Novel approaches to imaging epilepsy by MRI

Abstract

As the concept of a network of injury has emerged in the treatment of epilepsy, the importance of evaluating that network noninvasively has also grown. Recently, studies utilizing magnetic resonance spectroscopic imaging, manganese-enhanced MRI and functional (f)MRI measures of resting state connectivity have demonstrated their ability to detect injury and dysfunction in cerebral networks involved in the propagation of seizures. The ability to noninvasively detect neuronal injury and dysfunction throughout cerebral networks should improve surgical planning, provide guidance for placement of devices that target network propagation and provide insights into the mechanisms of recurrence following resective surgery.

Figure 1. ¹H magnetic resonance spectra from a column along the hippocampus from a control subject

The labeled resonances are water, Cr, MI, Ch and NAA. The locations of the magnetic resonance spectra are indicated by the red box overlaid on the anatomical image. Ch: Choline; Cr: Creatine; MI: Myoinositol; NAA: N-acetylaspartate.

Figure 2. ¹H magnetic resonance spectra from a patient with temporal lobe epilepsy

Note the decreases in NAA/Cr in the ipsilateral hippocampus are greater than that seen in the contralateral hippocampus, and that seen in controls (FIGURE 1). The spectra are overlaid on the anatomical image. Ch: Choline; Contra: Contralateral; Cr: Creatine; Ipsi: Ipsilateral; NAA: N-acetyl aspartate; MI: Myoinositol.

Figure 3. ³¹P spectrum from a control subject displaying the resonance of inorganic phosphate, phosphocreatine & ATP

Shown below is an image from a patient with temporal lobe epilepsy showing the decrease in PCr/ATP from the ipsilateral hippocampus. Contra: Contralateral; Ipsi: Ipsilateral; PCr: Phosphocreatine; Pi: Phosphatidylinositol.

Figure 4

Network of correlations (Pearson) of N-acetylaspartate/creatine between the hippocampus, anterior & posterior hippocampus and basal ganglia in patients with temporal lobe epilepsy.