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JUNE 2026 Paper 2 - Radiology Theory Exam

Full Model Answers (30 Marks Each)

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QUESTION 1 (10 Marks Total)

1a. Pulmonary Imaging Findings in Immunocompromised Individual (2 Marks)

• Chest X-ray (CXR) is the first line investigation
• High Resolution CT (HRCT) chest is more sensitive, especially when CXR is normal
• CT Pulmonary Angiography (CTPA) for suspected fungal angioinvasion

IMMUNOCOMPROMISED CHEST - PATTERN APPROACH
 ┌─────────────────────────────────────────────┐
 │  CXR/CT Finding         → Likely Diagnosis  │
 │  ─────────────────────────────────────────  │
 │  Bilateral GGO (upper)  → PCP               │
 │  Halo sign nodule       → Aspergillus       │
 │  Miliary nodules        → TB / Fungal       │
 │  Consolidation + LAD    → Bacterial         │
 │  Diffuse nodules        → Kaposi / Lymphoma │
 │  Air crescent sign      → Aspergilloma      │
 └─────────────────────────────────────────────┘

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1b. Imaging Findings of Infections in HIV+ and HIV- Individuals (4+4 Marks)

HIV POSITIVE (CD4-Dependent) Imaging Findings:

• Bacterial pneumonia: segmental/lobar consolidation, air bronchograms
• Same spectrum as immunocompetent

• Pulmonary TB: upper lobe cavitary disease, lymphadenopathy, pleural effusion
• Bacterial pneumonias more frequent

• CXR: Bilateral perihilar interstitial infiltrates, "bat wing" distribution, progressing to ground glass opacification
• HRCT: Bilateral ground glass opacification (GGO) - most characteristic
• Crazy-paving pattern (GGO + interlobular septal thickening)
• Upper lobe predominance
• Pneumatoceles in ~35% (thin walled cysts - risk of pneumothorax)
• Absent pleural effusion (distinguishing feature)
• Absence of lymphadenopathy

CXR in PCP:
        Right          Left
  apex  ░░░░░░░░░░░░░░░░░░
  upper ░░░░░░░░░░░░░░░░░░  ← Bilateral symmetric
  mid   ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓    perihilar GGO
  lower ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓    (bat-wing pattern)
  base  ░░░░░░░░░░░░░░░░░░  ← Bases relatively spared

  ░ = clear   ▓ = infiltrates

• CXR: Bilateral interstitial infiltrates, similar to PCP
• HRCT: GGO with or without consolidation, nodules
• Peribronchovascular distribution

• CXR: Bilateral lower lobe nodules, interstitial pattern
• May show miliary nodules
• Lymphadenopathy (mediastinal/hilar) - more common in HIV+
• Pleural effusion in ~30%

• CD4 < 50
• CXR: Diffuse reticulonodular pattern
• Mediastinal lymphadenopathy (hallmark)
• May be indistinguishable from TB

• CXR: Peribronchovascular nodules along bronchovascular bundles, flame-shaped
• HRCT: Peribronchovascular nodules, septal thickening, pleural effusion
• Lymphadenopathy
• "Cannonball" metastases in late disease

• Atypical presentation: lower lobe disease, hilar/mediastinal LAD, miliary pattern, no cavitation
• Primary-type pattern even in reactivation (because immunity cannot wall off)
• Pleural effusion common

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HIV NEGATIVE (Immunocompromised by other causes):

• CXR: Single or multiple nodules, poorly marginated
• HRCT: Halo Sign (nodule surrounded by ground-glass halo of hemorrhage) - EARLY SIGN
• Air crescent sign (crescent of air at periphery of nodule) - LATE SIGN (neutrophil recovery)
• Wedge-shaped consolidation (infarction from angioinvasion)

CT - Halo Sign:
        ┌──────────────────┐
        │   GGO halo       │
        │  ┌──────────┐    │
        │  │ Dense    │    │
        │  │ nodule   │    │
        │  └──────────┘    │
        │                  │
        └──────────────────┘
  Nodule = fungal necrosis
  Halo = hemorrhagic infarction

        ┌──────────────────┐
        │    ╭─────────╮   │
        │    │ Necrotic│   │
        │  ╭─┤ Ball    ├─╮ │
        │  │ ╰─────────╯ │ │
        │  ╰─────────────╯ │
        │   ↑ Air crescent │
        └──────────────────┘

• Early phase (<1 month): Bacterial pneumonia, pulmonary edema
• Middle phase (1-6 months): CMV (bilateral GGO, peribronchovascular), PCP, fungal
• Late phase (>6 months): Community-acquired, viral, Aspergillus

• CXR/CT: Consolidation, cavitation, multiple nodules
• May mimic tumor or TB

• Bilateral GGO, tree-in-bud, centrilobular nodules

• Bilateral GGO
• Organizing pneumonia pattern
• Peribronchovascular distribution

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QUESTION 2: Thoracic Findings in Connective Tissue Disorders (10 Marks)

Rheumatoid Arthritis (RA)

• Usual Interstitial Pneumonia (UIP) pattern: Most common
  • Bibasal subpleural honeycombing
  • Traction bronchiectasis
  • Reticulation
• Non-Specific Interstitial Pneumonia (NSIP): Bilateral GGO, basal predominance

• Pleural effusion (exudate, low glucose)
• Pleural thickening

• Bronchiectasis (particularly lower lobes)
• Follicular bronchiolitis
• Constrictive bronchiolitis (BO)

• Well-defined lung nodules, may cavitate
• Peripheral subpleural
• Caplan syndrome: Large nodules in coal miners + RA

• Pericardial effusion

RA Thoracic Findings - HRCT Pattern:
Upper lobes → Nodules, bronchiectasis
Middle       → Interstitial changes
Lower lobes  → UIP/NSIP: Honeycombing, GGO, traction bronchiectasis
Pleura       → Effusion, thickening

