Drs. Faith Meyers and Steven Perry are Emergency Medicine Residents at Carolinas Medical Center and interested in medical education. Along with the guidance of Dr. Michael Gibbs (Chair of Emergency Medicine), Dr. Jonathan Clemente (Chief of the Department of Radiology and Neuroradiology specialist), and Dr. Scott Wait (Chief of Pediatric Neurosurgery) they aim to help educate us on Neuroimaging. In this initial educational slideset, they are also joined by Dr. Andrew Perron, the creator of the “Blood Can Be Very Bad” Head CT interpretation framework. Follow along with the EMGuideWire.com team as they post the CMC Neuroimaging Case Studies. This set will cover: - The Neuroimaging Framework “Blood Can Be Very Very Bad.”

1. Blood Can Be Very Very Bad
A Head CT Interpretation Primer
Faith Meyers, MD & Steven Perry, MD
Department of Emergency Medicine
Carolinas Medical Center & Levine Children’s Hospital
Andrew Perron, MD - Guest Author
Department of Emergency Medicine, Dartmouth Health
Neuroimaging Case Studies #1
Michael Gibbs, MD – Lead Editor

2. Disclosures
▪ This CMC Imaging Mastery Project is proudly sponsored by the
Emergency Medicine Residency Program at Carolinas Medical Center.
▪ The goal is to promote widespread mastery of imaging interpretation.
▪ There is no personal health information [PHI] within, and when
included, all ages have been changed to protect patient confidentiality.

3. Dr. Perron Is Currently The Associate Dean of Graduate Medical Education As Well As The
Designated Institutional Official (DIO), At Dartmouth Health.
Dr. Perron Completed The
CMC EM Residency 1995 – 1998
(Chief Resident In 1998).
We Are Fortunate That Dr. Andrew Perron, Creator Of The “Blood Can Be Very Bad”
Head CT Interpretation Framework, Is Joining Us As A Guest Author For Our Very First
Neuroimaging Case Studies Presentation Of This New Series!

4. Objectives
▪ This presentation will provide you with a structured, evidence-based
approach to head CT interpretation.
▪ Future presentations will review specific neuroimaging topics using a
case-based approach, supported by the latest, most relevant literature.

5. Meet Our Neuroimaging Editorial Team
Andrew Asimos, MD, FACEP
Medical Director, Carolinas Stroke Network
Neurosciences Institute
Clinical Professor, Department of Emergency Medicine
Jonathan Clemente, MD, FACR
Chief, Department of Radiology, Carolinas Medical Center
Charlotte Radiology, Neuroradiology Section
Adjunct Clinical Associate Professor, Department of Radiology
Scott Wait, MD, FAANS
Chief, Pediatric Neurosurgery, Levine Children’s Hospital
Carolina Neurosurgery & Spine Associates
Adjunct Clinical Associate Professor, Department of Neurosurgery

6. Annals of Emergency Medicine 1998: 32(5):554-562.
Blood Can Be Very Bad
B = Blood
C = Cisterns
B = Brain
V = Ventricles
B = Bone
Purpose: To Quantify The Baseline Ability Of Emergency Medicine Residents To Interpret Cranial CTs And
To Test A Novel Method Of Cranial CT Interpretation Designed For Emergency Physicians In Training.

7. Annals of Emergency Medicine 1998: 32(5):554-562.
Methods:
• Pretest to assess baseline knowledge
• 2-hour course based on the “Blood Can Be Very Bad” framework
• Post-test 3 months following instructional training
Results:
83 residents from 5 different institutions were enrolled.
Pretest % Correct: 60% Post-Test % Correct: 78%
Conclusion:
A novel, structured approach to head CT interpretation significantly
improved the diagnostic accuracy of emergency medicine residents.1
195% CI 71%–85%, P<0.001, paired t test.

