Exam 1 Flashcards
Interpretative terms for various diagnostic Imaging modalities
Opacity
Anechoic
Hypoechoic
Hyperechoic
Sonolucent
Echogenic
Radiopharmaceutical uptake “uptake”
Attenuation
Signal intensity
Hyperintense
Hypointense
Isointense
Opacity:
relates to the amount of attenuation or x-ray absorption by the object. Attenuation causes an opaque area (bright or white) on a radiograph because absorbed photons do not reach the image plate. Depending on the ability of the object to absorb photons, various opacities can be distinguished.
-Air
-Fat
-Water (soft tissue)
-Bone
-Metal
Anechoic:
Black/dark, no echoes are returned to transducer
Hypoechoic:
Darker than surrounding or comparative structure (relative term)
Hyperechoic:
Brighter than surrounding or comparative structures (relative term)
Sonolucent:
General term for tissue that transmits sound to deeper structures
Echogenic:
General term for a tissue that reflects sound back to transducer. “Spleen has three hypoechoic nodules, and it is surrounded by anechoic fluid”
Radiopharmaceutical uptake “uptake” (Scintigraphy)
It can be decreased or increased compared to the expected normal. Areas of increased uptake are also called “hot” vs. “cold” terms usually kept out of reports.
Computed Tomography (CT)
Attenuation: it is a description of x-ray absorption rather than opacity or “density”
Hypoattenuation: decreased x-ray absorption compared to adjacent area. Dark, many photons reach the detector.
Hyperattenuation: Areas are bright, increased x-ray absorption. Few photons reach the detector.
MRI
Signal intensity: is the primary term used to describe the appearance of MR images
Hyperintense: implies an increased radio frequency signal that is returned from the tissues. Areas are bright
Hypointense: implies a decreased radio frequency signal is returned from the tissues. Areas are dark.
Isointense: implies two structures have the same signal intensity.
**Don’t use the term density to describe x-ray images”
How many views are the standard?
Why do we need three views of the thorax?
Three views
No excuse
15% of lesions will be missed if only one lateral view is made
Three views of the thorax because the lung on the lateral recumbency that is on the plate loses 50% of its volume. So it is under inflated.
Other views: ventrodorsal projection, right lateral projection, and left lateral projection.
Gravity causes the up areas to compress and remove the air of the bottom areas
-It is hard to separate the anatomy on the Hilum area from just one view.
-For example: case of labrador retriever with a splenic mass. The VD view shows the the soft tissue mass in the right lung. The right lateral view (against the plate, lung under inflated) shows the mass more dorsally oriented (radiopaque with the deflated lung), compared to the LEFT LATERAL view where the mass in BEST seen, radiolucent more contrast with the lung away from the plate.
How are right and left lateral views presented to the viewer?
They are both oriented with the head of the animal toward the left of the reader’s view.
-It is really important to flip it before the image is finalized.
VD and DV views Which one is better? does it matter?
Humanoid keeps scapula out of the lung field.
Regular VD is better
It does not matter as long positioning is good.
What are some common positioning errors ?
- Centering on diaphragm
- Elbow and triceps superimposed on thorax laterals
- Dropped sternum on laterals
- Axial rotation on ventrodorsal
How is the thorax approach divided?
Compartments
Lung
1. Interstitial
2. Alveolar
3. Bronchial
4. Vascular (also discuss with the heart)
Thoracic wall
Mediastinum
Pleural Space
Exposures for Digital Equipment
-Digital exposures are unique for each body/tissue
- kVp and mAs.
-Abdomen: kVp lower, mAs higher than thorax.
-Thorax: kVp higher, mAs lower than abdomen.
-Bone: kVp lower than abdomen and thorax, mAs higher than abdomen and thorax.
Exposure during Inspiration, when do we want to take a view? Why?
We only want to take a view during PEAK INSPIRATION
Variation between inspiration and expiration can cause alveolar pattern (false).
What are some aspects that affect normal appearance?
What is typical of the diaphragm on a left lateral view?