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Systemic Lupus Erythematosus (SLE)

• Most common thoracic manifestation
• Bilateral, exudative
• "Shrinking lung syndrome" - diaphragmatic dysfunction

• Bilateral airspace consolidation, GGO
• Lower lobe predominance

• NSIP pattern: bilateral basal GGO with reticulation

• Bilateral consolidation/GGO, rapid change

• Enlarged central pulmonary arteries

• Pericardial effusion (common)
• Libman-Sacks endocarditis (CT may show valve thickening)

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Systemic Sclerosis (Scleroderma / SSc)

• NSIP pattern (most common): Bilateral basal GGO, reticulation, traction bronchiectasis
• UIP pattern (less common)
• Subpleural sparing (distinguishes NSIP from UIP)

• Dilated central pulmonary arteries
• Enlarged right heart
• May be severe even with mild ILD

• Characteristic finding on CT chest
• Dilated air-filled esophagus seen behind heart/trachea
• Aspiration pneumonia as consequence

Scleroderma on CT:
  - Dilated esophagus (behind heart)
  - Bilateral basal NSIP pattern
  - Enlarged main pulmonary artery (PAH)
  - Pericardial effusion

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Dermatomyositis / Polymyositis (DM/PM)

• ILD: NSIP most common pattern
• Organizing Pneumonia (OP): Peribronchovascular consolidation
• Acute interstitial pneumonia (AIP) in rapidly progressive disease
• "Mechanic's hands" association - anti-Jo-1 antibody
• Aspiration pneumonia (due to esophageal/pharyngeal muscle weakness)

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Sjogren Syndrome

• Lymphocytic Interstitial Pneumonia (LIP): Bilateral GGO, thin-walled cysts
• NSIP pattern
• Follicular bronchiolitis
• Multiple pulmonary cysts (characteristic): Thin-walled, scattered, random distribution
• B-cell lymphoma (a complication)

Sjogren LIP on CT:
  - Bilateral GGO (diffuse)
  - Multiple thin-walled cysts (scattered)
  - Occasional consolidation
  - Lower lobe and peribronchovascular predominance

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Mixed Connective Tissue Disease (MCTD)

• Features overlap SLE, SSc, PM
• PAH: Most serious manifestation (similar to SSc)
• Pleuritis, ILD (NSIP)

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Summary Table - CTD Thoracic Manifestations

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QUESTION 3 (10 Marks Total)

3a. Enumerate Causes of Pulmonary Arterial Hypertension (PAH) (2 Marks)

• Idiopathic PAH (IPAH) - most common in young women
• Heritable PAH (BMPR2 gene mutation - most common)
• Drug and toxin-induced (anorexigens, methamphetamine, dasatinib)
• Associated with:
  • Connective tissue disease (SSc, SLE, RA)
  • HIV infection
  • Portal hypertension (porto-pulmonary)
  • Congenital heart disease (L→R shunts)
  • Schistosomiasis
  • Pulmonary veno-occlusive disease (PVOD)

• Heart failure with reduced EF, preserved EF
• Valvular disease (mitral stenosis, aortic stenosis)

• COPD, Interstitial lung disease
• Sleep-disordered breathing
• High altitude

• Organized thrombus in pulmonary arteries

• Hematologic (myeloproliferative, splenectomy)
• Systemic (sarcoidosis, histiocytosis)
• Metabolic (Gaucher, thyroid)

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3b. CXR and CT Findings of PAH (4+4 Marks)

CXR Findings of PAH:

• Enlarged main pulmonary artery (MPA): >29 mm in diameter at level of right PA
• Right descending pulmonary artery >17 mm (men) or >15 mm (women)
• Left pulmonary artery enlargement
• "Pruning" of peripheral vessels: Peripheral vascularity reduced while central vessels dilated - sharp tapering/cut-off

• Right ventricular enlargement: Filling of retrosternal space on lateral CXR
• Right atrial enlargement: Bulging right heart border
• Cardiomegaly
• Loss of normal pulmonary artery notch

• Peripheral oligemia (decreased vascularity)
• In chronic CTEPH: May show wedge-shaped infarcts

CXR Diagram - PAH:
         ←←← enlarged ←←←←←←←←
   ┌──────────────────────────────┐
   │    ╭───────────╮             │
   │    │ Trachea   │             │
   │   ╭╰───────────╯╮            │
   │   │   Aorta     │            │
   │  ┌┴─────────────┴┐           │
   │  │  ENLARGED MPA │           │
   │  └┬─────────────┬┘           │
   │  ╭╯             ╰╮           │
   │ ╭╯               ╰╮ enlarged │
   │ │ RA enlarged →→  │ RV       │
   │ ╰─────────────────╯          │
   │   ↑ Peripheral pruning ↑     │
   └──────────────────────────────┘

• Main pulmonary artery diameter > 29 mm
• Right descending PA diameter > 16 mm
• PA to trachea ratio > 1.0 (normal < 0.7)

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CT Findings of PAH:

• Main pulmonary artery (MPA) diameter >29 mm - most reliable
• MPA to ascending aorta ratio >1.0 (sensitivity 70%, specificity 92%)
• Bilateral pulmonary artery enlargement
• Pruning / abrupt tapering of peripheral pulmonary arteries

CT Cross-section at PA level:
     Ascending Ao
       ┌──────┐
       │      │   ← Ao diameter
       └──────┘
         ≈ 35mm
     Main PA
       ╭──────╮
       │      │   ← PA diameter > 29mm = PAH
       ╰──────╯       PA:Ao ratio > 1.0 = PAH

• Right ventricular hypertrophy/dilation: RV:LV ratio >1 in short axis
• Interventricular septal bowing (D-shaped LV): Leftward septal deviation at end-systole
• Right atrial dilation
• Tricuspid regurgitation (contrast reflux into IVC and hepatic veins)
• Pericardial effusion (severe PAH)

