radiology

INTRODUCTION TO NEURORADIOLOGY

Instructors

  • Seema Al-Shaikhli, MD

  • Dillon Daniels, DO

  • PGY-2/R1s, Diagnostic Radiology, University of Missouri – Kansas City

LEARNING OBJECTIVES

  • Understand basic radiology terminology and units.

  • Learn radiological features of ischemic and hemorrhagic strokes.

  • Understand the basics of commonly utilized neuroimaging studies.

  • Recognize the most appropriate initial clinical imaging in suspected stroke.

  • Understand the differences between noncommunicating and communicating hydrocephalus.

  • Touch on a few infectious/inflammatory etiologies.

GENERAL IMAGING TERMINOLOGY

1. X-ray Imaging

  • Opacity: Variation in density

    • Radiolucent: Appears black (indicating air)

    • Radiopaque: Appears white (indicating materials like bone or metal)

2. CT Imaging

  • Density: Measures X-ray attenuation via Hounsfield Units (HU)

    • Hypodense: Appears dark (indicating air, fat, edema, or infarct)

    • Isodense: Same density as surrounding tissue

    • Hyperdense: Appears bright (indicating acute blood, calcifications, or bone)

3. MRI Imaging

  • Intensity: Measures the signal of protons

    • Hypointense: Dark signal

    • Isointense: Similar signal

    • Hyperintense: Bright signal

    • Always specify sequence (T1 vs T2)

4. Ultrasound Imaging

  • Echogenicity: Measures sound wave reflection

    • Anechoic: Appears black (indicating simple fluid)

    • Hypoechoic: Appears dark gray

    • Isoechoic: Similar echogenicity

    • Hyperechoic: Appears bright (indicating fat, stone, gas)

CT PHYSICS AND TECHNIQUE

  • Hounsfield Units (HU) range from -1000 to +3000, used to assign values to different attenuations, with water defined as 0.

    • Case courtesy of Francis Fortin, Radiopaedia.org, rID: 77397

CLINICAL SCENARIOS

QUESTION 1

  • Scenario: A 65-year-old male presented to the ED with left-sided weakness and numbness that began 18 hours prior to arrival, suspected stroke.

  • What is the most appropriate initial imaging order?

    • Options:
      A. CT head with contrast
      B. CT head without contrast
      C. MRI brain with contrast
      D. MRI brain without contrast
      E. Digital subtraction angiography

ISCHEMIC STROKE

  • CT Findings:

    • Loss of grey/white matter differentiation

    • Dense vessel sign

    • Insular ribbon sign

    • Hypodensity (indicative of vasogenic edema) in the area corresponding to neurological deficits

    • Usually, CT Angiography (CTA) head/neck and CT perfusion imaging are also obtained.

    • Case courtesy of Frank Gaillard, Radiopaedia.org, rID: 17958

NEXT SCENARIOS

QUESTION 2

  • Scenario: You are the ED doctor. A healthy 52-year-old male presents with sudden onset right-sided weakness and numbness which started 2 hours before arrival.

  • What is the most appropriate initial imaging order?

    • Options:
      A. CT head with contrast
      B. CT head without contrast
      C. MRI brain with contrast
      D. MRI brain without contrast
      E. Transcranial ultrasound

CLINICAL REVIEW

  • Radiology report indicates: Normal CT brain with no evidence of acute infarct or hemorrhage, patient still with 0/5 strength in left upper and lower extremities.

  • Next steps after the initial imaging given the patient is NOT on blood thinners:

    1. tPA

    2. CT angiography head/neck (CTA head/neck)

    • tPA is administered, followed by a review of CTA findings.

DIAGNOSIS: ISCHEMIC STROKE

  • Impression: Acute left middle cerebral artery (M1 segment) occlusion.

    • recognizable large vessel occlusions include:

    • Middle cerebral arteries (M1 segment)

    • Anterior cerebral arteries (A1 segment)

    • Intracranial internal carotid arteries

PERFUSION IMAGING and CEREBRAL ANGIOGRAPHY

  • Note that these are different patients.

MAGNETIC RESONANCE IMAGING (MRI)

MRI SEQUENCES

  • T1 Sequence

    • Appearance: CSF is dark, Fat is bright

    • Use: Good for anatomical details

  • T2 Sequence

    • Appearance: CSF is bright, Fat is bright

    • Use: Good for identifying pathology/fluid

  • DWI (Diffusion Weighted Imaging)

    • Description: Detects random movements of water protons, crucial for stroke detection

  • ADC (Apparent Diffusion Coefficient)

    • Use: To confirm strokes

MAGNETIC RESONANCE ANGIOGRAPHY (MRA)

HEMORRHAGIC STROKE TYPES

QUESTION 3

  • Scenario: 78-year-old male with dementia history found on floor of nursing home.

  • What's the most appropriate initial study?

