Early diagnosis of human TSE by multimodality MRI: Spectroscopic detection of thalamic gliosis in a patient with FFI and normal FLAIR and diffusion-weighted imaging
Résumé
Recently, several reports underlined the usefulness of brain MRI for the diagnosis of
Creutzfeldt-Jakob dis ease. FLAIR sequence and diffusion-weighted imaging (DWI) are
considered as high sensitive sequences to detect signal alteration of the cortex and the
deep grey matter. Recent advances in therapeutic approach of patients with prion diseases
have emphasized the need for earlier diagnostic markers that would authorize the onset of
treatment before massive and irreversible lesions of the brain have occurred.
Consequently, we designed a radio -clinical study using a multimodality MRI
standardized procedure that aimed to estimate differential sensitivity of FLAIR, DWI and
MR spectroscopy for the diagnosis of human TSE. Here we report a case of familial fatal
insomnia with the D178N-129M mutation. FLAIR and diffusion-weighted sequences
were normal in the whole brain notably in both thalami. However, spectroscopic study
showed a striking increase of the peak of myo-inositol (mI) and of the mI/NAA ratio in
the thalamus when compared to the other studied brain regions of the patient (frontal
isocortex, lenticular nucleus and cerebellar vermis) and to the thalami of control cases (n
= 10). This metabolite pattern is indicating of gliosis. Because the MRI study was
performed only two days before death, we were able to strictly correlate the spectroscopic
data with the neuropathological lesions (including the severity of astrogliosis and
microglial activation) observed in the thalamus. From this observation, we can conclude
that 1) MR spectroscopy can detect prion-related lesions even when other sequences
appear normal 2) spectroscopic metabolite pattern well correlates with the
neuropathological one.