Diagnostic radiology errors and discrepancies (2).pptx

Diagnostic radiology errors and
discrepancies
• Dr. Vincent Batista Lemaire
• Locum Consultant Radiologist
• St. Richards Hospital ,University Hospital Sussex Hospitals Trust, NHS .
• Chichester , England , UK .

Dedicado a Mi padre Dr. Guarocuya Batista del Villar y mi
hermano Dr. Erasmo Vasquez Henriquez.

“perverse report”
• Request form CXR
• Clinical data : blank
• Report: “No evidence of leprosy “

Human Error
• Bad publicity from an assumption that perfection is
achievable.
• Any error or discrepancy must be punished .
• The public expects the correct answer all the time .
• Tv dramas, media reports describing the error or discrepancy
as a scandal .
• Unfavourable remarks by politician and lawyers alike.
• Medical malpractice claims have been initiated alleging the
radiologist’s failure to detect os acromial and os trigonum
• Societal and government trend of placing increasing
expectation and legal obligation on radiologist. Jury would
expect general radiologist to have the same skills as
subspecialty radiologist .

Grading or scoring Error
• 2014, Royal College of Radiologist (RCR):
“grading or scoring errors…was unreliable or
subjective…of questionable value, with poor
agreement .”
• Could fuel a blaming culture; there is danger
od deliberate or malicious misuse of error
scoring system in the pursuit of personal
grievance.

What happens to us
Anger
Shielding
Anxiety
Frustration

Is there a problem ?
• - Humans will always make errors and radiologist are not different. (RCR )
• - Errors occur in the absence of negligence , hence in the absence of breach of
standard of care.
• - - Diagnostic errors in medicine causes patient harm , with the rate of missed ,
incorrect, or delayed diagnoses estimated to be as high as 10-15%. Autopsy have
identified major diagnostic discrepancies up to 20% of cases , hence 1 in every 5
patients overall .
• Overconfidence …appears to be endemic in medicine. Compared results of
diagnosis of ICU patient and autopsy showed that “clinicians who were
“completely certain” of the diagnosis antemorten were wrong 40% of the time.”
• “errors”: more appropriate to concentrate on “discrepancies” between a report an
a retrospective review of a film or outcome .
.

• Worldwide radiologic examination approximately 1
billion . With a low error rate of 4% this would translate
in 40 million radiologist errors per year .
• - Some studies showed error rate of 10-15% with 2-20%
significant errors.
• - Unlike any other medical specialties, apart from
pathology, not only do we make errors but we store
images to allow retrospective review of our misses.

• -Radiologist Leo Henry Garland (1903-1966) pioneer in the study of
radiologist error discovered that even skilled and experienced
radiologist failed to note important findings on 30% of CXR that
were positive for disease and also had 2% of false positive .
• - Second reading interpretation performed by experienced
abdominal imaging radiologist from Massachusetts General
Hospital compared to previous CT abdominopelvic report
interpreted by either themselves or colleagues , they disagreed
which each other more than 30% of the time –intra-observer- and
disagreed with themselves more than 25% of the time –inter
observer.
• A cancer diagnosis (false-positive) rate of up to 61%has been
quoted in screening mammography (Nelson HD et al.)
• “…humans are incorrigibly inconsistent in making summary
judgments of complex information “. Daniel Kahneman.

Sample of published studies of
radiological error: Adrian P Brady
• 1.) 1993 , Harvey et al. : Mammography : ca identified on previous studies
in 41% when blindly reinterpreted , and 75 % when reviewers were aware
subsequence findings.
• 2.) 1990,1994, Markus et al. : Barium enema : average observer missed
30% of visible lesions .
• 3.)2008, Siewert et al. : Oncologic CT : discordant interpretation in 31-37%,
with resultant change in radiological staging in 19%, and change in patient
treatment in up to 23%.
• 4.) 2007, Briggs et al . : Neuro Ct & MRI: 13% major and 21% minor
discrepancy rates (undercalls, overcalls & misinterpretations) when
specialist neuroradiologist second reading of studies initially interpreted
by general radiologist.

