As a result, MRI has become the modality of choice for high-resolution structural imaging in epilepsy, with the use of IV contrast dependent on the underlying etiology of the seizures. Dedicated seizure protocols and acquisition on 3T magnets are important Seizures and Epilepsy considerations to improve lesion detection [31]. MRI is the study of choice in the assessment of structural lesions that are potentially resectable [16]. It can define the epileptogenic zone, that is, the minimum amount of cortex that should be resected to provide seizure-free outcome [16]. It should be noted that 20% to 30% of temporal epilepsy and 20% to 40% of patients with extra-TLE have no clear lesion seen on MRI [17]. Nevertheless, patients are more likely to be seizure-free when focal circumscribed lesions are identified on presurgical MRI compared with those patients who do not have these lesions [57,58]. Noncontrast CT and MRI have been advocated equally for accurate electrode localization [43]. HMPAO SPECT or SPECT/CT Brain Ictal and Interictal SPECT that uses perfusion agents like Tc-99m-HMPAO (hexamethyl-propylamine-oxime) or Tc-99m-neurolite provides an assessment of regional cerebral blood flow rather than brain metabolism. A seizure focus is typically demonstrated as an area of hypoperfusion on interictal examinations and hyperperfusion on ictal examinations [6]. The utility of isolated interictal cerebral perfusion assessment in patients without an anatomic imaging abnormality is limited, with one study finding that of all patients with seizures only 60% of interictal cerebral perfusion imaging was abnormal [59]. However, perfusion SPECT is complementary to structural imaging in presurgical planning. Statistical ictal SPECT co-registered to MRI was noted to identify a hyperperfusion focus in 84% of patients compared with 66% using subtraction ictal SPECT co-registered to MRI for seizure localization before TLE surgery and may be indicated for these cases [43].
Seizures and Epilepsy. As a result, MRI has become the modality of choice for high-resolution structural imaging in epilepsy, with the use of IV contrast dependent on the underlying etiology of the seizures. Dedicated seizure protocols and acquisition on 3T magnets are important Seizures and Epilepsy considerations to improve lesion detection [31]. MRI is the study of choice in the assessment of structural lesions that are potentially resectable [16]. It can define the epileptogenic zone, that is, the minimum amount of cortex that should be resected to provide seizure-free outcome [16]. It should be noted that 20% to 30% of temporal epilepsy and 20% to 40% of patients with extra-TLE have no clear lesion seen on MRI [17]. Nevertheless, patients are more likely to be seizure-free when focal circumscribed lesions are identified on presurgical MRI compared with those patients who do not have these lesions [57,58]. Noncontrast CT and MRI have been advocated equally for accurate electrode localization [43]. HMPAO SPECT or SPECT/CT Brain Ictal and Interictal SPECT that uses perfusion agents like Tc-99m-HMPAO (hexamethyl-propylamine-oxime) or Tc-99m-neurolite provides an assessment of regional cerebral blood flow rather than brain metabolism. A seizure focus is typically demonstrated as an area of hypoperfusion on interictal examinations and hyperperfusion on ictal examinations [6]. The utility of isolated interictal cerebral perfusion assessment in patients without an anatomic imaging abnormality is limited, with one study finding that of all patients with seizures only 60% of interictal cerebral perfusion imaging was abnormal [59]. However, perfusion SPECT is complementary to structural imaging in presurgical planning. Statistical ictal SPECT co-registered to MRI was noted to identify a hyperperfusion focus in 84% of patients compared with 66% using subtraction ictal SPECT co-registered to MRI for seizure localization before TLE surgery and may be indicated for these cases [43].