Spine

Question 1

Brief description of anatomy of intervertebral discs

What occurs to the disk that results in IVDD?

Myelography vs CT in evaluation of acute thoracolumbar IVDD in chondrodystrophic dogs. VRU 50.4 (2009)

Answer 1

Anatomy: Jelly donut center (nucleus pulposus), vs firmer rim, annulus fibrosis

Type 1: nucleus pulposus undergoes chondroid degeneration and minneralization, annulus fibrosus weakens, and disk material extrudes

Type 2: annulus fibrosis progressively thickens due to fibroid degeneration - progressive protrusion of the disc.

Question 2

Complications of myelography?

Myelography vs CT in evaluation of acute thoracolumbar IVDD in chondrodystrophic dogs. VRU 50.4 (2009)

Answer 2

Radiation exposure (techs/radiologists/patient), adverse reaction to contrast, asystole, intracranial subarachnoid hemorrhage, seizures

Question 3

In the article: Myelography vs CT in evaluation of acute thoracolumbar IVDD in chondrodystrophic dogs. VRU 50.4 (2009),

2 CT protocols, plain films, and meylography were compared (conventional vs helical).

What was benefits/sensitivity of each modality for site location and lateralization?

Answer 3

Conventional: Site: 87.4% sensitivity. Lateralization: 87.4%

Helical: Site: 88.4% sensitivity. Lateralization: 85%

Myelography: Site: 98% sensitivity. Lateralization 79%

Plain films: Site: 94% sensitivity

Question 4

In the article: Myelography vs CT in evaluation of acute thoracolumbar IVDD in chondrodystrophic dogs. VRU 50.4 (2009),

2 CT protocols and meylography were compared (conventional vs helical).

What were the drawbacks of each modality?

Answer 4

Myelography: time, risks (seizures, hemorrhage, asystole, contrast reaction), concurrent hemorrhage/swelling, filling of epidural space can make it difficult to interpret.

CT: Thin slices –> decreased SNR. Thicker slices –> decreased quality due to volume averaging.

Question 5

Evaluation of different CT techniques and myelography for diagnosis of acute canine myelopathy. VRU 51.3 (2010).

Compared conventional CT, CT angiography, CT myelography and standard myelography.
What is ranking of most sensitive to least sensitive?

What about when mineralized discs were excluded?

Answer 5

CT myelograph (97%) > Myelography (79%) > Conventional CT (66%) > Angiographic CT (53%).

When Mineralized discs were excluded - sensitivity of conventional and angiographic CT decreased by approximately 20%.

Question 6

Evaluation of different CT techniques and myelography for diagnosis of acute canine myelopathy. VRU 51.3 (2010).

Which imaging modality used in this study was reliant on mineralization or lytic lesions?

Answer 6

Conventional CT and CT angiography

Question 7

Evaluation of different CT techniques and myelography for diagnosis of acute canine myelopathy. VRU 51.3 (2010).

What was agreement between imaging modalities (myelography, CT myelography, CT angiography, Conventional CT), and in which examples were agreement improved?

Answer 7

Agreement was low for survery and angiographic CT (0.2 and 0.23, respectively) vs myelography and CT myelography (0.74 and 0.88).

Agreement was much higher when evaluating for large volume disc extrusion

Question 8

Evaluation of different CT techniques and myelography for diagnosis of acute canine myelopathy. VRU 51.3 (2010).

In this article, agreement was high for myelography and CT myelography, and low for conventional CT and angiography (except for when evaluating large mineralized disc extrusions).

Where did myelography struggle?

Answer 8

When spinal cord swelling was present. Spinal cord swelling was detected, but it was more difficult to evaluate where the extradural site or lateralization – was better on CT myelography.

Question 9

Was the vacuum phenomenom helpful in determining site of the lesion in the article:

Evaluation of different CT techniques and myelography for diagnosis of acute canine myelopathy. VRU 51.3 (2010).

Answer 9

No. 3/5 dogs were incorrectly localized based on vacuum phenomenon alone.

Question 10

What was overall conclusion of the study: Evaluation of different CT techniques and myelography for diagnosis of acute canine myelopathy. VRU 51.3 (2010).

Meaning - what imaging modality is recommended in each case?

