Radio diagnosis > MRI > Flashcards

MRI Flashcards

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1
Q

What is the standard magnetic field strength used in MRI?

A

1.5 Tesla

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2
Q

What is the advantage of using a 3 Tesla magnetic field in MRI?

A

It provides better contrast.

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3
Q

Is MRI considered ionizing radiation?

A

No, it is non-ionizing radiation and is safe in pregnancy.

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4
Q

What type of waves does MRI use, and what is it compared to in other imaging modalities?

A

MRI uses magnetic fields, unlike Ultrasound (USG) which uses sound waves.

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5
Q

What are the three main components involved in the MRI process?

A

Magnetic field, radiofrequency pulses, and relaxation of protons.

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6
Q

What determines the signal intensity in MRI?

A

Signal intensity is measured based on T1, T2, T2*, etc.

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7
Q

In a T1-weighted sequence, what is the signal intensity and appearance of fat?

A

Fat appears WHITE (High signal intensity) and is bright.

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8
Q

In a T1-weighted sequence, what is the signal intensity and appearance of gray matter?

A

Gray matter appears GRAY (Intermediate signal intensity) and is medium gray.

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9
Q

In a T1-weighted sequence, what is the signal intensity and appearance of white matter?

A

White matter appears WHITE (High signal intensity) and is bright.

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10
Q

In a T1-weighted sequence, what is the signal intensity and appearance of CSF/Fluid?

A

CSF/Fluid appears BLACK (Low signal intensity) and is dark.

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11
Q

How does blood typically appear in a T1-weighted sequence?

A

Blood signal intensity is variable depending on the flow state, but it can be bright in subacute hemorrhage.

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12
Q

What is a clinical use for T1-weighted sequences related to anatomy?

A

Best visualization of fat planes and general anatomy.

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13
Q

What is the mnemonic for remembering T1-weighted sequences?

A

T1 = T (Time to) = Fat & Gray matter appear Bright; CSF Dark

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14
Q

In a T2-weighted sequence, what is the signal intensity and appearance of CSF/Fluid?

A

CSF/Fluid appears WHITE (Very High signal intensity) and is very bright. This is a cardinal feature.

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15
Q

In a T2-weighted sequence, what is the signal intensity and appearance of edema?

A

Edema appears WHITE (High signal intensity) and is very bright.

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16
Q

How does blood typically appear in a T2-weighted sequence?

A

Blood appears BLACK/DARK.

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17
Q

What is a key clinical use for T2-weighted sequences?

A

Detecting edema, CSF, pathology, and tumors.

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18
Q

What is the mnemonic for remembering T2-weighted sequences?

A

T2 = water (fluid) = CSF BRIGHT; Edema BRIGHT; Blood DARK

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19
Q

What is the primary purpose of FLAIR (Fluid Attenuated Inversion Recovery) sequences?

A

To suppress the signal from CSF/fluid so that edema and pathology can be more easily visualized.

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20
Q

In a FLAIR sequence, what is the signal intensity and appearance of CSF/Fluid?

A

CSF/Fluid appears BLACK (Suppressed signal intensity) and is dark/suppressed.

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21
Q

In a FLAIR sequence, what is the signal intensity and appearance of edema and pathology?

A

Edema and pathology appear WHITE (High to Very High signal intensity) and are bright.

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22
Q

What is FLAIR best used for in clinical practice?

A

Best for detecting brain lesions such as MS plaques, ischemic stroke, tumors, and subarachnoid hemorrhage.

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23
Q

Which sequence is best for detecting edema?

A

FLAIR is best for edema detection, as edema appears brightest.

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24
Q

What does STIR stand for and what is its primary use?

A

STIR stands for Short Tau Inversion Recovery. Its primary use is for fat suppression, making it highly sensitive for detecting edema and bone marrow edema.

