basic in radiologie
TRANSCRIPT
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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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