Neuro: Brain/spine Flashcards
What are the categories of different cerebrovascular disease - and give examples of each. Concurrent medical conditions and long-term outcome in dogs with nontraumatic intracranial hemorrhage. VRU 53.4
CVA –> ischemic or hemorrhage Hemorrhage stroke - vessel rupture or coagulopathy
Primary or secondary hemorrhagic stroke
Primary - rupture of vessel without vascular malformation or coagulopathy, hypertension
Secondary - vascular abnormalities - tumors/infectious, coagulopathies, ischemic strokes transforming into hemorrhagic stroke Ischemic stroke –> non-hemorrhagic vs hemorrhagic non-hemorrhagic - disturbance to arterial or venous supply (thrombi), hypoperfusion
Hemorrhagic - ischemic infarcts with secondary hemorrhage. reperfusion of damaged vessels
In the paper:
Concurrent medical conditions and long-term outcome in dogs with nontraumatic intracranial hemorrhage. VRU 53.4.
Animals with hemorrhage were classified into three groups: Single >5mm lesion, Multiple >5mm lesions, and Multiple
Multiple lesions >5mm in size. A large number of these patients were infected with Angiostrongylus vasorum (heartworm) - these were the only patients with good outcome. All of the other patients in the group had metastatic neoplasia within the brain.
In the paper: Concurrent medical conditions and long-term outcome in dogs with nontraumatic intracranial hemorrhage. VRU 53.4. Animals with hemorrhage were classified into three groups: Single >5mm lesion, Multiple >5mm lesions, and Multiple
Multiple lesions
Describe the stages of magnetic susceptibility artifact and stages of blood degradation Concurrent medical conditions and long-term outcome in dogs with nontraumatic intracranial hemorrhage. VRU 53.4
Signal charactersitics are determined by paramagnetic effects of hemoglobin breakdown. MRI strength (stronger the magnet, the greater the susceptibility artifact), pulse sequence.
Oxyhemoglobin - <24h - hyperacute
Deoxyhemoglobin - 1-3d - acute
Methemoglobin (intracellular) 3-7d - early subacute
Methemoglobin (extracellular) - 7-14d - late subacute
Hemosiderin/Ferridin - >14d - chronic
What will each stage of hemorrhage appear on T1 and T2 sequences? Article: you just need to know this :)
Mnemonic: (T1 followed by T2): I Buy, It-D, Bit-D, BaBy, Doo-Doo
Hyperacute - T1 iso, T2 hyper
Acute - T1 iso, T2 hypo
Early subacute - T1 hyper, T2 hypo
Late subacute - T1 hyper, T2 hyper
Chronic - T1 hypo, T2 hypo
What are causes of increased signal intensity on T1 pre contrast images? Concurrent medical conditions and long-term outcome in dogs with nontraumatic intracranial hemorrhage. VRU 53.4
Methemoglobin, fat, proteinaceous fluid, melanin, calcification, paramagnetic substances (Fe, Mn), necrosis
Is brain scintigraphy reliable for detecting diffuse disease and normal patients?
No
What size tumor in man is consistently seen with brain scintigraphy? What is a factor that aids in visualization?
1994 Dykes - Retrospective Analysis Of Brain Scintigraphy In 116 Dogs And Cats
1 cm
peritumoral edema
Define sensitivity, specificity, PPV, NPV
1994 Dykes - Retrospective Analysis Of Brain Scintigraphy In 116 Dogs And Cats
Sensitivity is defined as the ability of a test to identify correctly those who have the disease
Specificity is defined as the ability of the test to identify correctly those who do not have the diseas
Predictive value of a positive test is the proportion of true positives (i.e., diseased individuals) among all those who have positive test results
Predictive value of a negative test is the proportion of non-diseased individuals among all those who have negative test result
Why might you have a technically poor brain scintigram? 6 reasons
1994 Dykes - Retrospective Analysis Of Brain Scintigraphy In 116 Dogs And Cats
insufficient activity administered
poor binding 99mTc to ligand
patient motion
insufficient time for clearance
decreased clearance due to severe renal disease
What does accumulation of radiopharmaceutical in abnormal brain depend on? (6 reasons)
1994 Dykes - Retrospective Analysis Of Brain Scintigraphy In 116 Dogs And Cats
increased vascularity
abnormal capillary permeability
uninhibited pinocytosis
adjacent reactive edema
increase in extracellular space of tumor
ability of tumor to transfer or bind molecules intracellularly
What two structures have activity that might hinder interpretation of a brain scan? and what can you do to help?
vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy
Parotid glands and choroid plexus
-administer sodium or potassium perchlorate prior to scan
Why might you have a false positive on a brain scan for a tumor?
vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy
- see normal structures not always visualized - cavernous sinus if not perfectly dorsal (aka obliquity)
- auricle can cause artifact
Name three reasons you might not visualize a brain tumor on a nuc med scan?
vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy
- outside place of focus/obscured by other structures that absorb/scatter radiation
- tumors on midline have low detection rates such as astrocytomas
- corticosteroid administration decreases peritumoral edema
Species, abnromalities
Canine, dorsal scan, area of increased uptake in cerebellar and medulla oblongata area
meningioma
vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy
Species, abnormalites - be specific
Dorsal brain scan, region of increased activity in left cerebellar region
meningioma
vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy
Species, abnormalities? What are the two ovoid regions of high activity? Assuming you can see the faint x region of activity labeled, name it.
Dorsal scan of a normal canine brain
Parotid salivary glands
Cavernous and petrosal sinuses
vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy
Species, abnormalities, labels
Lateral scan of a normal brain
A: vasculature of the scalp, underlying sheel, dorsal longitudinal sinus - progressively wider band coursing caudally
B: Nasopharynx - circular region of decreased activity
C: Parotid salivary gland
D: Transverse sinus courses in a rostroventral direction
vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy
What is differentiating factors between neoplasia and an intracranial mucocele?
Imaging diagnosis - Intracranial mucocele in a dog. VRU 49.6 2007.
Neoplasia - homogeneous enhancement/non-enhancing
Mucocele - peripheral ring enhancement
What is your diagnosis?
T1 post contrast image: Isointense, non-enhancing mass (peripheral ring enhancement) extending from nasal cavity through the frontal bone into the retro-orbital space as well into the cranial vault.
Intracranial mucocele
Imaging diagnosis - Intracranial mucocele in a dog. VRU 49.6 (2007).
Give a brief description of the physics behind a T2 weighted vs T2* weighted image
Susceptibility artifacts on T2*w MRI of the canine and feline spine. VRU 56.4 (2015)
T2: 180 refocusing pulse after initial pulse to cancel out local and external magnetic field inhomogeneities. Signal characteristics on T2w spin echo sequences are result of loss of transverse magnetization due to spin-spin interaction between protons (T2 decay)
T2*: No refocusing pulse - so image characteristics are susceptible to magnetic field inhomogeneities, as well as the T2 characteristics (due to loss of transverse magnetization)
What can cause susceptibility artifacts on T2* weighted images?
Susceptibility artifacts on T2*w MRI of the canine and feline spine. VRU 56.4 (2015)
paramagnetic blood degradation products (hemorrhage), mineralization or metallic particles
What is the signalment and presenting complaint of a patient with a spinal nephroblastoma?
Where is the tumor most likely located?
Young <4y of age
Most commony seen in large breed dogs (German shepherds, labs may be predisposed)
Most commonly seen at T9-L3
Clinical complaint: T3-L3 myelopathy
How much more likely is a dog with incomplete ossification of the atlas to have atlantoaxial subluxation?
CT variations in morphology of canine atlas in dogs with and without atlantoaxial subluxation. VRU 51.6
35x more likely for a dog with incomplete ossificaiton to have a luxation.
Describe incomplte ossification of the atlas… where does it occur?
CT variations in morphology of canine atlas in dogs with and without AA subluxation. VRU 51.6
3 sutures:
1 - dorsal aspect of neural arch
2 - left and right of the intercentrum (vertebral body)
Which breed group was more likely to have incomplete ossification in
CT variations in morphology of canine atlas in dogs with and without AA subluxation. VRU 51.6
Gun dogs.
Of the dogs described in the article:
CT variations in morphology of canine atlas in dogs with and without AA subluxation. VRU 51.6
Which group was more likely to have cervical signs?