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25
In STIR sequences, how does fat appear, and what is the benefit of this?
In STIR sequences, fat is suppressed and appears black. This removes the fat signal, leading to cleaner images and better visualization of other tissues.
26
What is the signal appearance of fluid and edema in STIR sequences?
Fluid appears white in STIR sequences, and edema appears very bright white, making STIR the most sensitive sequence for edema detection.
27
What are the clinical indications for using STIR sequences?
Clinical indications for STIR include edema detection (most sensitive), stress fractures, osteomyelitis, and acute inflammation.
28
What is the mnemonic for remembering the uses of STIR?
The mnemonic for STIR is: 'STIR = Super sensitive for Tissue edema and bone marrow'.
29
What is the purpose of fat saturation in T2-Fat Sat sequences?
The purpose of fat saturation in T2-Fat Sat sequences is to suppress the fat signal, making it appear black.
30
How do fluid and edema appear in T2-Fat Sat sequences?
Fluid and edema both appear white in T2-Fat Sat sequences, standing out clearly against the suppressed fat.
31
What are the clinical applications of T2-Fat Sat sequences?
T2-Fat Sat sequences are clinically used for joint imaging, edema in joints, and inflammation.
32
What does SWI stand for and what does it detect?
SWI stands for Susceptibility Weighted Imaging. It is used to detect hemosiderin deposits, microhemorrhages, and calcifications.
33
How do hemosiderin deposits and calcifications appear on SWI?
Hemosiderin deposits and calcifications appear hypointense (black) on SWI due to iron deposition.
34
What is a key finding on SWI for Diffuse Axonal Injury (DAI)?
Microhemorrhages, appearing as black dots, are detected on SWI and are considered the IOC for Diffuse Axonal Injury (DAI) in head trauma.
35
What is the mnemonic for SWI?
The mnemonic for SWI is: 'SWI = Sees Iron/bleeding (microhemorrhages as dark dots)'.
36
What are the clinical uses of SWI?
Clinical uses of SWI include head trauma (DAI detection), small hemorrhages, calcifications, and microangiopathy.
37
What do DWI and ADC stand for?
DWI stands for Diffusion Weighted Imaging, and ADC stands for Apparent Diffusion Coefficient.
38
How does acute ischemic stroke appear on DWI and ADC?
Acute ischemic stroke appears hyperintense (bright) on DWI and hypointense (low) on ADC, indicating restricted diffusion.
39
What does restricted diffusion mean in the context of DWI and ADC?
Restricted diffusion means that water molecules have limited movement. This is indicated by a hyperintense signal on DWI and a hypointense signal on ADC, and it is the most sensitive finding for acute stroke.
40
What is the meaning of unrestricted diffusion on DWI and ADC?
Unrestricted diffusion means water molecules can move freely. This is seen in normal tissue (isointense on DWI, normal ADC) and chronic infarcts or vasogenic edema (hyperintense on DWI, hyperintense on ADC).
41
What is the clinical IOC for acute ischemic stroke?
The clinical IOC for acute ischemic stroke is DWI and ADC, where a hyperintense lesion on DWI and a hypointense lesion on ADC indicate acute infarction.
42
What is the mnemonic for DWI?
The mnemonic for DWI is: 'DWI = Diffusion-weighted Imaging = Most sensitive for acute STROKE (bright lesion on DWI + low ADC)'.
43
What is DTI and what is its purpose?
DTI stands for Diffusion Tensor Imaging. Its purpose is to map the direction of white matter tracts using color coding.
44
What do the colors red, green, and blue represent in DTI?
In DTI, red represents left-right fibers, green represents anterior-posterior fibers, and blue represents superior-inferior fibers.
45
What is the clinical use of DTI?
DTI is used for surgical planning, particularly to assess tumor proximity to eloquent white matter.
46
What are the two main types of MRA mentioned?
The two main types of MRA mentioned are Time-of-flight (TOF) and Contrast-enhanced MRA.
47
What is the advantage of Time-of-flight (TOF) MRA?
The advantage of TOF MRA is that it allows for vascular imaging without the use of contrast agents.
48
When is Contrast-enhanced MRA preferred?
Contrast-enhanced MRA is preferred for better visualization of slow flow and the venous system.