-Breed and species: big chested dogs more difficult to interpret
-BCS: fat makes it more challenging to see soft tissue
-Technique
-Expiration vs. Inspiration
-Interpreter bias
Left lateral view
-Diaphragm has a wide shape in dog.
-Aorta
-carina
-Trachea
-Caudal vena cava
-Left Cr. lobe vessels (shifted dorsally since it is a left lateral)
-Right Cr. lobe
-Xyphoid
-Caudal vena cava
-Cupula (dome)
-Diaphragm in cats has three humps (DV)
-Main stem bronchi
-Trachea better seen in lateral vies
-Cranial mediastinum
-Caudal lobar vessels easier to see in DV view than lateral view.
What are the anatomic names of the lung lobes? can you spot them on an image?
What is the Pattern approach interpretation?
Right lung is the largest
Trachea comes down and bifurcates at the Corina
-Left Cranial, Cranial lobe
-Left Cranial, caudal lobe
-Left Caudal lobe
-Right Cranial lobe
-Right Medial lobe
-Right Caudal lobe
-Accessory lobe: overlaps right middle and part of the right caudals.
Pattern approach: it encourages a systematic approach, use a checklist when you read. It assumes most diseases often affect a single compartment (wrong, limitation). Rule outs constructed for changes in each compartment. It helps prevent overlooking lesions. Can help ranked differentials.
-Mediastinum
-Pleural
-Alveolar
-Interstitial
-Vascular
-Bronchial
-Thoracic wall
Visual perception: fine detail is limited to a 2 cm circle. Need to look at the edges. VFR sweeps
Scan a radiograph completely before calling it normal
Bronchial compartment, what does it consist of?
-Lobar bronchi and bronchioles
-Normal bronchial components are not well seen in normalcy
-Bronchial markings are seen on radiographs as:
Ring and tramlines (pair lines shadows)
Increased rings and tramlines = “bronchial pattern” means that it is increased in marking.
-Bronchial wall in very thin
-Normal bronchial walls are thin shadows between lobar vessels and the bronchial lumen.
-As animal ages they become mineralized.
-Always read/interpret in context, metastasize check then it is different than just aging, or if animal is coughing
What do you usually see in a Bronchial pattern radiograph?
- Increased ring shadows
-Walls are thickened “doughnuts”
-They are too thick and too numerous to be normal
Lungs are really busy, not black DSH
Always look at the edges of the radiograph
-It is not easy to pick up bronchial patterns on a VD view.
-Bronchi can also dilate, not tapering. = BRONCHIECTASIS, predisposes to pneumonia.
What does bronchi mineralization look like? what is it similar too but often mistakenly diagnosed?
-Bronchial walls and bronchial glands may become mineralized a benign change that may be confused with cancer, metastasize.
Alveolar Compartment: the most difficult
do we normally see it?
What is the black areas normally seen?
What does it look like when diseased?
What does atelectasis refer to?
-They are not normally seen on radiographs
-Sponge, air spaces nor seen, the interstitial space is what is seen, everything else is microscopic.
-End air spaces are black normally
-The artery or vein is on either side of a bronchus, but appear white on a radiograph.
-Diseased alveoli looks opaque cells. The sponge absorbs fluid = “Fluid opacity”
Terms
-Atelectasis (same as collapse in this course): decreased inflation, less than at expiration, but still some air left in bronchial tree.
-Collapse: same as atelectasis
-Consolidation: normal volume or near to normal volume, alveoli, and bronchial tree filled with fluid or cells.
What are the three alveolar patterns?
- Air bronchogram: “air bronchiogram sign”
-Ex pneumonia, fluid filled clouds make the bronchi visible/contrast where they would otherwise be black. - Lobar opacity: “lobar sign”
- Focal intense opacity: usually center of lung
- Lobar opacity: “lobar sign” Consolidation & Atelectasis (collapse)
- Focal intense opacity: usually center of lung
-Normal lung contrast diseased lung.
-Due to segmentation of lung (lobation)
-Will not see it on horses or humans
Consolidation: also gives a Lobar sign. Animals not responding to tx.
