Article
Diffusion Tensor Imaging (DTI) in patients with persistent vegetative state
Diffusion Tensor Imaging (DTI) bei apallischen Patienten
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Published: | May 8, 2006 |
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Objective: The diagnosis of the persistent vegetative state is still limited to the clinical examination. Imaging techniques do not play a role in setting the diagnosis. Diffusion tensor imaging (DTI) was used in order to try to visualize the affected area in the brain stem.
Methods: 12 patients in a persistent vegetative state after cerebral trauma were examined in a 1.5-T MRI device (INTERA, Philips Co) with coronal diffusion-weighted spin echo sequences. MRI was performed after a mean of 6 months following cerebral trauma. Six non-colinear gradient impulses were used along the corticospinal fiber tracts. For reconstruction of the fibers courses, an IDL-based (Interactive Data Language; Research System Inc.) fiber tracking tool was used. Furthermore, ADC (apparent diffusion coefficient) and FA (fractional anisotropy) were determined in the affected area and compared with a control group of 20 healthy test persons.
Results: The fiber representation showed an interruption of the corticospinal fiber tracts at the level of the mesencephalon in all patients. The ADC values in the affected area were normal to slightly increased as compared to the control group. The FA values were reduced by nearly 40%, indicating a damage at the cellular level. Patients undergoing early MRI after 5 months showed atrophic brain stem changes in the pons and mesencephalon indicating a damage at the cellular level.
Conclusions: With the help of DTI, the interruption of corticospinal fiber tracts could be visualized in patients with a persistent vegetative state for the first time. The FA values can be regarded as markers of the damage at the cellular level and might be important for indicating reversibility of a persistent vegetative state.