NEURO RADIOLOGY AND DIAGNOSTICS

Radiation (X-rays)

What is the primary mechanism of a CT Scan?

Magnets and radio waves

What is the primary mechanism of an MRI?

15-30 seconds

What is the typical speed of a CT scan?

20-30 minutes

What is the typical speed of an MRI?

Scan done once

In terms of sequences, how is a CT scan performed?

Each sequence separate

In terms of sequences, how is an MRI performed?

Widely available

How is the availability of a CT scan described?

Tertiary hospitals

Where are MRIs typically available?

~P5,000

What is the approximate cost of a CT scan?

~P12,000-15,000

What is the approximate cost of an MRI?

High (Choice for acute hemorrhage)

What is the sensitivity of a CT scan for bleeds?

Less sensitive for acute; great for aging bleeds

How does MRI sensitivity for bleeds compare to CT?

Poor due to bone artifacts

What is the quality of posterior fossa visualization on a CT scan?

Superior visualization/clarity

What is the quality of posterior fossa visualization on an MRI?

Pregnancy (Relative)

What is a contraindication for a CT scan?

Metal implants, pacemakers, defibrillators

What are three contraindications for an MRI?

Hounsfield Units (HU)

What is the name of the scale used for CT densities?

-1000

What is the HU value for Air?

Black (Hypodense)

How does Air appear on a CT scan?

-30 to -120

What is the HU value for Fat?

Dark Gray

How does Fat appear on a CT scan?

0

What is the HU value for Water / CSF?

Black/Dark Gray

How does Water / CSF appear on a CT scan?

+23 to +34

What is the HU value for White Matter?

Grayish

How does White Matter appear on a CT scan?

+32 to +41

What is the HU value range for Gray Matter?

Pale/White

How does Gray Matter appear on a CT scan?

+56 to +76

What is the HU value range for Acute Blood?

White (Hyperdense)

How does Acute Blood appear on a CT scan?

+130

What is the HU value for Contrast?

White

How does Contrast appear on a CT scan?

+140 to +200

What is the HU value range for Calcification?

Very White

How does Calcification appear on a CT scan?

+400 or more

What is the HU value for Bone?

Bright White

How does Bone appear on a CT scan?

Short TR/TE

What is the timing used for T1 Weighted MRI sequences?

Anatomic detail

What is the primary clinical use for T1 Weighted MRI?

Long TR/TE

What is the timing used for T2 Weighted MRI sequences?

Detecting pathologies like edema

What is the primary clinical use for T2 Weighted MRI?

Most sensitive for hyperacute infarcts

What is the primary clinical use for DWI?

10–30 minutes

How fast can DWI detect hyperacute infarcts?

Detects blood and calcium

What is the primary clinical use for GRE / SWI sequences?

Hypointense (dark)

How do blood and calcium appear on GRE / SWI sequences?

Estimating the penumbra

What is the primary clinical use for FLAIR sequences?

Salvageable tissue

What is the definition of penumbra in the context of FLAIR sequences?

Biconvex / Lentiform

What is the characteristic shape of an Epidural Hematoma (EDH) on a CT scan?

Crescentic

What is the characteristic shape of a Subdural Hematoma (SDH) on a CT scan?

Fills sulci, cisterns, fissures

What is the distribution of a Subarachnoid Hemorrhage (SAH) on a CT scan?

Often Arterial (e.g., MMA)

What type of vessel is typically involved in an Epidural Hematoma?

Venous (bridging veins)

What type of vessel is typically involved in a Subdural Hematoma?

Arterial (ruptured aneurysm)

What type of vessel is typically involved in a Subarachnoid Hemorrhage?

Does NOT cross

Do suture lines typically block an Epidural Hematoma?

May cross

Do suture lines typically block a Subdural Hematoma?

Not confined

How are suture lines related to Subarachnoid Hemorrhage?