Consolidation: small airways and alveoli filled radiopaque fluid or cells. Not air bronchogram, normal or decreased volume.
Atelectasis: little or no air in alveoli, LOBAR SIGN with LOW VOLUME. Common with COPD (disease in cats and dogs). The alveoli and bronchioles are flattened, small airways collapse, reduced lung volume. Can also cause an air bronchogram sign.
Labrador hit by a car: collapse due to tension pneumothorax.
What are the main differences between consolidation and atelectasis?
-Consolidation normal to near normal volume. No air bronchograms, alveoli and bronchioles filled with fluid or cells.
-Atelectasis: decreased volume, alveoli and bronchioles compressed but little to no fluid. air bronchograms if mild collapse, none if severe.
What are causes of alveolar pattern?
Pulmonary effacement, is it common, what is it?
- Pneumonia, bacterial, mycotic, aspiration
- Edema
- Hemorrhage/contusion
- Pneumothorax
- Lobbar torsion
- Neoplasia
Must be interpreted in the context of clinical presentation and signalment*
Pulmonary effacement
-Not common
-Usually early lesion, not bronchograms sign yet, but some disease present.
The pulmonary interstitium
The interstitial is the stroma or scaffolding of the lung. An interstitial pattern is ALWAYS present
Only see three things
1. Bronchioles: within interstitium
2. Air
3. Macroscopic blood and vessels.
False increased pulmonary interstitial pattern
-Due to under inflation: the most common false pattern
-Interstitial structures are surrounded by less air.
-Lateral views have more interstitial markings than ventrodorsal views
-Lungs look worse because of superimposition of both lungs.
What causes true unstructured interstitial pattern?
-Microscopic opacities scatter the x-ray beam
-Hazy and smudge image because the fluid or cells within the interstitial space
-Unsharp markings of normal structures
-similar to headlights in fog.
-Sometimes before disease progresses to pneumonia and presents alveolar pattern.
Structured More important to recognize than unstructured, peri bronchial markings.
Structured Interstitial Patterns
-Nodular and mass lesions
-Peri bronchial markings: discussed under bronchial patterns.
Nodular interstitial lesions
- Solid: soft tissue or mineral/bone: the most common type. Bullae or cyst
- Cavitary: Gas filled, Gas filled and fluid filled.
Must be at least 4-5 mm for detection
-air filled - black, with thin radiopaque wall. Thick wall if fluid filled and air.
Example: cystic areas in the lung from parasites such as Paragonimiasis. End on vessel: Dirofilariasis.
Prime differentials of nodular disease
-Neoplasia: metastatic most common. Primary: can be benign lesions. Coalescing nodules.
-Mycosis: Blastomycosis (can look like bacterial pneumonia), Histoplasmosis (thoracic nodules, nodules).
Appendix
Positioning: what are the common mistakes? what are the landmarks? what is dropped sternum?
-Center the thorax, not the diaphragm
-Landmarks: Manubrium/1st pair rib
-Last rib
-Thorax and abdomen combined are of no advantage, decrease image quality.
-Superimposition of triceps musculature: dependent limb in beam
-Dropped sternum: spine not aligned, sternum out of image., causes lack of visualization of all lungs.
-Oblique positions: limit assessment of lungs and shape of the heart. Spinous processes are tipped to right or left which causes the sternum to be tipped to the opposite side of midline.
-Overexposure/underexposure.
Lung Cases
- Chronic case of coughing Labrador retriever
-Several round structures that look like donuts.
-Too busy area.
-Bronchitis is not a radiographic diagnosis
-Increased mucus is not seen in radiographs. - siamese with coughing episodes (very common)
-Lots of rain shadows
-Looks like strictly in lung compartment not interstitium
-Numerous lines and rings.
-Bronchoconstriction makes it hard for cat to get the air out
-FLAD: feline lower airway disease NOT ASTHMA term
Radiographic changes:
-From none to severe
-Hyperinflation = bronchoconstriction
-Bronchial pattern = relapsing insults
-Cor pulmonale = pulmonary hypertension
-Collapsed right middle lobe = increased intrathoracic pressure
-Emphysema = increased end airspace pressure
-It can be acute or chronic
-Chronic: hazy
-Hard to tell in a radiograph, need CT
-Cats have more lung capacity than dogs.