9. “V” For Vessels Was Later Added To The Mnemonic:
“Blood Can Be Very Very Bad”

10. Blood Can Be Very Very Bad
A Structured Approach To Head CT Interpretation

11. A Few CT Basics Before We Start

12. 0 +40 +80 +1000
-1000 -40
-80
H20
⫽
⫽
Brain
CT Basics: Density
Blood
The Denser The Object, The Whiter It Is On CT
Bone
Air
Hounsfield Units

13. Standard Brain Bone
CT Basics: Windowing
Focuses The Spectrum Of Gray-Scale Used On A Particular Image

14. CT Basics: Windowing
Standard Brain
In This Case The Same
Image Is Seen With Two
Different Windows:
Windowing Alters The
Appearance And Contrast
Between Different Components
Of The Image. This May Make It
Easier To Identify Hemorrhages
That Are Either Subtle And/Or
Isodense With The Adjacent
Bone Or Brain.

15. CT Basics: Windowing
In This Case Bone Windows
(Two Lower Images) Provide
Improved Anatomic
Definition To A Vertex Skull
Fracture.

16. Acute Subacute Chronic
CT Basics: The Appearance Of Blood Over Time
Category Timing Appearance Compared With Brain
Acute 1 – 3 Days Bright White Hyperdense
Subacute 3 – 14 Days Light Gray Isodense
Chronic >14 Days Dark Gray Hypodense

17. •Blood
•Cisterns
•Brain
•Ventricles
•Vessels
•Bone
Blood Can Be Very Very Bad

18. B Is For Blood

19. B Is For Blood
Classification:
• Epidural
• Subdural
• Intraparenchymal
• Intraventricular
• Cerebellar
• Subarachnoid

20. B Is For Blood
Decision Making:
Question #1 Is blood present (yes/no)?
Question #2 What type of hemorrhage is it?
Question #3 Where is the bleeding located?
Question #4 What effect is it having?
Question #5 Are any immediate actions required?

21. B Is For Blood
Decision Making:
Question #1 Is blood present (yes/no)?
Question #2 What type of hemorrhage is it?
Question #3 Where is the bleeding located?
Question #4 What effect is it having?
Question #5 Are any immediate actions required?
Possible Immediate Actions:
• Hemodynamic stabilization?
• Airway protection?
• Anticoagulation reversal?
• Hyperosmolar therapy?
• Urgent consultation?
• Immediate transfer?
• Preparation for an urgent
procedure?
Possible Urgent Procedures:
• Hematoma evacuation?
• External ventricular drainage?
• ICP monitor placement?

22. Epidural Hematoma
• Classically described as an injury to
the middle meningeal artery
• If treated early (prior to coma),
mortality is low, i.e.: <20%
CT Features
• Lens-shaped
• Does not cross cranial sutures

23. 23-Year-Old In A
Car Crash
50-Year-Old
Fell Off A Ladder
37-Year-Old
Pedestrian Struck
Epidural Hematoma Cases From CMC

24. 40-Year-Old Fell
With A Head Strike
17-Year-Old Fell Off
His Skateboard
66-Year-Old
Pedestrian Struck
Epidural Hematoma Cases From CMC

25. Subdural Hematoma
• Acute SDH is a marker of severe
brain injury (mortality up to 80%)
• Chronic SDH results from slow
venous bleeding and is generally well
tolerated
CT Features
• Falx or sickle-shaped
• Crosses sutures but does not cross
the midline

26. Acute 1-3 Days Hyperdense (80-100 HU) relative to brain
Subacute 3-14 Days Variable density relative to brain
Chronic >14 Days Hypodense (<40 HU) relative to brain
Hounsfield
Units
Days
Hyperdense
Isodense
Hypodense
Subdural Hematoma CT Scan Density Decreases Over Time
100
20
1 14
Neurosurgery Clinical of North America 2017; 28:247-255.

27. Acute Subdural Hematomas (1-3 Days) – 3 Case Examples
Subdural Hematoma

28. Standard Window Brain Window CT Angiogram
Subdural Hematoma
Subacute Subdural Hematoma (3-14 Days) – Windowed In The Same Patient

29. Subdural Hematoma
Chronic Subdural Hematomas (>14 Days) – 3 Case Examples

30. Tentorial SDH Parafalcine SDH
Tentorial SDHs Layers On Top
Of The Tentorium Cerebelli.
Parafalcine SDHs Are Seen
Adjacent To The Falx Cerebri.
Subdural Hematoma

31. Parafalcine Subdural Hematoma
53-Year-Old In A Motor Vehicle Crash

32. Tentorial Subdural Hematoma
77-Year-Old Presents After A Fall

33. Intraparenchymal Hemorrhage
Hemorrhage within the brain substance:
• Hypertensive
• Spontaneous
• Traumatic
• Anticoagulation-associated
CT Features
• Appearance is location-dependent
• May involve the ventricles