49
What are the clinical indications for MRA?
Clinical indications for MRA include carotid stenosis, intracranial aneurysms, and arterial dissection.
50
In the MRI Signal Intensity Summary Table, what is the signal for Fat on T1?
Fat appears white on T1 sequences.
51
What is the signal for CSF on FLAIR sequences?
CSF appears black on FLAIR sequences.
52
How does edema appear on STIR sequences according to the summary table?
Edema appears white on STIR sequences.
53
What is the signal for acute blood on T2 sequences?
Acute blood appears black on T2 sequences.
54
Which sequence is the sequence of choice for detecting acute stroke according to Thumb Rule 1?
DWI + ADC sequences are the sequence of choice for detecting acute stroke.
55
What is the characteristic finding for MS plaques on FLAIR sequences?
MS plaques are typically FLAIR hyperintense and are often found in periventricular or infratentorial locations.
56
According to Thumb Rule 1, what sequence is best for visualizing microhemorrhages in head trauma?
SWI is the sequence best for visualizing microhemorrhages in head trauma, which appear as hypointense dots.
57
Which sequence is best for visualizing normal brain anatomy and gray/white matter differentiation?
T1 sequences are best for visualizing normal brain anatomy and gray/white matter differentiation.
58
What is the sequence of choice for detecting acute osteomyelitis (OM) in the spine according to Thumb Rule 2?
STIR is the sequence of choice for detecting acute osteomyelitis (OM) in the spine, as it shows bone marrow edema as hyperintense.
59
How does a stress fracture appear on STIR sequences?
A stress fracture appears as bone marrow edema, which is hyperintense on STIR sequences.
60
What is the best sequence for visualizing disc herniation in the spine?
Sagittal T2 sequences are best for visualizing disc herniation and nerve compression in the spine.
61
What is the IOC for spinal cord infarction?
T2 and DWI sequences are used for spinal cord infarction, with DWI showing restricted diffusion.
62
What are the common MRI findings for neurofibromas and schwannomas?
Neurofibromas and schwannomas typically appear hyperintense on T2 and enhance with contrast.
63
What is the origin of spinal meningiomas?
Spinal meningiomas originate from the dura.
64
What are the clinical indications for STIR (Short Tau Inversion Recovery) imaging?
STIR is best for edema detection, stress fractures, osteomyelitis, and acute inflammation.
65
In T2-Fat Sat imaging, what is the signal appearance of fat and why is it suppressed?
Fat is suppressed (appears black) to remove its signal and enhance the visualization of other tissues.
66
What is the signal appearance of fluid in T2-Fat Sat imaging and what is its purpose?
Fluid appears white (very bright) in T2-Fat Sat imaging, which enhances its visualization.
67
How does edema appear in T2-Fat Sat imaging?
Edema appears very bright white, standing out against the suppressed fat signal.
68
What are the clinical indications for T2-Fat Sat imaging?
T2-Fat Sat is used for joint imaging, detecting edema in joints, and inflammation.
69
What does SWI (Susceptibility Weighted Imaging) detect?
SWI detects hemosiderin deposits, microhemorrhages, and calcifications.
70
How do hemosiderin deposits appear on SWI?
Hemosiderin deposits appear hypointense (black) on SWI.
71
What is the appearance of microhemorrhages on SWI?
Microhemorrhages are detected as black dots on SWI.
72
What is a clinical indication for SWI in head trauma?
SWI is an indicator of Diffuse Axonal Injury (DAI) in head trauma.
73
How do calcifications appear on SWI?
Calcifications appear hypointense (black) on SWI.
74
What is a helpful mnemonic for remembering what SWI detects?
SWI = Sees Iron/bleeding (microhemorrhages as dark dots).
75
What are the clinical indications for SWI?
Clinical indications for SWI include head trauma (DAI detection), small hemorrhages, calcifications, and microangiopathy.
76
What does DWI stand for?
Diffusion Weighted Imaging
77
What does ADC stand for?
Apparent Diffusion Coefficient
78
In normal brain tissue, what is the DWI signal and ADC value?
DWI is isointense and ADC is normal.
79
What does an isointense DWI signal and normal ADC value indicate?