-Heart is more horizontal
-Spinous process larger than dogs’
-Tenting of the diaphragm normal during peak inspiration (pic).
What often occurs in cats with FLAD? hint: right middle lobe
What is the substitute term for bronchitis? what does it include?
-Due to increased intrathoracic pressure and or bronchiolar obstruction = Atelectic.
-They tend to not get better, can go on, just lose one lobe.
Small Airway Disease
-Includes bronchioles, terminal bronchioles and alveolar ducts.
-Interstitium also involved
-Only see bronchi and 1st-3rd order bronchioles on most radiographs.
-Flattened diaphragm means struggling to get rid of air.
Case 3 of 3 y. o. mixed breed dog with fever and coughing
Always make a thorough work up
Case 4 young labrador, owner stepped on thorax, now dysgenic and coughing blood.
-tip probably turned during trauma.
-Alveolar bleed from vascular damage
-Hospitalize and put on oxygen
Aelurostrongylus spp. in cat
MIXED PATTERN
Most common lung worm of cats
Cat with Cough and Eosinophili in Dog this pic
Nodule progresses to cystic lesion = gas filled
Parasitic Paragonimus spp.
-Trematodes develop in terminal bronchioles and alveolar ducts - eggs = intense inflammation
-Nodules earl, cavitary lesions (cysts) late.
-right lung preferred, probably due to bigger and more blood flow, at risk for pneumothorax.
Example of left lateral vs. right lateral thoracic view
Fake out End on Vessels, confused with metastasis
Blastomyces spores = military interstitial pattern
How to rule out metastasis?
Usually peripherally to the heart
Most metastatic nodules do not invade airways, so no coughing until late.
Metastasis
-Three views with good expansion
-Don’t attempt if patient is anesthetized
-Look peripherally for nodules larger than corresponding vessels
-Understand that nodules need to be at least 4-5 mm diameter to be seen on good quality images.
Lung tumor case
-Lobectomy good tx
-Right middle lobe removal
Thorax, Mediastinum, Esophagus
Lectures 10-11
The mediastinum
What can you see or not in a radiograph?
What are the four mediastinal reflections?
What is the anatomy of each?
-Separates the two pleural sacs and lungs
-It is fenestrated, thus pleural sacs communicate, which is important for pleural space topic.
-A few mm of space in the pleural space.
-Other communications: cervical fascial planes, retroperitoneal space, peritoneal cavity.
-The mediastinum is a reflection of the parietal pleura and the structures between.
-When bronchus come out of the trachea, there is a small space, important for pathology.
What you can see
-Fat
-Trachea
-Thymus
-Heart
-Esophagus
Plus What is present
-Principal Bronchi
-Nerves: vagus, phrenic, sympathetic trunk.
-Vena cava and aorta
-Thoracic duct
Mediastinal reflections
- Craniodorsal
- Cranioventral
- Caudoventral
- Vena caval reflection a.k.a plica vena cava (not seen in radiographs)
- Cranial mediastinum: has two reflections
CT image: sternal nodes if enlarged would be seen at area of red arrow
In radiographs: in large breeds deep chest we see reflection of mediastinum (sometimes). They are never straight. The reflection wraps around lungs. Appearance of cranioventral reflection varies with breed and body score.
-When the thymus is present “sail shape” on VD radiographs.
-the dorsal reflection often superimposes on the ventral impression.
The middle mediastinum surrounds the heart
- Caudal mediastinum: is complex and has 2 reflections
-Accessory lung lobe takes the spot in the center where the heart was on the last reflection
-Esophageal problem sometimes.
Caudo phrenic ligament, many terms for it. Can not be seen radiographically
Mediastenium on CT scan with
Not much pathology, except some problems if related to accessory lung lobe.
When it is displaced it may be a sign of pathology
What are the three main causes for Pneumomediastinum ?