Dogs with AA subluxation - 8/8 had cervical signs - 5 of which had incomplete ossification, 3 had normal ossification
Dogs WITHOUT AA subluxation, but with incomplete ossificaiton had no clinical signs.
What is a Schwannoma otherwise referred to?
Imaging diagnosis: Cranial cervical intraspinal schwannoma in a dog VRU 55.3
Benign peripheral nerve sheath tumor
What are imaging characterstics of a Schwannoma?
Imaging diagnosis: Cranial cerivcal intraspinal Schwannoma in a dog. VRU 55.3
Intradural, extramedullary (caudally) - near C-T junction
**Can be extradural cranially
T2 hyperintense
T1 iso/hypointense
Post contrast - strongly enhancing - homo/hetero
Benign - usually does not infiltrate into surrounding tissues or cause destruction of bone. Can cause widening of foramina
What are differences between a benign and malignant peripheral nerve sheath tumor?
Imaging diagnosis: Cranial cerivcal intraspinal Schwannoma in a dog. VRU 55.3
Malignant: may see hemorrhage, edema, invasion into adjacent structures, widening of the intervertebral foramina, obvious destruction of bone
Which are more common in dogs: malignant or benign peripheral nerve sheath tumors?
Imaging diagnosis: Cranial cerivcal intraspinal Schwannoma in a dog. VRU 55.3
Malignant
Peripheral nerve sheath tumors are frequently ______ in location in the ____ portions of the spinal cord.
In human reports, tumors cranially at C1-2 are frequently ____ in location. In fact, ____% of tumors have this distrubition. Why is this?
Imaging diagnosis: Cranial cerivcal intraspinal Schwannoma in a dog. VRU 55.3
1) Intradural, extramedullary
2) Caudal cervical/brachial plexus
3) extradural
4) 75%
Cranially - nerve roots of C1-2, come out at a right angle - spend very short time in the vertebral canal.
Caudally - nerve roots have an acute angle, and may travel further within the vertebral canal (intradurally).
What are findings of post-operative CT after brain tumor removal?
Early postoperative MRI findings in 5 dogs with confirmed and suspected brain tumors. VRU 56.5
Hemorrhage (hyperintensity), hyperintensity with enhancement at resection site.
2-3 weeks after surgery: ring-like enhancement around cavity.
In humans, what are common MRI findings found after craniotomy with brain tumor removal?
Early postoperative MRI findings in 5 dogs with confirmed and suspected brain tumors. VRU 56.5
Increased meningeal enhancement
Increased enhancement of choroid plexus after opening of ipsilateral lateral ventricle
Linear enhancement at resection margins
Solid parenchyma enhancement at sresection site
Occurrences of hemorrhage and ischemic infarction
What were authors feelings on detection of residual tissue on post-operative MRI within a few days after surgery?
Early postoperative MRI findings in 5 dogs with confirmed and suspected brain tumors. VRU 56.5
Could not truly differentiate between inflamed/irritated tissue secondary to surgical manipulation and residual tumor cells.
What were common post-operative MR findings in dogs after craniotomy for tumor removal?
Early postoperative MRI findings in 5 dogs with confirmed and suspected brain tumors. VRU 56.5
Residual tissue vs inflamed tissue from surgical manipulation
Linear enhancement of resection cavity
Meningeal enhancement
Increased contrast enhancement of choroid plexus when the ipsilateral ventricle was breached
Hemorrhage within and around resection cavity
restricted diffusion (ischemia)
All 4 had thin rim of hyperintensity on DWI that partially or fully encircled resection cavity - isointense to brain parenchyma on ADC
What are the early postoperative changes of the resection cavity after craniotomy for tumor removal, and late changes, seen in humans?
What interpretation difficulties may arise from the later changes?
Early postoperative MRI findings in 5 dogs with confirmed and suspected brain tumors. VRU 56.5
Early: thin, linear enhancement
Later: Becomes thicker and nodular - can make it difficult to differentiate between recurrent tumor.
Why does meningeal enhancement occur after craniotomies?