Above the dura

What is the dural boundary of an Epidural Hematoma?

Below the dura

What is the dural boundary of a Subdural Hematoma?

Between pial/arachnoid

What is the dural boundary of a Subarachnoid Hemorrhage?

13–30 Hz

What is the frequency of the Beta rhythm in EEG?

~20 (Smallest)

What is the typical amplitude of the Beta rhythm in uV?

Mental activity, deep thought, sedatives

What is the clinical significance of the Beta rhythm?

8–12 Hz

What is the frequency of the Alpha rhythm in EEG?

50–100

What is the typical amplitude of the Alpha rhythm in uV?

Normal resting adult (awake/relaxed)

What is the clinical significance of the Alpha rhythm?

4–7 Hz

What is the frequency of the Theta rhythm in EEG?

Greater than 50

What is the typical amplitude of the Theta rhythm in uV?

Drowsiness, emotional distress

What is the clinical significance of the Theta rhythm?

Less than or equal to 3 Hz

What is the frequency of the Delta rhythm in EEG?

Greater than 50 (Taller)

What is the typical amplitude of the Delta rhythm in uV?

Deep sleep (NREM), brain death

What is the clinical significance of the Delta rhythm?

Greater than 50/mm3 (Neutrophils)

What is the typical cellular count and type for a Bacterial CNS infection?

100–250 (High)

What is the typical protein range (mg%) for a Bacterial CNS infection?

Low (20–50)

What is the typical glucose range (mg%) for a Bacterial CNS infection?

10–100 (Lymphocytes)

What is the typical cellular count and type for Viral/Fungal CNS infections?

50–200

What is the typical protein range (mg%) for Viral/Fungal CNS infections?

Normal or slightly low

What is the typical glucose status for Viral/Fungal CNS infections?

Greater than 25/mm3 (Lymphocytes)

What is the typical cellular count and type for a TB CNS infection?

100–1,000 (Very high)

What is the typical protein range (mg%) for a TB CNS infection?

Very Low (less than 50)

What is the typical glucose status for a TB CNS infection?

Greater than 500 RBCs

What is the typical cellular finding for a Subarachnoid Hemorrhage on CSF analysis?

60–150

What is the typical protein range (mg%) for a Subarachnoid Hemorrhage on CSF analysis?

Normal

What is the typical glucose status for a Subarachnoid Hemorrhage on CSF analysis?

Normal or few WBCs

What is the typical cellular status for Multiple Sclerosis on CSF analysis?

Normal/Slightly high

What is the typical protein status for Multiple Sclerosis on CSF analysis?

Normal

What is the typical glucose status for Multiple Sclerosis on CSF analysis?

Increased IgG/Oligoclonal

What are the characteristic immunologic findings in CSF for Multiple Sclerosis?

Latency, Amplitude, Velocity

What three parameters does NCV (Nerve Conduction) measure?

Measures speed and axonal integrity

What is the clinical utility of NCV?

Activity at rest and contraction

What does EMG (Electromyography) measure?

Differentiates Myopathy vs. Neuropathy

What is the clinical utility of EMG?

Decrement vs. Increment

What does Repetitive Stimulation measure in EMG-NCV testing?

MG (Myasthenia Gravis)

Which condition is identified by a decrement in repetitive stimulation?

LEMS (Lambert-Eaton Myasthenic Syndrome)

Which condition is identified by an increment in repetitive stimulation?

EMG-NCV

What is the modality of choice for assessing the peripheral nervous system?

15–30 seconds

How long does a CT scan typically take?

20–30 minutes

How long does an MRI typically take?

CT Scan

Which scan uses Radiation (X-rays)?

MRI

Which scan uses magnets and radio waves?

CT Scan

Which modality is the choice for acute hemorrhage?

MRI

Which modality is great for aging bleeds but less sensitive for acute bleeds?

CT Scan

Which modality has poor visualization of the posterior fossa due to bone artifacts?