Normal:               PAH (D-sign):
   ┌────┐ ┌────┐         ┌────┐  ╔════╗
   │ RV │ │ LV │         │    │  ║    ║
   └────┘ └────┘         │ RV │  ║ LV ║
   RV:LV = 0.6           └────╯  ╚════╝
                         RV:LV > 1, LV D-shaped
                         ↑ RV pressure flattens IVS

• Mosaic attenuation: Geographic areas of high and low attenuation (air trapping)
• Peripheral oligemia (hypovascular areas)
• In CTEPH: Wedge-shaped parenchymal scarring, linear bands

• Dilated central pulmonary veins (Group 2/PVOD)

• Web, band, pouch defects in pulmonary arteries
• Mural thrombus (eccentric filling defect)
• Abrupt vessel cutoffs
• Bronchial artery enlargement (collateral supply)
• Mosaic perfusion on CT (best seen on expiratory scans)

• Centrilobular GGO nodules
• Interlobular septal thickening
• Pleural effusion
• Lymphadenopathy
• Dilated pulmonary veins

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QUESTION 4: Pediatric Fractures and Non-Accidental Injury (5+5 Marks)

Part A: Specific Features of Fractures in Pediatrics (5 Marks)

• Periosteum is thicker and more vascular
• Bone is more porous and plastic (deforms before breaking)
• Growth plates (physes) are present and are weaker than ligaments
• Remodeling capacity is greater

Unique Pediatric Fracture Types:

• Most common fracture in children
• Compression force → cortex buckles (kinks) on one side without breaking
• Metaphyseal location
• Distal radius most common site
• X-ray: Subtle cortical buckling/angulation, no displaced fracture line
• Inherently stable

Torus Fracture:
    ─────────── Normal cortex
    ─────╮╭──── Buckle (cortical kink)
    ─────╯╰──── 
    ─────────── 

• Incomplete fracture (like green stick breaking)
• Cortex breaks on tension side, remains intact on compression side
• Bowing with cortical breach on one side
• Shaft of long bone most common

Greenstick Fracture:
         ────────────
        /  Angulated 
       /   
      ╱  ← Fracture line through one cortex only
     ────────────
     (Compression side intact)

• Multiple microfractures along the bone - bone bends without discrete fracture line
• Ulna and fibula most common
• X-ray: Bowed cortex without visible fracture line
• Easy to miss!

• Involve the growth plate (physis)
• Physis is weakest link in pediatric skeleton

Salter-Harris Types (diagrammatic):
      Epiphysis
      ═══════════  ← Physis (growth plate)
      Metaphysis

Type I:    Type II:   Type III:   Type IV:   Type V:
  ══║══      ══╝══      ╔══════     ╔══╗══     ══╬══
  ══║══      ══╝══      ║══════     ║══╝══     (Crush)

• Traction through apophysis at muscle/tendon insertion
• Common in adolescent athletes
• Anterior inferior iliac spine (AIIS) - rectus femoris
• Anterior superior iliac spine (ASIS) - sartorius
• Ischial tuberosity - hamstrings

• Callus formation is rapid and exuberant
• Periosteal reaction more pronounced than adults
• Toddler's fracture: Spiral/oblique non-displaced tibial fracture from minor trauma in toddlers
• Clavicle and forearm are most common fracture sites overall

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Part B: Imaging Findings in Non-Accidental Injury (NAI) in Infants (5 Marks)

Classic/Specific NAI Fractures:

• Result from squeezing the chest
• Hands grip around chest and thumbs/fingers fracture posterior ribs near costovertebral junction
• X-ray: Fractures at posterior rib angle (medial 1/3)
• "Buckle handle" appearance
• New and old fractures in same child = pathognomonic
• Often only seen on oblique views or bone scan

Posterior Rib Fractures (squeezed chest):
         ┌──────────────────┐
         │  Spine           │
     ←─← │ ←← Force ←←     │
     Hands grip thorax      │
         │  ╲╲╲╲ Posterior  │
         │   fractures here │
         └──────────────────┘

• Highly specific for NAI
• Result from traction/rotational forces (gripping and twisting)
• Avulsion of cartilaginous metaphysis
• X-ray: Bucket-handle or corner fragment at metaphysis
• Distal femur, proximal and distal tibia most common

Classic Metaphyseal Lesion:
    ┌──────────────────────┐
    │   Shaft              │
    ╞══════════════════════╡  Metaphysis
    ↑╰──corner fragment ──╯↑
    (bucket handle or corner chip)

• Fractures at different stages of healing
• Periosteal reaction age:
  • Soft callus: 10-14 days
  • Hard callus: 14-21 days
  • Remodeling: >3 weeks

• Along diaphyses (gripping and twisting the baby)

• Spiral humeral fracture in child <18 months WITHOUT adequate explanation
• "Toddler's fracture" of tibia from walking is explained, but spiral humerus in infant is suspicious

• Multiple, bilateral, branching, crossing sutures, complex = suspicious for NAI
• Simple linear skull fractures alone may be accidental
• Intracranial injuries (subdural hematoma especially) are key finding

• CT/MRI: Subdural collections of DIFFERENT AGES (mixed density on CT)
• Bilateral SDH in infant = highly suspicious
• Diffuse axonal injury
• Retinal hemorrhages (fundoscopy)

CT Head - Shaken Baby:
    ┌─────────────────────┐
    │  Bilateral subdural │
    │  ╭──────────╮       │
    │  │  Brain   │       │
    │  ╰──────────╯       │
    │ ↑                 ↑ │
    │ SDH (crescent sign) │
    │ (Mixed density =    │
    │  different ages)    │
    └─────────────────────┘

• Deep soft tissue bruising not visible on X-ray

NAI Imaging Protocol:

1. Skeletal Survey (full): Initial + repeat at 2 weeks
2. CT Head: All suspected head injury
3. MRI Brain: Better characterization of brain injury
4. Bone scan (scintigraphy): Detects early/healing fractures missed on X-ray
5. Ophthalmology: Retinal hemorrhage

Differential Diagnosis of NAI:

• Osteogenesis imperfecta (OI): Blue sclerae, wormian bones, osteopenia
• Rickets: Metaphyseal irregularity, cupping, fraying
• Metabolic bone disease of prematurity
• Scurvy: Periosteal hemorrhage, Pelkan spurs

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QUESTION 5 (10 Marks Total)

5a. Lines/Tubes/Catheters in ICU Patient and Their Correct Position on CXR (6 Marks)

1. Endotracheal Tube (ETT)

• Tip should be 5 cm above carina (mid-trachea)
• Alternatively: at T3-T4 vertebral level
• 2-5 cm above carina is acceptable range
• With neck in neutral position

• Too deep: Right mainstem intubation (right is more vertical) → left lung collapse
• Too superficial: Tip in larynx or pharynx → inadequate ventilation

CXR - ETT Position:
    Carina at T4-T5
    ┌──────────────────┐
    │   Trachea        │
    │     │            │
    │     │ ← ETT tip  │  ← Should be here (5cm above carina)
    │     │            │
    │   Carina ───────→│  T4-T5 level
    │   /     \        │
    │  L.main  R.main  │
    └──────────────────┘

2. Central Venous Catheter (CVC) / Central Line

• Tip at cavoatrial junction (junction of SVC and right atrium)
• Radiologically: At level of right tracheobronchial angle / T4-T5
• Should NOT be in right atrium (arrhythmia risk)
• Should NOT be in right ventricle

CVC Position:
    SVC
     │
     │ ← Correct: cavoatrial junction
     │   (right tracheobronchial angle)
    RA
     │
    RV  ← Too deep (arrhythmia risk)

3. Pulmonary Artery Catheter (Swan-Ganz Catheter)

• Tip in right or left main pulmonary artery
• Should NOT be in peripheral pulmonary artery (wedged position at rest = risk of PA rupture)
• Should be within 2 cm of hilum

4. Nasogastric Tube (NGT)

• Tip should be below left hemidiaphragm
• Ideally in stomach, at least 10 cm below gastroesophageal junction
• Distal side hole below GEJ

• Coiled in esophagus
• Tip in right bronchus → lung placement (DANGEROUS - infusion into lung)
• Loop in nasopharynx

NGT Position Check on CXR:
    ─────── Carina level
    │ NGT → must cross midline at carina level
    │       then descend to left
    │
    ─────── Diaphragm
    
    ✓ Correct: tip below diaphragm, leftward stomach position
    ✗ Wrong: tip right of spine below carina = right bronchus

5. Intra-Aortic Balloon Pump (IABP)

• Tip 2-3 cm distal to origin of left subclavian artery
• At level of aortic knuckle / T4-T5
• NOT in aortic arch (too proximal - risk of cerebral emboli)
• NOT too distal (below renal arteries - renal ischemia)

6. Chest Drains

• Anterior, apical - 2nd intercostal space midclavicular line (anterior)
• Or in 4th-5th ICS mid-axillary line

• Posterior basal - 4th-5th ICS posterior-lateral

• All side holes should be within pleural cavity (beyond chest wall)
• Track should not cross midline

7. Pacemaker / Implantable Defibrillator Leads

Summary Table:

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5b. Difference Between Cardiogenic and Non-Cardiogenic Pulmonary Edema (4 Marks)

Pathophysiology:

• Cardiogenic: Elevated left atrial pressure → hydrostatic pressure overwhelms oncotic pressure → fluid leaks into interstitium and alveoli
• Non-Cardiogenic (ARDS): Inflammation/injury to alveolar-capillary membrane → increased permeability → fluid leaks regardless of hydrostatic pressure

Radiological Differences:

Stage 1 (PCWP 12-18 mmHg): Vascular redistribution
    Upper > Lower zone vessels (upright CXR)
    "Stag's antler" pattern

Stage 2 (PCWP 18-25 mmHg): Interstitial edema
    Peribronchial cuffing
    Kerley B lines (horizontal lines at bases, < 2cm)
    Kerley A lines (from hilum outward)
    Hilar blurring

Stage 3 (PCWP >25 mmHg): Alveolar edema
    Bilateral airspace consolidation
    "Bat wing" / perihilar distribution
    Air bronchograms

CXR - Kerley B Lines:
   ─────────────────── 
   |                 |
   |─────            |
   |─────  ← Kerley B│  (<2cm, horizontal, peripheral, base)
   |─────            |
   └─────────────────┘

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QUESTION 6: 25-Year Female with Gangrene in Fingers - Causes, Differentials and Imaging Features (10 Marks)

Clinical Context

Causes and Differentials:

1. Systemic Sclerosis (Scleroderma) - MOST LIKELY

• Doppler Ultrasound: Absent/markedly reduced or absent flow in digital arteries, severely reduced resistive index
• Digital subtraction angiography (DSA) / CT Angiography:
  • Bilateral smooth tapered occlusions of digital arteries
  • "Corkscrew" collateral arteries (tortuous corkscrew collaterals pathognomonic)
  • Abrupt cut-off of palmar arches and digital vessels
  • Proximal vessels (radial/ulnar) relatively spared initially
• X-ray hands: Calcinosis cutis (subcutaneous calcifications), acro-osteolysis (resorption of distal phalanges), soft tissue calcification
• Chest CT: Dilated esophagus, NSIP pattern ILD, enlarged PA

Corkscrew Vessels (Scleroderma):
    Normal:  ─────────────────
    SSc:    ~~~~~~~~~~~~~~~~~  (tortuous collaterals)
                   ↓ (occlusion)
             (no flow beyond)

