Thorax Flashcards
What phase of respiration is this and why?
Mid - Inspiration
Lateral radiograph, the location that the vertebrae the dorsal crus of the diaphragm intersect is > T10.
T11 - T12 intersection.
(Full inspiration is T13-L1)
Why is a systematic approach used to read radiographs?
To improve efficiency and accuracy.
When can conclusions be drawn when reading radiographs?
After the image has been FULLY evaluated.
- From the radiograph
- From clinical context, diagnostics and other info.
List 3 aspects of Step 1.
a) Identify the patient, date taken, labelling.
b) Document region and views.
c) Assess adequacy; routine study, number of views.
List 4 questions in Step 2 - Radiograph Quality Control.
a) Film quality:
exposure, artefacts, contrast, detail.
b) Diagnostic adequacy.
Centreing, patient positioning, collimation, beam angles, phase of respiration.
c) Is the study of diagnostic quality?
d) Are there risks in reading this tudy?
Step 3. Systemic Examination of included anatomy.
All included structures,
All parts of the structure
All normal signs
Is this a left or right thoracic lateral? Why?
Right lateral.
Heart is more oval shaped than in the left lateral.
Trachea drops slightly ventral near base of heart.
Diaphragm and lung shadow more parallel.
Is this a left or a right thoracic lateral? Why?
Left.
Heart is more parallelorgram / square shaped.
Trachea is straight.
Crus aren’t parallel.
Describe the (3) features of ALL fractures on a radiograph.
A radiolucent line, a step in the cortex and a space.
What parameters are used to determine if arteries and veins are normal in size?
Size:
- Arteries and veins = in size
- Lateral: 3/4 the size of the 4th rib
- VD: < the width of the 9th rib
Shape, margins and opacity
- Branching, tapering and get thinner towards the end
- Uniform soft tissue opacity
- Smooth sharp margins
Normal Position
- Veins: ventral and central
What is the minimum number of views required for a thoracic radiograph?
3.
Dorsoventral or Ventrodorsal
Left lateral-medial
Right lateral-medial
At what phase of inspiration should a thoracic radiograph be taken?
Full inspiration.
What is the ideal contrast for a thoracic radiograph?
The ribs should not stand out against the heart.
Usu. high kpV = low contrast.
If want to look for fractures do a second radiograph with lower kpV.
Outline the features for correct collimation and central ray position for a VD or DV of the thoracic cavity.
Centre beam position: centre beam midline over sternum at caudal aspect of scapula.
Lateral collimation: to edge of ribcage.
Cranial collimation: to thoracic inlet.
Caudal collimation: to two finger widths passed the xiphoid process.
Collimation:
- all lung lobes
- inc. cranial lobe and caudodorsal lung tips
Is this inspiration or expiration? Why?
Inspiration.
- Diaphragm further caudal and straight
- Angle of diaphragm at thoracic spine are wide dorsally and caudal to T12
- Lungs expanded:
- Large retrosternal lucency (right cranial lung lobe)
- Large dorsal lung area
- Area of accessory lung lobe is large and CVC
What phase of respiration is this? Why?
Inspiration
- Wider thorax
- Cupola - dome, peaked, narrow and caudal to T8
- Diaphragm angles wide and caudal 10th rib
- Lungs lucent
- Heart disinct.
What phase of respiration is this? Why?
Expiration
- Heart appears large relative to area of thorax
- Small volume of lungs
- Kinked CVC
Name 3 ddx for the appearance of the lungs in this radiograph.
Is this inspiration or expiration?
Expiration. NOTE: small volume of lungs, heart appears large compared to thorax, kinked CVC.
DDx:
- Fat thorax
- Abdominal pressure on diaphragm (heavily pregnant, severe ascites can make inspiration look like expiration).
- Underinflation due to airway disease
Name 2 aspects that should be aligned in a thoracic VD?
- Thoracic inlet and xiphoid should be inline with each other.
- Sternum should be directly over the spine.
NOTE: Sand bags and V-trough can be used to achieve this.
How should the patient be positioned for a lateral thorax?
Sternum and spine should be parallel to each other.
Do NOT put foam wedges under area of interest.
How should the centre beam be positioned in a lateral thorax?
Spine and sternum should be parallel.
Centre beam position: centre beam midline thorax at caudal aspect of scapula.
Venteral Collimation: to include sternum.
Dorsal Collimation: to include vertebral bodies.
Cranial Collimation: to thoracic inlet.
Caudal Collimation: to where last rib inserts at the spine.
Which radiographic view is usually best to assess the fundus on?
Abdominal - Right lateral.
(Gas in the fundus, fluid in the pylorus)
What can an underexposed thoracic radiograph mimic?
Lung disease
Pleural disease.
What can an overexposed thoracic radiograph mimic?
Pneumothorax
Emphysema
Bullae
In an overweight patient, what are some changes that can be seen on radiographs regarding the body walls and intrathoracic cavity?
Thickened body wall:
- increased soft tissue opacity over thorax (mimics lung disease as lungs are more radiopaque)
- decreased ventilation capacity and reduced lung volume
Intrathoracic fat accumulation:
- wide mediastinum - mimic mass
- mimic cardiomegaly
What are four ddx for mediastinal shift?
- Displacement
- dependency atelectasis
- adhesions
- loss of lung volume disease
Name four radiographic signs of mediastinal shift.
Heart shifted to thoracic wall
Diaphragm cranially displaced
Thorax NOT rotated
Decreased volume of hemithorax
(Can only move to wall by either stuff missing in the chest or pushed over by a mass)
List three changes to a thoracic radiograph with severe mediastinal shift to the right.
Right diaphragm is flat and cranially positioned.
The right lung volume is decreased
Marked increase in soft tissue opacity and reduction in gas opacity within the affected lungs.
What are the four radiographic signs of megaoesophagus?
- Tracheal stripe sign
- accentuation longus colli muscle dorsally
- +/- aspiration pneumonia
- Thin soft tissue lines to diaphragm (walls)
- +/- ventral tracheal position
What is the normal size of the pumonary vessels on lateral and VD?
Lateral: ¾ the width of T4
VD: same wide as rib at T9
