Thoracic Radiology

Thoracic Radiology

Wendy Blount, DVMNacogdoches TX

Thoracic Rads - Normal

Review of thoracic radiographs - Steps• Skeletal

– Spine, front limbs, ribs, sternum• Cranial abdomen• Airways, Lung fields• Great vessels

– Aorta, pulmonary arteries, cranial & caudal vena cava• Smaller vessels

– Internal thoracic arteries, pulmonary lobar a & v, brachiocephalic trunk, left subclavian artery

• Cardiac silhouette– Vertebral heart score, bulge

• Left Heart Failure? Right Heart Failure?


Why is it so difficult to evaluate cardiac and chamber size on radiographs?

• Comparing heart size to lung field size doesn’t work– Dogs of different conformation have different

ratios of heart size to lung size












ratios of heart size to lung size– Lung field size changes with the breathing cycle– Abdominal fat pushes the diaphragm cranially– Thoracic fat makes lung fields appear smaller

• Comparing heart size to vertebral size works better– Vertebral heart score



• Things can make the heart look bigger









• Things can make the heart look bigger– Pericardial fat– Pericardial effusion– Peritoneopericardial diaphragmatic hernia



• Things can make the heart look bigger– Pericardial fat– Pericardial effusion– Peritoneopericardial diaphragmatic hernia



• Things can make the heart look bigger– Pericardial fat– Pericardial effusion– Peritoneopericardial diaphragmatic hernia– Oblique positioning on VD/DV can make right

heart look bigger• MYTH - “increased sternal contact”

means right heart enlargement




Normal cats change with age• Long axis of the heart is more

horizontal in old cats (40%)• Aortic bulge develops (30%)

– Not due to hypertension or hyperthyroidism– At the aortic isthmus– Cardiac measurements in young & old cats are

the same, despite these conformational changes in the thorax


5.0 + 4.8 = 9.8 Vertebral Heart Score


Vertebral Heart Score• Measure heart long axis

– carina to the apex• Measure heart short axis

– Widest perpendicular to length• Count vertebrae from cranial aspect T4• Add together• Dogs – normal 8.5-10.5• Cats – normal 7-8

Heart Chambers – VD/DV - Left


LV - Left Ventricle

AV - Aortic Valve

AA - Ascending Aorta

DA - Descending Aorta



LV - Left Ventricle

AV - Aortic Valve

AA - Ascending Aorta

DA - Descending Aorta

LA – Left Atrium



Heart Chambers – VD/DV - Right


Right Ventricle

Pulmonic Valve

Main Pulmonary Artery

Right Pulmonary Artery

Left Pulmonary Artery

PV

Heart Chambers – VD/DV - Right



Heart Chambers – VD/DV – Clock Face• Aorta 12-1 o’clock

• LV 3-6 o’clock


Heart Chambers – VD/DV – Clock Face• Aorta 12-1 o’clock• MPA 1-2 o’clock• LV 3-6 o’clock• RV 7-9 o’clock


Heart Chambers – VD/DV – Clock Face• Aorta 12-1 o’clock• MPA 1-2 o’clock• LV 3-6 o’clock• RV 7-9 o’clock• LA has to be really big to see on VD


Heart Chambers – VD/DV – Clock Face• Aorta 12-1 o’clock• MPA 1-2 o’clock• LV 3-6 o’clock• RV 7-9 o’clock• LA has to be really big to see on VD• RA 9-12 o’clock


Heart Chambers – Lateral – Left

• LA – Left Atrium• MV – Mitral Valve• LV – Left Ventricle• AV – Aortic Valve• SV – Sinus of Valsalva• AAo – Ascending Aorta• BCT – Brachiocephalic Trunk• LS – Left Subclavian a.


Heart Chambers – Lateral – Right

• RA – Right Atrium• Raur – R Auricle• RV – Right Ventricle• MPA – Pulmonary a.


Heart Chambers – Lateral – Right

• RA – Right Atrium• Raur – R Auricle• RV – Right Ventricle• MPA – Pulmonary a.• RVOT – RV Outflow• PV – Pulmonic Valve• RPA – R Pulmonary a.• LPA – L Pulmonary a.