Answer 10

chondrodystrophic breeds paraparetic- Conventional CT is usually adequate.

Chondrodystrophic dogs that are plegic, spinal cord swelling, low volume cervical disc extrusion, non-chondrodystrophic breeds - may require CT myelography

Question 11

What MRI findings would you expect to see in an acute non-compressive nucleus pulposus extrusion?

De Risio, Luisa “association of clinical and MRI findings with outcome ind ogs with presumptive ANNPE: 42 cases” JAVMA 234.4

Answer 11

1. Focal hyperintensity within spinal cord overlying an intervertebral disc
2. Reduction in volume and signal of intervertebral disc on T2
3. Narrowed intervertebral disc space
4. Extraneous material or signal change within epidural space dorsal to affected disk
5. Minimal

Question 12

According toDe Risio, Luisa “association of clinical and MRI findings with outcome ind ogs with presumptive ANNPE: 42 cases” JAVMA 234.4, what MRI findings are correlated with an unsuccessful outcome?

Answer 12

Severity of neurologic signs

GRE hypointensity (hemorrhage within spinal cord)

PCSAL (cross-sectional area of lesion) - >90% had 92% chance of having unsuccessul outcome.

Question 13

In a 2009 Hecht paper, how did myelography,helical CT and conventional CT compare with regards to accuracy in detecting level and localization of extruded disc material in chondrodystrophic dogs?

Answer 13

They were similar and had a high degree of accuracy for level (myelography 94.7%, conventional 100%, helical 94.7%). Myelography was lessfor level and localization though conventional and helical CT were similar(myelography 78.9%, conventional 87.4%, helical 85.3%).

2009 Hecht - Myelography vs. computed tomography in the evaluation of acute thoracolumbar intervertebral disk extrusion in chondrodystrophic dogs

Question 14

What is the difference between Hansen Type I and II in terms of pathology?

Answer 14

Type I -nucleus pulposus undergoes chondroid degeneration and subsequent mineralization -> annulus fibrosus weakens and disk material can extrude into verterbral canal causing acute neuropathy = chondrodystrophic

Type II -annulus fibrosus undergoes progressive thickening due to fibroid degeneration which can result in progressive protrusion of the affected disk into the verterbral canal = large breed

Question 15

What are some adverse reactions of myelography?

Answer 15

Seizures, asystole, intracranial subarachnoid hemorrhage

2009 Hecht - Myelography vs. computed tomography in the evaluation of acute thoracolumbar intervertebral disk extrusion in chondrodystrophic dogs

Question 16

What can cause hemorrhage within the spinal cord?

Susceptibility artifacts on T2*w MRI of the canine and feline spine. VRU 56.4 (2015)

Answer 16

intervertebral disc extrusion, coagulopathy, trauma, iatrogenic trauma, hemorrhagic myelomalacia, neoplasia, parasitism, vascular malformations

Question 17

What are differentials for T2 hyperintensity within the spine?

Susceptibility artifacts on T2*w MRI of the canine and feline spine. VRU 56.4 (2015)

Answer 17

Necrosis, myelomalacia, intramedullary hemorrhage, inflammation, edema, neoplasia.

Question 18

What is common clinical complaint of patients presenting for ischemic myelopathy?

Answer 18

acute, asymmetric spinal cord disease that is non-painful and non-progressive after the initial 24h.

Degree of recovery depends on the severity of initial injury to the spinal cord.

Question 19

In the article MRI findings of suspected ischemic myelopathy (VRU 46.3 (2005)) - what were MR findings consistent with this diagnosis?

Answer 19

T2 images: hyperintense

T1: pre contrast: varied based on the age - early (3m)

Post contrast: mild enhancement in

Question 20

In humans, what are MR findings of ischemic myelopathy?

MRI findings of dog swith suspected ischemic myelopathy. VRU 46.3. (2005)

Answer 20

T2 hyperintensity (93%)

T1: hypointense (70%)

Contrast enhancement: 40% - usually occuring in middle aged lesions (5-6d), absent enhancement by 1m after accident.

Question 21

Give a brief description of the blood supply to the spinal cord

MRI findings of suspected ischemic myelopathy. VRU 46.3. (2005).

