Lecture 2- Chest Xray pt 1

views of a chest X-ray

• frontal

  • posteroanterior (PA)

  • anteroposterior (AP)

• lateral

  • left lateral

why order lateral chest xray

• determine location of disease seen on frontal view

• confirm presence of disease suspected on frontal view

• demonstrate disease not visible on frontal view

what to look for on lateral view xray

• retrosternal space

• hilar region

• fissures

• thoracic spine

• diaphragm and posterior costophrenic sulci

retrosternal space

• NORMAL

  • lucent crescent btwn sternum and ascending aorta/anterior heart

• ABNORMAL

  • soft tissue density filling normal space behind the sternum

hilar region: lateral view

• consists of pulmonary vasculature, pymph nodes, aft, and major bronchi

• NORMAL

  • no discrete mass present

• ABNORMAL

  • distinct, opaque hilar mass

fissures and lung fields; lateral view

major (oblique) and minor (horizontal) fissures should be pencil thin or not visible

thoracic spine: lateral view

NORMAL

• rectangular vertebra; bodies with parallel endplates

• disk spaces maintain height from top to bottom of thoracic spine

ABNORMAL

• narrowing of disc space

• vertebral body loses height (compression fracture)

• bony spurring

diaphragm and posterior costophrenic sulci: lateral view

NORMAL

• sharp posterior costophrenic sulci

• R and L hemidiaphragm

• R hemi is usually slightly higher and visible for its entire length front to back

• L hemi anterior edge usually not visible (silhoueted by heart anteriorly) and posterior edge seen sharply

• yellow: retrosternal spcae-clear

• green: hilar region- no mass

• red: fissures- VISIBLE

• blue: thoracic spine- good

• orange: diaphram and post costo sulci- slightly elevated

technical adequacy of chest xray

PRIMA

Penetration

Rotation

Inspiration

Magnification

Angulation

penetration of chest xray

• degree to which xrays have passed through the body

• adequate penetration:

  • outline of the thoracic spine visible through heart

• inadequate penetration

  • can mimic or hide disease

underpenetrated vs overpenetrated CXR

inspiration

• fills lungs adn contracts diaphragm

• 10 posterior ribs are visible above diaphragm

  • 8-9 in hospitalized pts

suboptimal inspiration

• compress and crowd the lung markings at the llung bases adn diaphram

• could be misleading of pneumonia or cardiomegaly

• only 7 posterior ribs visible

rotation

• adequate rotation: spinous processes are equidistant btwn the medial ends of the clavicle

severe rotation findings

• trachea appears shifted from midline (black arrow)

• left lung appears much larger, right lung appears smaller

• heart contour appears changed

• left hemidiaphragm appears raised (white arrow)

magnification

• plays a role in assessing heart size

• closer an object is to the surface on which it is being imaged, the more true to actual size the resultant object will be

  • PA view is more true to size

• farther away → more magnified

  • AP view

angulation

• orientation of xray beam passing through object

• views:

  • horizontal- normal

    • parallel to floor

    • medial end of the clavicle superimposes on 3rd or 4th rib

  • over angulated

    • bedridden pts that cannto fully sit up

    • clavicles are projected above first rib

airway (frontal)

• trachea: look for deviation other than aortic knob

• bronchi: should be visible

• carina: should be visible

breathing (frontal view)

• lungs

  • clear lungs fields

  • appropriate lung markings

• fissures/pleura

  • major and minor fissures should be pencil point thin or not visible

cardio anatomy: frontal view

• ascending aorta: shoudl not project more lateral than the RA

• aortic knob: will normally push trachea slightly to right

• right atria: should project more lateral than ascending aorta

• left atria: doe snot contribute to border of heart unless pt is rotated

• left ventricle: should not show significant enlargement

• descending aorta: parallels spine and barely visible

cardiac: heart size- frontal view

• normal: cardiothoracic <50% of internal diameter of thoracic rib cage

• AP view → slightly larger than 50% due to magnification

diaphragm: frontal view

• right hemi

  • slightly more elevated

• left hemi

  • no significant elevation

• costophrenic angles

  • sharp

lucency

darker area on the image; more xrays reaching detector

opacity

bright/whiter area on the image; more xrays absorbed, therefore less reaching detector

consolidation

complete filling of alveolar air spaces with fluid, pus, blood, cells, or other material

infiltrate

nonspecific radiologic term describing any abnormal opacity

air bronchogram

visibility of air in bronchus due to surrounding airspace disease

silhouette sign

• loss of visible edge that occurs when two objects of the same radiographic density (water and soft tissue) touch each other

airspace disease vs interstitial disease

• airspace: disease in the thin walled alveoli

  • fills alveolar space

• interstitial (infiltrative) disease: interstitium

  • btwm alveoli and blood vessel

  • contains lymphatic vessels, fibroblasts, adn ECM proteins

  • thickens walls btwn air spaces

airspace disease

• fluffy, cloud-like, hazy opacities

• indistinct margins that blend together

• may contain air bronchograms

  • fluid has replaced the air normally surrounding the bronchus, trapping air inside and givngit contrast to be visible

• may demonstrate silhouette sign

interstitial disease

• criss cross pattern

• reticular- lines

• nodular- dots

• reticulonodular- lines and dots

• margins- sharper and discrete

radiographic characteristics: pneumonia

• opacities

  • alveoli (airspace disease)

  • interstitial pneumonia- walls btwn air spaces become opaque

• air bronchograms may be present- air trappe din bronchi that cant escape

• clearing/resolution: typically occurs in <10days

  • pneumoccocal pneumonia may clea within 48 hrs