Heart Chambers – Lateral – Clock Face• LA (caudal waist) – 12-3 o’clock

• LV - 2-6 o’clock


Heart Chambers – Lateral – Clock Face• LA (caudal waist) – 12-3 o’clock

• LV - 2-6 o’clock• RV - 6-9 o’clock

• MPA – 10-11 o’clock – bulge at 1-2 o’clock


Heart Chambers – Lateral – Clock Face• LA (caudal waist) – 12-3 o’clock• CdVC – 2 o’clock• LV - 2-6 o’clock• RV - 6-9 o’clock• Raur – 9 o‘clock• RA not easily seen on the lateral view• CrVC – 10 o’clock• MPA – 10-11 o’clock – bulge at 1-2 o’clock

Thoracic Rads - Abnormal

Case #1 – 8 year old neutered male cocker spaniel – coughing



6.2 + 5.9 = 12.1


Case #1 – 8 year old neutered male cocker spaniel - coughing

• Skeletal, Cranial abdomen– No abnormalities noted

• Airways, Lung fields– Mild perihilar edema

• Great vessels– enlarged caudal vena cava

• Smaller vessels– enlarged pulmonary lobar veins

• Cardiac silhouette– Generalized cardiomegaly, enlarged LA



• Skeletal, Cranial abdomen– No abnormalities noted

• Airways, Lung fields– Mild perihilar edema

• Great vessels– enlarged caudal vena cava


• Cardiac silhouette– Generalized cardiomegaly, enlarged LA









• Left Congestive Heart Failure– Mild perihilar edema– enlarged pulmonary lobar veins– enlarged LA (generalized cardiomegaly)– Enlarged LV (elevated trachea)

• Right Congestive Heart Failure– enlarged caudal vena cava– Generalized cardiomegaly (RV enlargement)– (ascites, pleural effusion)



• Diagnosis by echo - DCM


Are rads or echo better for detecting congestive heart failure?

• radiographs

Are rads or echo better for detecting enlarged heart chambers?

• echo


Generalized cardiomegaly (all 4 heart chambers enlarged)Dogs• Dilated Cardiomyopathy• Mitral regurgitation• Tricuspid regurgitationCats• Dilated cardiomyopathy• anemia



Pseudocardiomegaly • No significantly enlarged heart chambers• Significantly enlarged cardiac silhouette• Pericardial effusion

– Hemorrhage – HBT or ruptured LA– Right heart failure – modified transudate– Infectious pericarditis– Idiopathic pericarditis

• Peritoneopericardial Diaphragmatic Hernia

• Pericardial fat

Case #2 – 15 month Maine coon cat – tachypnea, lethargy


5.1 + 3.8 = 8.9


Case #2 – 15 month Maine coon cat – tachypnea, lethargy• Skeletal & cranial abdomen• Airways, Lung fields

– No abnormalities noted• Great vessels

– caudal vena cava somewhat enlarged• Smaller vessels

– No abnormalities noted• Cardiac silhouette

– Generalized cardiomegaly, apex shifted right


Case #2 – 15 month Maine coon cat – tachypnea, lethargy• Skeletal & cranial abdomen• Airways, Lung fields

– No abnormalities noted• Great vessels

– caudal vena cava somewhat enlarged• Smaller vessels

– No abnormalities noted• Cardiac silhouette

– Generalized cardiomegaly, apex shifted right


Case #2 – 15 month Maine coon cat – tachypnea, lethargy

• Heart Failure??– Probably not

• Diagnosis– Echo showed dilation of LV and RV– Flea Anemia (PCV 10%)

Case #3 – 5 year old Maltese • honking cough• holosystolic murmur loudest L apex


Case #3 – 5 year old Maltese • honking cough• holosystolic murmur loudest L apex


6.0 + 7.1 = 13.1


Case #3 – 5 year old Maltese • continuous murmur is heard loudest at

the left axilla• Left Heart Failure

– pulmonary edema, LA enl, tracheal elevation• Airway Cough – enlarged LA

– compression of left bronchus and trachea• Bulge at 1:30 on VD, apex shifted right

– cardiomegaly (R or L or both?)


Heart Chambers – VD/DV – Clock Face• Aorta 12-1 o’clock

• MPA 1-2 o’clock• LV 3-6 o’clock• RV 7-9 o’clock

• LA has to be really big to see on VD• RA 9-12 o’clock


Case #3 – 5 year old Maltese • Diagnosis by echo - PDA

– Right heart normal

LISTEN TO THE LEFT ARMPIT!!

