F-18 FDG PET/CT for detection of malignant involvement of peripheral nerves: Case series and literature review

Purpose: To evaluate the role of positron emission tomography plus computed tomography (PET/CT) scans in detecting malignant involvement of the peripheral nerves (PNs). Material And Methods: We retrospectively reviewed medical records of all PET/CT studies performed at The University of Texas MD Anderson Cancer Center between 2003 and 2009, and selected patients in whom F-18 fluorodeoxyglucose (FDG) PET/CT findings were suspicious for malignant involvement of the PNs. We identified 26 cases of suspected tumorous involvement of the PNs that was subsequently confirmed by either biopsy or clinical follow-up. We evaluated the value of PET/CT in diagnosing malignant involvement of the PNs. Results: Of the 26 patients, 12 had lymphoma, 10 had breast cancer, 2 had lung cancer, 1 had colon cancer, and 1 had melanoma. In 21 patients, magnetic resonance imaging (MRI) was performed, either for follow-up of the PET/CT finding or to find an explanation for symptoms. MRI confirmed the presence of disease in only 9 patients, was interpreted as normal in 7 patients, and was inconclusive in 5 patients. FDG PET/CT was able to differentiate an active tumor from post-treatment fibrosis and could assess response to therapy with a high degree of confidence. Conclusions: Our results indicate that FDG PET/CT is helpful in diagnosing malignant involvement of the PNs, especially when findings from anatomic imaging (MRI or CT) are negative. In cases of known treated malignancy involving the PNs, follow-up by PET/CT has the advantage of high sensitivity for local recurrence.