Answer 21

Ventral spinal artery with central branch that extends through ventral fissure than branches to supply intermediate and ventral gray matter of spinal cord and surrounding white matter

Two paired, dorsolateral spinal arteries that suply dorsal gray and dorsolateral white matter

Question 22

What are MRI findings of acute ischemic myelopathy?

MRI findings and clinical associations in 52 dogs with suspected ischemic myelopathy. JVIM 21. (2007).

Answer 22

Focal, relative sharply demarcated intramedullary lesions, involving predominantly gray matter that is hyperintense on T2w images and iso or hypointense on T1 images.

Various degrees of contrast enhancement depending on time between onset of clinical signs and MRI

Question 23

The severity of clinical signs (most notably the ambulatory status) correlated with what imaging findings in the articleMRI findings and clinical associations in 52 dogs with suspected ischemic myelopathy. JVIM 21. (2007).

Answer 23

Length of hyperintense lesion on T2 sagittal images when compared to L2 or C6.

Maximal cross sectional area of hyperintense lesion on T2 images

AKA the longer and thicker the lesion - the more severe the clinical signs.

Question 24

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)

Answer 24

paramagnetic blood degradation products (hemorrhage), mineralization or metallic particles

Question 25

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)

Answer 25

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)

Question 26

In the prospective study comparing CT and MRI for detetction and characterization of IVDD (VRU 55.2 -2014), what was MRI more sensitive for?

Answer 26

Mri was more sensitive in general over CT (98% vs 88%) MR was more accurate at identifying site of IV herniation, spinal cord compression, differentiating disk extrusion and protrusion. MR was also more sensitive in detecting abnormalities in female, chondrodystrophic dogs, and dogs

Question 27

Differential list for dogs with thoracolumbar myelopathy?

Answer 27

Compressive and noncompressive intervertebral disk hrenaition, discospondylitis, FCE, myelitis, trauma, congenital malformations, degenerative disease, neoplasia Comparison between CT and MRI for detection and characterization of TL myelopathy caused by IVDH in dogs. VRU 55.2 (2014)

Question 28

What breeds are associated with dermoid sinus'?

Answer 28

Rhodesian ridgeback, boxers, shih-tzu, yorkies, chows True dermoid cyst in a rhodesian ridgeback JSAP 41 (2000)

Question 29

What are dermoid sinuses/cysts? True dermoid cyst in a rhodesian ridgeback JSAP 41 (2000)

Answer 29

Incomplete division between skin and spinal cord during embryological separation of ecotderm from the CNS

Question 30

What are classifications of dermoid sinuses/cysts? True dermoid cyst in a rhodesian ridgeback JSAP 41 (2000)

Answer 30

All have to do with relationship of supraspinatous ligament. 1 - extends to the supraspinous ligament and attaches 2 - second does not extend to ligament, but attaches by fibrous strand 3 - does not extend to supraspinous ligament and does not attach 4 - attached to dura matter 5 - subcutaneous structure - does not open to external skin or extend into deeper muscle or ligamentous layers

Question 31

What is the signalment and presenting complaint of a patient with a spinal nephroblastoma? Where is the tumor most likely located? Spinal cord nephroblastoma in dogs - 11 cases (1985-2007) JAVMA 238.5

Answer 31

Young

Question 32

What are congenital causes of cauda equina syndrome? Sacral lesion resembling OCD in the German shepherd dog VRU 33.2

Answer 32

Primary stenosis of the verrtebral canal in small breed dogs, spinal dysraphism, transitional vertebrae, dysgenesis of LS vertebral and lumbosacral instability

Question 33

What are acquired causes of cauda equina compression: Sacral lesion resembling OCD in the German shepherd dog VRU 33.2

Answer 33

Intervertebral disc disease and secondary instability of LS junction. Fractures/luxations, discospondylitis, primary/metastatic tumors, vascular disease

Question 34

What is the appearance of a sacral OCD lesion? Sacral lesion resembling OCD in the German shepherd dog VRU 33.2

Answer 34

- sacral endplate is angled caudally - lipping of the dorsal border -reducing the dorsoventral diameter of the spinal canal - Radiolucent defect in dorsal aspect of the endplate and 1+ osseous fragments in the vertebral canal - Sclerosis

Question 35

Which breed and sex is predisposed to a sacral OCD lesion?

