Voxel-based relaxometry for cases of an unresolved epilepsy diagnosis

• Published in: Epilepsy research 2012-03, Vol.99 (1), p.46-54
• Main Authors: Kosior, Robert K, Sharkey, Rachel, Frayne, Richard, Federico, Paolo
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Anticonvulsants. Antiepileptics. Antiparkinson agents; Biological and medical sciences; Case-Control Studies; Epilepsy; Epilepsy - diagnosis; Epilepsy - physiopathology; Female; Follow-Up Studies; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Hippocampal sclerosis; Humans; Magnetic Resonance Imaging - methods; Male; Medical sciences; Middle Aged; MRI; Nervous system (semeiology, syndromes); Neurology; Neuropharmacology; Partial seizures; Pharmacology. Drug treatments; Relaxometry; Temporal lobe epilepsy; Young Adult
• ISSN: 0920-1211; 1872-6844
• DOI: 10.1016/j.eplepsyres.2011.10.015

Summary Purpose Voxel-based relaxometry (VBR) is a technique in which a voxel-level statistical comparison of quantitative MR T2 maps is performed to identify regions with significantly elevated T2 relaxation time. Our objective was to assess the performance of single-subject VBR at 3 T as a diagnostic tool for patients whose diagnosis of epilepsy or seizure focus location is uncertain. Methods Fifty-nine patients with possible epilepsy or known epilepsy, but an unknown focus and forty-five healthy controls were studied. All subjects were scanned at 3 T using a Carr–Purcell–Meiboom–Gill MR sequence. Single-subject VBR was performed at a significance level of α = 0.001. Patients were classified based on whether the diagnosis of epilepsy was in question and whether there was a suspected focus. A VBR score was determined based on the presence of VBR abnormalities in any of 13 predefined regions per hemisphere. Results All patients exhibited significantly more median VBR abnormalities than controls ( p < 0.05). VBR abnormalities were seen in 69% and 89% of patients with a normal or questionably abnormal MR scan, respectively. Nineteen of the 27 patients with a suspected focus (70%) had VBR abnormalities in the suspected focus, with additional regions of involvement being elucidated. VBR also correctly predicted the seizure focus in 50% of patients whose seizure foci were confirmed based on follow-up history or clinical investigations. Conclusions Single subject VBR can help identify potential seizure foci in patients whose seizure foci are uncertain.