Complementary value of metabolic and tau PET imaging in the diagnosis of corticobasal degeneration

Excerpt

A 66-year-old man presented with speech disturbances and progressive memory loss for 3 years. He also reported gradual stiffness, hypertonia, and right limb apraxia in the last 2 years. Corticobasal syndrome (CBS) was suspected in light of asymmetric motor and higher cortical symptoms [1, 2]. CBS may be a manifestation of corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), frontotemporal lobar degeneration (FTLD), Alzheimer’s disease (AD), and posterior cortical atrophy [1, 3, 4]. To shed light on the underlying causes of CBS, the patient underwent metabolic [18F]FDG PET imaging and tau PET imaging with the novel tracer [18F]Florzolotau(APN-1607) [5‐7]. The results of [18F]FDG PET (a–c) revealed asymmetrically reduced FDG uptake in the bilateral frontal lobes, basal ganglia, and thalamus. A markedly decreased tracer accumulation was evident on the left side (white arrow), whereas a moderate reduction was observed on the right. Tau PET imaging (i–k) revealed an increased tracer accumulation in areas characterized by hypometabolism on [18F]FDG PET. But the area of glucose hypometabolism was more widespread than the tau binding area. These findings were suggestive of CBD and ruled out other CBS-associated tauopathies (i.e., PSP, FTDL, and AD) [5, 8‐10]. In our patient, combining metabolic and tau PET imaging provided complementary value in the assessment of CBD and allowed a differential diagnosis of CBS. …