Missed breast cancer
• 35% of both interval cancers and screen-
detected cancers could be classified as missed.
• “missed”: detectable at retrospective review
of a previous obtained mammogram that was
prospectively reported as showing negative,
benign, or probably benign findings d as
missed
• Leslie R Lamb et al . ; Missed Breast Cancer : Effects of Subconscious Bias and lesion characteristic .
RadioGraphics Vol.40 , No 4,Jun 12 2020

Stages in imaging cycle
• 1. clinical question ; request of imaging
modality ; patient preparation and
cooperation .
• 2. imaging acquisition and processing .
• 3. Radiologist reporting and communication of
results.

Types of errors
• 1. perceptual
• 2. interpretative

Perceptual errors
• - All too often , a finding that is readily apparent in retrospect
is inexplicably missed.
• The consistency of experimental results on radiologist
perceptual errors reported worldwide, involving radiologist at
all levels of training and experience working in a wide variety
of clinical setting and across all imaging modalities , argues
convincingly against the idea that radiologist who make errors
are simply to blame for being careless , sloppy , or negligent
or for underperforming in some way; rather, the phenomenon
or radiologist underperception and misperception appears to
be an unvarying feature of the extremely complex system in
which radiologist operate. (Michael A Bruno et al.)

Perceptual errors
• 1. combined sensation in a historic frame of experience
and knowledge form a perception of normal or
abnormal structure .
• 2. perceptual error : those in which and important
abnormality is simply not seen on the images ,
• To be considered a perceptual error, the finding would
need to be deemed sufficiently conspicuous and
detectable in retrospect by the interpreting radiologist
or in the consensus of his or her peers. 60-80% false
negative . A few false positive , seen but no present .

CXR most common Perceptual errors
Jennifer J Donald and Stuart A Barnard: Common patterns in 558 diagnostic radiology errors

CXR most common Perceptual errors
Distribution of missed nodules. Median 16 mm

Cranial imaging most common
Perceptual errors

Body CT most common Perceptual
errors

Cognitive and interpretative errors
• 1. Cognitive : distinguish pathology from non-
pathology, and provides either a single
differential diagnosis .
• 2.Interpretative : 20%-40%
• 3.Radiologist may see an abnormality or a normal
variant , but they misunderstand its meaning or
importance , resulting in an incorrect diagnosis .
• 4. False positive : overcalling ; false negative :
undercalling

Radiologic Error Classification System 12-category
system developed by Kim and Mansfield
• Kim and Classification Scheme for Errors in Diagnostic Radiology
• Cause of Error Explanation Occurrence (%)
• 1.Complacency : An unimportant finding is appreciated but attributed to the wrong
• cause –a more serious cause (false-positive finding) 0,9
• 2.Faulty reasoning : A finding is appreciated and interpreted as abnormal
• but is attributed to the wrong cause (true-positive finding misclassified) 9.0
• 3.Lack of knowledge : A finding is seen but is attributed to the wrong cause
• because of a lack of knowledge on the part of the interpreter 3.0
• 4.Under-reading (missed finding) : A finding is present on the image but is missed 42.0

• 5.Poor communication : An abnormality is identified and interpreted correctly
• but the message does not reach the clinician 0.0
• 6.Technique : A finding is missed because of the limitations of the
• examination or technique 2.0
• 7.Prior examination : A finding is missed because of failure to consult prior
• radiologic studies or reports 5.0
• 8.History : A finding is missed because of inaccurate or incomplete clinical history 2.0
• 9.Location A : finding is missed because of the location of a lesion outside
• the area of interest on an image “tunnel vision”, “scrolling error”,
• “innattentional blindness” ,”gorilla in the midst syndrome”. 7.0

