JC13 (Surgery) - CXR Flashcards

(30 cards)

1
Q

Define size cut-off for lung mass

A
<3cm = nodule 
>3cm = mass

One nodule in one location = solitary pulmonary nodule (SPN)

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2
Q

Investigations for solitary pulmonary nodule (SPN)

A

Refer to previous CXR

1) SPN present in previous CXR:
- No growth over 2 year = likely Benign
- Interval growth = suspect malignant, proceed to CT scan

2) SPN not present in previous CXR:
- CT scan
- Bronchoscopy
- Sputum analysis

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3
Q

Imaging features of benign lung nodules

A

Benign: Round shape, well-circumscribed, smooth margin, uniform/ central calcification, Fat-containing, Minimal enhancement

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4
Q

Ddx infective cavitating lesion in lung (5)

A

Infections:
- Pulmonary Abscess: intermediate to thick wall, peripheral contrast enhancement, necrotizing center, +/- fluid level

  • Septic Emboli (pathogens cause thrombosis in peripheral pulmonary capillaries): multiple peripheral nodular or wedge-shaped opacities with a broad base against the pleura
  • Mycobacterium tuberculosis infection: upper lobe cavitary disease (immunocompetent) or lower lung zone disease, adenopathy, and pleural effusions (immunocompromised/ children)
  • Non-tuberculous Mycobacterial (NTMB) Infection (e.g. M. avium-intracelluare and M. kansaii): similar upper zone TB but no hemoptysis
  • Aspergillosis/ Aspergillus fumigatus: ground glass halo, fungal ball lesions that appear cavitary, crescent-shape air collection
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5
Q

CT Lung:
- Types
- Section width
- Function

A

Volumetric/ Helical/Spiral CT scan
- Used with IV contrast to enhance nodule characteristics
- Timing of IV contrast is determined by different pathologies (e.g. timing to contrast for PE is different from lung cancer
- Used for examining lung mass (no section width that can miss lesions)

High resolution CT scan
- No contrast used
- Used for interstitial lung disease
- 1-2mm slices taken 10mm apart

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6
Q

Use Hounsfield units to define nodule malignancy in contrast CT thorax.

A

Contrast CT:

  • Nodule enhanced:
    a) >25HU = malignant
    b) Between 15 and 25 HU = Indeterminate
    c) <15HU = Benign
  • Nodule not enhanced: Benign
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7
Q

Imaging features of malignant lung nodules

A
Malignant: Lobulated shape, spiculated margins (due to rapid growth)
eccentric/ speckled calcification 
Pleural retraction 
Marked enhancement 
Heterogeneous
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8
Q

An solitary lung nodule has enhancement of 20HU in contrast CT. Is this malignant or benign?

A

Indeterminate

  • Nodule enhanced:
    a) >25HU = malignant
    b) Between 15 and 25 HU = Indeterminate
    c) <15HU = Benign
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9
Q

Plan of action after finding indeterminate nodule in lung

A

Close follow-up with CXR/ CT (3-6 months)

Percutaneous or transbronchial biopsy/ Resection to find cause

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10
Q

Investigations for suspected lung carcinoma

A

Contrast CT scan: TNM staging +/- biopsy at thorax and upper abdomen

Bronchoscopy: biopsy + BAL

Post-bronchoscopy sputum analysis

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11
Q

Name of lung tumor that is associated with upper limb motor deficit?

Structures that may be invaded?

A

Pancoast tumor

brachial plexus
Erosion of rib and left transverse process
soft tissue of back

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12
Q

3 uses of CT in management of lung cancer?

A

1) Staging, determine operability
2) Radiation planning, find disease extent, location and limit collateral damage
3) Re-evaluate treatment response

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13
Q

Limitation of contrast CT in examining mediastinal LN

A

Hard to assess:
Size

Cause of LN enlargement (inflammation or metastasis?)

Microscopic metastasis

Indeterminate chest wall or mediastinal invasion

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14
Q

List 5 ancillary investigations for lung cancer

A

Flexible bronchoscopy

Mediastinoscopy + biopsy

Transesophageal USG + biopsy

Thoracotomy + nodal sampling

PET scan (18-FDG)

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15
Q

Biopsy techniques for proximal vs peripheral lung lesions

A

Proximal lesion (close to hilum):

  • Saline washing and brushing for microscopy and cytology
  • Biopsy under direct vision for histology

Peripheral lesion: not visualized directly

  • BAL for microscopy and cytology
  • Transbronchial biopsy for histology
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16
Q

Indication for MRI in imaging lung cancer

A

Superior sulcus lung tumors* specific use **

Chest wall and brachial plexus invasion (e.g. Pancoast tumor)

17
Q

1 advantage and 1 disadvantage of PET/CT scan for lung cancer

A

18-FDG for hypermetabolic lesions:

Adv: detect occult metastasis with high sensitivity

Disadv.
High sensitivity but low specificity, false positive rate high (e.g. TB nodules)

18
Q

3 advantages of CT as first-line imaging for lung cancer

A

Favorable cost
Quick
Allow simultaneous exam intrathoracic and abdominal organs

19
Q

Ddx diffuse lung nodules* (categorize into miliary, cavitory and calcific nodules)

A

miliary nodules:
- miliary tuberculosis
- silicosis
- pulmonary sarcoidosis
- diffuse pulmonary metastases
- diffuse panbronchiolitis

cavitatory nodules
- septic pulmonary emboli
- cavitating metastases
- multiple cavitating infections

calcific nodules
- tuberculosis
- silicosis
- calcified pulmonary metastases

20
Q

Interstitial lung disease

  • Type of scan indicated
  • Interval width
A

High resolution CT, no contrast - High spatial resolution, reduced radiation

1mm sections at 10mm intervals

21
Q

Functions of HRCT in evaluation of diffusion lung lesions?

