PA view Chest

Is this film centered? How do you determine it? Why is that important?

• No this film is rotated
  • The distance between the medial end of clavicle and trachea should be equal, in well centered film.
  • Clavicles should appear similar
• If the film is not centered, position of mediastinum cannot be relied on for significance.

Is this PA or AP view? How can you tell? 

• PA view
  • Scapula is seen in periphery of thorax
  • Clavicles project over lung fields
  • Posterior ribs are distinct
  • Position of markers
  • If you see air fluid level in stomach, it is an upright film.
    • PA view films are taken with the patient upright

Is this PA or AP view? How can you tell? 

• AP view
  • Scapulae are over lung fields
  • Clavicles are above the apex of lung fields
  • Position of markers
  • Anterior ribs are distinct

Why is it important to know whether it is PA or AP view? 

• Normal standards for the following are in PA view only. Gravity, changes them in AP view.
  • Cardiac size 
  • Width of mediastinum
  • Position of diaphragm
  • Meniscus of pleural effusion
  • Vascular shadows

• Heart appears larger
• Mediastinum widens
• Diaphragms are higher
• Pleural effusions layers posteriorly
• Pulmonary vessels size is same in upper and lower lung fields

Is this film exposed properly How do you evaluate exposure?  

• Yes it is appropriate
  • With correct exposure you should barely see the inter vertebral disc through the heart
    • If you see them very clearly the film is overexposed
    • If you do not see them it is underexposed

Is the exposure appropriate? Whys is it important to assess exposure?

• No it is overexposed
  • Small lung lesions may not be detected in overexposed film (more black)
  • Lung fields will appear dark in overexposed films and can be misinterpreted as emphysema
  • Interstitial markings may appear prominent and can be mistaken for interstitial disease in under exposed film (more white).

• The dome of the Diaphragm should be over 10th posterior rib with full inspiration

What are the problems if the patient has not taken full inspiration? 

• Mediastinum appears wider
• Heart appears enlarged
• Lung markings appear prominent in base of lungs and can be mistaken for interstitial disease

How do you number the ribs?

• You can number either posterior or anterior portion of ribs
• Identify the transverse process of the first thoracic vertebra and the articulating rib and number it 1.
  • Transverse process of thoracic vertebra are slanted upwards, while that of cervical vertebra are slanted downwards.
• Number the ribs sequentially

What is the purpose of numbering ribs?

• To describe the location of a lesion in chest x-ray.
• Ribs provide the horizontal axis while the vertical lines provide the vertical axis.

Identify Vertebra, scapula, clavicle

Draw the outline of Mediastinum  Where do you measure the mediastinal width?

• I suggest assessment of mediastinal width at three levels
  • Para tracheal
  • Supra cardiac vessel area
  • Cardiac

What is the normal width of mediastinum at tracheal level?

What is the normal width of mediastinum at supra cardiac vessel area?

How do you measure heart size? What is the normal range for heart size?

• Drop a vertical line along the lateral most thoracic position on both sides
  • The distance between them is  trans thoracic diameter
• Drop vertical lines along lateral edge of right heart and left heart margins
  • The distance between them measures heart size
• Normal heart size is less than half of trans thoracic diameter.

• Cartilaginous rings are thicker and can be seen in the x-ray.
• Cartilage decreases beyond segmental bronchi and hence they cannot be recognized.

What is the carinal angle in this film? What is the significance of widened carinal angle?

• Normal carinal angle is around 
• Widened carinal angle can be seen in
  • subcarinal mass / lymph nodes
  • left atrial enlargement

Identify oblique and transverse fissure in PA view.

• You cannot see oblique fissure in PA view
• Transverse fissure is at the level of 4th anterior rib on right side.

How does location of transverse fissure help you?

• The fissure moves up with RUL loss of lung volume
• The fissure moves inferiorly with loss of RML lung volume

Identify left and right hilum. What is the normal relationship?

• Left hilum is slightly higher than right
  • If you draw a horizontal line at the level of lower edge of left hilum it should reach the upper edge of right hilum.
• In less than 5% they are the same level.

 How is altered relationship between left and right hilum helpful in diagnostic interpretation?

• It gives clues to loss of lobar lung volumes
  • Left hilum will be pulled up with LUL atelectasis
  • Left hilum will be pulled down with LLL atelectasis
  • Right hilum will be pulled up with RUL atelectasis
  • Right hilum will be pulled down with RLL atelectasis
  • Hilar position does not change with RML atelectasis because of small volume of RML
• Displaced by mass

Compare and contrast vascular markings in upper vs. lower lung fields in PA view.

• The vascular markings are more prominent in base of lungs compared to upper lung fields
• This is due to gravity dependent increased blood flow to bases

List conditions, where vascular markings are prominent in upper lung fields 

• Mitral stenosis
• Congestive heart failure
• Alpha one antitrypsin deficiency
• High output states

• There is paucity of vascular markings in outer third of lung fields
• In left to right shunts (ASD, VSD, PDA) and in high output states, there is increased pulmonary flow, the vascular markings in the outer third will be prominent.
• In interstitial disease, lymphangitic malignant spread and in CHF with increased lymphatic flow the markings in outer third will be prominent.