Early postoperative MRI findings in 5 dogs with confirmed and suspected brain tumors. VRU 56.5
Meningeal inflammation due to hemorrhage, meningeal thickening and fibrosis.
What is importance of these changes:
1) Increased DWI signal with hypointense ADC signal
2) Increased DWI signal around resection cavity with isointense ADC signal?
Early postoperative MRI findings in 5 dogs with confirmed and suspected brain tumors. VRU 56.5
1) Ischemic infarction - in humans can be associated with new, or worsening neurologic deficits and delayed recovery.
2) Normal thing to occur after surgery - not sure why this occurs.
What is the underlying cause of central european tick-borne meningoencepahlitis?
3T MRI of 12 cases of central european tick borne meningoencepahlitis. VRU 57.1
RNA virus transferred by Ixoides tick
How does central european tick borne meningoencephalitis destroy the nervous system?
3T MRI of 12 cases of central european tick borne meningoencepahlitis. VRU 57.1
Cytokine mediate entry
Infection of endothelial cells
Once in - virus targests the neurons –> neuroinflammation, neuronal death, and lastly, BBB disruption
Why is there no contrast enhancement of the lesions seen in central european tick born meningoencepahlitis?
3T MRI of 12 cases of central european tick borne meningoencepahlitis. VRU 57.1
The virus disrupts the BBB last.
First the virus destroys the neurons
Finally, the virus destroys astrocytes which bridge endothelial cells and the neurons
What portions of the brain/brainstem/spinal cord are affected by central european tick borne meningoencephalitis
3T MRI of 12 cases of central european tick borne meningoencepahlitis. VRU 57.1
thalamus
hippocampus
brain stem
basal nuclei
ventral horn of the gray mater in the cervical spine
What are imaging characteristics of central european tick borne meningoencepahlitis?
3T MRI of 12 cases of central european tick borne meningoencepahlitis. VRU 57.1
Bilateral and symmetrical lesions of the thalamus, hippocampus, brain stem, basal nuclei ventral horn of the gray matter of the spinal cord
T2/FLAIR - hyperintense
T1 - is/hypointense
Post contrast - no enhancement - frequently do not image late enough in stage of disease where BBB is disrupted
Describe the stages of hemorrhage on CT images
Intracranial hemorrhage: principles of CT and MRI interpretation - European Radiology 2001
Increased signal due to globin products
Hyperacute: (30-40HU) iso to slightly increased density due to hematoma
Acute: Clot forms (60-80 HU) - Fibrin and globin. Enhancement can occur. Clot retraction begins
Mature hematoma - retraction occurs at HU of 80-100
Hypodense halo secondary to edema can occur in any phase
Decreased attenuation by 0.7-1.5HU / day
What are differences between epidural, subdural and subarachnoid hemorrhage?
Intracranial hemorrhage: Principles of CT and MRI
Epidural: biconves mass that crosses dural folds (falx cerebri, tentorium cerebelli), but not sutures
Subdural - peripheral, crescent-shaped collection of blood that can cross suture lines, but is limited by falx and tentorium
Subarachnoid: mixture of blood and CSF ‘infiltrating’ into parenchyma from the periphery.
Describe the time of hemorrhage phage on MRI
Intracranial hemorrhage: CT and MRI Principles. European radiology
Hyperacute: <24 hours:
Acute: 1-3d:
Early subacute: 3-7d
Late subacute: 7-14d
Chronic: >14d
Described the degradation of hemoglobin based on the time frame of hemorrhage on MRI
Intracranial hemorrhage: CT and MRI principles. European Radiology
Hyperacute: <24h - oxyhemoglobin
Acute: 1-3d - deoxyghemoglobin
Early subacute: 3-7d - methemoglobin in RBC
Late subacute: 7-14d - free methemoglobin
Chronic: >14d - hemosiderin
Described T1/T2 changes based on stages of hemrorhage on MRI
Intracranial hemorrhage: CT and MRI principles. European Radiology
All are listed as T1/T2
Hyperacute: <24h - Iso (can be hypo)/Hyper
Acute: 1-3d - Iso (can be hypo)/dark
Early subacute: 3-7d - Hyper/Hypo
Late subacute: 7-14d - Hyper/Hyper
Chronic: >14d - Hypo/hypo