When the left heart is markedly enlarged, right heart size can be difficult to evaluate on radiographs


Case #4 – 12 year old Mini Poodle- holosystolic murmur L apex• Skeletal, cranial abdomen, airways,

Lung fields, Great vessels, small vessels– No abnormalities noted

• Cardiac silhouette– VHS high if you include LA– VHS normal if you exclude LA– Huge LA

• No signs of congestive heart failure


Case #4 – 12 year old Mini Poodle- holosystolic murmur L apex• Diagnosis

– Mitral regurgitation• Treatment

– Cough suppressants• Monitoring

– Chest rads every 6 months – Sooner if respiratory rate while sleeping >40


Case #4 – 12 year old Mini Poodle- holosystolic murmur L apex

You can have a Huge LA and even LV without CHF

CHF is rarely present without enlarged LA



3 Most Common Causes of L Heart Enlargement1.MR2.PDA3.SAS

Case #5 – 4 year old DSH- Murmur heard on annual – left sternum


4 + 3.5 = 7.5


Case #5 – 4 year old DSH- Murmur heard on annual – left sternum• Skeletal, cranial abdomen, Lung fields,

airways, Great vessels, small vessels– No abnormalities noted

• Cardiac silhouette– VHS normal– Enlarged LA on VD

• No signs of congestive heart failureDiagnosis by echo - HCM


Case #5 – 4 year old DSH- Murmur heard on annual – left sternum

LA is seen more easily on the VD in cats• LA sits more cranial in the catLA is seen more easily on lateral in dogsVHS usually does not include LA in cats• Other chambers need to be enlarged to perceive

cardiomegaly on the lateral in cats

Case #6 – 10 year old mixed dog- Gagging up white foamy fluid, mitral murmur



Case #6 – 10 year old mixed dog- Gagging up white foamy fluid, mitral murmur• Skeletal, Cranial abdomen, Great vessels

– No abnormalities• Airways, Lung fields

– Elevated trachea, compressed left bronchus– Perihilar edema


• Cardiac silhouette– VHS 11.5, generalized cardiomegaly, enlarged LA


Case #6 – 10 year old mixed dog- Gagging up white foamy fluid, mitral murmur

• Left Heart Failure

• Echo diagnosis – severe mitral regurgitation

Case #7 – 1 yr old Golden Retriever- Episodes of collapse with exercise



Case #7 – 1 yr old Golden Retriever- Episodes of collapse with exercise• Skeletal, Cranial abdomen, Airways,

Lung fields, small vessels– No abnormalities

• Cardiac silhouette– VHS 9.5– aortic bulge & enlarged LA on lateral

• No signs of congestive heart failure• Echo diagnosis – severe SAS


Loss of Cranial Waste1.Dilated Aortic Arch

• SAS• PDA• Tetralogy of Fallot

2.Enlarged RAuricle• TR• Heartworm Disease

3.Heart Base Tumor (RA, Aortic Body)• HSA, chemodectoma, myxosarcoma

Case #7 – 12 yr old Mixed Terrier- Chronic cough and cyanosis



Case #7 – 12 yr old Mixed Terrier- Chronic cough and cyanosis• Skeletal, Cranial abdomen, Vessels

– No abnormalities• Airways, Lung fields

– Pronounced airway pattern• Cardiac silhouette

– VHS 10-10.5, RV enlargement, apex shifted L• No heart failure


Case #7 – 12 yr old Mixed Terrier- Chronic cough and cyanosis

• Echo diagnosis– RV thickening– Suspect pulmonary hypertension

• Clinical Diagnosis– Severe chronic pulmonary disease


Case #7 – 12 yr old Mixed Terrier- Chronic cough and cyanosisWhat does it mean when the apex is

shifted right?– LV enlargement or generalized cardiomegaly

What does it mean when the apex is shifted left?– RV enlargement


Case #7 – 12 yr old Mixed Terrier- Chronic cough and cyanosisRV enlargement must be moderate to

severe to see on radsRA enlargement difficult to appreciate on

rads unless severe (cause)– TR

Lifting of the apex off the sternum on lateral view means RV enlargement

Measuring RV enlargement on Lateral View of the Thorax

Thoracic Rads - Abnormal3.75 / 1 = 3.75


Measuring RV enlargement on Lateral View of the Thorax

1. Measure heart long axis• Carina to apex

2. Measure heart short axis• Widest point perpendicular to long axis

3. Short Axis - Divide Cranial part by Caudal part• Cranial is <2.5x Caudal in normal dogs• (Cr >2.5x Cd) means RV enlargement


Case #8 – 10 month old English PointerEjection murmur loudest at heart base on

left side


Case #8 – 10 month old English PointerEjection murmur loudest at heart base on

left side• Skeletal, Cranial Abdomen, Airways,

Lung fields, small vessels– normal

• Great vessels– pulmonary artery enlarged

• No signs of Congestive Heart Failure


Case #8 – 10 month old English PointerEjection murmur loudest at heart base on left• Causes of enlarged MPA (dogs)

– PS (RPA, LPA, lobar aa/vv not enlarged)– PDA (lungs overcirculated – lobar aa and vv enlarged, but

not tortuous)– Pulmonary hypertension (RPA, LPA lobar aa enlarged)