Unrestricted diffusion, indicating normal brain tissue.
80
What is the DWI signal and ADC value in acute ischemic stroke?
DWI is hyperintense (bright) and ADC is hypointense (low).
81
What does restricted diffusion on DWI and a low ADC value signify?
This is the most sensitive finding for acute stroke.
82
What is the mnemonic for DWI and its sensitivity?
DWI = Diffusion-weighted Imaging = Most sensitive for acute STROKE (bright lesion on DWI + low ADC).
83
What is the clinical IOC for DWI in acute ischemic stroke?
DWI is the gold standard for acute ischemic stroke, characterized by a hyperintense signal on DWI and a hypointense signal on ADC, indicating acute infarction.
84
What is the DWI signal and ADC value in a chronic infarct?
DWI is hyperintense and ADC is hyperintense.
85
What does a hyperintense DWI signal and hyperintense ADC value suggest?
Unrestricted diffusion, indicating an old stroke.
86
What is the DWI signal and ADC value in vasogenic edema?
DWI is hyperintense and ADC is hyperintense.
87
What does a hyperintense DWI signal and hyperintense ADC value indicate in the context of edema?
Unrestricted diffusion, often seen with tumor edema.
88
What is the DWI signal and ADC value in cytotoxic edema?
DWI is hyperintense and ADC is hypointense.
89
What does a hyperintense DWI signal and hypointense ADC value suggest?
Restricted diffusion, seen in acute ischemia and infection.
90
What does DTI stand for?
Diffusion Tensor Imaging
91
What is the primary purpose of DTI?
To map white matter tract direction.
92
What does the color red represent in DTI color coding?
Left-right fibers.
93
What does the color green represent in DTI color coding?
Anterior-posterior fibers.
94
What does the color blue represent in DTI color coding?
Superior-inferior fibers.
95
What are the uses of DTI?
Surgical planning and assessing tumor proximity to white matter.
96
What is the clinical IOC for DTI?
DTI is used for pre-operative planning for brain tumors located near eloquent white matter.
97
What does MRA stand for?
MRA stands for Magnetic Resonance Angiography.
98
What is the primary use of Time-of-flight (TOF) MRA?
Time-of-flight (TOF) MRA is used for vascular imaging without contrast.
99
What is a key advantage of TOF MRA?
A key advantage of TOF MRA is that no gadolinium is needed.
100
When is contrast-enhanced MRA particularly useful?
Contrast-enhanced MRA is better for slow flow and the venous system.
101
What contrast agent is used in contrast-enhanced MRA?
Gadolinium is used as a contrast agent in contrast-enhanced MRA.
102
What are some clinical applications for MRA?
Clinical applications for MRA include carotid stenosis, intracranial aneurysms, and arterial dissection.
103
In the MRI Signal Intensity Summary Table, what appears bright (white) on a T1 sequence?
Fat appears bright (white) on a T1 sequence.
104
In the MRI Signal Intensity Summary Table, what appears dark (black) on a T1 sequence?
CSF and bone cortex appear dark (black) on a T1 sequence.
105
In the MRI Signal Intensity Summary Table, what appears bright (white) on a T2 sequence?
Fat, CSF, and edema appear bright (white) on a T2 sequence.
106
In the MRI Signal Intensity Summary Table, what appears dark (black) on a T2 sequence?
Blood (acute) and bone cortex appear dark (black) on a T2 sequence.
107
In the MRI Signal Intensity Summary Table, what appears bright (white) on a FLAIR sequence?
Fat, edema, and blood (acute) appear bright (white) on a FLAIR sequence.
108
In the MRI Signal Intensity Summary Table, what appears dark (black) on a FLAIR sequence?
CSF appears dark (black) on a FLAIR sequence.
109
In the MRI Signal Intensity Summary Table, what appears bright (white) on a STIR sequence?
CSF, edema, and blood (acute) appear bright (white) on a STIR sequence.
110
In the MRI Signal Intensity Summary Table, what appears dark (black) on a STIR sequence?
Fat appears dark (black) on a STIR sequence. Bone cortex is variable.
111
What is the appearance of edema on a T1 sequence?
Edema appears gray on a T1 sequence.
112
What is the appearance of acute blood on a T1 sequence?
Acute blood appears white on a T1 sequence.
113
What is the appearance of acute blood on a T2 sequence?
Acute blood appears black on a T2 sequence.
114