A

Characterize disease for diagnosis

Define location and extent

Localize site for biopsy

Post-treatment evaluation

22
Q

Typical Hounsfield Units of air, water, fat, soft tissue, and calcified matter

A
Air = -1000
Water = 0
Fat = 20 
Soft tissue = 30-50
Calcification = >150
23
Q

Ddx systemic diseases that cause cavitating lung nodules

A

Granulomatosis polyangiitis: autoimmune vasculitis in respiratory tract and kidneys

Rheumatic nodules: necrobiotic nodule at periphery or subpleural space

Sarcoidosis (rare <1%): round/ oval nodules in peri-hilar/ peripheral areas

Malignancies: Pulmonary metastasis from SCC (e.g. from GIT, breast CA, sarcomas, Adenocarcinomas…)

Cystic lung diseases by pneumocystis jirovecii: Langerhgans cell histiocytosis, lymphangioleiomyomatosis (LAM), lymphocytic interstitial pneumonia (LIP)

24
Q

Ddx Solitary Pulmonary Nodules

A

Neoplastic - Benign:
- pulmonary hamartoma
- pulmonary chondroma
- primary pulmonary meningioma: rare

malignant
- bronchogenic carcinoma
- solitary pulmonary metastasis
- lymphoma
- carcinoid tumors

inflammatory
- granuloma
- lung abscess
- rheumatoid nodule
- pulmonary inflammatory pseudotumor
- small focus of pneumonia: round pneumonia

congenital
- arteriovenous malformation
- lung cyst
- bronchial atresia with mucoid impaction

miscellaneous
- pulmonary infarct
- intrapulmonary lymph node
- mucoid impaction
- pulmonary hematoma
- pulmonary amyloidosis

25
Mimics of solitary pulmonary nodules
nipple shadow cutaneous lesion (e.g. wart, mole) rib fracture or other bone lesion vanishing pseudotumor of congestive heart failure summation of markings radiological artifact
26
CXR Technical Quality checklist
Projection: AP or PA, check for marking for AP, check if scapulae overlies the lungs in AP, Cardiac shadow might appear magnified in AP Orientation: Check L/R markings, beware of dextrocardia and lung pathologies with mediastinal shift Rotation: Check medial ends of both clavicles are equidistant from the vertebral spinous process. If one end is nearer than the other, that side will appear whiter Penetration: Vertebral body just seen through the lower cardiac shadow Degree of inspiration: Check right hemidiaphragm is between 5th and 7th rib, count 6 anterior ribs and 10 posterior ribs above the diaphragm
27
CXR basic anatomical structure checklist - AP/ PA film
Lung fields - Equal transradiancy - Horizontal fissure should from from 6th rib in the axillary line to the hilum - Check for volume loss in one or both sides of the lungs - Check for discreet or generalized shadows Hilum - Left hilum should be lower than right hilum - Difference <2.5cm - Compare shape, density, concavity of each side Heart - Check cardio-thoracic ratio <0.5 Mediastinum - Clear edge - Fuzzy edge indicates nearby consolidation or collapse Diaphragm - Right hemidiaphragm higher than left, <3cm - Outline smooth - Below diaphragm: any free gas, dilated bowels Costophrenic angle - Clear, well-defined Trachea - Central, slight deviation to right at aortic knuckle Bones - Scapulae, vertebrae, ribs - Check for density changes and fractures Soft tissue: any enlargement
28
CXR anatomical structure checklist - Lateral film
Diaphragm - Right hemidiaphragm streched across whole throax, passes through heart border - Left hemidiaphragm disappear towards posterior border of heart - Double check with AP/PA film, check if gastric air bubble is the same distance from left hemidiaphragm on lateral film - Check costophrenic angles (e.g. pleural effusion blunting angles) Lung fields - Check equal transradiancy, check lesions Retrosternal space - Anterior mediastinal mass will obliterate the space and turn it white Position of horizontal fissure - Normally passes from midpoint of the hilum to anterior chest wall - Displaced fissure indicate SOL - Oblique fissure should pass from T4/5 vertebral through hilum to anterior third of diaphragm Hilum density, check lesion Vertebral bodies - Normally more translucent more caudally - Check same size, shape, density, outline - Check collapse, lesion
29
Localizing lesion on CXR
Right lung: Zones: - Upper = above right anterior border of 2nd rib - Middle = between 2nd and 4th rib - Lower = between 4th rib to diaphragm Silhouette sign - Obscures cardiac shadow = right middle lobe - Obscures diaphragm = right lower lobe Fissure - Posterior to oblique fissure = right lower lobe - Anterior to oblique fissure = right middle or upper lobe - Above horizontal fissure = right upper lobe Left lung: - Posterior to oblique fissure = Left lower lobe - Anterior to oblique fissure = Left upper lobe
30