Specific Imaging Findings

Physiologic parenchymal calcifications are generally confined to the globi pallidi, but can be seen elsewhere in the basal ganglia, and in the cerebellar dentate nuclei. They are typically punctate or smudgy and almost always bilateral. Occasionally they can be quite prominent. T1 and T2 signal intensities vary depending on the concentration of calcium salts within the tissues. T2*-weighted sequences demonstrate blooming with signal loss due to increased magnetic susceptibility.

Pertinent Clinical Information

Basal ganglia calcifications are an incidental finding in roughly 1% of head CTs. They generally occur over the age of 30 and their prevalence increases with age. The median age at which physiologic basal calcification is seen is in the 60s. They usually have no clinical significance. However, if they are observed in patients with extrapyramidal signs or under the age of 30, clinical evaluation to rule out an underlying endocrine process affecting calcium and phosphate metabolism should be undertaken.

Differential Diagnosis

Fahr Disease

1. • also involves cerebral white matter and cerebellum

Hyperparathyroidism, Hypoparathyroidism (188)

1. • may involve thalamus, white matter, cerebellum, and dura

2. • abnormal serum PTH levels

Aicardi–Goutières Syndrome (186)

1. • also thalamic, periventricular and cerebellar calcifications

2. • leukodystrophy with abnormal white matter signal

3. • cerebral atrophy

4. • presents in infancy

Radiation/Chemotherapy-Induced Leukoencephalopathy (26, 191)

1. • CT hypodense and T2 hyperintense white matter

2. • typically in young children

3. • calcifications are primarily in the white matter

Congenital HIV Infection

1. • also frontal white matter and cerebellar calcifications