18 Introduction to Chest Radiology 1 (2) Flashcards Preview

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Flashcards in 18 Introduction to Chest Radiology 1 (2) Deck (34):
1

Normal chest radiograph

  • Components
  • Search pattern
  • Concept

  • Components
    • Standard views
    • Radiographic densities
    • Film exposure
    • Chest CT
  • Search pattern
    • Heart
    • Mediastinum
    • Lungs
    • Chest wall
  • Concept
    • Place area of interest next to cassette

2

Standard radiographic views

  • Postero-anterior (PA)
  • Antero-posterior (AP)
  • Left lateral CXR

3

Postero-anterior (PA) CXR

  • X-ray traverses posterior to anterior
  • Heart next to cassette
  • Patient is upright
  • 6 feet from X-ray tube
  • Decrease image magnification
  • Increase sharpness
  • Full inspiration

4

Antero-posterior (AP) CXR

  • X-ray traverses anterior to posterior
  • Patient upright, supine
  • Spine next to cassette
  • 3 feet from x-ray tube
  • Increase image magnification
  • Decrease sharpness
  • PA is preferred

5

Left Lateral CXR

  • X-ray traverses R --> L
  • Left side next to film
  • Heart & aorta on left
  • Decrease magnification
  • Evaluate behind heart
  • Summation of lungs

6

5 radoigraphic densities

  • 5 radiographic densities
  • Anatomic structures differ in density

  • 5 radiographic densities
    • Air - lungs, trachea
    • Fat
    • Soft tissue - fat, blood, muscle
    • Bone - calcium
    • Metal - hardware, contrast
  • Anatomic structures differ in density
    • Low density material (air) represented as black
    • Dense material (bone, metal) represented as white
    • Body tissues are varying degrees of grey

7

Image exposure

  • Unexposed X-ray film
  • Anatomic structures differ in density
  • Dense tissue

  • Unexposed X-ray film starts off as white
    • When radiated, the silver ion (black) in x-ray film emulsion precipitates
    • The more radiation that X-ray film receives, the blacker it becomes
  • Anatomic structures differ in density
    • Attenuation of X-rays depends on density and thickness of tissues
    • X-ray image is a map of X-ray attenuation
  • Dense tissue (bone) blocks more radiation from reaching the film
    • Air – black
    • Soft tissue – grey
    • Bone – white

8

Computed axial tomography (CT)

  • Cross-sectional imaging
  • Computer processing and reconstruction
  • Superior tissue contrast, anatomic localization
  • Bread-slicer, view from feet
  • Helical multi-detector technique
  • High radiation dose

9

Computed axial tomography (CT)

  • Helical multi-slice CT acquisition
  • Multi-detecter helical CT
  • High resolution chest CT (HRCT)

  • Helical multi-slice CT acquisition
    • Interpolated data from 4 detector rows
    • 4, 16, 64, 128, --> 320 MDCT
    • UPMC: 64 MDCT is the work horse
  • Multi-detecter helical CT
    • Scout image
    • Breathe in
    • Hold it (~20s)
    • Breathe
  • High resolution chest CT (HRCT)

10

MDCT: axial data set

  • Stack of images
  • Axial plane
  • 300 - 500 images
  • 0.63 mm thin

11

CT contrast bolus timing

  • Start IV contrast before the CT
  • Scan continuously at one level

12

Shortness of breath

  • Pulmonary emboli
  • Venous blood clots travel to lung

13

Radiation dose

  • PA & lateral CXR
    • 20 mrem = 0.2 mSv
    • ~10 days natural background radiation
  • Chest CT
    • Equivalent to 400 CXR
    • 3-5 rad = 5 mSv
    • ~ 2 years background radiation
    • 1 mSv = 5+ cancers per 100,000 individuals

14

Search pattern

  • Heart
  • Mediastinum
  • Lungs
  • Pleura
  • Hila
    • Trachea & bronchi
    • Pulmonary arteries
    • Pulmonary veins
  • Chest wall

15

The heart

  • Location
  • 2 parallel pumps
  • Heart size
  • Heart borders
    • Right
    • Left

  • Left of midline
  • 2 parallel pumps
    • Right
      • Low pressure
      • Deoxy blood to lung
    • Left
      • High pressure
      • O2 blood to body
  • Heart size: < half diameter of thorax
    • Post-partum cardiomyopathy: heart is too big
  • Heart borders
    • Right 
      • SVC & RA
    • Left
      • Aortic arch
      • Main pulmonary artery
      • Left ventricle
      • (Left atrial appendage)

16

The mediastinum

  • General
  • Consists of...
  • Problems

  • General
    • Central compartment
    • Potential space
    • Lined by parietal pleura
  • Consists of...
    • Heart, aorta, vessels
    • Thymus
    • Esophagus & trachea
    • Lymph nodes
  • Problems
    • Encapsulated thymoma
    • Mediastinal mass: lymphoma
    • Neurofibroma

17

Esophagus

  • Squamous cell cancer
  • Adenocarcinoma
  • Oral contrast ingested

18

The lungs consist of...