34. Classic Patterns Of
Hypertensive
Intraparenchymal
Hemorrhages
Pontine 10%
Putamen /External Capsule 65% Lobar 10%
Thalamic 15%

35. Intraventricular Hemorrhage
Results when an intraparenchymal
hemorrhage ruptures into the
ventricular cavity
CT Features
• Blood in the ventricular system
• May or may not see obstructive
hydrocephalus, depending on the
hemorrhage site and amount

36. 59-Year-Old With A History Of Hypertension Presents Minimally Responsive.
Arrow (→) Demonstrates Blood Filling The 4th Ventricle

37. 64-Year-Old With A History Of Hypertension Presents With Headache And Confusion.

38. 47-Year-Old With A History Of Hypertension Collapses At Home.

39. Cerebellar Hemorrhage
A neurosurgical emergency that
often requires immediate surgical
decompression
CT Features
• Hemorrhage in the posterior fossa
• High-risk features:
• Brainstem compression
• Loss of basilar cisterns
• Acute hydrocephalus

40. 49-Year-Old Found Unresponsive On The Floor By His Wife.

41. 79-Year-Old Female Presents In Coma.
Acute Cerebellar Hemorrhage With Mass Effect And Obstructive Hydrocephalus.
Arrows (➛) Demonstrate Transependymal Flow Of CSF. This Occurs When Intraventricular Pressure Exceeds
The Ability of CSF To Remain Within The Ventricles, Causing It To Extrude Into The Substance Of The Brain.

42. 50-Year-Old With Headache, Vomiting And Ataxia

43. Subarachnoid Hemorrhage
CT Features
Blood in the cisterns, sulci, and/or on
the cortical surfaces
Cerebral Aneurysms 75% - 80%
AV Malformations 5%
Vasculitis <1%
No Cause Identified 10%

44. N Engl J Med 2006;355:928.

45. 43-Year-Old With Uncontrolled Hypertension Presents With An Acute Headache.

46. 43-Year-Old With Hypertension And Acute Headache.
ACOM Aneurysm

47. Anterior Communicating Artery Aneurysm Endovascular Coil
43-Year-Old With Uncontrolled Hypertension Presents With Acute Headache.

48. 57-Year-Old With Severe Headache And Vomiting.
57-Year-Old With Severe Headache And Vomiting.

49. Right Middle Cerebral Artery Aneurysm Endovascular Coil
57-Year-Old With Severe Headache And Vomiting.

50. • Blood
•Cisterns
• Brain
• Ventricles
• Vessels
• Bone
Blood Can Be Very Very Bad

51. C Is For Cisterns

52. C Is For Cisterns
• The cisterns represent potential spaces between adjacent brain
structures.
• When extra volume is added to the brain “case” (blood, edema,
tumor) these potential spaces may become compressed. This can be
a radiographic sign of ongoing or impending intracranial
hypertension.
• On CT, the cisterns at the base of the brain are typically described as
either “open” or “effaced”/ “obliterated” (closed).

54. Pons
Suprasellar
Cistern
Cerebral Aqueduct
(4th Ventricle)
Perimesencephalic
Cistern
Effaced Basilar Cisterns In A Patient
With A Cerebellar Mass (*)
High Pontine Level
Normal/Open
*

55. Cerebral
Peduncle
Suprasellar
Cistern
Quadrigeminal
Cistern
Effaced Basilar Cisterns In A Patient
With A Large Subdural Hematoma (*)
Cerebral Peduncle Level
Normal/Open
*

56. Quadrigeminal
Cistern
Sylvian
Cistern
Interhemispheric
Cistern
Effaced Basilar Cisterns In A Patient With
Diffuse Subarachnoid Hemorrhage
Mid-Brain Level
Normal/Open

57. Effaced Basilar Cisterns In A Patient With
Diffuse Subarachnoid Hemorrhage
Effaced Basilar Cisterns In A Patient
With A Cerebellar Mass
Effaced Basilar Cisterns In A Patient With
A Large Subdural Hematoma
Mid-Brain Level Cerebral Peduncle Level High Pontine Level
Normal/
Open
Normal/
Open
Normal/
Open

58. • Blood
• Cisterns
•Brain
• Ventricles
• Vessels
• Bone
Blood Can Be Very Very Bad

59. B Is For Brain

60. B Is For Brain
• Examination of the brain is complex, with many potential diagnoses
• Interpretation strategy:
Assess for:
• Symmetry
• Shift
• Gray-white differentiation
• Areas of hyper- or hypoattenuation
• Pneumocephalus
Step 1: What do you see?
Step 2: What could it represent?

