CCP 212 Radiology ☢️ Flashcards
CCP approach to CXR interpretation
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- Patient Information
- Previous Imaging
- Technique
- Adequacy
- Heart
- Mediastinum
- Lungs and Lung Borders
- Soft Tissues
- Bones
- Lines and Tubes
ensuring CXR “adequacy”
definition and specific markers
- Before interpreting a chest X-ray it is important to assess the quality of the image
- Image quality influences your interpretation
The three items one must confirm to ensure a CXR image is “adequate” are:
- Penetration
- Rotation
- Inspiration
CXR “penetration” definition and anatomic markers
- Lower thoracic vertebral bodies should be visible through heart
- intervertebral discs of the mid-thoracic spine should be clearly visible
CXR “rotation” definition and anatomic markers
Spinous process should be centred between clavicular heads
The spinous processes of the thoracic vertebrae should be in the midline at the back of the chest. They should form a vertical line that lies equidistant from the medial ends of the clavicles, which are at the front of the chest.
Rotation of the patient will lead to off-setting of the spinous processes so they lie nearer one clavicle than the other
CXR “Inspiration”
Posterior 10th rib (or anterior 6th rib) at right cardiophrenic sulcus
Cardiothoracic Ratio
the ratio of maximal horizontal cardiac diameter to maximal horizontal thoracic diameter (inner edge of ribs/edge of pleura). A normal measurement is 0.42-0.50
- CT Ratio > 0.5 on PA View
- CT Ratio > 0.6 on AP View
Mediastinum definition and anatomic markers
Midline of the chest between the pleura of each lung and extends from sternum to the vertebral column
Widened mediastinum differential diagnoses
- Widening of vessels (dissection, for example)
2. Mass (tumor)
Silhouette Sign
Sign refers to pathological loss of a structure’s silhouette
i.e. Heart borders against the adjacent lung segments as seen with patchy lung infiltrates
Focal Airspace Disease
Increased Pulmonary Opacity
- Pneumonia, Atelectasis,
- Pulmonary embolism (i.e. infarct or hemorrhage)
- Neoplasm
Diffuse or Multi-Focal Airspace Disease
Increased Pulmonary Opacity
- Pulmonary edema (CHF or non-cardiogenic) → Central opacification with peripheral clearing (bat-wing)
- Pneumonia
- Hemorrhage (i.e. trauma, immunologic)
- Neoplasm
Fine Reticular Pattern
Increased Pulmonary Opacity
- Interstitial pulmonary edema
- Interstitial pneumonitis
Air bronchogram
air-filled bronchi (dark) being made visible by the opacification of surrounding alveoli (grey/white).
It is almost always caused by a pathologic airspace/alveolar process, in which something other than air fills the alveoli.
Radiographic Stages of CHF on CXR
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- Cephalization (redistribution)
- Interstitial Pulmonary Edema (interstitial edema)
- Airspace Pulmonary Edema (alveolar edema)
definition of “Cephalization” on CXR
Abnormal thickening of upper lung vascular markings relative to lower lung vasculature
also known as: “vascular re-distribution” or “upper lobe blood diversion”
Interstitial Pulmonary Edema findings on CXR
- Increased interstitial markings
- Pulmonary venous hypertension (upper zone hilar
venous distension)
Airspace Pulmonary Edema findings on CXR
Air space filling → diffuse or patchy distribution
“Bat-wing” central distribution is typical
Perihilar haze is early sign
Signs of Interstitial Edema on CXR
- Peri-bronchovascular connective tissue thickening
- Peri-bronchial cuffing
- Septal connective tissue thickening
- Kerley B Lines (thickened interlobular septae)
- Pronounced inter-lobar thickening
Peribronchial cuffing definition
- haziness or increased density around the walls of a bronchus or large bronchiole seen end-on
- sometimes described as a “doughnut sign”.
vascular re-distribution (CHF) definition
- blood vessels in the upper lung zones become larger than the ones in the lower lung zones (the inverse of normal..)
