Neuroimaging of Basal Ganglia Calcifications

Abstract

Basal ganglia calcifications are a frequent neuroimaging finding upon cerebral computerized tomography (CT) and may incidentally be identified in about 1 % of otherwise normal elderly subjects. The clinical picture of symptomatic basal ganglia calcifications includes neuropsychiatric abnormalities and movement disorders. Idiopathic cases, often referred to as Fahr's disease, idiopathic basal ganglia calcification (IBGC) or bilateral striato-pallido-dentate calcinosis (BSPDC), are either familial, mostly with an autosomal dominant mode of inheritance, or, less commonly, sporadic. Secondary causes such as disorders of calcium metabolism, vascular malformations, phacomatoses, tumors, or parasitical infections of the central nervous system may also lead to intracranial mineralization deposits. Apart from the basal ganglia (striatum and pallidum), a variety of anatomical structures can be affected by calcification, including the dentate nucleus, thalamus, and subcortical white matter. Calcifications typically show a symmetric distribution and differ in intensity and localization among affected subjects. Cerebral CT is the diagnostic gold standard to verify intracerebral calcifications. In contrast, magnetic resonance imaging (MRI) appears to have a rather low sensitivity and specificity and often MRI results remain inconclusive. Recently, transcranial sonography was consistently shown to reveal symmetric hyperechogenic areas of the basal ganglia corresponding to mineralization in patients with BSPDC. However, systemic investigations on the diagnostic value are lacking. Functional radioligand imaging methods provide an opportunity to demonstrate changes in the nigrostriatal function, local brain perfusion, and glucose metabolism. This chapter aims to clarify the heterogeneous terminology of basal ganglia calcifications and addresses the etiology and diagnostic approaches. Assets and drawbacks of different diagnostic tools are discussed.