Diffusion tensor imaging demonstrates deviation of fibres in normal appearing white matter adjacent to a brain tumour

The objective was to study fibre orientation in the cerebral white matter o f a patient with a brain tumour using diffusion tensor imaging (DTI). A patient with a mild left hemiparesis and a tumour in the right frontal lo be and 20 healthy volunteers were scanned with a DTI sequence. The scans we re spatially normalised and the fibre orientation in the patient compared w ith the fibre orientation in normal controls. DTI disclosed a change of the orientation of fibres in the patient compared with normal controls. In the normal appearing white matter adjacent to the tumour fibres deviated from the normal superior inferior orientation in th e corona radiata by about 30 degrees. This finding was consistent with a di splacement by distant mass effect rather than a destruction of fibres, in a greement with the neurological examination. In conclusion, DTI demonstrated deviation of fibres in normal appearing whi te matter adjacent to a tumour. The technique will improve understanding of the effects of structural abnormalities on fibres. This will assist the in terpretation of clinical findings and functional imaging studies and guide neurosurgical interventions.