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CVM 6101Radiographic Anatomy of the

ThoraxDaniel A. Feeney DVM, MS

Professor of Veterinary Radiology

College of Veterinary Medicine

University of Minnesota

Veterinary Medical CenterUNIVERSITY OF MINNESOTA

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Veterinary Medical CenterUNIVERSITY OF MINNESOTA

CVM 6101 [Imaging Anatomy]

• Goals & Expectations:– Identify specific structures or parts thereof– Understand why the views (projections) look as they do– Keep in mind that the items listed in the “to know” lists

are from the perspective of practicing radiologists– If asked, be able to describe what soft-tissue (muscle,

tendon, ligament, vessel, or alimentary/parenchymal) structure(s) attach to, pass through, or lie in contact with a given anatomic landmark or region

Veterinary Medical CenterUNIVERSITY OF MINNESOTA

CVM 6101 [Imaging Anatomy]

• Approach:– Introductory lectures defining the important structures

and how they are viewed radiographically– Open session, instructor proctored group laboratory

exercises wherein actual radiographs of the anatomic structures are viewed and understood

– Web-based self-study sets both available on CD and from the web site http://www.academic-server.cvm.umn.edu/radiology//

Veterinary Medical CenterUNIVERSITY OF MINNESOTA

CVM 6101 [Imaging Anatomy]

• Sources of Information:– Anatomy Textbooks– Radiographic Anatomy Textbooks– General Veterinary Imaging Textbooks– U-MN Medical Imaging web site

http://www.academic-server.cvm.umn.edu/radiology//

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Veterinary Medical CenterUNIVERSITY OF MINNESOTA

Normal Thoracic Architecture[lateral perspective]

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Normal Lateral View: inspiration/expiration

Normal Ventrodorsal View: inspiration/expiration

Normal Cat Normal “FAT” Cat

Mediastinal Lymph Nodes

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KEY[for dorsal perspectives]

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Normal Thoracic Architecture[dorsal perspective (high)]

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Normal Thoracic Architecture[dorsal perspective (mid)]

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Normal Thoracic Architecture[dorsal perspective (low)] Interpretive Background: THORAX

• Pleural space: “potential” space between the visceral pleura (directly surrounding the lungs) and the parietal pleura (lining the thoracic cavity and reflecting over the mediastinum) [not normally visible]

• Mediastinal space: “potential” space between the right and left mediastinal (parietal) pleural reflection [not normally visible]

• Pericardial sac: sac that directly surrounds the heart [not normally visible]

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Interpretive Background: THORAX

• Pleural space: contains NOTHING• Mediastinal space: contains EVERYTHING

except the lungs and the caudal vena cava with its accompanying right phrenic nerve

• Pericardial sac: contains only the heart

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Interpretive Background: THORAX

• Mediastinal Space

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Normal Dog Lateral View Normal Dog VD View

Cross-section of Thorax @ Heart Thymic “Sail” Sign (VD)

Anterior Mediastinal Mass Interpretive Background: THORAX

• Pleural Space

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Normal Dog Thorax Cross-section of Thorax @ Heart(solid lines are pleura)

Concept of Fluid/Air Shift[DV]: Air/Fluid

Concept of Fluid/Air Shift[VD]: Air/Fluid

Diagnostic Pleurogram(From Bhargava) Pleural Disease Classification

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Pleural Fluid Interpretive Background: THORAX

• Pericardial Sac

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Normal Dog Thorax Cross-section of Thorax @ Heart(dotted lines are pericardial sac)

Pericardial Effusion CVM 6101 [Imaging Anatomy]

• Diaphragm: Broad Anatomic Regions– R and L crura– Cupola (dome)

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Diaphragmatic Anatomy Diagram [From Grandage] CVM 6101 [Imaging Anatomy]

• Diaphragm:– V D/D V and R L/L R views– Beware of superimposed structures including

vertebrae, ribs, sternebrae, lungs, stomach, nipples, fascial planes, trachea, etc.

– Remember, the diaphragm is a sling-like muscle that “actively” contracts (caudally) and “passively” relaxes (cranially) [numerous influences such as lungs, abdominal fat, etc.]