- Retrogade leak from broncho alveolar rupture (from blunt thoracic trauma or Iatrogenic hyperinflation)
- Caudal extension from neck: cervical trauma
- Tracheal leak: E-tube over inflation, trauma especially cat.
Case Mediastinal air contrast structures not usually seen
Pneumothorax won’t give pneumomediastanium, but pneumomediastinum can give a pneumothorax.
-Trachea wall visible as in a thin line
-Aorta
-Caudal vena cava
What can cause a mediastinum shift right or left of midline?
- Unilateral underinflation
- Unilateral overinflation
- Pulmonary mass
What does general anesthesia cause within 2 minutes of induction?
What causes a mimic of mediastinal shift?
What is a common origin of mediastinal masses?
Case Golden Retriever with Lymphoma. FNA = lymphoma
-Causes pseudo-alveolar lesions
-Less air = less contrast of parenchymal lesions
-Hypoinflation
-Gravity
Will miss nodules and small airway changes.
Pitfall
-Oblique position instead of straight VD view can micmic mediastinal shift.
Mediastinal masses
-A mass would move tissues, bronchi, vessels. If they are the same size then vessel need CT or take another at 3 weeks bc can’t tell right away.
-Lymph nodes
-Thymus
-Heart base
-Esophagus
-Cyst (cats)
-Aberrant thyroid tissue (cats)
- Thoracic lymph nodes:
a. Sternal
b. Tracheobronchial (thorax)
c. Craniomediastinal (thorax, cervical).
Main Ddx for thoracic lymphadenopathy
-Neoplasia (metastatic, lymphoma)
-Mycotic infection
CT accessory lobe
Accessory lobe mass Ddx
-Tumor
-Granuloma
-Torsion (pleural effusion)
-a lesion in the accessory lobe can mimic a mediastinal mass
-Accessory globe lies within a recess between place vena cava and mediastinal pleura of left pleural space
Mediastinal mass vs. pulmonary mass
Congenital vs. aging mass in cat pics
- Pulmonary mass usually surrounded by air, not mediastinal mass
- Mediastinal mass is on midline or in a reflection
Can use ultrasound to rule out/in
Esophagus
Anatomy
Motility disorders
Foreign bodies
Hernias
Tumors
Fluoroscopy is expensive, highly radioactive, “static contrasts”
Esophagram: full strength commercial barium suspension (contraindicated if perforation present)
-Immediate VD and Lateral radiographs.
-Rule out motility disorder
-Identify obstruction or stricture
-Define a suspected mediastinal mass
-I do not have an endoscope
-Dx for megaesophagus, radiopaque foreign body
-Perforation, can lead to barium mediastinitis and granuloma
-Sedatives (inhibit motility)
-Barium aspiration: cough, mucociliary action, lymphatic drainage. Will cough for a long time, but likely to recover.
Normal vs. dilated esophagus
What are the common sites of esophageal foreign bodies?
- Thoracic inlet
- Heart base
- Esophageal hiatus
Aspiration pneumonia
Esophagitis: can get better
Megaesophagus
PRAA
Brachicephalic breeds and heart based tumors, need CT scan
Heart Base tumors
Pleural space principles and cases
too much fluid or too much gas
Anatomy
-Parietal pleura: Stoma allows drainage of lymphatic
-viceral pleura
Intrapleural pressure is negative to prevent the lungs from collapsing
1. Continous strong drainage lymphatic allows negative pressure to form
2. Mechanical coupling -5mmHg
-Surfactant will keep alveoli from collapsing
**Normally not see pleura and pleura cavity/fluid unless >25 lb dog need ~100 ml Lesser amounts seen in ultrasound. **
Chronic respiratory diseases = fissure lines, pleural scars
Abnormal fissures, fluid lines wider at hilum than periphery, not set with scars
-VD view best
-Fake outs, mineralization, scapular shadows, skin folds.
Costal cartilages miniralization
What can happen to the pleura and pleural space?