• MPA enlargement– Not easily seen on lateral in dogs– not readily seen in cats

• This case – echo diagnosis– PS – need spectral Doppler to measure gradient across– RV thickening


LPA, RPA, lobar aa enlarged and tortuous• Pulmonary Hypertension1.HW Disease2.Primary PH3.Chronic Respiratory Disease

Case #9 – 6 month old poodle with murmur found on physical exam




Dx – PDA with no CHF

Measuring pulmonary lobar arteries1.Caudal lobar aa should be same width as a rib

– Seen best on the VD/DV view 2.cranial lobar aa 0.75x 3rd or 4th rib

– Seen best on the lateral view



Dx – PDA with no CHF

Measuring pulmonary lobar arteries1.Caudal lobar aa should be same width as a rib

– Seen best on the VD/DV view 2.cranial lobar aa 0.75x 3rd or 4th rib

– Seen best on the lateral view


Case #10 – 5 yr old DSH catTachypnea


Case #10 – 5 yr old DSH cattachypnea• Ascites in the cranial abdomen• Perihilar edema• HUGE Caudal Vena Cava• Enlarged pulmonary lobar veins• Elevated trachea (LV enlargement)• Enlarged Lauricle on VD• Marked generalized cardiomegaly (VHS

10.5)


Case #10 – 5 yr old DSH catTachypneaEnlarged Caudal vena cava-size varies with respiratory cycle-only severe enlargement is reliably detected-maximum width < length T5 or T6Causes• Right heart failure• Mass obstructing Caudal Vena Cava

– Thrombus, tumor






Case #11 – 2 yr old DSH catTachypnea• VHS 8.75• Left Heart Failure

– Patchy pulmonary edema (caudal)– Enlarged pulmonary lobar vv

• Right Heart failure– Pleural effusion

• Echo diagnosis – hypertrophic cardiomyopathy

Case #12 – 6 yr old WestieADR



Case #12 – 6 yr old WestieADRVHS 8.5 (low normal)• Clinical diagnosis – severe dehydration• Causes of microcardia

– Severe dehydration– Addison’s Disease– Pneumothorax (heart lifted off the sternum)

• Should also see collapsed lung lobes

Thoracic Rads - Review

Left Heart Failure• Pulmonary edema (alveolar if severe)• Pleural effusion in cats• Pulmonary lobar veins much larger than

arteries• Enlarged LA + compression of L bronchus

– Not a sign of heart failure per se– But LHF is rarely present without LA enlargement

• + Enlarged LV– Tracheal elevation– Cardiomegaly (increased VHS)


Right Heart Failure• Pleural effusion

– Can obscure evaluation of the heart, lungs and great vessels

• Enlarged caudal vena cava• Ascites

– Modified transudate• Often concurrent with left heart failure

– Generalized cardiomegaly (increased VHS)• RHF alone:

– HWDz, Chaga's Disease, pericardial disease


Chronic Bronchitis• Increased or mineralized airway pattern• Peribronchiolar infiltrates

– May progress to bronchopneumonia– Interstitial pattern– Alveolar pattern (air bronchograms) if severe

• Signs of pulmonary hypertension– Enlarged pulmonary artery and lobar aa

• No signs of heart failure


Patent Ductus Arteriosus-left to right shunt (aorta to MPA)-volume expansion• + Enlarged pulmonary artery• + Pulmonary overcirculation

– Enlarged pulmonary lobar aa & vv• Enlarged descending aorta• Enlarged LV

– Tracheal elevation– Increased VHS

• Enlarged LA – + compression left bronchus

• + pulmonary edema


Sub-Aortic Stenosis-pressure overload left side• + Enlarged LV on rads

– Increased VHS– Not as marked as volume overload

• Enlarged ascending aorta• Left Heart Failure due to aortic

insufficiency is rare• Death more often due to arrhythmia


Pulmonic Stenosis-pressure overload right side• + Enlarged RV on rads

– Not as marked as volume overload• Enlarged MPA• Right Heart Failure due to pulmonic

insufficiency is rare• Death more often due to arrhythmia


Ventricular Septal Defect-left to right shunt (LV to RV)-volume expansion• + RV enlargement• + Pulmonary overcirculation

– Enlarged pulmonary lobar aa & vv• Enlarged LV

– Tracheal elevation– Increased VHS

• Enlarged LA – + compression left bronchus

• + pulmonary edema


Atrial Septal Defect-left to right shunt (LA to RA)-lower pressure differential, so no

significant volume expansion• + RV enlargement• + RA enlargement

– Enlarged pulmonary lobar aa & vv• Heart failure is rare

(handout)

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Thoracic Radiology