ARDS definition
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- Respiratory symptoms within 1 week of known clinical insult
- Bilateral opacities on chest imaging not explained by other pulmonary pathology
- Respiratory failure not explained by heart failure or volume overload
- Decreased P/F Ratio
Bones assessment in CXR interpretation
- Ribs
- Shoulders
- Vertebral column
Lines and Tubes assessment in CXR interpretation
- Endotracheal Tube
- Central Line
- Gastric Tube
- Chest Tube
- Pacemaker and Leads
Three basic views for cervical spine XR
- Lateral
- AP
- Open mouth (odontoid view)
approach to CT-Head interpretation
“ABBCS”
- Asymmetry
- Blood
- Brain
- CSF Spaces
- Skull and Scalp
FAST exam 4 areas
this is the “classic” FAST windows, not the updated/new school “eFAST”
- Peri-hepatic and hepato-renal space
- Peri-splenic
- Pelvis
- Pericardium
FAST Perihepatic Scan location
Probe placed in right mid to posterior axillary line at level of 11th and 12th ribs
FAST Perisplenic Scan location
Probe placed on left posterior axillary line between 10th and 11th ribs
FAST Pelvis Scan Technique
- Ultrasound probe in transverse plane, immediately above symphysis
pubis. - Starting at 0°, slowly sweep caudally to 30°.
- Demonstrate the bladder.
- Optional: Rotate probe 90° so beam in sagittal plane to provide another view of bladder, rectum, rectovesicular pouch.
FAST Pericardial Scan Technique
SUBCOSTAL VIEW
- Ultrasound probe placed in coronal plane, in subxiphoid region of chest.
- Place moderate pressure on abdominal wall, perform AP sweep until heart visualized.
- Sweep through heart slowly, from anterior to posterior until heart disappears at each
extreme.
coronal/frontal plane
plane dividing the body into dorsal and ventral parts.
axial/transverse plane
plane that divides the body into superior and inferior parts
saggital/longitudinal plane
anatomical plane which divides the body into right and left parts.
anechoic
black
hypoechoic
dark
hyperechoic
bright
ETT Height should be ‘x’ above carina?
- 5cm above carina.
2. This allows for head flexion and extension without “pushing” the tube into the R bronchus.
NG versus OG tube on CXR
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NG tube appears larger because it has two radiopaque line that create the illusion of a bigger structure
Silhouette sign
Blurring of the interface between structures on CXR
right heart border on CXR
right atrium
left heart border on CXR
LA and LV
LA top 1/4, LV bottom 3/4
Air bronchograms can be described as
A region of bronchiole that is surrounded by increased opacity, highlighting the air-filled bronchiole.
The 3 radiographic stages of CHF are:
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- Stage 1 = Cephalization (thickening of upper lung vascular markings relative to lower lung vasculature)
- Stage 2 = Interstitial Pulmonary Edema (increased interstitial markings + pulmonary venous HTN)
- Stage 3 = Airspace Pulmonary edema (air space filling with diffuse and patchy distribution; “bat wing”)
Non-central distribution patterns of pulmonary edema on CXR can usually be attributed to:
Non-cardiogenic causes of pulmonary edema (ie. negative pressure from choking/laryngospasm, ARDS, etc).
The two main indications for abdominal XR are:
- Perforation
2. Obstruction
Free air under the diaphragm indicates ____.
Perforation.
Air should always be contained within the bowel.
Free air in the abdomen post-surgery (from CO2 injection) may last for up to __ days.
10 days.
Free air should not be increasing over serial abdominal XRs.
Rigler’s sign
Visible bowel wall from air on both sides of the bowel wall
Large bowel vs small bowel identification on XR
Large bowel = Presence of haustra.
Small bowel = Presence of valvulae conniventes.
Haustra
Sac-like pockets that make up the large bowel.
Mucous folds DO NOT cross the full width of the large bowel.
Valvulae conniventes
Mucousal folds of the small bowel.
They cross the full width of the small bowel on abdominal XR.
“Free ABDO” acronym for abdominal XR interpretation
Free air Air Bowel wall Density Organs
The “ABCS” of cervical spine XR
Alignment
Bone
Cartilage
Soft tissue
Cervical XR Odontoid view is used for:
Visualization of C1 and C2
through open mouth
When assessing alignment on cervical spine XR, identify these four lines:
- Anterior vertebral line.
- Posterior vertebral line.
