Easily Missed Findings in Emergency Radiology

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Easily Missed Findings in Emergency Radiology
Case-based session 1 Brain
Diego B Nunez Jr. MD. MPH.
Clinical Professor and Chairman
Department of Radiology-Hospital of St. Raphael
Yale University School of Medicine
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OBJECTIVES

• Illustrate frequent diagnostic errors when
  interpreting emergent brain imaging using common
  clinical scenarios Learning from
  mistakes
• Review the diagnostic clues and risk management
  pointers that can minimize perception and
  interpretation errors and their consequences

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Errors in Radiology

• Perceptual errors
  False negative
  interpretation or misses (finding not seen)
• Cognitive/interpretation errors
  Failure to
  recognize the ramifications or significance of a
  finding. Usually the result of poor
  judgment, incomplete knowledge or technical
  factors
  

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Which of the following representsthe most common
type of error when interpreting emergent brain CTs

• The finding is missed
• Overeading/misinterpresting a
  finding as abnormal
• The finding is identified but passed as
  normal or insignificant
• The finding is identified but attributed to
  the wrong disease

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Perceptual errors are most common
Errors in Radiology
Berlin Hendrix, AJR 170863
Errors on Head CT typically result from
subtle perceptual misses rather than from
faulty interpretation of a finding once it is
recognized
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This patient had a 24 hour follow up CT that
revealed an obvious infarct. Where will it be?

• Left cerebellum
• Pons
• Left frontal
• Right parietal

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(No Transcript)
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10/31/08
Missed MCA clot
Left frontal opercular infarct
11/1/08
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Post Traumatic (Neck hyperextension) Right
Internal Carotid Dissection and MCA Infarct
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Why do we miss pertinent findings?

• Incomplete clinical information
• Subtle, inconspicuous finding
• Coexisting findings/lesions
• Unexpected or unusual presentation of disease

Factors related to the interpreter !
A. Satisfaction of search error (multiple
abnormalities) B. Inadequate search error (no
systematic approach) C. Errors of analysis
(lack of knowledge)
Errors of omission and communication
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Indication Trauma
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Convexity midline fracture, epidural hematoma
and unsuspected right frontal contusion
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Indication CVA
Infarct in opposite side than suspected. CVA is
not enough
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Why do we miss pertinent findings?

• Incomplete clinical information
• Subtle, inconspicuous finding
• Coexisting findings/lesions
• Unexpected or unusual presentation of disease

Factors related to the interpreter !
A. Satisfaction of search error (multiple
abnormalities) B. Inadequate search error (no
systematic approach) C. Errors of analysis
(lack of knowledge)
Errors of omission and communication
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(No Transcript)
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28 y.o. patient with severe craniofacial trauma
Acutely expanding epidural hematoma
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isodense subdural hematoma
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28 y.o. front passenger involved in major
collision. Depressed sensorium.
Glasgow score 6.
Hemodynamically stable
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48 y.o. woman with increasing headaches for 2
days
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Intracranial hypotension syndrome

• Orthostatic headaches and neck pain, nausea and
  vomiting. Diverse origin
• Most cases related to CSF leak (dural
  violation)

Thick dura without leptomeningeal enhancement
Downward displacement of the brain and
enlarged pituitary gland
Subdural fluid collections
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Why do we miss pertinent findings?

• Incomplete clinical information
• Subtle, inconspicuous finding
• Coexisting findings/lesions
• Unexpected or unusual presentation of disease

Factors related to the interpreter !
A. Satisfaction of search error (multiple
abnormalities) B. Inadequate search error (no
systematic approach) C. Errors of analysis
(lack of knowledge)
Errors of omission and communication
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64 y.o with left sided weakness

• Suprasellar Meningioma

• Right Pontine Infarct

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57 y.o. ED patient with right sided weakness
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3. Coexisting lesions Meningioma infarct
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3. Coexisting lesions as a cause of perceptual
error
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72 y.o. female found unconscious
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Satisfaction of search errors
We stop the search after detecting the obvious
finding! The obvious captures attention and
decreases vigilance for more subtle abnormalities

• Use automatic check lists
• Systematic approach to image interpretation

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Why do we miss pertinent findings?

