Interpretation of diagnostic images

What do you need when approaching diagnostic imaging?

Recognition

Report

Analysis

Recognition

Spotting the abnormality

Report

Describing the abnormality

Analysis

Diagnosing the abnormality

What do you need?

Imaging study

An appropriate viewing area

Reference material

Reporting media

What is an adequate viewing area?

Dark room, light box, computer with high-resolution monitor, etc

Reference amterials can include

Reporting media can be

patient record,

If you increase the x rays reaching film then you

increase the film blackening

If your tissue is increasing in radio-opacity, then

increased x ray absorption leading to decreased image blackening/density

Metal and bone appear

white on radiographs

Soft tissue and fluid appear

grey on radiographs

Gas appears

black on radiographs

When should you assess image quality?

Before interpretation

Inadequate image quality can lead to

false positives and false negatives

If a potential diagnostic image is not good enough then you should

REPEAT it!

3 stage approach: Phase 1

Look at everything. Recognize what you can.

3 stage approach: Phase 2

Report, identify, and describe abnormalities

3 stage approach: Phase 3

Interpret/analysis, make a diagnosis, generate a ddx (most likely to least)

Plan further investigation/treatments

Recognition (Stage 1) should include

Systematic search of the ENTIRE image (system by system or area by area)

Key points of recognition:

Do not get distracted by obvious lesions, read the whole image

Remember at least two orthogonal views

Orthogonal views means

views at 90 degree angles from each other

Insert images from lecture

I

nsert images from lecture

How can you report abnormalities in a diagnostic image?

YOU NEED TO KNOW NORMAL

Descriptors to describe changes in diagnostic images (Roentgen Signs)

Size, shape, margin, number, position/location, opacity/echogenicity/signal, internal structure, function (dynamic studies and US)

What can cause increased size on diagnostic images?

Hypertrophy, hyperplasia, inflammation, neoplasia, edema, congestion, torsion, cystic disease

What can cause decreased size on diagnostic images?

Atrophy, hypoplasia, congenital effects

What can cause abnormal shape/margins?

Trauma, hypertrophy, hyperplasia, neoplasia, abscesses, necrosis, ulceration, hematoma

What can cause loss of visibility in diagnostic images?

Surrounding disease (free fluid →altered opacity of nearby organs)

What can cause increased number of normal structures in diagnostic images?

Accessory development centers, congenital abnormality

What can cause decreased number of normal structures in diagnostic images?

Anomaly, extopia, previous surgery

What can cause a small number of lesions in diagnostic images?

Primary disease

What can cause a large number of lesions in diagnostic images?

Malignancy, metastatic

What can cause abnormal position or displacement in diagnostic images?

Adjacent mass or organ/space enlargement, Traction, torsion, hernia/rupture, ectopia

What can cause an increased opacity in radiographic images?

Fluid/soft tissue accumulation, mineralization

What can cause a decreased opacity in radiographic images?

Air accumulation, decreased bone density, fat accumulation

What can cause alteration in US and CT images?

Inflammation, neoplasia, rupture, congenital

During interpretation, generate differentials for

All abnormalities (some may be incidental)

Structured list of differentials should be presented with

most likely first

A differential that explains all changes should be

ranked higher/first

Consider other clinical findings, they may

influence your differential list, some may be insignificant

What does VITAMIN D stand for? V:

Vascular

What does VITAMIN D stand for? I:

Infalmmatory/infectious

What does VITAMIN D stand for? T

Traumatic, toxic

What does VITAMIN D stand for? A

Anomalous (including congenital)

What does VITAMIN D stand for? M

Metabolic

What does VITAMIN D stand for? 2nd I

Iatrogenic, Idiopathic

What does VITAMIN D stand for? N

Neoplastic, Nutritional

What does VITAMIN D stand for? D

Degenerative

Imaging report: Patient and Study details

Patient ID, breed, age, Date of study, iamges obtained (views and modalities)

Imaging report: Image quality

Imaging report: Description

Imaging report: Summarize and differentials

Imaging report: Refine differential list

Imaging report: Plan

Informed interpretation Pros:

Allows you to be aware of history prior to image interpretation

Informed interpretation Cons:

Risk of bias, over reading images (look for disease when no disease is present)

Blind interpretation Pros:

No bias, less likely to terminate examination early

Blind interpretation cons:

Longer and less structured differential list

“Blind Interpretation is most commonly

A second opinion

Search errors:

You missed the lesion (or interpreted it as normal)

You did not look at the entire image

You did not note absence of normal structure

Possibly due to inadequate image quality

Failure to assess complex area (ex skull)

Under-reading errors

Failure to identify lesion

Failure to consider appropriate differentials (avoided with blind film reading)

Failing to reconsider differentials when presented with new evidence

Over-reading errors

Not recognizing breed/species variations

Identifying normal features as pathology

Failure to recognize non-diagnostic images

Mistaking an incidental finding for significant pathology

Analysis errors

Generation of incorrect or incomplete differential list

Inappropriate further investigation recommendations