# Chest X-ray
## ID

* name
* age
* date
* modality

## Marker

* Right or Left

## Position

* Medial ends of the clavicles should be equidistant from the spinous processes at the midline to rule out rotation

## Quality

* Penetration
** thoracic disc spaces should be just visible through the heart
*** overexposure → too dark
*** underexposure → too white

## Respiration

* good inspiration → 6th anterior, 10th posterior ribs at MCL
* right hemidiaphragm at 6th anterior rib
* poor inspiration:
** poor aeration, vascular crowding, widened central shadow

## Hardware

* Comment on any lines, lead placements, tubing, etc.

## Bones

* C-spine, T-spine → alignment, disc space spacing, lytic or blastic lesions
* shoulder girdle, ribs, humerus, sternum → fractures, osteopenia, deformities
* vertebra OA (lateral view)
** subchondral (beneath the cartilage) sclerosis
** subchondral cysts
** narrowing of joint space
** osteophytes

## Extrathoracic soft tissue

* breast shadow, nipple
* supra-clavicular, axillary areas → masses
* subcutaneous emphysema

## Mediastinum

* size, shape
* mainstem and segmental bronchi, lymph nodes
* great vessles
* hila → relationship, size

## Trachea

* position (centered, some rightward shift at level of carina)
** shift - pneumothorax, mass
** carina widened - LA enlargement, subcarinal node

## Heart Shadow

* cardiothoracic ratio (only on full inspiration PA views)
** should be < 50%
* enlarged chambers
** LA - double shadow on right border
** RA - ↑ width of right hemidiaphragm
** LV - ↑ heart width
** RV - lateral view: retrosternal space ↓
* calcifications
* aortic knuckle - unfolded due to age

## Chest Wall

* follow pleura for signs of pneumothorax
** loss of lung markings in the periphery
** line of visceral pleura seen on expiration view
* pleural thickening
** ↑ width of white line along inside of ribcage, esp. near diaphragm
* costophrenic angles → pleural effusion
** small effusions (< 100 mL) may be only seen in the lateral view

## Diaphragms

* compare hemidiaphragms
** obscured → lower lobe pneumonia, pleural effusion
** flattened → hyperinflation, tension pneumothorax
** elevated → phrenic nerve paralysis, hepatomegaly
** air under diaphragms → perforated GI tract

## Lung Fields

* compare lung fields in the ICS on L vs. R, up vs. down

## Air Space Disease

* cardinal features:
** air bronchogram
** fluffy, patchy poorly marginated appearance
** lobar or segmental distribution
* ddx:
** pus (pneumonia)
** fluid (pulmonary edema)
** blood

## Interstitial Disease

* pathology involves the interlobular connective tissue
* cardial features:
** linear densities - Kerley B lines (< 2 cm long, 1 mm thick, reach lung edge)
** reticular pattern (thin, well defined linear densities, honeycomb arrangement)
** nodular pattern
* ddx: pulmonary edema, collagen disease (fibrosis), sarcoidosis, viral pneumonia

## Pulmonary Edema

* edema initially collects in the interstitium
** loss of definition of pulmonary vasculature
** peribronchial cuffing
*** bronchi seen end-on appear as white rings
* in CHF, the normally thin-walled bronchi become framed in interstitial fluid
** best seen in vicinity of hila
* Kerley B lines
* reticulonodular pattern
* thickening of interlobar fissures
* with progression, fluid begins to collect in the alveoli, causing diffuse air space disease (bat wing or butterfly pattern), tend to spare the intermost lung fields
* ddx: cardiogenic, renal failure

## Atelectasis

* cardinal signs:
** deviation of a fissure
** crowding of vessels
** hilar, mediastinum shift
* common causes: obstructive, compressive
* in absence of a known etiology, bronchogenic carcinoma must be ruled out

## Lymphadenopathy

* lymph node groups: paratracheal, hilar, aorto-pulmonary window, subcarinal
* hilar, AP window → widen mediastinum, flatten AP window contour
** lung cancer, lymphoma, sarcoidosis, and tuberculosis
* subcarinal - ↑ angle of tracheal bifurcation to 90°

## Abdomen

* liver size
* spleen size
* stomach (gastric bubble)
* colon (bowel gas)
- free air under diaphragm - pneumoperitoneum

## Misc
### CHF

* upper lobe redistribution of vessels
* Kerley B-lines (usually seen near diaphragm)
* right effusion at base
* perivascular cuffing
* pulmonary edema (interstitial, then airspace consolidation)
* venous engorgement
** normally extend 2/3 of the distance to periphery
** vessels seen to extend farther than normal

### Unilateral Left Sided Effusion

* trauma, infection, SLE, PE, malignancy

### Mediastinal Mass

* anterior mediastinum
** thyroid masses, thymomas, teratomas, lymphomas
* middle mediastinum
** lymphadenopathy, lymphoma, aortic aneurysm
* posterior mediastinum
** aneurysm of descending aorta, esophageal masses, hiatus hernia
* lateral view
** RVH
** effusion → accentuation of lines of major and minor fissures