• 10.Satisfaction of search : A finding is missed because of failure to continue to
• search for additional abnormalities after the first
• abnormality was found , Premature termination 22.0
• 11.Complication : A complication from a procedure 0.5
• 12.Satisfaction of report (alliterative error: “I saw a saw that could out saw any other saw I ever
saw”; aliteracion : “tres tristes tigres “)
• A finding was missed because of overreliance on the radiology report from a
previous examination ; error in one report followed by error in next report” 6
• CONCLUSION:
• Delayed diagnoses were not recognized on subsequent radiologic examinations in about one
third of the cases. The most common types of error were underreading , satisfaction of
search, faulty reasoning, and location of the finding.
• Kim YW, Mansfield LT. Fool me twice: delayed diagnoses in radiology with emphasis on perpetuated errors. AJR Am J
Roentgenol 2014;202(3):465–470.

Most common biases
• A) anchoring bias: locks onto some salient feature too early in the diagnostic
process and discounts conflicting or new information gained subsequently .
• B) availability bias : recent experience with a disease may inflate the future
likehood of its being diagnosed again (conversely, if a disease has not been see for
a long time, it may be underdiagnosed).
• C) confirmation bias : look for confirmatory evidence to support a diagnostic
hypothesis and to ignore evidence that refutes the hypothesis .
• D) outcome bias, preference to opt for diagnosis decision that will lead the patient
to a better final outcome
• E) zebra retreat , self doubt about a remote or unusual diagnosis even though the
patient ‘s history and imaging finding support it .
• F) frame bias: initially viewing the images prior to reading the clinical details

Human brain
• The human brain is a network of about 20 billion
neurons – nerve cells – linked by several trillion
connections. Not to mention glial cells, which
scientists used to think were inactive scaffolding,
but increasingly view as an essential part of how
the brain works. Our brains give us movement,
language, senses, memories, consciousness and
personality. We know a lot more about the brain
than we used to, but it still seems far too
complicated for human understanding.

Human brain
• Many of these simple networks occur in the visual system. We used to
think that the eye was like a camera, taking a “snapshot” of the outside
world that was stored in the brain like a photo stuck in an album. It uses a
lens to focus an image on to the retina at the back of the eye, which
functions a bit like a roll of film – or, in today’s digital cameras, a charge-
coupled device, storing an image pixel by pixel. But we now know that
when the retina sends information to the brain’s visual cortex, the
similarity to a camera ends.
• Although we get a strong impression that what we are seeing is “out
there” in front of us, what determines that perception resides inside our
own heads. The brain decomposes images into simple pieces, works out
what they are, “labels” them with that information, and reassembles
them.
• An effective way to infer how something functions is to see what it does
when it goes wrong. It may be hard to understand a bridge while it stays
up, but you can learn a lot about strength of materials when it collapses.

Most common illusions of sensations in
Radiology :Mach bands and background
effects

Selective looking
• It is a well-known phenomenon that we do not
notice anything happening in our surroundings
while being absorbed in the inspection of
something; focusing our attention on a certain
object may happen to such an extent that we
cannot perceive other objects placed in the
peripheral parts of our visual field, although the
light rays they emit arrive completely at the visual
sphere of the cerebral cortex.'' Rezso« Ba¨lint
1907 (translated in Husain and Stein 1988, page
91)

Gorilla in the mist syndrome
• https://www.youtube.com/watch?v=wdVXco6
YDgg
• 48 times the size of the nodules.
• 83% of radiologist did not see the gorilla.

Selective looking :
UNDER-READING (MISSED FINDING )
2014
2015
2016

F/U lung lesion ; missed oesophageal cancer.

Selective looking :
Acute appendicitis ; missed oesophageal cancer.

Selective looking :
Ca prostate ; missed tiny met in the R ischial tuberosity

Selective looking :

Pellegrini –Stieda: window setting and zoom

Sleeve patellar fracture: window
and magnification .

Subchondral lesion : window setting

Window setting

3 days before
Cardiac arrest
Always compared with previous available exams

Window setting : background

Check the veins and nodes

Window setting : background liver window width and level for pancreas

CHANGE WINDOW SETTING (BACKGROUND): NEVER REPORT A VENOGRAM
OR ANGIOGRAM WITHOUT A BASE LINE CT OR MRI

Apart of checking the appendix check the terminal ileum for skip lesions

Tiny RCC

Look very carefully when only one kidney is left after RCC

?cyst

No everything is a cyst

Review skull base, mandible , paranasal sinuses , orbits …

UNDER-READING (MISSED FINDING )?
Reported normal.