Answer 35

German shepherd dogs - males In the study - in the clinical group there was a sex ratio of 10:1. Sacral lesion resembling OCD in the German shepherd dog VRU 33.2

Question 36

When are dogs with a sacral OCD lesion likely to become clinical? Sacral lesion resembling OCD in the German shepherd dog VRU 33.2

Answer 36

Clinically normal G. Shepherds with sacral OCD were younger than 18m. German shepherds with sacral OCD and clinical signs - were found to be 2 years younger (4.8y) than the remaining dogs who had cauda equina compression without the sacral OCD lesion (6.8y)

Question 37

In the paper: Sacral lesion resembling OCD in the German shepherd dog VRU 33.2 what was the prevalence of this OCD lesion in the group of German Shepherds that were evaluated (both clinical and non-clinical)?

Answer 37

30% of German shepherds in the clinically abnormal group | 6% of German shepherds in the clinically normal group

Question 38

Rank the prevalence of extradural/intradural extramedullary/intramedullary from most common to least common. Intramedullary spinal cord neoplasia in 53 dogs. JVIM 27

Answer 38

Extradural (61% [50%]), Intradural extramedullary (23% [35%]), intramedullary (16% [15%]). [ ] - signify from other reports

Question 39

What are types of primary spinal tumors that were not included in the paper : Intramedullary spinal cord neoplasia in 53 dogs. JVIM 27?

Answer 39

Lymphoma or histiocytic sarcoma

Question 40

What was age prevalence for primary vs secondary intramedullary spinal tumors? Intramedullary spinal cord neoplasia in 53 dogs. JVIM 27

Answer 40

Primary - younger (6y) vs Secondary - older (11y)

Question 41

Which type of intramedullary tumor (primary or secondary) is most common in the cervical region? Intramedullary spinal cord neoplasia in 53 dogs. JVIM 27

Answer 41

Primary - 100% of tumors in the cervical region were primary tumors: ependymomas, astrocytomas, oligodendrogliomas, nephrogblastomas

Question 42

What vertebral length measurement is associated with a poor outcome in dogs with ischemic myelopathy? Association of clinical and magnetic resonance imaging findings with outcome in dogs suspected to have ischemic myelopathy: JAVMA 233.1

Answer 42

>2x the length of C6 or L2 = stronger predictor for a poor prognosis Sensitivity - 100% (all dogs that had poor outcome were in this group) Specificity - 63% (there were multiple dogs who had good outcome in this group as well)

Question 43

What Cross sectional area percentage is associated with a poor outcome in dogs with ischemic myelopathy? Association of clinical and magnetic resonance imaging findings with outcome in dogs suspected to have ischemic myelopathy: JAVMA 233.1

Answer 43

>67% Sensitivity - 100% (all dogs with poor outcome had lesion >67% of CSA) Specificity - 57% (also some dogs that had good outcome that were > 67%)

Question 44

What is typical history of dogs with ischemic myelopathy? Association of clinical and magnetic resonance imaging findings with outcome in dogs suspected to have ischemic myelopathy: JAVMA 233.1

Answer 44

Acute non-progressive, nonpainful myelopathy

Question 45

What MRI findings are consistent with an acute non-compressive nucleus propulsus extrusion? Association of clinical and magnetic resonance imaging findings with outcome in dogs suspected to have ischemic myelopathy: JAVMA 233.1

Answer 45

Focal intramedullary hyperintensity on T2w Overlying disc space Reduction in volume/signal intensity of nucleus pulposus, disruption of epidural fat, extraneous material within extradural space

Question 46

What is the 3 compartment method of evaluating spinal fractures/luxations? MRI characteristics fo suspected vertebral instability associated with fracture of subluxation in 11 dogs VRU 53.5

Answer 46

Dorsal: vertebral arch, spinous process, articular processes, lamina, pedicles, dorsal ligamentous complex (facet joint capsule, interarcuate ligaments, interspinous ligaments, supraspinous ligaments) Middle: dorsal longitudinal ligament, dorsal aspect of annulus fibrosis, dorsal margin of vertebral body Ventral: remainder of the vertebral body, lateral and ventral aspects of annulus fibrosus, nucleus pulposus, ventral longitudinal ligament

