ABSTRACT
BACKGROUND AND PURPOSE: In Friedreich's ataxia (FRDA), frataxin deficiency results in iron redistribution in the dentate nuclei (DNC). Clusters of iron cause inhomogeneities in a magnetic field and result in a reduction in T2 relaxation time (T2). METHODS: T2 was prospectively evaluated in DNC, putamen, substantia nigra (SN), cerebellar white matter (CWM) and caudate and the correlation with clinical parameters was investigated. Thirty-five patients (range 9-51 years) and 44 controls (12-49 years) underwent T2 multi-echo sequence in a 3T scanner. Twenty-three patients (12-50 years) and 19 controls (14-49 years) were reassessed after 1 year. T2 was evaluated using specialized software (Aftervoxel) and severity of disease was quantified with the Friedreich Ataxia Rating Scale (FARS). RESULTS: T2 of both DNC was significantly shorter in the FRDA group at baseline (right, 58.6 ± 8.3 ms vs. 63.7 ± 8.1 ms, P = 0.013; left, 56.7 ± 7.7 ms vs. 62.6 ± 6.8 ms, P = 0.001). No significant difference was found between groups regarding the SN, putamen, CWM and caudate T2. DNC T2 values correlated with age, FARS total score and FARS III subscore on both sides. Prospectively, there was a significant reduction of T2 in FRDA patients in right and left DNC (P = 0.001 and 0.009) but not in other structures. Amongst controls, none of the regions significantly changed after 1 year. DNC T2 change over time correlated with GAA expansions and clinical deterioration (expressed by a change in FARS scores). CONCLUSIONS: DNC T2 values are abnormal in FRDA, progress over time and correlate with ataxia severity. These results strongly suggest that DNC relaxometry can be a useful neuroimaging marker in FRDA.
Subject(s)
Cerebellar Nuclei , Disease Progression , Friedreich Ataxia/diagnosis , Magnetic Resonance Imaging/methods , Neuroimaging/methods , Adolescent , Adult , Biomarkers , Child , Cross-Sectional Studies , Female , Follow-Up Studies , Friedreich Ataxia/genetics , Humans , Male , Middle Aged , Young AdultABSTRACT
BACKGROUND AND PURPOSE: In mesial temporal lobe epilepsy, MR imaging quantification of hippocampal volume and T2 signal can improve the sensitivity for detecting hippocampal sclerosis. However, the current contributions of these analyses for the diagnosis of hippocampal sclerosis in 3T MRI are not clear. Our aim was to compare visual analysis, volumetry, and signal quantification of the hippocampus for detecting hippocampal sclerosis in 3T MRI. MATERIALS AND METHODS: Two hundred three patients with mesial temporal lobe epilepsy defined by clinical and electroencephalogram criteria had 3T MRI visually analyzed by imaging epilepsy experts. As a second step, we performed automatic quantification of hippocampal volumes with FreeSurfer and T2 relaxometry with an in-house software. MRI of 79 healthy controls was used for comparison. RESULTS: Visual analysis classified 125 patients (62%) as having signs of hippocampal sclerosis and 78 (38%) as having normal MRI findings. Automatic volumetry detected atrophy in 119 (95%) patients with visually detected hippocampal sclerosis and in 10 (13%) with visually normal MR imaging findings. Relaxometry analysis detected hyperintense T2 signal in 103 (82%) patients with visually detected hippocampal sclerosis and in 15 (19%) with visually normal MR imaging findings. Considered together, volumetry plus relaxometry detected signs of hippocampal sclerosis in all except 1 (99%) patient with visually detected hippocampal sclerosis and in 22 (28%) with visually normal MR imaging findings. CONCLUSIONS: In 3T MRI visually inspected by experts, quantification of hippocampal volume and signal can increase the detection of hippocampal sclerosis in 28% of patients with mesial temporal lobe epilepsy.