UNDER-READING (MISSED FINDING )?
Was quite normal. 

SATISFACTION OF SEARCH
Check the arteries

Peritoneal nodules ; missed PE

Prostate ca , missed rectal cancer.

R renal calculus ; missed peritoneal nodules.

Shoulder arthrography ; missed lung nodule

Ground-glass infiltrates, missed ribs fractures

Lung tumour; missed PE in middle lobe and rib fracture

FAULTY REASONING
Apart of meningioma there are dural calcifications and osteomas

FAULTY REASONING
Calcified pseudotumor of the neuroaxis

FAULTY REASONING
Active Paget , melanoma metastasis : never r/o metastasis .

FAULTY REASONING
Diaphragmatic Slip (muscular bundles that cause hepatic invagination in a patient with
stomach antral ca )

FAULTY REASONING
Focal lesion in L1 with subtle low T1 signal and high signal on T2/STIR: H/O thyroid ca ;
Possible atypical haemangioma but f/u to r/o met : is a fat poor haemangioma .

FAULTY REASONING :20 Y OLD FEMALE
CARDIAC AREST AFTER ANAPHILAXIS
CT T2W

FAULTY REASONING :HYPOXIC
ISCHEMIC ENCEPHALOPATYY
20 years 10 years
T2W

20 years 12 years
DWI

ADC

ABNORMALITIES OUTSIDE AREA OF INTEREST
(BUT VISIBLE)
Mass and lymphadenopathy : lymphoma , sarcoma , fibrous histicocytoma
Diagnostic : Castleman Disease: angio-follicular lymph node hyperplasia

(BUT VISIBLE)
RCC seen in the localizer for lumbar spine : look to all localiser

(BUT VISIBLE)
2018 2019

(BUT VISIBLE)
2020

SATISFACTION OF REPORT:ALLITERATIVE
REASONING
index
Perforation and f/u

SATISFACTION OF
REPORT:ALLITERATIVE REASONING
X 2 X 4 X 7
Always check again

SATISFACTION OF

SATISFACTION OF
Patient with breast cancer : looks for mets: missed small meningioma , satisfaction
of search and alliaterative reasoning : 2013, 2014, 2016, 2016, 2017, 2019 bingo 2020!

INACCURATE OR INCOMPLETE CLINICAL HISTORY
Breast mets: I did not check previous CT
4 years before : sarcoid

CORRECT REPORT FAILING TO REACH
REFERRING CLINICIAN
2016 2016 2017
Inspissated bile Wall-thickened Tumour vs.
abscess
Significant finding overlooked
because was no in the conclusion
Referred for GB polyp

History
82 y/o F : epigastric pain , weight loss , dysphagia : recent OGD normal, US normal.
CT: no sinister but has oesophageal cancer at OGJ : normal OGD !!

Individual performance
• No follow Gaussian (normal) distribution but Paretian (power) distribution
where most performers are below “average”, and thus less productive and
more likely to make mistakes than the super-performers.

Factors/causes of errors
• Technique or Image acquisitions errors : the
lesion is hidden due to limited or suboptimal
scanning .
• Perceptual /cognitive /interpretative
• External causes and communications

Perceptual /cognitive /interpretative
• Training , Experience, Intellect
• Concentration ,Perceptual skill
• Fatigue, illness , mood
• Shortcuts: viewing one place
• Failing to optimized tools : window setting
• Attempting to interpret grossly poor quality
images.
• Failure to compare to all previous images or
pertinent studies available

Improvement 1
• Look at the image as it belong to your best friend.
• Training
• Attending courses
• Peer review
• Discrepancy ,MDT and morbimortality meetings .
• Share diagnostic mistakes
• Perform our own interpretation before reading the
previous radiology report to avoid alliterative errors
• Pay attention to the first and last image , to the scout
view or localizer , at the corners .

