Roentgen Signs and Interpretation

Principles

January 11, 2010

Radiographic Opacities

Air Least opaque

FatWaterBoneMetal Most opaque

The absolute blackness or whiteness of any specific opacity is also affected by thickness

70504

All 5 opacities can

be seen in this

radiograph

70504

All 5 opacities can

be seen in this

radiograph

Air

Fat Soft tissue or water

Bone

Metal

Opacities are important because…

without different opacities, radiographs would have no information

a lesion’s opacity gives a clue to the abnormality

Radiograph of dog with pneumonia…huh?

101546

A dog with a huge lipoma of the

thigh

Radiographic Geometry

Radiographs are 2-dimensional Patients are 3-dimensional Some problems of 2D radiographs

• Loss of depth perception

• Superimposition

• Summation shadows

Depth Perception

105046

Superimposition

A normal structure appears in an unexpected location and is misinterpreted as a lesion

Superimposition

81510

Cystic calculi?No, nipples

superimposed on bladder.

73934

Superimposition

Chip Fracture?No, ergot superimposed

on joint.

Ergot

Fibrous tissue under ergot

126240

R

Lung Nodule?

Superimposition

No, a tick

Summation Sign

A special case of superimposition where overlapping structures create a summationopacity that is not really present in the patient.

80545

Abdominal mass?

No, summation of kidneys

67630

Lytic lesion in ischium?

No, overlying anal sac gas

Silhouette Sign

The effacement (loss of visualization) of the border of two structures of the same radiographic opacity that are in contact.

X-RAY BEAM

HEART

LUNG

CORONARY ARTERY

PULMONARY ARTERY

PULMONARY ARTERY

Coronary Artery?No! Impossible

75880

Pleural Effusion: DV vs. VD

Heart

Heart

DV VD

DV VD82270

Naming Radiographs

Point of EntrancePoint of ExitUse correct anatomic terminology

Naming Radiographs

DorsopalmarPalmarodorsal

DorsoplantarPlantarodorsal

CraniocaudalCaudocranial

Interpretation Signalment and history Physical examination Is the radiograph normal?

• Hardest call Describing abnormalities

• Roentgen signsWe rarely make a diagnosis from

radiographs

Is It Normal or Not? Reference books Build a

collection…not done Radiograph opposite

limb…not done Experience…difficult Can’t decide …get

help

Roentgen SignsSize

Shape

Number

Location

Margination

OpacityA66208

Roentgen SignsSize

Shape

Number

Location

Margination

Opacity75437

Roentgen SignsSize

Shape

Number

Location

Margination

Opacity66195

Roentgen SignsSize

Shape

Number

Location

Margination

Opacity73874

Summing It Up What is signalment and history

• Could be misleading Compile roentgen signs Formulate a list of possibilities

• D,A,M,N,I,T,V Plan on how to get to the next step

• More imaging• Invasive procedure

Principles of Interpretation

Review SessionJanuary 13, 2010

Be able to point out the 5 radiographic

opacities in the following image

Identify the object in the following image

and, if you can identify it, what

gender is it?

The following cat’s thoracic aorta appears more conspicuous than

the aorta in a normal cat. What could cause this?

84310

The owner of the following cat reports that the cat was playing with

some pills that had spilled from a container and may have eaten

some. You radiograph the cat’s abdomen. What is your assessment

of the stomach.

82336

The liver, spleen, kidneys and bladder are not visible

in the following feline abdominal radiograph.

Why?

The opacities in a patient that are created as a result of the overlapping of structures are

called…..

The radiographic principle that leads to the obscuring of

small intestinal serosal margin detail by the

accumulation of peritoneal fluid is the…

Which of the following structures would not be visible in a lateral thoracic

radiograph of a normal dog?

Left coronary artery Left cranial lobe pulmonary artery Caudal vena cava Descending aorta

This dog in the next image became acutely paralyzed.

What do you tell the owner?

68118

This dog was hit by car and cannot

walk…what diagnosis can be made from

this image?

What roentgen sign(s) is/are illustrated in each

of the following radiographs?

100336

Here is a lesion

What is this? Use

• D• A• M• N• I• T• V

Name the following radiographic projections

Is this radiograph oriented properly?