# Clinical Cases: Neuroimaging

## Case 1: Acute Subdural Hematoma

### Patient Demographics
- **Age:** 78 years
- **Sex:** Male

### Chief Complaint
Found on floor, confused, after witnessed fall

### Presenting Symptoms
The patient was found on the floor by his wife after she heard him fall in the bathroom. She estimates he was down for approximately 15 minutes. He is now confused and unable to recall the event. He takes warfarin for atrial fibrillation. His wife reports he has seemed "more unsteady" over the past month with several near-falls.

### Physical Exam Findings
- **Vital Signs:** BP 168/94 mmHg, HR 82 bpm (irregular), RR 16/min, Temp 36.8C
- **GCS:** 13 (E3V4M6)
- **Neurological:** Confused, oriented to person only, left-sided facial droop, left arm drift with decreased strength (4/5), left leg 4+/5, plantar response extensor on left
- **Head:** 4 cm hematoma over right temporal region
- **Pupils:** Equal and reactive, 3mm bilaterally

### Imaging Findings and Interpretation
**Non-Contrast Head CT:**
Window Settings Used:
- Brain windows (W:80, L:40): For parenchymal detail
- Subdural windows (W:150, L:50): For extra-axial collections
- Bone windows (W:2000, L:400): For skull fracture evaluation

**Findings:**
- **Acute Subdural Hematoma:** Large crescent-shaped hyperdense (55-60 HU) collection over the right cerebral convexity
- **Thickness:** Maximum thickness 18 mm
- **Extent:** Extends from the frontal to the occipital region, crossing suture lines
- **Mass Effect:**
  - 12 mm leftward midline shift at the level of the septum pellucidum
  - Effacement of the right lateral ventricle
  - Compression of the right cerebral hemisphere with sulcal effacement
- **Herniation:** Early subfalcine herniation with the right cingulate gyrus displaced under the falx
- **No Skull Fracture:** Bone windows demonstrate no acute fracture
- **Brain Parenchyma:** No underlying intraparenchymal hemorrhage

**Density Analysis:**
The hyperdense appearance (55-60 HU) indicates acute hemorrhage. Subdural hematomas become isodense at 1-3 weeks and hypodense when chronic. The homogeneous density suggests single acute hemorrhage event rather than acute-on-chronic bleeding.

### Diagnosis
Acute subdural hematoma with significant mass effect and early subfalcine herniation in anticoagulated patient

### Management
1. **Immediate Actions:**
   - Emergent neurosurgery consultation
   - Reversal of anticoagulation: 4-factor PCC + Vitamin K IV
   - Check INR (resulted at 3.2)
   - Elevate head of bed to 30 degrees
   - Seizure prophylaxis with levetiracetam

2. **Surgical Intervention:**
   - Emergency craniotomy for hematoma evacuation given:
     - Thickness >10 mm
     - Midline shift >5 mm
     - GCS decrease from baseline
     - Focal neurological deficits
   - Surgery performed within 4 hours of presentation

3. **Post-operative Course:**
   - Post-operative CT showed successful evacuation with improved midline shift
   - Gradual neurological improvement over 1 week
   - Discussion regarding anticoagulation resumption (delayed 2 weeks, then transitioned to DOAC with lower bleeding risk)

### Radiological Image

![Acute Subdural Hematoma CT](case_01_image.jpg)

**Image Description:** Non-contrast head CT demonstrating a large acute subdural hematoma. The hyperdense (white) crescent-shaped collection overlies the right cerebral convexity, causing significant mass effect with midline shift and compression of the right lateral ventricle.

**Source:** Wikimedia Commons - "CT scan of subdural hematoma"
**URL:** https://commons.wikimedia.org/wiki/File:Subdural_hematoma.jpg
**License:** Creative Commons Attribution-Share Alike 3.0 Unported

---

## Case 2: Acute Ischemic Stroke - Large Vessel Occlusion

### Patient Demographics
- **Age:** 64 years
- **Sex:** Female

### Chief Complaint
Sudden onset right-sided weakness and difficulty speaking

### Presenting Symptoms
The patient was in her normal state of health when her husband noticed she suddenly developed slurred speech and her right arm "went limp" at 10:15 AM. EMS was activated immediately. She arrived at the stroke center at 10:52 AM (last known well: 37 minutes ago). She has a history of hypertension and hyperlipidemia. She takes amlodipine and atorvastatin.

