup<F-FDG PET/CT and neuropathic tumor antibody detection were retrospectively collected and followed-up on. ROC curve analysis was performed to compare the diagnostic efficacy of PET/CT, neuronal antibodies, and their combined detection results. Results: Among the 56 patients with suspected PNS, there were 20 with malignant tumors, including 19 cases complicated with PNS and 1 patient with spinal cord metastasis which also le d to neurological symptoms. <sup<18</sup<F-FDG PET/CT imaging indicated tumors or possible tumors in 23 cases, of which 20 cases were true positive, 3 cases were false positive (the follow-up results were reflux esophagitis, reactive bone changes, or inflammatory lesions in the neck), and the remaining 33 cases were true negative. The sensitivity, specificity, and accuracy of PET/CT were 100%, 91.7%, and 94.6%, respectively. There were 33 cases with positive neuroantibodies, including 8 cases of tumors with PNS (3 cases with anti-amphiphysin antibody encephalitis, 2 cases with anti-GABAb antibody encephalitis, 1 case with anti-Yo antibody encephalitis, and 2 cases with anti-Hu antibody encephalitis). Moreover, there were 25 cases without tumors (10 cases with LGI1 antibody encephalitis, 3 cases with anti-amphiphysin antibody encephalitis, 1 case with anti-Hu antibody encephalitis, 3 cases with anti-GABAb antibody encephalitis, 3 cases with anti-Yo antibody encephalitis, 1 case with Anti-caspr2, 1 case with GAD65, 1 case with NMDA, 1 case with PNMA, and 1 case with SOX1 antibody (1 case each). Of these, 23 cases were negative (12 cases with tumor). The sensitivity, specificity, and accuracy of the neuronal antibody test were 40.0%, 30.6%, and 33.9%, respectively. Furthermore, the sensitivity, specificity, and accuracy of the combined detection were 100.0%, 33.3%, 57.1%, 50%, 94.4%, and 78.6%, respectively. ROC analysis showed that the AUC was 0.958 (<i<P</i<=0.000<0.05; 95% CI 0.904~1.000), 0.353  (<i<P</i<=0.070>0.05; 95% CI 0.199~0.506), 0.667 (<i<P</i<=0.040<0.05; 95% CI 0.528~0.806), and 0.672 (<i<P</i<=0.034<0.05; 95% CI 0.514~0.830). Conclusion: Whole-body 18F-FDG PET/CT has the potential to  be the first choice for noninvasive tumor screening in patients with suspected PNS.