Diagnostic Radiology SC006: Emergency Radiology

Question 1

Emergency Radiology

Answer 1

• Availability and rapid response to the radiology team is important —> but there are limitations
• Balance the potential delay caused by imaging and the need for urgent management

Urgent requests:

1. Direct communication with Radiologist on-call
2. Please know your patient
3. Check **INR, **PT / aPTT, ***blood counts for interventional radiology
4. Check period of fasting (in case of resuscitation due to contrast allergy / other urgent surgery)
5. Obtain informed consent

Process:

1. Ensure haemodynamic stability, ABC
2. History + P/E
3. Radiology

Radiologist’s role:

• Member of the management team
• Examinations are tailored to the clinical situation
• Accurate interpretation
• All abnormalities communicated to the clinician (verbally and written in case-notes)

Question 2

Head trauma

Answer 2

Clinical condition of the patient determines whether imaging is required or not
—> GCS gives indication of urgency of imaging

Indications to be put on request form:

• Focal neurologic findings
• Altered level of consciousness after trauma
• Clinical signs of basilar fracture (e.g. raccoon eyes)
• Evidence of CSF leak from nose or ear
• Penetrating head injury
• Significant facial fracture

Modality:

1. ***Non-contrast CT
   - Sufficiently diagnostic alone in most cases to end the imaging workup
   - Other views: Bone window (see fracture site), 3D CT reconstruction
2. MRI
   - Not 1st line imaging
   - Useful in:
   —> Post-traumatic syndromes (e.g. diffuse axonal injury)
   —> Shear injury
   —> Subtle haemorrhage / edema
   —> Aneurysms (MR Angiography)
3. Skull X-ray
   - generally not useful, except in suspected open and depressed fractures (but can be diagnosed by CT anyway)

Question 3

Fever + Neurologic signs: CNS infection

Answer 3

S/S:

1. Altered mental state and fever
2. Acute, severe headache
3. 1st seizure in an individual with fever + other constitutional signs
4. Immunocompromised host with new onset of neurological signs

Modality:

1. Lumbar puncture
   - Gold standard for diagnosis of meningitis
2. MRI / CT (with ***IV contrast —> highlight area of infection)
   - Exclude intracranial mass before LP
   - Identify parenchymal brain infection / extra-axial collection or empyema

Abscesses:
- Rim-enhancing lesion with hypodense edema around lesion

Question 4

Cord compression

Answer 4

Acute myelopathy:

• Emergency diagnosis + treatment to prevent permanent neurologic dysfunction
• Cord compression from spinal metastases / trauma / acute disc prolapse

Modality:

1. ***MRI
   - Modality of choice / Only choice (for looking at spinal cord)
   - Cord compression / impingement
2. CT
   - Fracture, Subluxation, Dislocation
   - Further evaluation of X-ray findings
   - Evaluation of areas not well visualised on standard views (e.g. C7/T1, C1/2)
3. Spine X-ray
   - Initial assessment
   - AP + Lateral + Open-mouth view (look at odontoid process)
   - All 7 cervical vertebrae must be visualised, including cervicothoracic junction + craniocervical junction

Algorithm for ordering imaging:
Blunt cervical spine trauma
—> Cervical spine X-ray
—> Suspected cord injury —> MRI
—> Suspected bone injury —> CT

Question 5

Acute SOB: PE

Answer 5

DDx:

• Pulmonary infection
• Pulmonary edema
• Neoplastic disease (e.g. massive pleural effusion, lung collapse)
• Others

S/S of PE:

1. SOB sudden onset
2. Haemoptysis
3. Pleuritic chest pain

Modality:

1. CXR
   - Normal (33%): no lung infarction
   - Atelectasis (small area of collapse)
   - Focal oligaemia (rare)
   - Peripheral segmental wedge-shaped consolidation (54%) (non-specific: DDx: infection)
   - Pleural effusion
   - **Hampton’s Hump (triangular pleural based density with apex pointed towards hilum): sign of pulmonary infarction
   - **Westermark’s sign: Dilation of pulmonary vessels proximal to embolism and collapse distal
2. CTPA
   - Visualise main branch + segmental PA
   - Limitations: lack of visualisation of subsegmental (i.e. small) PA (but may not need treatment anyway)
   - Emboli isolated to subsegmental / smaller PA branches are only manifestation of PE in 6-30% of cases
3. V/Q scan
   - Limited by confounding lung changes (e.g. abnormal CXR by pleural effusion, consolidation)
4. Conventional pulmonary angiography
   - Gold standard, but seldom necessary
   - Invasive procedure

Sensitivity and Specificity:

1. CTPA
   - sensitivity 82-94%
   - specificity 78-95%
2. V/Q scan (high, intermediate and low probability)
   - sensitivity 98%
   - specificity 10%
3. V/Q scan (high probability)
   - sensitivity 41% (potentially miss some)
   - specificity 97%

Question 6

DVT

Answer 6

Modality:

1. Ultrasound with colour Doppler + compression
   - primary imaging modality for suspected DVT
   - sensitivity (excluding calf) 95%, specificity 98%
   - lack of flow + cannot compress: presence of clot
   - clot: echogenic

Question 7

Acute abdomen: Ruptured viscus

Answer 7

Modality:

1. **Erect CXR (1st line)
   - detect subphrenic gas / gas under diaphragm
   - **Left lateral decubitus AXR to detect free air in ill patients who cannot sit / stand
   - Erect AXR is NOT indicated
   - ***Rigler sign (bowel wall well delineated on both sides)

Question 8

Blunt abdominal trauma

Answer 8

Modality:
1. CT contrast
- 1st line to evaluate haemodynamically stable patients
- **IV contrast (+ **Oral contrast in conscious patient)
—> IV contrast essential for diagnosis of **visceral injuries + active arterial **extravasation
- Detection + Grade severity + Prognosticate organ injury
- Guide management (operative / conservative)

Detect:

• Subcapsular / Intraparenchymal haematomas
• Lacerations
• Fractures
• Vascular pedicle injury

Question 9

RLQ pain: Acute appendicitis

Answer 9

Diagnosis: mainly Clinical (not imaging)

Imaging:

• Reduce negative appendectomy rate
• Atypical signs and symptoms
• USG / CT: institutional preference + local expertise

Modality:

1. USG
   - Indications: Paediatric, Pregnant, Women with normal body habitus
   - Blind pouch, no peristalsis
   - >6mm AP diameter, Appendicolith, Periappendiceal abscess
2. CT
   - Indications: Obese patients, Suspected perforation
   - With / Without IV/oral contrast
   - >6mm AP diameter, Appendicolith, Periappendiceal inflammation (e.g. soft tissue stranding)

Question 10

Hypotension and Abdominal pain: Ruptured AAA

Answer 10

• Nearly 100% mortality rate if surgery is not performed urgently
• Mostly arteriosclerotic (others: mycotic / pseudoaneuryms)
• If imaging is not immediately available —> take patient to surgery

S/S:

• Abdominal / Back pain
• Tender abdominal mass
• Hypotension

Modality:
1. CT
- **Non-contrast CT immediately to make diagnosis
- **IV contrast helpful If time allows
—> Active bleeding from aortic aneurysm into retroperitoneum
—> Focal dense collection of contrast-enhanced blood
- Also capable of doing multiplanar reformation for surgical planning

2. USG
   - Screening of suspected abdominal aneurysm in ***asymptomatic patient
   - Limited in ability to delineate extent

Question 11

Acute scrotal pain: Torsion of testis

Answer 11

• If untreated, testicular necrosis can occur within ***6 hours after the onset of symptoms
• Clinically if there is reasonable likelihood of torsion —> no imaging —> surgery ***without delay

DDx:

• Torsion of the appendix testis
• Acute epididymitis / epididymo-orchitis
• Incarcerated inguinal hernia
• Testicular trauma

Modality:

1. Doppler USG of testis
   - No ***intratesticular arterial flow signals
   - Darker, swollen