  • Pleura - surrounds lung
  • Lung parenchyma
  • Tracheo-bronchial tree
  • Pulmonary arteries (PA)
  • Pulmonary veins (PV)
  • Hila

19

Pleura

  • Pleural development
  • Pleura
  • Parietal pleura
  • Visceral pleura
  • Pleural fluid / effusion

  • Pleural development
    • Pleura begins as single layer
    • Lung invaginates into coelomic cavity
    • Single layer of pleura folds back on itself to form 2 layered membrane
  • Pleura
    • Potential space
  • Parietal pleura
    • Lines diaphragm
    • Chest wall
    • Mediastinum
  • Visceral pleura
    • Lines the lobes
    • R & L major fissures
    • (R) minor fissure
  • Pleural fluid / effusion
    • Hemothorax
    • Fluid "meniscus"

20

Pleura

  • Pleural gas
  • Visceral pleura
    • Lines...
    • L major fissure
    • R major & minor fissure
    • R major fissure

  • Pleural gas
    • Pneumothorax
  • Visceral pleura
    • Lines the lobes
    • L major fissure
      • LUL & LLL
    • R major & minor fissure
      • RUL & RML
    • R major fissure
      • RUL - RML from RLL

21

Fissures on CT

22

Lung parenchyma

  • Sponge, air-filled
  • Clear & more lucent at bases
  • No distinct markings
  • Right is bigger, 3 lobes (RUL, RML, RLL)
  • Left upper, lower lobes

23

Consolidation

  • Normal chest radiograph & CT
  • (Air space) consolidation

  • Normal chest radiograph & CT
    • Lungs are clear
  • (Air space) consolidation
    • Too white
    • Alveolar air replaced by fluid, blood, pus, tumor
      • --> confluent opacity
    • Obscures architecture (broncho-vascular)
    • Focal, patchy, or diffuse

24

Ground glass opacity

  • Too white
  • Hazy increased lung attenuation
  • Broncho-vascular markings preserved
  • Partial filling of alveoli, interstitial thickening, increased capillary blood flow
  • “Smeared chalk”
  • Edema, pneumonia

25

Atelectasis

  • Too white
    • Decreased inflation
    • Decreased volume
    • Increased reabsorption
    • Increased opacity
  • "Ectasia"
    • Dilation, expansion
    • Aortic ectasia - mildly dilated aorta
    • Bronchiectasis - bronchial dilatation
  • Atelectasis
    • Gr. ateles “imperfect” + ektasis “expansion”
    • “Collapse” of lung, volume loss

26

Lobar atelectasis

  • RUL
    • Decreased inflation of segment, lobe, or lung
    • Reabsorption of air
    • Involved lung has decreased volume, increased opacity
    • Mucous plug, stricture, tumor, or extrinsic compression of bronchus
    • Non-involved lung responds
  • RML

27

Interstitium

  • Continuum of loose supporting connective tissue in lung
  • Interstitial lung disease
    • Tissue around airways & air spaces thicken, with preservation of alveolar air
  • Pulmonary lobule
    • Septa
    • Arteriole
    • Bronchiole
  • Pulmonary edema

28

Alveolar ducts and pulmonary acinus

  • Microscopic anatomy
  • Fibrosing alveolitis
  • Reticular pattern

  • Microscopic anatomy
    • Terminal airways
    • Alveolar ducts
    • Acini
  • Fibrosing alveolitis
    • Alveolar collapse
    • UIP / IPF
  • Reticular pattern
    • Fibrosis
    • Honeycomb

29

Problems

  • Air trapping
  • Smoker
  • Renal cell carcinoma mets
  • 21 yo man with cough

  • Air trapping
    • COPD
    • Too black
  • Smoker
    • Nodule < 3 cm
  • Renal cell carcinoma mets
    • Mass x 3 cm
  • 21 yo man with cough
    • Cystic fibrosis
    • Bronchiectasis

30

Tracheo-bronchial tree

  • Ao displaces trachea to right
  • Trachea --> main bronchi (T5)
  • Left main bronchus is longer (5cm) & lower
  • Right main bronchus is shorter, more vertical
  • Normal bronchioles imperceptible

31

Pulmonary arteries

  • Right PA in front of right main bronchus
  • Left PA arches over left main bronchus
  • Left hilum superior
  • Vertically oriented
  • Follow bronchi
  • Problem: pulmonary hypertension

32

Hila

  • PA, PV, bronchus --> lung
  • PA makes up bulk
  • Left hilum higher (98%)
  • Both same height (2%)
  • Right hilum not normally superior to left
  • Equal size & attenuation

33

Normal chest imaging

  • CXR important tool
  • PA, AP, Lateral
  • Radiographic densities gas, fat, water, M+
  • Film exposure
  • Chest CT: x-section
  • Location

34

Chest imaging: search pattern

  • Heart
  • Lungs
  • Don't normally see...

  • Heart size
    • Hilum
    • Pulmonary arteries
    • Vascularity
  • Lungs are clear
  • Don’t normally see...
    • Interstitium
    • Bronchioles
    • Pulmonary veins
    • Pleura
    • Mediastinum

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