Apparent Diffusion Coefficient Measurements. A Reliable Tool for the Diagnosis of Creutzfeldt-Jakob Disease

Creutzfeldt-Jakob disease (CJD) is a rare, rapidly fatal neurodegenerative disorder. The gold standard test for a positive diagnosis of definite CJD is histopathological confirmation, usually post-mortem; however, an autopsy study is not always feasible in all health settings.

We performed a cross-sectional analysis of a retrospectively enrolled cohort of patients with suspected prion disease between 2008 and 2019. Only patients with complete medical histories who fulfilled a diagnostic checklist were enrolled. The magnetic resonance imaging (MRI) sequences (T2-FLAIR and DWI) were analyzed, and the apparent diffusion coefficients (ADCs) were calculated for five regions of interest (ROIs) in each cerebral hemisphere.

In total, 72 MRI scans were post-processed. The series included 47 cases of CJD, including 25 genetic and 22 sporadic cases, in addition to 25 age-paired controls with non-prion encephalopathies. The neostriatum showed the most significant difference in ADC values (×10^-3 mm²/s) at 0.5946 in the left anterior putamen vs. 0.8644 in the control encephalopathies (p < 0.001; 95% confidence interval: 0.5751-0.6142 vs. 0.7812-0.9476), while the other ROIs also showed significant differences. The best cut-off value to differentiate CJD from other encephalopathies was identified as 0.65×10^-3 mm²/s, with no significant differences in this coefficient between sporadic and genetic cases.

Quantitative ADC measurements made in the basal ganglia seem to be the most useful ante-mortem diagnostic tool for differentiating CJD from non-prion encephalopathies when cerebrospinal fluid real-time quaking-induced conversion or other specific misfolded protein detection tests are inaccessible.