Question 47

What is the radiographic sensitivity for finding ALL fractures and subluxations in a dog with acute spinal canal injury? Radiographic sensitivity and NPV of acute spinal trauma VRU 47.6

Answer 47

72% - fracture | 75% - subluxation

Question 48

What is the NPV for radiographs for finding all fractures? Radiographic sensitivity and NPV of acute spinal trauma VRU 47.6

Answer 48

49% | If you don't see a fracture - there's a 49% chance you are correct

Question 49

What were NPV for fracture fragments within the canal, vertebral canal narrowing, spinal cord compression? Radiographic sensitivity and NPV of acute spinal trauma VRU 47.6

Answer 49

Fragments in canal: 57.5% Vertebral canal narrowing: 51% Spinal cord compression: 35%

Question 50

Based on the 3 compartment method ofevaluating spinal fractures - when is a fracture considered unstable? MRI characteristics of suspected vertebral instability associated with fracture of subluxation in 11 dogs VRU 53.5

Answer 50

When 2 or more of the compartments are disrupted

Question 51

Where was strongest agreement for detecting ischemic myelopathy vs ANNPE? Inter and intraobserver agreement for diagnosing presumptive ischemic myelopathy and acute noncompressive pulposus extrusion in dogs using MRI VRU 57.1

Answer 51

Presence of lesion overlying vertebral body - IM (94%) | Overlying an intervertebral disc - ANNPE (85%)

Question 52

Where were significant associations between agreement and imaging findings? Inter and intraobserver agreement for diagnosing presumptive ischemic myelopathy and acute noncompressive pulposus extrusion in dogs using MRI VRU 57.1

Answer 52

Overlying intervertebral body versus disk lateralization decreased volume of disk extradural material

Question 53

Which findings had poor interobserver agreement? Inter and intraobserver agreement for diagnosing presumptive ischemic myelopathy and acute noncompressive pulposus extrusion in dogs using MRI VRU 57.1

Answer 53

disc space narrowing | disc degeneration

Question 54

What was the appearance of hyperacute subperiosteal vertebral hemorrhage? Imaging diagnosis - Spontaneous subperiosteal vertebral hemorrhage in a greyhound. VRU 55.4

Answer 54

Extradural T2 hyperintense (to gray matter, not to CSF) T1 isointense to normal parenchyma No contrast enhancement

Question 55

What are other differentials for an extradural mass effect?

Answer 55

Hematoma/hemorrhage - varying characteristics based on stage Tissue mass cyst-like structure

Question 56

Differentials for GRE hypointensities? Imaging diagnosis - Spontaneous subperiosteal vertebral hemorrhage in a greyhound. VRU 55.4

Answer 56

``` hemorrhage bone air ferrous material fibrous tissue ```

Question 57

What structures can lymphoma affect within the spine? Where is CNS lymphoma NOT commonly seen? MRI findings of lymphoma in the canine spine. VRU 57.2

Answer 57

Vertebrae (common), paraspinal soft tissues, vertebral canals Frequently will be in more than one compartment USUALLY not an intramedullary lesion

Question 58

Which part of the vertebral body did lymphoma frequently affect? MRI findings of lymphoma in the canine spine. VRU 57.2

Answer 58

medullary cavity of the vertebral body - without cortical destruction

Question 59

What were MR characteristics of lymphoma lesions? MRI findings of lymphoma in the canine spine. VRU 57.2

Answer 59

T2, STIR hyperintense T1 - iso/hypointense Strongly contrast enhancing Ill-defined, poorly circumscribed/irregular Findings on STIR are significan

Question 60

Why are the findings on STIR significant in cases of lymphoma in the vertebral body? MRI findings of lymphoma in the canine spine. VRU 57.2

Answer 60

Bone marrow - frequently suppresses on STIR images Lymphoma - medullary cavity of the vertebral body will remain hyperintense on STIR - suggestive of a myeloproliferative/myelodysplastic disease

Question 61

Which tumor localization was MR worst at identifying? MRI features of tumors of the spine and spinal cord in dogs. VRU 40.6

Answer 61

Intradural extramedullary

Question 62

What is a chemical shift artifact? MRI features of tumors of the spine and spinal cord in dogs. VRU 40.6

Answer 62

Fat and water have different Larmor frequencies. The difference between these frequencies is linearly related to MRI strength. Because of this, will result in mis-registration of fat at a fat-soft tissue interface in the frequency encoding direction. (will have separation between fluid [csf] and fat [epidural] on MR) Example: Signal void surrounding CSF

Question 63

What are differentials for an intradural extramedullary mass? MRI features of tumors of the spine and spinal cord in dogs. VRU 40.6

Answer 63

meningioma | nerve sheath tumor

Question 64

What are differentials for ane xtradural tumor? MRI features of tumors of the spine and spinal cord in dogs. VRU 40.6

Answer 64

fibrosarcoma lymphosarcoma osteosarcoma plasmacytoma

Question 65

What is a gibbs truncation artifact? MRI features of tumors of the spine and spinal cord in dogs. VRU 40.6

Answer 65

