Basic in Radiologie

8/13/2019 Basic in Radiologie

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Who, why, when, and how to start wit

radiology ?

Denis Novak DVM MRCV

www vetnovak com
http://www.vetnovak.com/http://www.vetnovak.com/


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science


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Visual perception and radiographicinterpretation

Visual inacCcuracies

Slow dark adaptation

Peripheral glare


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Theory of percepts Visual signals are compared with mental images stored in memory

Visual signals induce a compatible mental image in our mind

The percepts are continuously modified by experience

What we see is a percept


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Perceptual distortions

The density of the FOUR central squares is the same


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Perceptual distortions

The density of the FOUR central squares is the same


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Subjective contours

Position of the organ relative to film surface Parallel Oblique Perpendicular

Dependent of object being fixed or movable Bowel loop (movable) Heart (relatively fixed) Main-stem bronchus (fixed)


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Subjective contoursRelationship with the primary x-ray beam


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Subjective contours

Shape

View 1

View 2


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multistability of perceptions


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principles of interpretation

Rabbit vs seagull (vs horse)


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COUNT THE fs

FINISHED FILES ARE THERESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THEEXPERIENCE OF MANY YEARS

OF EXPERT OBSERVATION


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How many f s???

2 4 72

7 6 5 39 8 0

2 34 9 1 6 30


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COUNT THE fs

FINISHED FILES ARE THERESULT O F YEARS OF SCIENTIFIC STUDY COMBINED WITH THEEXPERIENCE O F MANY YEARS

O F EXPERT OBSERVATION


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COUNT THE fs

FINISHED FILES ARE THERESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THEEXPERIENCE OF MANY YEARS

OF EXPERT OBSERVATION


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Knowledge, emotions, perception See what we expect to see we do not see

something that contradicts our thinking

Search for pulmonary metastasesYoung dog = probably negative studyOlder dog = probably positive study


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Visual search for lesions

Vision is blurred during eye movement

We see only when the eye is still


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3 dimensional conceptRadiograph is a 2 dimensional shadowgraph of a 3 D objectCreate mental 3 D picture

Minimum two views at 90 degree

Anatomy and radiology textbooks for reference


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Th di i l i g


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Three dimensional image

Value of oblique views


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Image formation

relative tissue densities


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Radiolucent areas let more radiation pass through and expose the film

and create a darker shadow e.g. gas.


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Radiodense areas prevent X rays reaching the

film and create a lighter shadow e.g. bone.


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Radiographic techniques


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Tissue thickness

Thickness and radiopacity are interrelatedAs thickness increases, radiopacity increases ________________________________________________

principlesof interpretation


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principles of interpretation

Tissue composition

water density tissues


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Density


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Contrast

peritoneal fat contrasts with the liver

fat is a friend in radiology

Lack of contrast


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Lack of contrast

Peritoneal fluid erases the contrast and makes individual organ identification impossible


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Silhouetting


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SilhouettingIf two structures of similar radio-opacity are in contact their margins cannot be

distinguished


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ProjectionsLatero - medial (Medio-lateral) - lateral

Dorso ventral sternal recumbency / Ventro dorsal dorsal recumbency.

Cranio caudal ; Caudo cranialDorso palmar (carpus distally)/Dorso plantar (tarsus distally)

Rostro - caudal / Rostro - cranial


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Left to right lateral radiograph of the thorax

Right lateral


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Dorsoventral


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Right Medio-lateral


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Right craniocaudal

Right lateral


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Left to right lateral radiograph of the abdomen

Right lateral


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flexed and extended view


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contralateral limb


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stress view


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str

ess

Skyline view


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Skyline view


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Organ vs. Area


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Please take 2 views !


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Please, take 2 views !


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ART


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Getting Started


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Getting Started

Radiology (imaging) is applied anatomy use it Pathology, surgery and medicine is very important

Understand how the image is generatedErrors in perception or interpretation may lead to

incorrect assessment


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Viewing area

Quiet areaAdequately darkened

At least 2 view boxesBright light illuminator


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Examining the radiograph

Check the label Views identified and right and left side marked Good quality radiographs


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R a d

i o g r a p h i c e v a l u a t i o n

I d e n t i

f y t h e

s t u

d y

C h e c k t h e q

u a

l i t y

f o r :

n u m

b e r o

f v i e w s ,

p a t i e n t p o s i t i o n i n g

,

t e c h n i q u e

, t e c h n i c a

l e r r o r s

,

a r t i f a c t s

P o s i t i o n r a

d i o g r a p

h i n a s t a n

d a r d m a n n e r

T r y t o

l o o k a t

b o t h v i e w s w h i l e

r e a

d i n g

R e a

d r a

d i o g r a p

h s t w i c e

U s e t e x t

b o o

k s ,

a t l a s , m o

d e l s

, n o r m a

l r a

d i o g r a p

h s

B e c o n s i s t e n t


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X ray is only a picture in time Clinical signs may precede radiographic signs

Take additional studies

Radiographic features

in the lungs change within 24 hoursIn the bone change within 7 days


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Errors: False positive diagnosis False negative diagnosis

What does an error mean for the patient? Inappropriate therapy Euthanasia Untreated disease

Review with experts to eliminate errors

Radiographic Interpretation


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Sources of errors

Scanning or searching errorscorner errors Did not find the expected lesion

Recognition errorsseen, perceived, BUT not recognized as an abnormality

Decision errorsWhat is important??

Egocentric errors - (I found what I knew would be there)


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...keep in mind... Imaging tests evaluate for normal vs. abnormal

structure or function Some diseases do not change morphology Some images do not contain a lesion

Its ok to be normal!

causes & differential diagnoses


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causes & differential diagnoses

CONGENITAL/DEVELOPMENTAL METABOLIC/NUTRITIONAL TRAUMATIC INFLAMMATORY/INFECTIOUS NEOPLASTIC DEGENERATIVE

V I T A M I N D

R di hi I t t ti


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Knowledge Experience

To tie together Make specific conclusion Practice, practice, practice

Radiographic Interpretation


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Radiographic interpretation

Anatomical method of examining the films

Identify visual features of the radiographs

Possible structural changes

Type of pathology

Differential diagnosis Combination of findings with clinical data

Diagnosis


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Prioritize

Next step


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A systematic approach to interpretation is fundamental.

thx to j.p.morgan and p.mantis


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Basic in Radiologie

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