2. Thromboangiitis Obliterans (Buerger's Disease)

• Normal proximal vessels (aorta, femoral, brachial)
• Abrupt occlusion of distal small vessels (digital, palmar, plantar)
• "Corkscrew collaterals" are also characteristic (similar to SSc)
• Segmental occlusions with normal intervening segments
• No calcification of vessel walls (unlike atherosclerosis)

3. Raynaud's Phenomenon (Primary and Secondary)

• Digital plethysmography: Diminished waveforms

4. Antiphospholipid Antibody Syndrome (APS)

• Digital artery thrombosis on DSA/CTA
• Multiple occlusions at different vascular levels
• May show embolic occlusions
• CT/MRI brain: Multiple ischemic infarcts (different ages)
• Echocardiography: Valve thickening (Libman-Sacks)

5. Vasculitis

• Young Asian women
• Large vessel vasculitis
• CT Angiography: Wall thickening and enhancement of aorta and branches, stenosis/occlusion of subclavian (causing arm claudication), dilated aorta
• Digital involvement possible as downstream effect

• Microscopic polyangiitis, Wegener's, Churg-Strauss
• Imaging: Renal infarcts, pulmonary infiltrates, digital ischemia

6. Embolism (Cardiac origin)

• Atrial fibrillation, left atrial thrombus, infective endocarditis, atrial myxoma
• Echocardiogram: Thrombus in LA/LV, valve vegetations
• DSA: Embolic occlusion (filling defect), clean vessel walls

7. Ergotamine Toxicity / Drug-induced

• Vasospasm from vasoconstricting drugs
• DSA: Smooth, elongated bilateral narrowing of multiple vessels (rat-tail appearance)

8. Cryoglobulinemia

• Cold-induced precipitation of immunoglobulins → thrombosis
• Associated with hepatitis C
• Imaging: Digital artery occlusions, purpura

Imaging Approach for This Patient:

Step 1: Plain X-rays hands/wrists
         → Calcinosis (SSc), Acro-osteolysis, Joint disease

Step 2: Doppler USS of upper limb arteries
         → Assess flow, resistive index

Step 3: CT Angiography (CTA) or MR Angiography
         → Map extent of disease

Step 4: DSA (if intervention planned)
         → Gold standard

Step 5: Echocardiogram
         → Cardiac source of embolus

Step 6: CT Chest
         → ILD (CTD), aortic disease (Takayasu)

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QUESTION 7: 50-Year-Old Male with Massive Hemoptysis - Approach to Imaging and Management (10 Marks)

Definition

Causes of Massive Hemoptysis:

Imaging Approach:

Step 1: Chest X-Ray (CXR)

• Immediate, bedside
• May show:
  • Opacification of bleeding lung
  • Cavitary lesion (TB, abscess, aspergilloma)
  • Mass (carcinoma)
  • Consolidation (pneumonia, infarction)
  • Bronchiectasis (tram-track lines)

Step 2: CT Chest (Multidetector MDCT) - MOST IMPORTANT

• CTPA (CT Pulmonary Angiography): Maps vascular anatomy, identifies bleeding site
• Multiplanar reconstruction helps localize
• Identifies: Cavities, fungus ball, tumor, bronchiectasis

Aspergilloma (Fungus Ball) on CT:
    ╭──────────────────╮
    │    Cavity        │
    │  ╭────────╮      │
    │  │ Fungus │      │
    │  │  ball  │      │ ← Dependent position
    │  ╰────────╯      │
    │                  │
    ╰──────────────────╯
    Air crescent between ball and wall (Monod sign/halo)
    Ball changes position with posture

Step 3: Bronchoscopy

• Localize side of bleeding (right vs left)
• May be therapeutic (tamponade, coagulation, blockers)
• Limitation: Cannot identify bleeding vessel, limited in massive hemoptysis

Step 4: Bronchial Artery Angiography (DSA) - Definitive for Intervention

• Arise from descending thoracic aorta at T5-T6
• Right intercostobronchial trunk (most common variant)
• 1-3 on right, 1-2 on left

• Bronchial artery hypertrophy (>2 mm = abnormal)
• Tortuous, dilated bronchial arteries
• Systemic-pulmonary collaterals
• Active contrast extravasation (hemorrhage into bronchi)
• Hypervascularity / tumor blush
• Pseudoaneurysm
• Bronchopulmonary shunts

Bronchial Arteriogram - Abnormal:
    Aorta
      │
      ├──→ Dilated bronchial art.
      │         │
      │         ├──→ Hypervascularity
      │         │
      │         └──→ Active bleed (contrast in bronchus)
      │
      └──→ Collateral from intercostal aa.

Management:

1. Initial Stabilization (ABC):

• Position: Bleeding lung DOWN (protective position)
• Supplemental oxygen
• IV access, blood products
• Intubation if needed (selective bronchial intubation of healthy side)

2. Bronchial Artery Embolization (BAE) - Treatment of Choice

• Femoral artery approach
• Catheterize bronchial arteries
• Super-selective catheterization of feeding vessels
• Embolization: PVA particles (350-500 μm), coils, gelfoam

3. Surgery

• Indication: BAE failure, PAVM, localized resectable disease
• Options: Lobectomy, pneumonectomy, wedge resection

4. Endovascular - Pulmonary Artery

• For rare cases (PAVM, Rasmussen aneurysm in TB)
• Coil embolization of PAVM

Rasmussen Aneurysm (TB-related):

• Pseudoaneurysm of pulmonary artery within TB cavity
• Treatment: Coil embolization of pulmonary artery aneurysm

---

QUESTION 8: AV Fistula Mapping and Complications and Imaging Features (5+5 Marks)

Part A: AV Fistula Mapping (5 Marks)