``` # of phase encoding steps is decreased in relation to frequency encoding steps to save time. With excessive reduction – may be mis-mapping of image in phase direction. Other article: errors in Fourier transformation in structures with abrupt transitions (high to low signal – spinal cord and CSF) ``` Example: T2 weighted images of spinal cord - linear hyperintensity superimposed in central region.

Question 66

What are the layers and spaces of meninges within the spinal canal (outside --> in) Myelographic artifacts. VCNA 30.2

Answer 66

``` Epidural space Dura mater (pachymeninges) Subdural space Leptomeninges Arachnoid membrane Subarachnoid space Pia mater ```

Question 67

What does dura matter attach to within the calvarium? In the spinal cord? Myelographic artifacts. VCNA 30.2

Answer 67

Calvarium - attaches to the periosteum | SC - separated from the periosteum by the epidural space

Question 68

Where does the epidural space originate? Myelographic artifacts. VCNA 30.2

Answer 68

Caudal atlas --> caudally | Does not extend cranially to the cerebellomedullary cistern

Question 69

What is the conus medullaris? Myelographic artifacts. VCNA 30.2

Answer 69

Tapering caudal portion of the spinal cord including S2-C5

Question 70

``` Where is the 3 sacral spinal segments located in Cats? Avg sized dog? Large dogs? Small dogs? ``` Myelographic artifacts. VCNA 30.2

Answer 70

Cats - L6 Avg dogs - L5 Large dogs - L4 Small dogs - L6

Question 71

Where is lumbar cistern located? Myelographic artifacts. VCNA 30.2

Answer 71

2-3cm caudal to the conus medullaris, where the dural mater ends.

Question 72

What is the appearance of an epidurogram? Myelographic artifacts. VCNA 30.2

Answer 72

Undulating linear opacities on both views Amorphous borders due to presence of epidural fat Accumulation around the nerve roots that extend out of the vertebral canal May see 3 lines on lateral view: dorsal column is thin, the lucent space representing the epidural fat, a middle line that represents the subarachnoid space, and a ventral column that is thick

Question 73

What does a subdural injection look like? Myelographic artifacts. VCNA 30.2

Answer 73

Best seen on the lateral view Dorsal column - dorsal portion will be straight, the ventral portion is undulating Ventral column - smoother than the dorsal column This contrast can extend into the foramen magnum

Question 74

What does a central canalogram appear? Myelographic artifacts. VCNA 30.2

Answer 74

Centrally located, smooth contrast column

Question 75

What is the Gibbs truncation artifact? Truncation artifact in MRI of the canine spinal cord VRU Pre-published (2016)

Answer 75

line of abnormal signal intensity that occurs parallel to an interface between tissues of markedly different signal intensity

Question 76

Where is Gibbs truncation artifact most commonly seen, and why? What sequences and what does it look like. Truncation artifact in MRI of the canine spinal cord VRU Pre-published (2016)

Answer 76

Seen as a hyperintensity on T2w in the central region of the spinal cord. Hypointense on T1 images Occurs in this area because of differences between the spinal cord and CSF

Question 77

What is brief physics explanation behind the Gibbs truncation artifact? Truncation artifact in MRI of the canine spinal cord VRU Pre-published (2016)