• Incomplete clinical information
• Subtle, inconspicuous finding
• Coexisting findings/lesions
• Unexpected or unusual presentation of disease

Factors related to the interpreter !
A. Satisfaction of search error (multiple
abnormalities) B. Inadequate search error (no
systematic approach) C. Errors of analysis
(lack of knowledge)
Errors of omission and communication
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4. Unexpected presentation of disease
Inadequate Search Error

• Areas not often included in the search
  pattern in the emergency/on-call setting

• Lack of checklist approach
• Emphasize in resident education

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Unexpected presentation of disease
Rotation/Posterior fossa artifact
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Cognitive/interpretation errors

• Failure to recognize the ramifications or
  significance of a finding.

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The most commonly unrecognized lesion in emergent
neuroimaging is

• 1. Facial fractures
• 2. Subdural hematoma
• 3. Cervical spine fracture
• 4. Missed or undercalled stroke

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The most commonly unrecognized lesion in emergent
neuroimaging is

• 1. Unrecognized hemorrhage 15
• 2. Missed or undercalled stroke 22
• 3. Cervical (spine/airway) lesion 14
• 4. Missed facial fracture 11

Branstetter et al Articles from RSNA 2005
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Only one of these patients has an infarct
1
2
3
5
4
4
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Early CT signs of ischemia
Dense MCA
Insular ribbon
Hypodense Basal ganglia
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65 y.o. male patient with Rt. arm weakness and
facial droop with mild impairment of language
expression
Detection facilitated by soft-copy visual review
at a PACS workstation with variable non-standard
window and center level settings
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Why do we miss pertinent findings?

• Incomplete clinical information
• Subtle, inconspicuous finding
• Coexisting findings/lesions
• Unexpected or unusual presentation of disease

Factors related to the interpreter !
A. Satisfaction of search error (multiple
abnormalities) B. Inadequate search error (no
systematic approach) C. Errors of analysis
(lack of knowledge)
Errors of omission and communication
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1

• Necrotizing encephalitis in adults
• Acute confusion, seizures, fever, coma
• Speech impairment (temporal lobe)
• Typical distribution temporal lobes, insula,
  orbitofrontal region and cingulate gyrus
• 75 mortality if untreated. Early Dx.

Patient 1 Herpes Simplex Encephalitis (Type 1)
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Brain abscesses
Patient 3 35 y.o. female with Crohns disease
who presents to the ED with 3 days history of
headaches and right sided weakness
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Patient 4- 66 y.o patient with right hemiparesis
DX. Glioblastoma
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Patient 5 MT Lung Ca initially dx. as infarct
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THE FALSE POSITIVES
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Meningioma mimicking epidural hematoma in
trauma patient
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4 different ED patients- Only 1 has a significant
finding
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1
2
3
4
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Motion and positioning artifacts
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False dense MCA sign
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Patient 3 False Subarachnoid hemorrhage
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• Beam hardening non-uniform x ray beam
• attenuation through uneven skull thickeness

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4
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Patient 4 Venous sinus thrombosis
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23 y.o female patient brought to the ED after
seizures and rapid onset of aphasia
Superior Sinus Thrombosis Venous Hemorrhagic
Infarct
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CT Delta sign
MR Delta Sign
High density triangle

• Acute dehydration
• Hypercoagulable states
• Chemotherapy
• Infection (sinus, meninges)
• Pregnancy
• Trauma

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Other Frequently Missed Diagnoses in Emergent
Neuroimaging

• Subarachnoid hemorrhage
• Incidental aneurysms
• Suprasellar mass/Skull base lesions

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Other Frequently Missed Diagnoses in Emergent
Neuroimaging
48 y.o. female patient presents with acute onset
headache
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Subarachnoid hemorrhage
Can be subtle
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MVA. Minor head trauma?
Right frontal subarachnoid hemorrhage
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Errors in Emergent Neuroimaging

• Review of diseases
  Acute ischemia, SAH, small/isodense extraaxial
  collections, DAI
• Specific locations
  Posterior fossa, skull base, interhemispheric
  fissure, and interpeduncular cistern
• Common false
  motion, rotation, beam hardening artifacts, dense
  MCA

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Avoiding errors Risk imaging pointers

• Pay proper attention to clinical information!
• Look at the images before reading prior reports
• Be willing to take a second look, particularly
  when requested by a concerned clinician
• Systematic approach to image interpretation Be
  aware of alternate presentation of disease and
  recognize the anatomic sites where lesion
  perception may be difficult, i.e. posterior fossa
  and skull base.

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Avoiding errors Risk imaging pointers

• Remember ! The diagnostic possibilities in
  emergent brain CT are relatively limited and we
  typically miss subtle findings
• Significant on-call errors made by residents can
  be minimized by focusing our teaching on the
  perceptual manifestations of Neuroradiology