What is the appearance of acute blood on a FLAIR sequence?
Acute blood appears white on a FLAIR sequence.
115
What is the appearance of acute blood on a STIR sequence?
Acute blood appears white on a STIR sequence.
116
What is the primary use of DWI (stroke) sequences?
DWI sequences are used to detect stroke.
117
How does edema appear on a DWI sequence?
Edema appears hyperintense on a DWI sequence.
118
What is the appearance of CSF on a T1 sequence?
CSF appears black on a T1 sequence.
119
What is the appearance of CSF on a T2 sequence?
CSF appears white on a T2 sequence.
120
What is the appearance of CSF on a FLAIR sequence?
CSF appears black on a FLAIR sequence.
121
What is the sequence of choice for brain tumors in MRI?
T1 (contrast) + T2/FLAIR
122
What signal intensity is typically seen for brain tumors on T2/FLAIR sequences?
T2 hyperintense
123
What is the characteristic finding for a brain tumor on MRI?
Mass with edema
124
Which sequences are most sensitive for diagnosing acute stroke on MRI?
DWI + ADC
125
What are the signal characteristics of acute stroke on DWI and ADC sequences?
DWI hyperintense, ADC hypointense
126
What is the sequence of choice for identifying MS plaques on MRI?
FLAIR
127
What signal intensity is characteristic of MS plaques on FLAIR sequences?
FLAIR hyperintense
128
What are common locations for MS plaques seen on MRI?
Periventricular/infratentorial lesions
129
What is the sequence of choice for acute hemorrhage on MRI?
T2/SWI
130
How does acute hemorrhage typically appear on T2/SWI sequences?
T2 hypointense (black blood)
131
What is the finding for acute hemorrhage on T2 sequences?
Blood appears dark on T2
132
What is the sequence of choice for DAI (head trauma) on MRI?
SWI
133
What are the characteristic findings for DAI on SWI sequences?
Hypointense dots
134
What do hypointense dots on SWI sequences indicate in the context of head trauma?
Microhemorrhages visible
135
What is the sequence of choice for visualizing normal brain anatomy on MRI?
T1
136
What is a key advantage of using T1 sequences for normal brain anatomy?
Best for anatomical detail
137
What anatomical differentiation is best seen on T1 sequences?
Gray/white matter differentiation
138
What does the mnemonic 'CNS = FLAIR for MS, DWI for stroke, SWI for trauma' refer to?
Key MRI sequences for specific CNS pathologies
139
What are neurofibromas often associated with in terms of location and MRI findings?
Neurofibromas are often found in the spine and nerve roots, and appear hyperintense on T2-weighted MRI sequences, enhancing with contrast.
140
What is the origin of neurofibromas?
Neurofibromas originate from the peripheral nerve sheath.
141
Describe the typical MRI findings for a schwannoma.
Schwannomas are typically hyperintense on T2-weighted MRI sequences and enhance with contrast.
142
What is the cellular origin of schwannomas?
Schwannomas originate from schwann cells.
143
Where are spinal meningiomas commonly located, and what is a characteristic MRI finding?
Spinal meningiomas are typically found intradurally and show homogeneous enhancement on MRI.
144
What is the origin of spinal meningiomas?
Spinal meningiomas originate from the dura.
145
What is the primary imaging sequence used for detecting neurogenic tumors in the context of IOC MRI?
IOC MRI for neurogenic tumors utilizes specific sequences to identify these lesions.
146
What is the main finding on STIR sequences for acute osteomyelitis?
Acute osteomyelitis typically shows bone marrow edema, which appears STIR hyperintense (BRIGHT).
147
How does a stress fracture appear on a STIR sequence?
A stress fracture is identified by edema at the fracture site, appearing STIR hyperintense.
148
What is the STIR finding for sacroiliitis, often associated with ankylosing spondylitis?
Sacroiliitis presents as SI joint edema, which is STIR hyperintense.
149
What MRI finding on a STIR sequence is indicative of a bone contusion?
Bone contusion is characterized by marrow contusion edema, appearing STIR hyperintense.
150
What does the mnemonic 'STIR' stand for in relation to bone marrow edema?
STIR stands for 'Super Tracker of bone marrow edema', highlighting its use for inflammation, stress fractures, and osteomyelitis.
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