- Abnormal fluid accumulation
- Scarring
- Air accumulation: pneumothorax
- Masses
- Diaphragmatic hernia
All effusions look the same
-Usually bilateral, occasionally unilateral or asymmetric
-Hydrothorax, Chylothorax, hemathorax, pyothorax.
What are the most common causes of pleural effusions?
- Congestive heart failure
- Neoplasia: blocked stroma
- Trauma
- Chylothorax
- Hypoproteinemia
What are the three pleural effusion -Roentgen Signs?
- Wide interloper fissures: fluid between adjacent lobes (red arrows) “fissure lines”
- Retraction of lung surface from neural surface of thoracic wall: fluid between parietal and visceral pleura (yellow arrows)
- Retrosternal opacification next card
Example of moderate pleural effusion
Retrosternal opacification
Fluid pooled on the ventral abdomen “Draping” of ventral lung margin
Additional Roentgen signs of pleural effusion
Chronic pleural effusion
Decreased visualization of cardiac silhouette
Obscured diaphragmatic outline
Blunting of costrophrenic sulci.
Additional imaging with pleural effusion, Ultrasound
Ultrasound is helpful
-More sensitive than radiography
-Can identify masses obscured by fluid. Anechoic areas
-Can nor determine type of effusion
CT
-Also helpful identify obscured lesions
-More topography than u/s this better for surgical planning
Notes about Pleural Effusion
-All effusions look the same
-Thoracocentesis and cytological examination needed for diagnosis
-Ultrasound good: however thoracic u/s technically difficult. Can find masses, thickened pleura. Helpful for FNA
-CT better
Pleura Space Cases Let 13
5 yr DSH Cat
-Dyspnea
-Distented Abdomen
-Occasional vomiting, diarrhea
-Hematology unremarkable, except for low albumin (1.2 g/dl)
Findings
-Bilateral pleural effusion, moderate or chronic?
-Peritoneal effusion
-Increased bowel gas.
-Aerophagia: swallowing of air
DDx
-Protein losing enteropathy, renal protein loss, liver disease.
-Heart failure
-Disseminated neoplasia
Further tests
-Thoracocentesis = transudate
-Cytologic
-Abdominal/thoracic ultrasound = thick small intestines, prominent mesenteric lymph nodes.
Differentials
-Inflammatory bowel disease (IBD), lymphoma
Ultrasound case 1
IBD
Case 3 6 yr, Retriever, hunting dog
-Mild dyspnea
-Malaise
-Muffled lung and heart sounds
-Low grade fever
-Inflammatory leukogram
Pleural effusion
-Thorocacentesis: Tomato soup exudate, mixed inflammatory cells with Rod bacteria: E. coli (cultured)
-Phyothorax: pus in the pleural cavity, also called empyema.
-Common causes: Thoracic trauma, bite wound in cats, Grass awn inhalation: migrate along the bronchial tree to pleural space.
-Scalloping of ventral lung margins
-Retrosternal opacification
-Obscured diaphragm
Case 4
4 yr old mixed breed dog that fell out of pickup truck.
-Dyspnea
-Muffled heart sounds
Findings
-Bilateral pneumothorax
-Moderately severe, probably developing tension pneumothorax
-VD not as helpful as lateral views
-DV more convincing
-Intensive care for monitoring and tx for shock
Case 5, 2 year old DSH cat, fell from a treee
-Dyspnea
-Muffled heart and lung sounds
Findings:
-Effacement of heart
-Loss of normal diaphragmatic contour
-Pleural fissures right hemithorax
-Loss of right diaphragmatic crus
-Mediastinal shift to left
-Wide right 5th intercostal space
Diagnosis
-Diaphragmatic hernia
-Ultrasound performed, right side of liver in right pleural cavity.
Case 6, 6 yr old Bassett, “heavy breathing”
FAKE OUT: false pleural effusion of Bassett hound.
S-like confirmation = “double shadow”
Notes about Pleural Effusion
-All effusions look the same
-Thoracocentesis and cytological examination useful adjuncts to diagnosis
-Ultrasound good, thoracic technically difficult, can find masses, thickened pleura, helpful for biopsy or FNA.
-CT better
