Interpreting Neuroradiology

1. What study type? (Default: CT head non-contrast — specify MRI brain, CTA, MRA, spine CT/MRI)
2. What is the clinical indication? (Default: Obtain actual indication — stroke, headache, trauma, mass)
3. Is this a stroke code/alert? (Default: No — if yes, time-critical workflow applies)
4. Are prior neuroimaging studies available? (Default: No priors)
5. Was contrast administered? (Default: Non-contrast for CT; specify for MRI)
6. Is the patient pediatric? (Default: Adult — pediatric requires age-appropriate assessment)
7. Is there neurosurgical hardware present? (Default: No — if yes, assess for complications)

Documents to Request

• Current imaging study (all sequences/reconstructions)
• Prior neuroimaging for comparison
• Clinical presentation (GCS, focal deficits, symptom onset time)
• Requisition with specific clinical question
• Neurosurgical/intervention notes if post-procedure
• Relevant lab values (coagulation studies if hemorrhage, tumor markers)

Step 1: CT Head Non-Contrast — Systematic Review

Evaluate in a fixed sequence to prevent missed findings:

1. Gray-White Matter Differentiation

• Loss of gray-white differentiation = acute ischemia (earliest CT sign, visible 6–12 hours)
• Insular ribbon sign, obscured lentiform nucleus = MCA territory infarct
• ASPECTS score for anterior circulation stroke (10-point scale, each region = 1 point deducted)

2. Hemorrhage Assessment

3. Ventricles and CSF Spaces

• Ventricular size: Evans index (frontal horn width / biparietal diameter; >0.3 = ventriculomegaly)
• Temporal horn dilatation = earliest sign of hydrocephalus
• Asymmetry suggesting mass effect or trapped ventricle

4. Midline Shift

• Measure at septum pellucidum

• 5 mm = significant; consider surgical evaluation

• Subfalcine, transtentorial, tonsillar herniation patterns

5. Calvarium and Skull Base

• Fractures: linear, depressed, basilar (opacified mastoid air cells, pneumocephalus)
• Bone window review is mandatory in trauma

6. Extracranial Structures

• Scalp hematoma, foreign bodies
• Paranasal sinuses (air-fluid levels in trauma = fracture)
• Orbits (if included)

Step 2: MRI Brain — Sequence-Specific Interpretation

Acute Stroke MRI Protocol Interpretation

• DWI-FLAIR mismatch: DWI positive + FLAIR negative = onset likely <4.5 hours (thrombolysis eligible)
• Perfusion-diffusion mismatch: Perfusion deficit > diffusion deficit = salvageable penumbra (thrombectomy candidate)
• ASPECTS on DWI: Same 10-region scoring as CT

Step 3: Brain Mass Characterization

WHO Tumor Grade Features on MRI

Step 4: Spine Imaging — Systematic Approach

Alignment

• Anterior vertebral body line, posterior body line, spinolaminar line, spinous process tips
• Listhesis: measure as percentage of vertebral body width (Grade I: 0–25%, Grade II: 25–50%, etc.)

Vertebral Bodies

• Height loss: mild (<25%), moderate (25–40%), severe (>40%)
• Signal abnormality: edema (acute fracture), fat (chronic/healed), enhancing (tumor, infection)
• STIR sequence is the gold standard for differentiating acute vs. chronic compression fractures

Disc Assessment

• Protrusion: focal, broad-based; location (central, paracentral, foraminal, far lateral)
• Extrusion: extends beyond disc space; migration (superior/inferior)
• Sequestration: free fragment separated from parent disc
• Disc nomenclature per NASS/ASSR/ASNR consensus terminology

Spinal Canal and Neural Foramina

• Central canal stenosis: mild, moderate, severe (effacement of CSF, cord compression)
• Neural foraminal stenosis: mild, moderate, severe (fat obliteration, nerve root compression)
• Cord signal: myelomalacia (T2 bright, T1 dark) vs. edema (T2 bright, normal T1)

Step 5: Report Structure

Impression — Prioritized

1. Critical/emergent findings first (hemorrhage, acute stroke, cord compression)
2. Primary diagnosis addressing clinical question
3. Secondary findings with management implications
4. Incidental findings with appropriate follow-up recommendations

Stroke-Specific Reporting

• ASPECTS score
• Vascular territory
• Estimated time of onset (if DWI-FLAIR mismatch available)
• Large-vessel occlusion site (if CTA performed)
• Hemorrhagic transformation (if present)

Checkpoint B: Post-Draft Alignment (Mandatory)

1. Was every anatomic compartment evaluated (parenchyma, ventricles, extra-axial, calvarium)?
2. Is hemorrhage excluded or characterized with appropriate grading?
3. For stroke, is ASPECTS calculated and vascular territory identified?
4. Is mass lesion characterized as intra-axial vs. extra-axial with differential?
5. Is midline shift quantified and herniation assessed?

Quality Audit

• Systematic review covers all compartments (parenchyma, ventricles, extra-axial, bone)
• Gray-white matter differentiation is assessed
• Hemorrhage is characterized by type, location, and grading scale
• Midline shift is measured in millimeters at septum pellucidum
• ASPECTS score is documented for anterior circulation strokes
• DWI/ADC maps are reviewed for acute ischemia
• All MRI sequences are individually assessed
• Brain masses are characterized as intra-axial vs. extra-axial
• Spine alignment is assessed using standard reference lines
• Disc pathology uses consensus nomenclature (protrusion, extrusion, sequestration)
• Canal and foraminal stenosis are graded (mild, moderate, severe)
• Cord signal abnormality is documented and differentiated (edema vs. myelomalacia)
• Critical findings trigger immediate communication per institutional policy
• Bone windows are reviewed in CT trauma studies

Guidelines

1. For stroke code activations, provide a preliminary verbal interpretation within minutes — document the formal read afterward.
2. Always review bone windows on CT head — skull fractures and calvarial metastases are invisible on brain windows alone.
3. Use ASPECTS scoring for anterior circulation strokes — scores <6 predict poor outcome and influence thrombectomy decisions.
4. DWI-FLAIR mismatch on MRI indicates onset within approximately 4.5 hours and may qualify the patient for thrombolysis even with unknown onset time (WAKE-UP trial criteria).
5. Characterize brain masses by location (intra-axial vs. extra-axial), enhancement pattern, and associated features before offering a differential — this determines neurosurgical approach.
6. On spine MRI, use STIR sequences to differentiate acute (edema-bright) from chronic (fat-signal) compression fractures — this distinction determines whether vertebroplasty/kyphoplasty is appropriate.
7. Document cord compression as an emergency — spinal cord compression with neurologic deficit requires surgical evaluation within hours.
8. Apply the modified Fisher scale for subarachnoid hemorrhage to predict vasospasm risk — this guides neurocritical care management intensity.