61. CT Findings
• Irregular circular density of the left temporal area
• Loss of overlying sulci
• Moderate effacement of the left lateral ventricle
What Do You See?
• Symmetry – Discrete region of asymmetry
• Shift – None grossly
• Gray-white differentiation – Abnormal
• Areas of hyper/hypo-attenuation – Discrete
hypo-attenuated area
• Pneumocephalus – none
49-Year-Old With Headache And
Right Leg Weakness & Numbness.
What Could It Represent?
• Neoplasm, hygroma, abscess, metastasis, infarct

62. T1
T2 FLAIR
Contrast
49-Year-Old With Headache And
Right Leg Weakness And Numbness.
MRI W/ and W/O Contrast Reveals
Left Temporal Abscess With Edema

63. 32-Year-Old With Headache, Nausea,
Fever, Altered Mental Status.
What Do You See?
• Symmetry – Discrete region of asymmetry
• Shift – Focal anterior midline shift rightward
• Gray-white differentiation - Abnormal
• Areas of hyper/hypo-attenuation – Discrete
• hypo-attenuation, surrounding hyper-
attenuation
• Pneumocephalus – punctate area L frontal lobe
What Could It Represent?
• Neoplasm, hygroma, abscess, metastasis, infarct
CT Findings
• Circular density of the left frontal lobe
• Surrounding edema
• Punctate dot of air beneath the frontal bone

64. T1
32-Year-Old With Headache, Nausea,
Fever, Altered Mental Status.
MRI W/ and W/O Contrast Reveals
Left Frontal Abscess
T1
T2 FLAIR
Contrast

65. Classic MRI Findings of Intracranial Abscess and Empyema
FLAIR : Vasogenic Edema T2: Dark Hemosiderin Rim DWI : Restricted Diffusion T1+ : Ring Enhancing
Abscess
Subdural
Empyema
DWI : Restricted Diffusion
T1+ : Rim Enhancing T1+ : Rim Enhancing
Diffusion
Weighted Imaging
(DWI) is key to the
imaging diagnosis.
Abscess and
empyema will
typically show
“lightbulb bright”
restricted diffusion
centrally.

66. 34-Year-Old With A History Of
Migraines Presents With Two Weeks
Of Headache, Nausea, And Confusion.
CT Findings
• Large area of hypoattenuation of the left frontal-
parietal cortex
What Do You See?
• Symmetry – Diffuse asymmetry
• Shift – Midline shift rightward
• Gray-white differentiation - Abnormal
• Areas of hyper/hypo-attenuation – Large area of
hypo-attenuation L hemisphere
• Pneumocephalus – none
What Could It Represent?
• Neoplasm, hygroma, abscess, metastasis, infarct

67. MRI W/ and W/O Contrast Reveals
A Mass With Surrounding Edema
34-Year-Old With A History Of
Migraines Presents With Two Weeks
Of Headache, Nausea, And Confusion.
T1 Contrast T2
FLAIR

68. Gray-White Differentiation On CT Imaging
Normal Gray-White Differentiation
In The Healthy Brain The Gray And White Matter
Can Be Distinguished By Their (Adjacent) Different
Shades Of Gray.
Loss Of Gray-White Differentiation
This Is A Radiographic Sign Of Cerebral Edema.
Local: Ischemia, Inflammation, Infiltration
Global: Prolonged Hypoxia And Or Hypotension
Notice The Difference On The Next Slide…

69. 35-Year-Old Presents In Coma Following Cardiac Arrest Due To An Opioid Overdose.
CT Demonstrates Diffuse Loss Of Gray-White Differentiation And Cistern Effacement.
35-Year-Old Healthy Patient With A Normal Head CT

