Decreased cerebellar activity on FDG PET/CT secondary to diffuse idiopathic cerebellar calcification

Cerebellar hypometabolism on FDG PET has been described in several conditions, for example, chronic alcohol abuse, antiepileptic medication use, multiple system atrophy, and cerebellar infarction. Corresponding cross-sectional examination is paramount in distinguishing possible etiologies because each condition has a relatively characteristic appearance. We present a case of an asymptomatic patient with diffuse cerebellar hypometabolism found incidentally on FDG PET/CT performed for suspected recurrence of gastric carcinoma. Accompanying CT images demonstrated calcification of the cerebellum and therefore confirmed the etiology of diffuse idiopathic cerebellar calcification. Identifying this diagnosis is critical for using the cerebellum as a standard to evaluate other brain structures.