MRI Head

OVERVIEW

  • T2 (transverse relaxation time constant) = water/CSF is white
  • T1 (longitudinal relaxation time constant) = water/CSF is black
  • PD image – the effects of T1 and T12 are eliminated so the intensity of the signal depends on the density of protons in the tissue.
  • FSE (fast spin echo): allows rapid image acquisition, thereby minimising movement artifact
  • Fat suppressed images: useful for imaging bony structures
  • FLAIR (fluid attenuated inversion recovery): eliminates signal from CSF -> sensitive to oedema and inflammation
  • DWI (diffusion weighted image) + Apparent Diffusion Coefficient (ADC): can distinguish vasogenic oedema from cytotoxic oedema
  • gadolinium contrast: doesn’t normally cross the BBB but in areas where there is BBB break down -> contrast will high light area.

DISORDERS

Herpes Encephalitis

  • temporal and frontal lobe oedema
  • does not enhance with contrast

Multiple sclerosis

  • multiple white matter areas of increased intensity
  • spinal cord and cerebral

Chiari Malformation

  • cerebellar tonsils below the foramen magnum (at least 5mm)
  • narrow posterior cranial fossa
  • elongation of 4th ventricle
  • obstructive hydrocephalus
  • syringomyelia or hydromyelia

Infarction

  • DWI: increased signal
  • DWI + ADC: reduced signal

Sagittal Sinus Thrombosis

  • CT: hyperdensity in the sinus (increased with contrast), empty delta sign
  • MRI venogram: abnormal flow

CCC Neurocritical Care Series

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the  Clinician Educator Incubator programme, and a CICM First Part Examiner.

He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.

His one great achievement is being the father of three amazing children.

On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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