• Radiocephalic (Cimino-Brescia): Radial artery to cephalic vein (wrist) - gold standard
• Brachiocephalic: Brachial artery to cephalic vein (elbow)
• Brachiobasilic: Brachial artery to basilic vein (arm)
• AV Graft: Synthetic (PTFE) graft connecting artery to vein

Pre-operative Mapping (Vascular Access Planning):

• Radial artery diameter ≥ 1.5-2.0 mm at wrist
• Peak systolic velocity (PSV) > 50 cm/s
• Absence of stenosis, calcification, obstruction
• Assessment of palmar arch patency (Allen's test + Doppler)

• Cephalic vein diameter ≥ 2.5-3.0 mm at wrist/forearm
• Tourniquet applied to distend vein
• Continuous lumen without gaps or stenosis
• Course/tortuosity mapped for surgical planning
• Absence of valves in critical segments

• Fistula flow rate > 500-600 mL/min for hemodialysis adequacy
• Dilated, thickened vein with arterial waveform
• Increased flow velocity in feeding artery

• Used when US inconclusive or central vein obstruction suspected
• Central vein mapping (subclavian, brachiocephalic, SVC)
• 3D reconstruction shows entire outflow pathway

AV Fistula Anatomy:
    Radial Artery → Anastomosis → Cephalic vein
    ─────────────→ ╔══╗ ←─────────────────
                   ║  ║  Fistula
    Anastomosis   ╚══╝
    (end-to-side or side-to-side)
    
    Blood flow: Artery → Fistula → Dilated vein → AV site

• No radiation
• Excellent for subclavian, brachiocephalic, SVC stenosis
• Used pre-transplant or when CTA contraindicated

---

Part B: AV Fistula Complications and Imaging Features (5 Marks)

1. Stenosis (Most Common - 50-80% of failures)

• Juxta-anastomotic (within 2 cm of anastomosis) - most common
• Outflow vein stenosis
• Central vein stenosis (subclavian/SVC)

• Duplex USS:
  • Focal velocity increase at stenosis (PSV > 400 cm/s or PSV ratio > 2.0)
  • Post-stenotic turbulence
  • Reduced fistula flow rate (<500 mL/min)
  • Vein diameter narrowing

Stenosis on Doppler:
    Normal:   ─────────── (laminar flow, PSV ~200 cm/s)
    Stenosis:  ──╮╭───── (focal narrowing)
                 ╰╯
    Post-stenotic: turbulence, high PSV (>400)

2. Thrombosis

• Complete occlusion of fistula
• Clinical: Non-palpable thrill, no bruit
• Duplex USS: No flow on color Doppler, echogenic thrombus in lumen
• Management: Pharmacomechanical thrombolysis (alteplase), surgical thrombectomy

3. Aneurysm / Pseudoaneurysm

• True aneurysm: Fusiform dilatation of venous segment (>3x normal diameter)
• Pseudoaneurysm: Pulsatile hematoma with extravascular blood, develops after needle puncture
• Duplex USS: Swirling flow in pseudoaneurysm ("yin-yang" sign on color Doppler)
• Risk of rupture or skin ulceration

Pseudoaneurysm - Yin-Yang Sign:
    ╭────────────────╮
    │  ╭──╮   ╭──╮  │
    │  │→→│   │←←│  │  Color Doppler:
    │  ╰──╯   ╰──╯  │  Red and Blue swirling
    ╰────────────────╯
       (yin-yang appearance)

4. Steal Syndrome

• Reversal of flow in distal artery (away from hand)
• Mechanism: High-flow fistula "steals" blood from distal hand → ischemia, hand pain, paresthesia, gangrene
• Duplex USS:
  • Reversed diastolic flow in radial artery distal to anastomosis
  • Absent/reduced palmar arch flow
  • PSV in distal radial artery is negative (reversal)
• Management: DRIL procedure (Distal Revascularization with Interval Ligation), banding

Steal Syndrome Flow Pattern:
    Radial artery:
    Proximal → → → → Anastomosis
                        ↓ (fistula)
    Distal   ← ← ← ← (reverse flow!)
                        ↑ Flow steals from hand

5. High-Output Cardiac Failure

• Very high fistula flow (> 2 L/min)
• Causes volume overload → cardiac failure
• Echo: Dilated LV, pulmonary hypertension
• Management: Banding/ligation

6. Venous Hypertension / Arm Swelling

• Central vein obstruction (subclavian/SVC stenosis)
• Arm edema, distended collateral veins on chest wall
• CT/MR Venography: Central vein stenosis
• Fistulogram: Central stenosis, collateral veins

7. Infection

• Rare in native AVF, more common in grafts
• USS: Perigraft fluid, abscess, pseudoaneurysm
• CT: Air in graft, fluid collection

8. Non-Maturation (Failed Fistula)

• Fistula fails to dilate adequately for dialysis use
• Criteria for maturation: Diameter ≥ 6mm, flow ≥ 600 mL/min
• USS: Outflow vein diameter < 6mm, stenosis
• Fistulogram: Identifies correctable lesions

---

QUESTION 9: 35-Year Male with RTA and Hematuria - Imaging Approach and Management (10 Marks)

Introduction

Initial Assessment: ABCs and Clinical Triage

• Gross hematuria
• Microscopic hematuria + hypotension (SBP < 90 mmHg)
• Mechanisms: High-speed deceleration, flank contusion, direct impact
• Pediatric trauma (image even microscopic hematuria)
• Significant mechanism without hematuria (possibility of renal pedicle injury)

Imaging Approach:

Step 1: FAST Ultrasound (Focused Assessment with Sonography in Trauma)

• Immediate bedside
• Detects free fluid in: perihepatic (Morison's pouch), perisplenic, pericardial, pelvic (pouch of Douglas)
• Limitations: Cannot grade renal injury, operator-dependent
• Positive FAST → immediate CT or surgery

