[F]FDG, [C]PiB, and [F]AV-1451 PET Imaging of Neurodegeneration in Two Subjects With a History of Repetitive Trauma and Cognitive Decline

Trauma-related neurodegeneration can be difficult to differentiate from multifactorial neurodegenerative syndromes, both clinically and radiographically. We have initiated a protocol for imaging of patients with suspected TBI-related neurodegeneration utilizing volumetric MRI and PET studies, including [F]FDG indexing cerebral glucose metabolism, [C]PiB for Aβ deposition, and [F]AV-1451 for tau deposition. To present results from a neuroimaging protocol for evaluation of TBI-related neurodegeneration in patients with early-onset cognitive decline and a history of TBI. Patients were enrolled in parallel TBI studies and underwent a comprehensive neuropsychological test battery as well as an imaging protocol of volumetric MRI and PET studies. Findings from two patients were compared with two age-matched control subjects without a history of TBI. Both chronic TBI patients demonstrated cognitive deficits consistent with early-onset dementia on neuropsychological testing, and one patient self-reported a diagnosis of probable early-onset AD. Imaging studies demonstrated significant [F]AV-1451 uptake in the bilateral occipital lobes, substantial [C]PiB uptake throughout the cortex in both TBI patients, and abnormally decreased [F]FDG uptake in the posterior temporoparietal areas of the brain. One TBI patient also had subcortical volume loss. Control subjects demonstrated no appreciable [F]AV-1451 or [C]PiB uptake, had normal cortical volumes, and had normal cognition profiles on neuropsychological testing. In the two patients presented, the [C]PiB and [F]FDG PET scans demonstrate uptake patterns characteristic of AD. [C]PiB PET scans showed widespread neocortical uptake with less abnormal uptake in the occipital lobes, whereas there was significant [F]AV-1451 uptake in both occipital lobes.