====== Neuroimaging ======

Neuro[[imaging]] refers to the set of [[technique]]s used to visualize the [[structure]] and function of the [[nervous system]], particularly the brain. It is essential in clinical neurology, neurosurgery, psychiatry, and neuroscience research.

===== Categories =====

==== Structural Neuroimaging ====
  * **CT (Computed Tomography)**:
    * Best for: acute hemorrhage, skull fractures, hydrocephalus.
    * Pros: Fast, widely available.
    * Cons: Radiation exposure.
  * **MRI (Magnetic Resonance Imaging)**:
    * Best for: brain tumors, demyelination, infarcts, malformations.
    * Common sequences:
      * T1-weighted: anatomy
      * T2-weighted / FLAIR: edema, lesions
      * DWI/ADC: acute stroke
      * SWI/GRE: microbleeds, calcifications
    * Advanced:
      * 3D volumetry
      * High-field MRI (3T/7T)

==== Functional Neuroimaging ====
  * **fMRI (Functional MRI)**:
    * BOLD signal (blood oxygenation level dependent).
    * Used in pre-surgical planning and cognitive studies.
  * **PET (Positron Emission Tomography)**:
    * Tracer uptake (e.g., FDG for glucose metabolism).
    * Detects early changes in tumors and neurodegenerative diseases.
  * **SPECT (Single Photon Emission CT)**:
    * Brain perfusion studies.
    * Often used in epilepsy diagnosis.

==== Electrophysiological Imaging (Complementary) ====
  * **EEG (Electroencephalography)**:
    * High temporal resolution for seizures and cortical function.
  * **MEG (Magnetoencephalography)**:
    * Measures magnetic fields from neuronal activity.
    * Localizes functional cortex.

===== Advanced Techniques =====
  * **DTI (Diffusion Tensor Imaging)**:
    * Shows white matter tracts (tractography).
    * Key for neurosurgical navigation.
  * **MR Spectroscopy (MRS)**:
    * Analyzes brain metabolites: NAA, choline, lactate.
  * **ASL (Arterial Spin Labeling)**:
    * Measures cerebral perfusion without contrast.

===== Clinical Applications =====
  * Tumor detection and grading
  * Preoperative planning in neurosurgery
  * Stroke and penumbra identification
  * Dementia (atrophy and hypometabolism)
  * Epileptic focus localization
  * Traumatic brain injury assessment