Novel Imaging Techniques Using F-18-Florbetapir Pet/Mri Can Guide Fascicular Nerve Biopsy In Amyloid Multiple Mononeuropathy

Background: Multiple mononeuropathy is a rare presentation of primary (AL) amyloidosis and nerve biopsy is usually needed for diagnosis. Conventional imaging is useful to identify proximal nerve involvement but may be inadequate. We report a patient with multiple mononeuropathy whose presentation was suggestive of AL amyloid neuropathy and in whom repeated tissue biopsies were negative for amyloid (including two sensory nerves and one muscle).Methods: The patient underwent magnetic resonance imaging (MRI) and whole body F-18-florbetapir positron emission tomography (PET)/MRI.Results: Whole body F-18-florbetapir PET/MRI revealed abnormal low-level florbetapir uptake in the right proximal tibial and peroneal nerves, which provided a target for a sciatic bifurcation fascicular nerve biopsy that was diagnostic of AL amyloidosis.Conclusions: F-18-florbetapir PET/MRI imaging is a promising diagnostic tool for patients with suspected peripheral nerve amyloidosis (including multiple mononeuropathy) in whom conventional imaging and nerve and muscle biopsies miss the pathology.