External causes and communications.
• Heavy workloads : ER , large volume of cases , fast turnaround ,
many study in short period, numerous body part.
• Distractions : noise, chat , phone calls (increased 12% like hood of
error).Internet , whatsapp , mails .
• Overly rapid pace.
• Failure to review the voice recognition ; copy-paste errors ,
template.
• Failure to communicate regarding unexpected important finding.
• Failure of PACS server to retrieve prior exam .
• Lack of immediate online diagnostic references resources.
• Tele radiology services

More improvements
• Quality management (QI: Quality Improvement
)activities: Events and Learning meetings , audits,
continuing education, appraisal .
• Check-list : reduce errors of omission in a wide
variety of fields including aviation, critical care
medicine and presumably radiology. Widely used
on PET-CT; remind radiologist to take a second
look at certain aspects , areas , and features of
the images.

More improvements
• Structured report; standardizing, for cancer,
measurements . Thyroid US , mammography BI-RADS
, Prostate PI-RADS , CT colonography Classification ;
etc improving communication .
• Double reading : widely used in mammography
reading .
• PET-CT, computer-aided detection and Artificial
intelligence (AI): highlight neglected areas in
mamography, lung nodule detection , Ct
colonography .
• Improving individual physician factors.

Learning from discrepancy meeting
• 1. A reporting discrepancy occurs when a
retrospective review, or subsequent information
about patient outcome, leads to an opinion
different from that expressed in the original
report.
• Acceptance of the concept of necessary fallibility
needs to be encourage; public education can help
. Fortunately , many errors identified by
retrospective reviews are of little or no
significance to patient ; conversely , some
significant errors are never discovered (A.Brady)

Hindsight bias
• “Tendency for people with knowledge of the
actual outcome of an event to believe falsely
that they would have predicted the outcome
“(Berlin , L)

Experts
• One who knows more and more about less
and less until he knows absolutely everything
about nothing .

CUOTE
• IT IS SAID, THE WISE LEARN
FROM THE MISTAKES OF OTHERS,
THE SMART LEARN FROM THEIR
OWN MISTAKES, AND THE
FOOLISH LEARN FROM NEITHER.

REFERENCES
•
• Daniel Kahneman. Thinking, Fast and Slow. Farrar, Straus and Giroux , ISBN 978-0-347-27563-1;
2013.
• Michael A Bruno et al . Understanding and Confronting Our Mistakes: The Epidemiology of Error in
Radiology and Strategies for Error reduction .RadioGraphics 2015; 35:1668-1676.
• Common patterns in 558 diagnostic radiology errors. Jennifer J Donald and Stuart A Barnard.
Journal of Medical Imaging and Radiation Oncology 56 (2012)173-178
• Adrian P Brady .Error and discrepancy in radiology: inevitable or avoidable?. Insights Imaging
(2017)8: 171-182
• Stuart E Mirvis. Toward decreasing diagnostic errors. The Journal of Practical Medical Imaging and
Management .
• Young W Kim and Liem T Mansfield. Fool Me Twice: Delayed Diagnoses in Radiology With Emphasis
on Perpetual Errors. AJR 2014; 202: 465-470
• Adrian Brady et al. Discrepancy and Error in Radiology: Concepts, Causes and Consequences .
Ulster Med J 2012; 81(1): 3-9
• The RCR : REAL , Radiology Events and Learning . real@rcr.ac.uk
• Clinical radiology. The RCR : Standards for Learning from Discrepancy Meetings. www.rcr.ac.uk
• Christopher E. Bickle et al . Now You see It , Now you Don’t: Visual Illusions in Radiology .
RadioGraphics 2013; 33:2087-2102.
•

Swirl sign
85 y/o woman :Lobar haemorrhage . Almost no surrounding
edema. The basal ganglia are spared. Low density in the core
In keeping with active bleeding . Severe edema effacing
the sulci and sylvian fissure.

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