Imaging description

Creutzfeldt–Jakob disease (CJD) is a rare prion-mediated disease with progressive and invariably fatal outcome. The imaging features differ according to the disease subtype (sporadic, variant, familial, and idiopathic). The most common form, sporadic CJD (sCJD), accounts for 85% of cases and has relatively characteristic imaging features [1,2]. High T2, FLAIR, and DWI signal in the striatum and cerebral cortex occurs classically (Figs. 39.1, 39.2), with thalamic involvement in a smaller number of cases. High-signal changes on DWI and FLAIR sequences have a very high sensitivity and accuracy for the detection of sCJD, exceeding 90% [2]. There is generally lack of enhancement with intravenous contrast, and T1-weighted images tend to be normal. Similarly, CT demonstrates cerebral atrophy but is otherwise normal. DWI imaging changes reflect true restriction of diffusion and are accompanied by apparent diffusion coefficient (ADC) changes. The DWI abnormalities precede FLAIR and T2 signal change and tend to persist for a long period of time.

A variant form of CJD (vCJD) has been described and linked to bovine spongiform encephalopathy (BSE). Symmetric areas of high signal in the pulvinar thalami are pathognomonic and termed the “pulvinar sign.” This sign alone has a sensitivity of 78–90% and specificity of 100% for vCJD [2]. Similar to sCJD, these signal changes are seen on T2, FLAIR, and DWI sequences and there is no contrast enhancement. Although signal changes in pulvinar may be present in sCJD cases, these are less pronounced compared to signal change in the striatum.