- Spinolaminar line.
- Posterior spinous line (curved).
The “ABBCSS” of CT head
- Asymmetry
- Blood
- Brain
- CSF
- Skull
- Scalp
Subdural hematoma generalized CT features
- typically unilateral
- crescent distribution around the periphery
- not limited by sutures
- fill dural reflections (falx cerebri, tentorium)
Epidural hematoma CT (aka Extradural hematoma) features:
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- bi-convex (or lentiform) in shape (this means convex on both sides. curving or bulging outward)
- beneath the squamous part of the temporal bone
- EDHs are hyperdense, somewhat heterogeneous, and sharply demarcated
SAH CT features:
- Diffuse blood across subarachnoid space
- blood within the cisterns and sulci
- May blunt the appearance of the cerebral peduncles
- May present with obstructive hydrocephalus.
intra parenchymal hemmorhage CT features:
Focal opacity in haemorrhage location of parenchyma
DAI findings on CT
Loss of grey/white differentiation
Hypoechoic appearance on ultrasound
- Dark (poor echogenicity)
2. example: blood/fluid
anechoic appearance on ultrasound
- black (no echogenicity)
2. example: blood/fluid
hyperechoic appearance on ultrasound
- white (high echogenicity)
2. example: bone
Describe “acoustic shadowing” on ultrasound
- occurs when a dense structure produces a shadow behind it
Describe “acoustic enhancement” on ultrasound
Sound bounces between the proximal and distal walls of a cyst or fluid-filled space.
Produces a brighter image on the distal wall of tissue.
Describe mirror image artifact on ultrasound
- A mirror image is reflected on the opposite side of a dense structure
- This occurs in images that have air on the distal side of a dense structure (ie. bladder)
Linear probe is best for assessing
Shallow structures
Phased array or curvilinear probes are best for assessing
Deeper structures (ie. IVC or organs)
“Optimizing” an U/S image
Centring the image in the screen, adjusting the gain, adjusting the depth
Explain what “Spine sign” is
Being able to see the spine through a fluid-filled space
abnormal finding when assessing the lung bases, because air will reflect reverberation, rather than producing spine imaging
BART mnemonic (ultrasound)
“Blue away, red towards”
Mnemonic for doppler imaging
ONSD ultrasound depth target
3mm behind the optic disk
This ensures the area is undistorted by the optic disk
Why is ONSD a reliable surrogate for ICP?
only area outside the cranium that is subject to the same pressure that ICP elicits
The ONS is continuous with the subarachnoid space
Ultrasound guided ONSD evaluation for ICP contraindications
- Depressed skull fracture
- Globe trauma
- Hydrocephalus
IVC collapsibility index equation
( [IVC max - IVC min] / IVC max ) x 100
Classic case COPD features found on CXR
- Radiolucent and hyperinflated lungs
- Flat diaphragms
- Narrow heart shadow
- Increased anteroposterior chest diameter seen on lateral X-ray
5 major densities seen on CXR
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- Black (gas)
- Dark-grey (fat)
- Light-grey (soft tissue/fluid)
- Nearly-white (bone/calcification)
- White (metal)
mediastinum measurement PA vs AP
normal range for mediastinum
- 6cm PA
- 8cm AP
deep sulcus sign on CXR is indicative of….
pneumothorax
direction of flow in doppler ultrasound
B - Blue
A - Away
R - Red
T - Towards
ACUTE subdural bleed CT image characteristics
- typically unilateral
- hyperdense crescent distribution around the periphery
- central hypodensity represents active bleeding
- acute bleed mixed with CSF may appear less dense
- density is variable in coagulopathic patients, e.g. warfarinised
SUB-ACUTE subdural bleed CT image characteristics
- over the first couple of weeks, the blood is broken down
- density approaches that of the brain
- may be tricky to see
CHRONIC subdural bleed CT image characteristics
- over time, the hematoma approaches CSF density
aortic knob (aka aortic knuckle) definition and anatomic markers
- distal aortic arch as it curves posterolaterally to continue as the descending thoracic aorta
- It appears as a laterally-projecting bulge, as the medial aspect of the aorta cannot be seen separate from the mediastinum
- It forms the superior border of the left cardiomediastinal contour