Step 2: CT Abdomen and Pelvis with IV Contrast - GOLD STANDARD

1. Non-contrast phase: Detect hematoma, calculi, baseline attenuation
2. Arterial/Nephrographic phase (100 seconds): Parenchymal enhancement, vascular injuries, lacerations
3. Delayed excretory phase (5-10 min): Urinary extravasation, collecting system injury, ureteric injury

CT Protocol - Renal Trauma:
    ┌──────────────────────────────────────┐
    │  Non-contrast → Nephrographic →      │
    │  Excretory phase                     │
    │                                      │
    │  Non-contrast: hematoma density      │
    │  Nephrographic: laceration depth     │
    │  Excretory: urine leak (contrast     │
    │             in collecting system)    │
    └──────────────────────────────────────┘

AAST Renal Trauma Grading (American Association for Surgery of Trauma):

AAST Renal Trauma Grades:

Grade I:   ╭────╮           Grade II:  ╭──╮╭──╮
           │╰──╯│ Contusion            │Lac│  │ Hematoma
           ╰────╯                      ╰──╰╯──╯

Grade III: ╭──╮ ╭──╮       Grade IV:  ╭──╮  ←extravasation
           │  laceration│             │  │→→ urine leak
           ╰──╯ ╰──╯                  ╰──╯

Grade V:   ╭──╭─╮╮  Shattered / Non-enhancing (pedicle avulsion)

• Hypodense linear defect through renal parenchyma
• Perirenal hematoma (crescentic hyperdense collection)
• Hematoma in Gerota's fascia

• Non-enhancing kidney (renal artery avulsion/thrombosis)
• Active contrast extravasation (pseudoaneurysm or arteriovenous fistula)
• Segmental infarcts (wedge-shaped non-enhancement)

• Medial urinary extravasation on delayed phase → pelvicalyceal or ureteric injury
• Lateral extravasation → fornical rupture (minor, usually benign)

• Rare, high-energy trauma
• Delayed CT: Medial extravasation without distal opacification
• "Megaureter" above injury site

Step 3: Retrograde Urethrogram (RUG) - if urethral injury suspected

• Type 1: Stretch (intact mucosa, no extravasation)
• Type 2: Partial tear (extravasation, contrast reaches bladder)
• Type 3: Complete tear (no contrast in bladder)

Step 4: Cystogram - for bladder injury

• Fill bladder with 350 mL dilute contrast
• Assess for extravasation

• Intraperitoneal rupture: Contrast surrounds bowel loops, fills peritoneal space (requires surgery)
• Extraperitoneal rupture: Contrast in pelvic soft tissues, "flame-shaped" (most managed conservatively with catheter drainage)

Bladder Injury on CT Cystogram:
    Intraperitoneal:              Extraperitoneal:
    ╭─────────────────╮           ╭──────────────╮
    │ Contrast around │           │ Flame-shaped │
    │ bowel loops     │           │ extravasation│
    │  ↕              │           │ in pelvis    │
    │  Bladder rupture│           │              │
    ╰─────────────────╯           ╰──────────────╯

Management:

Conservative (Non-operative) Management - Grade I, II, III:

• Bed rest, IV fluids, monitoring
• Serial CT for monitoring
• Urological consultation
• Grades I-III: >95% managed non-operatively

Endovascular Management:

• Angioembolization: For Grade IV-V with active arterial bleeding (contrast blush on CT)
  • Selective catheterization of renal artery
  • Embolize with coils or gelfoam
  • Preserves renal parenchyma
  • Success rate 70-90%
• Endovascular stenting: For renal artery dissection

Surgical Management:

• Indications: Hemodynamic instability, failed embolization, expanding hematoma (>25%), Grade V injury
• Options: Renorrhaphy (repair), partial nephrectomy, nephrectomy

Urinary Extravasation:

• Most resolve spontaneously (70-80%)
• Persistent: JJ ureteric stent or percutaneous nephrostomy

---

QUESTION 10 (10 Marks Total)

10a. Anatomy of Pericardium (3 Marks)

Layers:

• Tough fibrous sac
• Composed of dense collagen
• Attached to: Diaphragm (inferiorly), sternum (sternopericardial ligaments), great vessels (superiorly)
• Prevents overdistension of heart
• Fused with adventitia of great vessels

• Parietal Layer: Lines inner surface of fibrous pericardium
• Visceral Layer (Epicardium): Adherent to heart surface
• Between parietal and visceral layers: Pericardial cavity with 15-35 mL of fluid (lubricant)

Pericardium - Cross Section:
    ┌───────────────────────────────────┐
    │  Fibrous Pericardium (outer)      │
    │  ┌────────────────────────────┐   │
    │  │ Parietal serous pericardium│   │
    │  │ ┌──────────────────────┐  │   │
    │  │ │ Pericardial cavity   │  │   │
    │  │ │ (15-35 mL fluid)     │  │   │
    │  │ │ ┌──────────────────┐ │  │   │
    │  │ │ │ Visceral layer   │ │  │   │
    │  │ │ │  (Epicardium)    │ │  │   │
    │  │ │ │ ┌──────────────┐ │ │  │   │
    │  │ │ │ │ Myocardium   │ │ │  │   │
    │  │ │ │ └──────────────┘ │ │  │   │
    │  │ │ └──────────────────┘ │  │   │
    │  │ └──────────────────────┘  │   │
    │  └────────────────────────────┘   │
    └───────────────────────────────────┘

Pericardial Recesses and Sinuses:

• Between ascending aorta/pulmonary trunk anteriorly and superior pulmonary veins/LA posteriorly
• Accessible by finger behind aorta during surgery
• Appears on CT as fluid-containing space posterior to aorta, anterior to right PA

• Behind left atrium, surrounded by pulmonary veins and IVC
• Blind ending (J-shaped)
• Important: Fluid here does NOT communicate readily with main pericardial space