    • Options:
      A. CT head with contrast
      B. CT head without contrast
      C. MRI brain with contrast
      D. MRI brain without contrast
      E. MRA brain

ACUTE SUBDURAL HEMORRHAGE

  • Key Features:

    • CT findings include:

    • Crescent-shaped appearance

    • Crosses sutures

    • Does NOT cross midline

    • Hemorrhage is located under the dura and above the arachnoid mater

    • Commonly results from tearing of cortical veins

    • Clinical vignette: Typical in elderly falls or shaken baby syndrome

CONTINUED MANAGEMENT

  • Next steps based on patient status (stable, expanding, symptomatic, herniation risk)

QUESTION 4

  • Young male (22) involved in motorcycle accident with lucid interval followed by drowsiness.

  • Most appropriate initial study?

    • Options:
      A. CT head with contrast
      B. CT head without contrast
      C. MRI brain with contrast
      D. MRI brain without contrast
      E. MRA brain

EPIDURAL HEMORRHAGE

  • Key Features:

    • Most often from rupture of the middle meningeal artery

    • Blood rapidly accumulates in the epidural space (above the dura)

    • Typical vignette involves trauma, lucid interval followed by a decline in consciousness

    • CT findings:

    • Biconvex (lens-shaped) hyperdense blood products

    • Does NOT cross suture lines but CAN cross midline

    • Associated with skull fractures

    • Treatment can include surgical evacuation or conservative management with repeat CT

QUESTION 5

  • 42-year-old woman with uncontrolled hypertension presenting with severe headache and associated symptoms.

  • Most appropriate initial study?

    • Options:
      A. CT head with contrast
      B. CT head without contrast
      C. MRI brain with contrast
      D. MRI brain without contrast
      E. MRA brain

SUBARACHNOID HEMORRHAGE

  • Key Features:

    • Most commonly arises from the rupture of a saccular aneurysm

    • Blood accumulates in the subarachnoid space (between arachnoid and pia mater)

    • Characteristic clinical vignette: Thunderclap headache with no preceding event

    • CT findings:

    • Hyperdense blood products lining the sulci

    • Treatment options include endovascular coiling or conservative management with follow-up CT

UNDERSTANDING HYDROCEPHALUS

QUESTION 3

  • 84-year-old male with altered mental status.

  • What is the diagnosis following a head CT evaluation?

    • Options:
      A. Normal head CT
      B. Normal pressure hydrocephalus
      C. Obstructive hydrocephalus
      D. Ex-vacuo dilatation
      E. Colloid cyst

HYDROCEPHALUS

  • Definition: Dilation of the ventricles due to increased volume of cerebrospinal fluid (CSF).

    • Types:

    1. Communicating hydrocephalus

      • Treatment: Ventricular shunt placement

    2. Noncommunicating hydrocephalus

      • Treatment: Surgical removal of a tumor causing obstruction

    3. Ex-vacuo dilation

      • Appearance of increased CSF due to decreased brain parenchyma (atrophy), typically with normal intracranial pressure (ICP), and no treatment necessary.

QUESTION 4

  • Scenario: 26-year-old woman with sore throat and significant oropharyngeal swelling.

  • Next order?

    • Options:
      A. CT Head with contrast
      B. CT Head without contrast
      C. CT Angiogram
      D. CT Max/Face
      E. CT Soft Tissue Neck with contrast

CT SOFT TISSUE NECK

  • Anatomy diagrams outline specific spaces:

    • Retropharyngeal Space

    • Danger Space

    • Prevertebral Space

    • Paraspinal Space

    • Buccopharyngeal Fascia

    • Alar Fascia

    • Prevertebral Fascia

    • Platysma

    • Masticator Space

    • Trapezius

    • Parotid Capsule

    • Case courtesy of Frank Gaillard, Radiopaedia.org, rID: 5344

QUESTION 5

  • 78-year-old male with lung cancer, alertness change, and extremity weakness following a non-contrast CT.

  • Next appropriate step in evaluation/management?

MRI HEAD WITH CONTRAST

  • Sequences discussed include Axial T1 and T1 C+

INFECTIONS IN NEUROIMAGING

  • Key conditions covered:

    • Meningitis

    • HSV Encephalitis

QUESTION 6

  • 37-year-old female with unilateral vision loss and optic disc swelling evaluated with MRI Head.

  • Clinical suspicion: Multiple sclerosis (MS).

MULTIPLE SCLEROSIS

  • Overview:

    • Most common disabling CNS disease in young adults, with a higher prevalence in women in their 20s and 30s.

    • Characterized by autoimmune inflammation and demyelination.

    • Clinical presentations include optic neuritis, internuclear ophthalmoplegia (INO), hemiparesis, sensory deficits, and bladder/bowel dysfunction.

    • Clinical course is typically relapsing and remitting.

QUESTIONS?

  • Contact Information:

    • Seema Al-Shaikhli: s.al-shaikhi@umkc.edu

    • Dillon Daniels: dillond32@gmail.com