Identify Aortic knob, Aortopulmonary window  (AP window) and the main Pulmonary artery What is the significance of full AP window?

• Nodes
• Aortic aneurysm
• Dilated or aneurysm of pulmonary artery

• Vascular and interstitial markings appear more prominent over breast shadows and should not be misinterpreted.
  • This is particularly true with lactating breasts.
• Markings in lateral chest will be normal, where there is no superimposition of breast

What is the significance of one missing breast?

• A missing breast could be a clue to prior mastectomy for cancer breast
• Unilateral basal "hyper lucency" could be due to mastectomy.

Identify costophrenic angles What does the blunting of costophrenic angle imply?

• Blunting of ocstophrenic angle is either due to pleural fluid or fibrosis

Which diaphragm is higher and why?

• Right diaphragm is higher than left
• Congenital position of heart determines which diaphragm is lower
• Position of normal liver is not a determinant of which diaphragm is higher

RUL projection in PA view

RML projection in PA view

LLL projection in PA view

Lingula projection in PA view

RLL projection in lateral view

LLL projection in lateral view

Superior segment of RLL

Apical segment of RUL

Cardio vascular system

How do you measure heart size? What is the normal range for heart size?

• Drop a vertical line along the lateral most thoracic position.
  • The distance between them is  trans thoracic diameter.
• Drop vertical lines along lateral edge of right heart and left heart margins.
  • The distance between them measures heart size.
• Normal heart size is less than half of trans thoracic diameter.

• SVC
• Ascending Aorta
• Right hilum
• Right atrium
• Inferior vena cava

Identify structures along left edge of mediastinum

• Aortic knob
• Left hilum
• Left atrial appendage
• Left ventricle

Identify Left ventricle

Identify right ventricle

Identify left atrium

Lateral view Chest

Do you routinely take left lateral or right lateral chest?

• Left lateral
  • With left lateral chest the heart is close to the cassette and gives a sharper image of heart.

Identify Sternum and Loui's angle. What are the important landmarks at Loui's angle?

• Carina
• Mediastinum is divided into superior and inferior compartments

Identify axillary fold and  Scapula

• These overlapping shadows make it very difficult to evaluate upper lung field in lateral view.

Identify Vertebra. Is there a difference in radio density along the Spine.

• Upper vertebra are superimposed by shoulders and appear white and indistinct.
• Lower vertebra are darker and distinct
• Density and clarity of lower vertebra is uniform

Identify oblique, transverse fissure. What is the normal position of oblique and transverse fissures? 

• Left oblique fissure T3 to Diaphragm
• Right oblique fissure T3 to Diaphragm
• Transverse fissure: From right oblique horizontally at 

What is the significance of position of fissures?

• Oblique fissures move anteriorly with upper lobe atelectasis
• Oblique fissures move posteriorly with lower lobe atelectasis
• Transverse fissure moves inferiorly towards oblique fissure in RML atelectasis

Identify aortic, pulmonary arches  and AP window

Which chambers form anterior and posterior margins of heart in the lateral view?

• RV anteriorly
• Left atrium posteriorly

Identify retro sternal air space. What is normal retro sternal space?

• Heart is in contact with sternum in lower one third.
• Upper two thirds of sternum is separated from heart by radio lucent lungs

Identify left and right diaphragms . How did you arrive at your answer?

• Phenomenon of divergence
  • Right diaphragm and right hemi thorax project outside left hemi thorax.
• Stomach bubble is immediately below left diaphragm
• Anterior one third of left diaphragm is lost because of heart sitting on it
• Right diaphragm is seen in its entirety
• By identifying the oblique fissures in contact with the diaphragm.

Identify the costophrenic angle

• The posterior costophrenic angle is the most dependent portion in upright position, where fluid accumulates first.

Identify left and right pulmonary artery

• Right main projects as round density as you are looking at an end on view of the horizontally aligned vessel
• Left main wraps around LUL orifice

Identify trachea , RUL and LUL orifices.

• LUL orifice seen in its entirety because it is wrapped around by left pulmonary artery
• RUL orifice is not seen distinctly. If it is seen clearly most likely there is a cuff of lymph nodes encircling it.

Position of esophagus. Identify Tracheo esophageal stripe

• Esophagus is in the posterior mediastinum, behind trachea and heart.
• Posterior wall of trachea and anterior wall of esophagus are in opposition and form the tracheo esophageal stripe.

CT Chest Cross sectional Anatomy

Identify structures level 1

Identify structures level 2

Identify structures level 3

Identify structures level 4

Identify structures level 5

Identify structures level 6

Identify structures level 7

Identify structures level 8

Identify structures level 9

Identify structures level 10

CT angiogram

• SVC

• IVC

• Right atrium

• Right Ventricle

• Left ventricle

• Left atrium

• Pulmonary artery

  • Main

  • Right

  • Left

• Pulmonary vein

• Aorta

• Azygous vein

Bronchogram