70. • Blood
• Cisterns
• Brain
• Ventricles
•Vessels
• Bone
Blood Can Be Very Very Bad

71. V Is For Ventricles

72. V Is For Ventricles
• Cerebral spinal fluid (CSF) is a clear, colorless fluid that bathes and
cushions the brain and spinal cord
• CSF is secreted by the choroid plexus in the lateral and 4th ventricles
• CSF secretion equals its removal, with 150-250cc present at all times
• Abnormal CSF flow may affect the size of the ventricles

73. Ventricular System

74. Normal Flow Of Cerebrospinal Fluid

75. Hydrocephalus
Non-Communicating Hydrocephalus
Occurs when the flow of CSF is blocked along one or more of the narrow passages connecting
the ventricles.
Communicating Hydrocephalus
Occurs when the flow of CSF is blocked after it exits the ventricles. The word “communicating”
refers to the fact that CSF can still flow between the ventricles, which remain open.
Congenital Hydrocephalus
Is present at birth and may be caused by either events or influences that occur during fetal
development, or genetic abnormalities.
Acquired Hydrocephalus
Develops at the time of birth or at some point afterward. This type of hydrocephalus can affect
individuals of all ages and may be caused by injury or disease.

76. Lateral
Ventricles
Atrium Occipital
Horn
Lateral
Ventricles
Atrium Occipital
Horn

77. Occipital
Horn
Third
Ventricle
Frontal
Horn
Foramen of
Monro

78. Frontal
Horns
Third
Ventricle
Sylvian
Fissure

79. 75-Year-Old Presents With One Month Of Unsteadiness And Frequent Falls. CT Imaging Demonstrates A
4.7 cm Mass Pressing On The Pons And Medulla (*) Causing Acute Obstructive Hydrocephalus.
Clear Lateral Ventricle
Enlargement Occipital Horn
Enlargement
Pronounced
Third Ventricle
Temporal Horn Becomes
Clear (“Comma Sign”)
*

80. 2-Month-Old With Congenital Hydrocephalus.
T1
T2
Cranial MRI

81. 52-Year-Old Presents With Acute Headache And Confusion. CT Demonstrates Diffuse Subarachnoid Hemorrhage That
Fills The Basilar Cisterns. There Is Blood In The Cerebral Aqueduct (➛) Causing Acute Obstructive Hydrocephalus.
➛

82. 33-Year-Old With Chronic Hydrocephalus

83. • Blood
• Cisterns
• Brain
• Ventricles
• Vessels
•Bone
Blood Can Be Very Very Bad

84. V Is For Vessels

85. Vascular Territories Of The Cerebrum

86. Hyperdense Artery Sign
Increased arterial density representing a radiologic sign of ischemic stroke.
In one study1, two features increased diagnostic accuracy:
Middle Cerebral Artery Dense MCA Sign
Posterior Cerebral Artery Dense PCA Sign
Basilar Artery Dense Basilar Sign
Vertebral Artery Dense Vertebral Sign
• Hounsfield Units ≥43
• Density Ratio >1.22
1Cerebrovascular Disease 2000 10(6):419-423.
2Affected Artery Segment/Unaffected Segment

87. Hyperdense MCA Sign Right MCA (M1) Occlusion
71-Year-Old With Acute Left-Sided Weakness And Slurred Speech.

88. Hyperdense MCA Sign
80-Year-Old With Dense Right Hemiparesis, Aphasia And Inability To Follow Commands.
Left MCA (M1) Occlusion

89. Hyperdense MCA Sign
49-Year-Old Presenting With Right-Sided Weakness, Aphasia And Leftward Gaze Deviation.
Left MCA (M1) Occlusion

90. Hyperdense MCA Sign
77-Year-Old Presenting With Aphasia, Right Gaze Preference, And Left Hemiplegia.
Right MCA (M1) Occlusion

91. 83-Year-Old Presenting Ataxia, Left-Sided Weakness And Blurred Vision
Right PCA Occlusion
Hyperdense PCA Sign

92. Hyperdense Basilar Sign
52-Year-Old Presenting With Headache, Aphasia, Right-Sided Weakness.
Partial Basilar Artery Occlusion

93. “V” Is For Vessels
Publications On The Topic By The CMC Crew!

