Diffusion-weighted versus volumetric imaging of the striatum in early symptomatic Huntington disease

Measurement of striatal volume using magnetic resonance imaging (MRI) provides a marker of striatal degeneration in Huntington disease (HD). Recent evidence suggests that diffusion-weighted MRI (DWI) may also detect striatal damage in HD. Here, we compared the sensitivities of volumetric MRI and DWI at distinguishing 10 patients with early symptomatic HD from 12 age-matched controls. Additionally, we assessed longitudinal changes in striatal volume and diffusivity in 8 of the HD patients over a 2-year period. At baseline, HD patients had significantly smaller volumes and significantly higher trace of the diffusion coefficient (Trace(D)) values of putamen and caudate than controls, but the volume differences were relatively larger than the Trace(D) differences. Putaminal and caudate volumes were outside the normal range in 9 of 10 HD patients, whereas Trace(D) values of putamen and caudate were abnormal in 8 and 6 of 10 HD subjects, respectively. During 2-year follow-up, there was significant volume loss of HD putamen (mean change: -8.0%) and caudate (mean change: -12.7%). By contrast, longitudinal Trace(D) changes of putamen (mean change: 4.0%) and caudate (mean change: 3.8%) did not reach statistical significance. Thus, volumetric MRI seems more sensitive to striatal degeneration in early symptomatic HD than DWI.