In recent years, the development of neuroimaging technology has greatly improved clinical research, understanding, and diagnosis and treatment of epilepsy. Currently, in addition to cranial X-ray plain films, cranial ultrasonography (CUS), computed tomography (CT), magnetic resonance imaging (MR I), positron emission tomography (PECT), single photon emission computed tomography (SPECT), digital subtraction angiography (DSA) and magnetic resonance angiography (MRA) are available.
CT
For the imaging diagnosis of central nervous system diseases, CT has less overall sensitivity and specificity than MRI, and this is also true for its use in epilepsy. However, CT examination has unique application value in the following cases and is generally used as an adjunct to MRI imaging diagnosis.
1. for the detection of calcified lesions, such as tuberous sclerosis, oligodendroglioma cysticercosis nodules. sturge-Weber syndrome and some other pathological calcifications of the basal ganglia. Conventional MRI lacks the ability to show calcifications.
2.For patients with contraindications to MRI, such as pacemakers and metal implants, only CT examination can be performed.
3.For those with clinical suspicion of acute intracranial hemorrhage such as post-epilepsy intracranial hemorrhage determination.
Scanning and diagnostic points.
1.Most of them are scanned by cephalometric flat scan, parallel to the canthal axis. Unless there are contraindications to MIR, CT-enhanced scans and complex image post-processing reconstruction are generally not taken at present, and direct MRI is recommended for those who still cannot be identified by plain scan.
2, Diagnosis pay attention to the structural morphology of the cerebellum, cerebellum and brainstem, and the presence of abnormal high and low density abnormal areas in the skull.
Magnetic resonance imaging (MRI)
MRI is a multi-directional and multi-parameter imaging, with clear anatomical structure and can show malformed blood vessels. The positive rate of MRI in adults with epilepsy is 74%, according to data.
Scope of application.
There are no contraindications to MRI examination (e.g., patients with pacemakers and metal implants), so it is suitable for both initial and repeat epilepsy examinations.
2, because MRI has the disadvantages of greater noise, relatively confined environment and longer imaging time, pay attention to the reasonable disposal of patients with claustrophobic syndrome and young children during the examination.
PECT
Positron emission tomography (PECT) images can be used to understand whether the metabolism in brain tissue is normal, and the metabolic rate in different regions can be calculated based on the dynamic changes of the images. It has been shown that 80% of temporal lobe interictal seizures show hypometabolism in the epileptogenic area, which is larger than the structural changes shown by CT and MRI or the electrophysiological changes shown by EEG, and may even involve the upper part of the ipsilateral lateral fissure and parietal lobe. Therefore, in patients with normal CT and MRI, it is useful to localize to the lateral side, while in partial epilepsy outside the temporal lobe, especially when the MRI is normal and the conventional EEG is not focally abnormal, interictal PECT is more significant.
Digital subtraction angiography (DSA)
Subtraction angiography, a photographic technique that eliminates the images of bone and soft tissue from the angiogram film by computer, highlighting only the blood vessels on the image film.
Indications.
①Intracranial vascular diseases, such as atherosclerosis, embolism, stenosis, occlusive disease, arteriopathy, arteriovenous malformation, arteriovenous fistula, etc.
②Intracranial occupying lesions, such as intracranial tumors, abscesses, cysts, hematomas, etc.
③Various extracerebral hematomas due to cranial trauma.
④Observation of cerebrovascular circulation status after surgery.
Contraindications.
①Allergic to contrast agent.
②Severe hypertension with diastolic blood pressure greater than 110 mmHg (14.66 kPa).