94. Western of Emergency Medicine 2020; 21(3):694-702.
Methods:
Case control study of the utility of the dense basilar sign (DBS) in patients with confirmed acute basilar
artery occlusion (BAO) versus a control group of suspected acute stroke patients without BAO.
Results:
60 BAO and 65 control patients were included in the analysis:
• Qualitative assessment of the DBS had poor sensitivity (54% - 72%) and specificity (55% - 89%) for BAO.
• Quantitative measurement improved the specificity of the DBS for the diagnosis of BAO. Using an ROC
curve, a threshold of 61.0 Hounsfield units had a specificity of 85% - 94%.
Conclusion:
These results demonstrate the importance of quantitatively evaluating basilary artery density, and if this
value exceeds 61 Hounsfield units, BAO should be strongly suspected.

95. American Journal Of Emergency Medicine 2021; 42:221-224.
Example Of A Normal Basilar Artery On Non-Contrast CT (50 HU).

96. Case #1
8-year-old with lethargy, disconjugate gaze, inability to speak,
difficulty following commands.
Rx: Mechanical thrombectomy within 5 hours of symptom
onset, with complete revascularization and recovery.
Case #3
14-year-old with altered mental status after collapsing. Unable
to speak, follow commands. Roving eye movements.
Rx: TPA within 1.5 hours. Thrombectomy within 2.5 hours.
Now independent, walking with a brace, otherwise recovered.
Case #2
13-year-old with fever, altered mental status and disconjugate
gaze. Moving all extremities but not following commands. A
non-contrast CT at 9 hours revealed an acute cerebellar infarct
and a CT-A later revealed BAO of the basilar apex.
American Journal Of Emergency Medicine 2021; 42:221-224.

97. • Blood
• Cisterns
• Brain
• Ventricles
• Vessels
•Bone
Blood Can Be Very Very Bad

98. B Is For Bone
➤
➤
→

101. Sagittal Suture
Coronal Suture
Frontal Bone
Parietal Bones

103. Lambdoid Suture
Occipital Bone
Parietal Bone
Temporal Bone
(Squamous Part)
Superior Orbital
Fissure
Optic Canal
Anterior
Clinoid Process
Dorsum Sellae
Frontal Sinuses

105. Sphenoid Sinuses
Occipitomastoid Suture
Temporal Bone
(Mastoid Part)
Temporal Bone
(Petrous Part)
Mastoid Air Cells
Occipital Bone
Internal Auditory Canal
Carotid Canal
Frontal Process
Of The Maxilla
Ethmoid Sinuses

107. Carotid Canal
Temporomandibular
Joint
External
Auditory Canal
Zygomatic Arch
Carotid Canal
Jugular Foramen
Maxillary Sinuses

109. Mastoid Process Of
The Temporal Bone
Mandible
Mandibular
Condyle
Nasal Septum
Pterygoid Plates

111. Occipital Condyles
Styloid Process Of
The Temporal Bone
Hard Palate
Dens (C2)
Atlas - Posterior Arch (C1)
Transverse Foramen (C1)
Atlas – Anterior Arch (C1)
Maxilla

112. 27-Year-Old Falls And
Strikes His Head While
Skateboarding.
CT Demonstrates A Vertex
Subdural Hematoma (➤)
Bone Windows Provide
Superior Definition Of Skull
Fracture Fragments (→)
➤
➤
➤
→

113. 7-Year-Old Falls Off The
Playground Equipment
Landing On His Head.
A CT Scan Of The Brain
Demonstrates A
Depressed Skull Fracture
(➤)
Bone Windows Provide
Anatomic Definition Of The
Fracture Fragments (→)

114. 7-Year-Old Falls Off The
Playground Equipment
Landing On His Head.
CT Images After
Surgical Elevation of
Fracture Fragments (→)

115. 9-Month-Old Who Fell Off Of A Changing Table.
CT Demonstrates A Large Epidural Hematoma And A Linear Skull Fracture.

116. Blood Can Be Very Very Bad
A Structed Approach To Head CT Interpretation
This Presentation With Remain Readily Accessible To You On Our
Website As We Launch Future CMC Neuroimaging Case Studies!

117. Visit Our Website
www.EMGuidewire.com
For A Complete Archive Of Imaging Presentations And Much More!

118. See You Next Month!