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CVM 6101 [Imaging Anatomy]

• Diaphragm:– Appearance changes depending on DV vs. VD views

(with the X-ray beam is centered on the heart): • On DV views, the diaphragm usually has one broad dome

which corresponds to the cupola• On VD views, the diaphragm usually has “3 humps”

corresponding to the two crura and the central cupola• Appearance related to beam divergence and diaphragm

orientation relative to the diverging beam

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Diaphragm Appearance:VD vs. DV (From Grandage)

CVM 6101 [Imaging Anatomy]

• Diaphragm:– Appearance changes depending on R vs. L recumbent

lateral views (with the X-ray beam is centered on the heart):

• On R lateral views, the diaphragmatic crura are usually parallel with the R crus more cranial and blending with the caudal vena cava

• On L lateral views, the diaphragmatic crura usually cross with the L crus being more cranial, but the R crus still blends with the caudal vena cava

• Appearance related to right crus being more cranial, but the down-side crus is forced forward by visceral weight

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Diaphragm Appearance:Right vs. Left Lateral (From Grandage)

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Normal Dog Thorax Normal Dog ThoraxRight/Left lateral

Normal Dog ThoraxVD/DV Diaphgram: paralysis

Extrapleural Lesion (diaphragmatic hernia) Interpretive Background: THORAX

• Thoracic Wall

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Pleural Disease Classification Normal Dog Thorax

Thoracic Wall: flail chest Interpretive Background: THORAX

• Airways

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Interpretive Background: THORAX

• Upper Airways (extrapulmonary):nasal passages, pharynx. larynx

• Lower Airways (extrapulmonary): extrathoracic tracheaintrathoracic tracheaproximal mainstem bronchi

• Intrapulmonary Airways: distal mainstem bronchi bronchioles[airways distal to 3rd order bronchi not

normally visible]

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Pharyngeal Collapse: Diagram

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Normal Larynx/Pharynx Normal Dog Lateral View

Diagram: Airway Subdivisions[dog & cat]

Extrathoracic Tracheal Collapse:Expiration/Inspiration

Interpretive Background: THORAX

• Lungs

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Interpretive Background: THORAX

• Left Lobes (radiologist’s functional perspective):cranial portion of left cranial (left cranial)caudal portion of left cranial (left middle)left caudal (left caudal)

• Right Lobes: right cranialright middleright caudalaccessory

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Lung Diagram [lateral view] Lung Diagram [VD view]

Alveolar Disease: pneumonia Interpretive Background: THORAX

• Heart and Vessels

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Interpretive Background: THORAX• Thoracic Circulatory Pattern:

cranial/caudal* vena cavaright atrium* tricuspid valveright ventricle* pulmomary trunk*lobar pulmonary arteries*lobar pulmonary veins*left atrium* mitral valueleft ventricle* aorta*

• * sufficiently visible to be survey radiographically useful

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Heart Diagram [lateral view]Cardiac Perspective Lateral Thoracic View

Aorta

Vena CavaCaudal

Trachea

HEART

12:00

3:00

6:00

9:00

Cranial Cardiac Waist:Aorta, Rt. Atrium, Pulmonary Trunk

Caudal Cardiac Waist:Lt. Atrium

Right Ventricle

Left Ventricle

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Normal Dog Lateral View Heart Diagram [VD view]Cardiac Perspective Ventrodorsal Thoracic View

R L

12:00

3:00

6:00

9:00

Main Pulmonary Trunk

Aorta (hidden in mediastinum)

Left Auricle

Left VentricleRight Ventricle

Right Atrium

HEART

Normal Dog VD View Normal Non-selective Angiocardiogram (dog)

Normal Cranial Vena Cavogram(dog)

Normal Caudal Vena Cavogram(dog)

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Pulmonic Stenosis Pulmonic Stenosis

Interpretive Background: THORAX• Intrapulmonary Circulatory Pattern:

– ARTERY/BRONCHUS/VEIN TRIAD(one in each major lung lobe)

– USED AS INDIRECT INDICATOR OF LEFT HEART FUNCTION (vein) and pulmonary flow resistance (artery)

• lobar pulmonary arteries– Dorsal to veins on lateral views– Lateral to veins on VD/DV Views

• lobar pulmonary veins– Ventral to veins on lateral views– Medial to veins on VD/DV Views

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Lung Vessel Diagram [lateral view]Lobar Pulmonary Vessels (left lateral view)

artery

vein

bronchus

Pulmonary Hypertension[heartworm disease]

Pulmonary Hypertension[canine heartworm disease]

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Pulmonary Venous Congestion[early congestive LEFT heart failure]

Pulmonary Venous Congestion[early congestive LEFT heart failure]

Specific References: THORAX• Grandage J: Posture, gravity and radiographic

interpretation. J Am Vet Radiol Soc 22:80, 1979.

• Grandage J: Radiology of the dog’s diaphragm. J Small Anim Pract 15:1, 1974.

• Bhargava AK, Rudy JL, Diesem CD: Radiographic anatomy of the pleura in dogs as visualized by contrast pleurography. J Am Vet Radiol Soc 10:61, 1969.

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General References: THORAX• Thrall DE (ed): Textbood of Veterinary

Diagnostic Radiology. WB Saunders, Philadelphia, 2002.

• Burk RL, Feeney DA: Small Animal Radiology and Ultrasonography. Saunders/Elsevier, Philadelphia, 2003

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And you think this is tough???

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