### Physical Exam Findings
- **Vital Signs:** BP 178/102 mmHg, HR 88 bpm (regular), glucose 142 mg/dL
- **NIHSS Score:** 18
  - Level of consciousness: Alert (0)
  - Gaze: Forced left gaze deviation (2)
  - Visual fields: Right hemianopia (2)
  - Facial palsy: Right lower facial weakness (2)
  - Motor arm: Right arm no movement (4)
  - Motor leg: Right leg minimal movement (3)
  - Ataxia: Unable to assess right side
  - Sensory: Moderate deficit right side (1)
  - Language: Moderate aphasia (2)
  - Dysarthria: Moderate (1)
  - Neglect: Visual and sensory neglect (1)

### Imaging Findings and Interpretation
**Non-Contrast Head CT (Door-to-CT: 12 minutes):**
- **Hyperdense MCA Sign:** Linear hyperdensity in the left M1 segment of the middle cerebral artery, representing acute thrombus
- **Early Ischemic Changes:** Subtle loss of gray-white differentiation in the left insular cortex (insular ribbon sign)
- **ASPECTS Score:** 9 (1 point deducted for insular involvement)
- **No Hemorrhage:** No evidence of intracranial hemorrhage
- Candidate for IV thrombolysis

**CT Angiography (CTA):**
- **Left M1 Occlusion:** Complete occlusion of the left middle cerebral artery at the M1 segment
- **Thrombus Length:** Approximately 8 mm
- **Collaterals:** Good pial collateral filling to the left MCA territory via ACA and PCA
- **Proximal Vessels:** Patent left ICA without significant stenosis
- **Right Circulation:** Patent

**CT Perfusion:**
- **Core (CBF <30%):** 15 mL in left MCA territory
- **Total Hypoperfused (Tmax >6s):** 120 mL
- **Mismatch Volume:** 105 mL
- **Mismatch Ratio:** 8:1 (significant penumbra present)

**Interpretation:**
Large vessel occlusion with small ischemic core and large penumbra - excellent candidate for mechanical thrombectomy.

### Diagnosis
Acute ischemic stroke, left MCA territory, due to left M1 occlusion; eligible for IV thrombolysis and mechanical thrombectomy

### Management
1. **IV Alteplase (tPA):**
   - Door-to-needle time: 28 minutes
   - 0.9 mg/kg IV (10% bolus, remainder over 60 minutes)
   - Administered while preparing for thrombectomy ("drip and ship" not needed as already at comprehensive stroke center)

2. **Mechanical Thrombectomy:**
   - Groin puncture at 11:45 AM
   - Aspiration thrombectomy with stent retriever
   - TICI 3 recanalization achieved (complete reperfusion)
   - Puncture-to-recanalization: 32 minutes

3. **Post-Procedure:**
   - 24-hour NIHSS: 4 (significant improvement from 18)
   - Post-thrombectomy CT: Small left insular infarct, no hemorrhagic transformation
   - Stroke workup: Echo, telemetry, lipid panel, HbA1c
   - Started on high-intensity statin and dual antiplatelet therapy
   - Source identified: Paroxysmal atrial fibrillation on telemetry
   - Transitioned to anticoagulation for secondary prevention

### Radiological Image

![CT Perfusion Stroke](case_02_image.jpg)

**Image Description:** CT perfusion imaging in acute ischemic stroke demonstrating the mismatch between the small ischemic core (irreversibly damaged tissue shown in red/dark) and the larger area of hypoperfusion (penumbra - potentially salvageable tissue). This mismatch identifies patients who may benefit from reperfusion therapy.

**Source:** Radiopaedia - Educational reference on stroke imaging
**URL:** https://radiopaedia.org/articles/ct-perfusion-in-acute-stroke
**License:** Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported

---

## Case 3: Glioblastoma Multiforme

### Patient Demographics
- **Age:** 58 years
- **Sex:** Male

### Chief Complaint
Progressive headaches and new-onset seizure

### Presenting Symptoms
The patient presents after a witnessed generalized tonic-clonic seizure at home. His wife reports he has complained of worsening headaches over the past 6 weeks, initially attributing them to stress. The headaches are worse in the morning and associated with nausea. She has also noticed personality changes, with him becoming more "flat" and less interested in activities. He had one episode of word-finding difficulty last week that resolved within minutes.

