4/3/2015

1

Interpretation of

Thoracic Radiographs:

A Cardiologist’s

Perspective

Michelle Rose, DVM, DACVIM

(Cardiology)

Overview

• Radiographic anatomy of the heart and great vessels

• Clinical pearls and common pitfalls

• Radiographic examples of various cardiopulmonary diseases

Radiography of the Heart

• Radiographs reflect the response of the heart and blood vessels to the hemodynamic abnormalities that are present. (They usually do not show the heart defect itself.)

– Mild disease: Usually no radiographic changes.

– Moderate: ± radiographic changes.

– Severe: Radiographs are most helpful here. Look for the expected chamber enlargement(s) and great vessel dilation.

Positioning

1. Entire bony thorax on radiograph.

2. Front legs pulled forward.

3. Caudal outline of diaphragm included.

4. On DVs and VDs, thoracic spine superimposed over sternum.

• Centered over 5th-6th ICS

Positioning

5. On laterals, the costochondral junctions of both sides should overlap. Ribs should not extend above the spine.

6. Peak inspiration.

7. Consistency with the same patient.

Anatomy – Lateral View

4/3/2015

2

Summary – Lateral View

• Bulge in cranial waist of the ♥ silhouette:

– Ascending Ao, MPA, RA ↑

• Bulge in caudal waist of the ♥ silhouette:

– LA ↑

• Dorsal elevation of trachea:

– LV or RV ↑

• Increased sternal contact:

– RV ↑

D/V or V/D view Anatomy – D/V or V/D view

• Bulge at 12:00:

– Ascending Ao ↑

• Bulge at 1:00:

– MPA ↑

• Bulge at 2:00-3:00:

– Left auricle ↑

• Bulge in desc. Ao:

– PDA

4/3/2015

3

Anatomy – D/V or V/D view

• “Cowboy sign:”

– Left atrium ↑

• “Reverse D:”

– RV ↑

• Bulge at 9:00-11:00:

– RA ↑

4/3/2015

4

Vertebral Heart Score

Vertebral Heart Score

Caveats of the VHS

Normal:

Dogs: 8.7-10.7 Cats: 6.9-8.1

• Some dogs naturally have a high VHS:

– Boston Terrier (< 14.5) Boxer (< 13.2)

– Bulldog (< 16.1) CKCS (< 11.6)

– Greyhound (12) Pomeranian (< 12.3)

– Pug (12.5) Whippet (< 12.3)

DV or VD?

VD:

• Easier to do

• Larger area of the accessory lung lobe visible

• Recommended view for pulmonary parenchyma

• More compromising to dyspneic patients

DV or VD?

DV:

• Harder to do

• Recommended view for assessment of the cardiac silhouette

• Not compromising to dyspneic patients

• Easier to view caudal lobar pulmonary arteries

4/3/2015

5

QuickTime™ and ah264 decompressor

are needed to see this picture.

Overview

• Radiographic anatomy of the heart and great vessels

• Clinical pearls and common pitfalls

• Radiographic examples of various cardiopulmonary diseases

Pitfalls:

Inspiratory vs Expiratory

• Goal: peak inspiration.

– Maximizes the contribution of inhaled air to subject contrast.

– Ensures consistency.

– Lateral views emphasize the nondepedent part of the lung.

Pitfalls: The perceived

heart based tumor

• There is natural redundancy in the trachea of normal dogs.

• If the head and neck of a dog are flexed during a lateral radiograph, the trachea tends to deviate dorsally in the cranial thorax. This mimics a mass effect.

• A true mass will be accompanied by increased soft tissue opacity ventral to the trachea.

4/3/2015

6

Pitfalls: Lazy hearts and

tortuous aortas

• The heart of an aging cat assumes a more horizontal position on lateral radiographs.

• The aorta may appear tortuous with a prominent ventral deviation in the mid-thorax.

• There can be a prominent aortic knob on the VD radiograph.

Pitfalls: The RPA

is not a lymph node

• On the right lateral view, the right pulmonary artery may sometimes be seen end-on ventral to the carina.

• Enlarged hilar lymph nodes appear dorsalto the carina and often ventrally depress the caudal trachea.

Clinical Pearls:

Canine CHF • Congestive heart failure in the dog is

typically:

– Caudodorsal

•Caveat: Can be cranioventral, but is worse caudodorsally

– Symmetrical

•Caveat: Sometimes R > L

– Worse centrally

– Vessels don’t HAVE to be enlarged

4/3/2015

7

Clinical Pearls:

Feline CHF • Congestive heart failure in the cat is

typically:

– Ventral

•Caveat: Can be dorsal, but is worse ventrally

– Interstitial (even nodular interstitial) or alveolar

– Vessels don’t HAVE to be enlarged, but they often are

= 3.5

= 5.0

4/3/2015

8

More Things to Remember

about Feline CHF

• Left atrial enlargement is hard to see on the lateral view.

– If you see it, the LA is huge!

• Severe hypertrophic cardiomyopathy may not cause obvious radiographic cardiomegaly.

Clinical Pearls:

Bronchopneumonia

• Infectious or aspirated

• Alveolar pattern

• Typically a ventral distribution, often asymmetric

• Consolidation of the affected lung lobe(s) often results in a mediastinal shift

Overview

• Radiographic anatomy of the heart and great vessels

• Clinical pearls and common pitfalls

• Radiographic examples of various cardiopulmonary diseases

4/3/2015

9

Sig:

10 year old

MN Golden;

coughing

Sig: 12 week MI Wire Fox

Terrier; asymp murmur

Sig: 8 year FS Golden;

lethargic, no murmur

4/3/2015

10

Sig: 6 year MN Shih Tzu; coughing

VHS = 11.1

Sig: 10 year FS Toy

Poodle; coughing, dyspneic

Sig: 8 year old MN Sheltie;

coughing, dyspneic VHS = 10.9

4/3/2015

11

Sig: 2 year old FS Beagle;

asymp heart murmur

I could show

you more

awesome

radiographs,

but I’m out

of time! :)