• Sternopericardial
• Phrenicopericardial (to central tendon of diaphragm)
• Vertebropericardial

Normal CT/MRI Anatomy:

• CT: Pericardium appears as thin hyperdense line (1-2 mm) between pericardial fat (inside and outside)
• Normal pericardial thickness on CT: < 2 mm
• Fluid in pericardial cavity: fluid density (0-20 HU)

---

10b. CT and MRI Findings of Constrictive Pericarditis (7 Marks)

Pathophysiology:

CT Findings:

• Pericardial thickness > 4 mm is abnormal (normal < 2 mm)
• Focal or diffuse
• May be circumferential or localized (especially over RV and AV groove)
• CT can measure precisely

• PATHOGNOMONIC feature for CP (when combined with symptoms)
• Eggshell calcification encasing the heart
• Irregular, dense calcification visible on non-contrast CT
• Distribution: AV groove, right heart border, diaphragmatic surface most common

CT - Pericardial Calcification (Non-contrast):
    ┌────────────────────────────────┐
    │                                │
    │    ████████████████████        │
    │   █                  █        │
    │  █  Right heart       █       │
    │  █  left heart         █      │
    │   █  (encased)        █       │
    │    ████████████████████        │
    │   ↑ Dense calcium (HU >400)   │
    └────────────────────────────────┘

• Tubular/conical right ventricle: Compressed RV (flattening)
• Dilation of right atrium and left atrium (backpressure from restricted filling)
• Enlarged IVC and SVC (venous hypertension)
• Small right and left ventricles (restricted filling)
• Normal left ventricular ejection fraction

• Septal bounce / paradoxical septal motion on dynamic CINE MRI

• Dilated IVC and hepatic veins (IVC > 21 mm)
• Hepatic congestion (heterogeneous liver parenchyma, mosaic pattern)
• Pleural effusion (bilateral, right > left)
• Ascites
• Peripheral edema (clinical, not CT)

• Obliteration of pericardial sinuses
• Tethering of epicardium to pericardium

CT Summary - Constrictive Pericarditis:
    ┌─────────────────────────────────┐
    │  1. Pericardial thickening >4mm │
    │  2. Calcification (eggshell)    │
    │  3. Tubular/conical RV          │
    │  4. Dilated RA, LA              │
    │  5. Dilated IVC, hepatic veins  │
    │  6. Bilateral pleural effusions │
    │  7. Ascites                     │
    └─────────────────────────────────┘

---

MRI Findings:

• No radiation
• Superior soft tissue contrast
• Functional assessment (CINE MRI)
• Can distinguish constrictive pericarditis from restrictive cardiomyopathy

• 4 mm on MRI is pathological

• Appears as:
  • Low signal (dark) on T1 and T2: Fibrous/calcified pericardium
  • High signal on T2: Active inflammation/edema

• Fibrous pericardium: Low T1, Low T2 (hypointense on both)
• Inflammatory/active pericarditis: High T2 signal (edema)
• Late gadolinium enhancement (LGE): Enhancing pericardium = active inflammation (responds to anti-inflammatory treatment)
• No enhancement: Calcified/fibrotic = surgical pericardiectomy required

MRI Signal - Pericardium:
    T1 weighted:   Dark pericardium (fibrous)
    T2 weighted:   Dark = fibrosis; Bright = inflammation
    T1+Gd (LGE):  Enhancement = active inflammation
                  No enhancement = calcified/fibrotic

• Septal bounce: Abrupt paradoxical interventricular septal motion in early diastole
  • Septum moves toward LV in early diastole, then back
  • "Septal bounce" or "diastolic septal flattening"
• Respirophasic septal shift (enhanced with respiratory maneuvers)
• Ventricular interdependence: Right heart expands at expense of left with inspiration

CINE MRI - Septal Bounce:
    Inspiration:    Expiration:
    ╭─────────────╮  ╭─────────────╮
    │ RV ↑  → LV │  │ RV ↓  ← LV │
    │    ╲        │  │       ╱     │
    │     ╲ IVS  │  │      ╱ IVS  │
    │      ╲      │  │     ╱       │
    ╰─────────────╯  ╰─────────────╯
    
    Septal movement: ← → ← → (bouncing)

• Abrupt halt of ventricular filling in mid-diastole (dip-plateau / square root sign on pressure tracing)
• Corresponding to pericardial restraint

• Pericardium adherent to epicardium
• No normal pericardial sliding on CINE

• Dilated IVC, hepatic veins
• Pleural effusions
• Hepatic congestion

CP vs Restrictive Cardiomyopathy (Important Differential):

---

SUPPLEMENTAL IMAGING DIAGRAMS

Schematic: Pulmonary Artery Hypertension - CXR vs CT

CXR:                          CT:
  ┌─────────────────┐           ┌─────────────────┐
  │   PA            │           │ MPA > 29mm      │
  │  ╭──────╮       │           │ PA:Ao > 1.0     │
  │ ╭╯ MPA  ╰╮      │           │ RV:LV > 1.0     │
  │ │enlarged│      │           │ D-sign (IVS)    │
  │ ╰╮      ╭╯      │           │ Mosaic          │
  │  ╰──────╯       │           │ attenuation     │
  │  ↑ Pruning      │           │ Pericardial eff │
  └─────────────────┘           └─────────────────┘

Schematic: Cardiogenic vs Non-Cardiogenic Pulmonary Edema

Cardiogenic:                Non-Cardiogenic (ARDS):
  ┌────────────────┐          ┌────────────────┐
  │ Big heart      │          │ Normal heart   │
  │ Perihilar dens │          │ Peripheral dens│
  │ Kerley B lines │          │ No Kerley B    │
  │ Effusions      │          │ No effusions   │
  │ Upper lobe     │          │ Air bronchograms│
  │ diversion      │          │ (diffuse)      │
  └────────────────┘          └────────────────┘

---