Answer 77

Occur as a consequence of the Fourier transformation (converts spatial domain --> frequency domain so that kernels can e applied --> back into image). At the boundaries of tissues with markedly different signal intensities (tissue fluid interfaces) data is truncated in k-space (chest of drawers) resulting in misrepresentation of the data on either side of the boundary

Question 78

How can the Gibbs artifact be reduced? Truncation artifact in MRI of the canine spinal cord VRU Pre-published (2016)

Answer 78

Increaseing the spatial resolution (decreasing FOV, increasing matrix size) using pre-reconstruction filters post-processing optimization techniques

Question 79

Using low vs high spatial resolutions - what is difference in the appearance of the Gibbs artifact? Truncation artifact in MRI of the canine spinal cord VRU Pre-published (2016)

Answer 79

Low resolution: The single, linear region of hyperintensity were wider and more intense High resolution: Multiple, small lines of hyperintensity that were very narrow

Question 80

After an artificial compression was placed on the spinal cord - what did different spatial resolutions due to Gibbs artifact? Truncation artifact in MRI of the canine spinal cord VRU Pre-published (2016)

Answer 80

Low resolution: concentric runcation artifacts overlapping spinal cord impeding evaluation of signal intensity of the spinal cord High resolution: slightly increased hyperintensity, likely due to merging of multiple hyperintense lines into one larger intense line. (constructive interference)

Question 81

What is the problem with Gibbs artifact in clinical cases of spinal cord compression? Truncation artifact in MRI of the canine spinal cord VRU Pre-published (2016)

Answer 81

If this is th eonly change in the spinal cord - it is impossible ot determine whether the hyperintensity represents a true lesion, or if it is due to constructive interference of a gibbs artifact

Question 82

What is criteria described to differentiate between IVDD protrusion/extrusion on MR? Evaluation of MRI guidelines for differentaition between TL IVD extrusions and protrusions in dogs VRU pre-published (2016)

Answer 82

Protrusion: 1) midline instead of lateralized IV herniation 2) partial, instead of complete intervertebral disk degeneration (has heterogeneous appearance on T2) Extrusion: 1) Presence of single disk herniation 2) dispersed IV disk material beyond borders of IV disk space

Question 83

When blinded observers were given guidelines for how to interpret extrusion/protrusion - did this improve or worsen their diagnoses? Evaluation of MRI guidelines for differentaition between TL IVD extrusions and protrusions in dogs VRU pre-published (2016)

Answer 83

Improved them significantly (even for observers with 0 experience) Overall without guidelines - 71% (45-89%) Overall with guidelines - 79% (53-93%)

Question 84

What are the MR findings of leukoencephalomyelopathy in rottweilers and leonbergers? MRI and genetic investigation of a case of rottweiler leukoencephalomyelopathy BMC vet research 2013 MRI findings in rottweiler with leukoencephalomyelopathy JAAHA 2013 Novel leukoencephalomyelopathy in Leonbergers 2007

Answer 84

Bilaterally symmetric, intra-axial, T2 hyperintense lesions associated with the dorsolateral funiculi in the cervical spine No contrast enhancement Less common findings: other white matter lesions in the brain: pyramid, caudal cerebellar peduncle, trapezoid, crus cerebri, trigeminal nerve, optic tract

Question 85

Histopathologically - what was found in dogs with leukocephalomyelopathy in rottweilers and leonbergers? MRI and genetic investigation of a case of rottweiler leukoencephalomyelopathy BMC vet research 2013 MRI findings in rottweiler with leukoencephalomyelopathy JAAHA 2013 Novel leukoencephalomyelopathy in Leonbergers 2007

Answer 85

significant myelin loss in the dorsolateral funiculi, pyramid, trapezoid, caudal cerebellar peduncle, cerebellar white matter (only affecting white matter) axon degeneration astrocytosis

Question 86

Clinical findings seen in dogs wtih leukoencephalomyelopathy? MRI and genetic investigation of a case of rottweiler leukoencephalomyelopathy BMC vet research 2013 MRI findings in rottweiler with leukoencephalomyelopathy JAAHA 2013 Novel leukoencephalomyelopathy in Leonbergers 2007

Answer 86

progressive, long-strided gait, with appearance of stiffness, over-reaching of the limbs when walking, (consistent with general proprioceptive ataxia) and upper motor neuron tetraparesis that begin around the age of 1.5-3.5