### Physical Exam Findings
- **Vital Signs:** BP 146/88 mmHg, HR 78 bpm, afebrile
- **GCS:** 15 (post-ictal period resolved)
- **Neurological:**
  - Subtle right pronator drift
  - Mild expressive aphasia with word-finding pauses
  - Right-sided facial weakness (central pattern)
  - Subtle right-sided neglect
  - Fundoscopic exam: Blurred optic disc margins bilaterally (papilledema)

### Imaging Findings and Interpretation
**MRI Brain with and without Contrast:**

**T1-Weighted Pre-Contrast:**
- Large heterogeneous mass in the left frontal lobe
- Central hypointensity consistent with necrosis
- Surrounding hypointense vasogenic edema

**T2-Weighted/FLAIR:**
- Extensive surrounding T2/FLAIR hyperintensity representing vasogenic edema
- Edema extends into the corpus callosum
- Mass effect with effacement of the left frontal horn and 8 mm rightward midline shift

**T1-Weighted Post-Gadolinium:**
- Thick, irregular ring enhancement surrounding central necrosis
- Enhancement is heterogeneous with variable thickness
- Maximum enhancing tumor dimension: 5.2 x 4.8 cm
- No additional enhancing lesions to suggest multifocal disease or metastases

**Diffusion-Weighted Imaging:**
- Restricted diffusion at the periphery of the mass (high cellularity)
- Central non-restricted area (necrosis)

**MR Perfusion:**
- Elevated relative cerebral blood volume (rCBV) in the enhancing component
- rCBV ratio 4.2 (compared to contralateral white matter)
- Consistent with high-grade neoplasm

**MR Spectroscopy:**
- Elevated choline peak (increased cell membrane turnover)
- Decreased N-acetylaspartate (NAA) - neuronal loss
- Elevated choline/NAA ratio
- Lipid/lactate peak (necrosis)

**Differential Diagnosis:**
1. Glioblastoma multiforme (most likely given imaging characteristics)
2. Metastatic disease (less likely given single lesion, no primary identified)
3. Primary CNS lymphoma (typically homogeneous enhancement, crosses midline)
4. Abscess (would expect more restricted diffusion centrally, rim thinner medially)

### Diagnosis
Imaging highly consistent with glioblastoma multiforme (WHO Grade IV astrocytoma); confirmed on surgical pathology with IDH-wildtype, MGMT unmethylated

### Management
1. **Immediate:**
   - Dexamethasone 10 mg IV then 4 mg q6h for vasogenic edema
   - Levetiracetam for seizure prophylaxis
   - Venous thromboembolism prophylaxis (high-risk tumor)

2. **Tumor Board Discussion:**
   - Multidisciplinary review with neurosurgery, neuro-oncology, radiation oncology, neuropathology

3. **Surgical Resection:**
   - Maximal safe resection with awake craniotomy and cortical mapping (given proximity to language areas)
   - Gross total resection achieved on post-operative MRI

4. **Adjuvant Treatment:**
   - Concurrent temozolomide and radiation therapy (Stupp protocol)
   - Followed by adjuvant temozolomide cycles
   - Consider tumor treating fields (TTFields)

5. **Follow-up Imaging:**
   - MRI brain with contrast every 2-3 months to monitor for recurrence
   - Use RANO criteria for response assessment

### Radiological Image

![Glioblastoma MRI](case_03_image.jpg)

**Image Description:** T1-weighted post-gadolinium MRI demonstrating glioblastoma multiforme with characteristic thick, irregular ring enhancement surrounding a central area of necrosis. Significant surrounding vasogenic edema and mass effect with midline shift are visible.

**Source:** Wikimedia Commons - "MRI of glioblastoma"
**URL:** https://commons.wikimedia.org/wiki/File:Glioblastoma_multiforme.jpg
**License:** Creative Commons Attribution-Share Alike 3.0 Unported

---

## Learning Points

1. **Subdural vs. Epidural Hematoma:** Subdural hematomas are crescent-shaped, cross suture lines, and are typically venous in origin. Epidural hematomas are biconvex (lens-shaped), do not cross sutures, and are usually arterial. This distinction affects prognosis and management urgency.

2. **Acute Stroke Imaging Protocol:** Non-contrast CT excludes hemorrhage, CTA identifies large vessel occlusion, and CT perfusion quantifies the ischemic core and penumbra. The mismatch between core and penumbra guides thrombectomy decisions, especially in extended time windows.

3. **Brain Tumor Characterization:** Key MRI features distinguishing glioblastoma include irregular thick ring enhancement, central necrosis, vasogenic edema, elevated rCBV on perfusion, and characteristic spectroscopy findings. These help differentiate from metastases, lymphoma, and abscess.

4. **Window Settings in Head CT:** Different window and level settings optimize visualization of specific pathology. Brain windows (W:80, L:40) show parenchymal detail, subdural windows (W:150, L:50) detect thin extra-axial collections, and bone windows (W:2000+) evaluate skull fractures.