シャドーイング練習: MRI Brain Sequences - radiology video tutorial - 動画で英語スピーキングを学ぶ
練習モードを選ぶ
各モードは全画面の練習ルームで開きます。
133 文
文が短すぎたり長すぎる場合は、Editをタップして調整してください。
1
Hello and welcome to the Radiopaedia Adult Brain MRI Review Course.
2
I'm Frank Gaylord and I'll be presenting the majority of the content during this course.
3
This pre-course video is really an introduction to make sure
4
that we're all on the same page as we'll be covering
5
a great deal of material during the actual live presentation and during the remainder of the videos.
6
A degree of familiarity with MRI sequences is expected.
7
And so this talk is really just to make sure that we're all on the same page.
8
I'm not going to be going into a great deal of detail into any of the sequences, and in fact we won't be touching on any of the physics,
9
but just to ensure that we understand the appearance of all of the main ones and the terminology used.
10
There are a great number of MRI sequences, so much so that I think in many ways it's easier to consider MRI.
11
a collection of modalities because the differences between different sequences is almost as large, if not larger, than between some different modalities.
12
So when we talk about sequences, there's no single way of grouping them or of discussing them.
13
But a useful one is to think about what the dominant weighting or the dominant characteristic that's been examined.
14
And then there's a number of modifiers applied to each of these.
15
So let's start with the main two that we are used to thinking about.
16
T1 weighted and T2 weighted.
17
These are the two fundamental anatomical sequences upon which many other sequences are built.
18
And different tissues have different appearances depending on which sequence is chosen.
19
They are characterized by specific TR and TE intervals, with T1 being short and short and T2 being long and long.
20
And this is their typical appearance.
21
The easiest way to identify a T1-weighted sequence is to examine the relationship between white matter and grey matter.
22
where the white matter is whiter than the grey matter.
23
So they match.
24
The white matter is white and the grey matter is grey.
25
In contrast, T2-weighted sequences have the opposite relationship with the grey matter being more hyper-intense compared to the white matter,
26
which is really quite dark.
27
And yes, of course, the CSF is bright on T2 and dark on T1, but as we'll see shortly, that's not always the safest way of identifying them.
28
A number of substances are hyper intense on T1, with the ones most relevant to the brain being blood product,
29
fat, some protonaceous material and contrast enhancement.
30
Proton density is an intermediate sequence characterized by a long TR
31
but a short TE and has appearances that were very useful in the early era of MRI in examining white matter
32
making white matter lesions easier to identify
33
than T2 or T1 The role of proton density has largely been superseded by flare imaging or fluid attenuated inversion recovery
34
to the point that very rarely is a proton density performed in modern day protocols.
35
So essentially we can forget about proton density, brain imaging, as of being only of historical value.
36
It's important to note however that proton density as a sequence is still alive
37
and well in other parts of the body and is particularly useful in musculoskeletal.
38
So if we take T1 and T2 weighted imaging we can see the first ways that we can modify these images.
39
The first is to add gadolinium and then perform T1 weighted sequences.
40
In this case where we have a thalamic primary brain tumor with some hemorrhagic change which has intrinsic high T1 signal,
41
we can see that another component of it demonstrates contrast enhancement.
42
The most common modifier for T2 weighted images is fluid attenuation,
43
usually referred to as FLARE for fluid attenuated inversion recovery.
44
And here we see this same tumor standing out more brightly against the white matter
45
and adjacent brain parenchyma now that the CSF within the ventricles has been attenuated.
46
Note that despite the attenuation of a CSF such that it is dark, similar to the appearance on T1,
47
the relationship of the white matter to the grey matter has remained that of a T2 weighted sequence.
48
And this is why this relationship is more important and an easier way to identify a T1 versus a T2 weighted sequence.
49
Otherwise, a flare sequence can be mistaken for a T1.
50
The next most important way that T1 images can be manipulated is to apply fat suppression.
51
This can be done both on pre-contrast or on post-contrast images.
52
Here we have a case of a pericolosal lipoma with a large amount of very hyper-intense fat seen in the midline.
53
When we perform contrast, it is a little bit difficult to tell whether there is contrast enhancement at the margins
54
or whether this represents merely fat.
55
the slice position is not always the same
56
so exact comparison is difficult one could assume that this is enhancement
57
but one may be just seeing the result of slightly different positioning
58
so what we can perform is fat saturation or fat suppression
59
where only fat loses signal and contrast remains high signal
60
and here we can see
61
that at the margins of this tumor there's only very minimal contrast enhancement with the bulk of the tumor completely attenuating out.
62
Note that in the scalp it's a subcutaneous fat
63
that becomes dark with the scalp remaining hyper-intense post-contrast due to the administration of gadolinium.
64
Fat-saturated post-contrast T1 sequences are routine in most parts of the body because of the presence of significant amounts of fat.
65
This is not the case in the brain where fat is an abnormal substance
66
and as such for purely intraparenchymal lesions fat saturation is usually not performed.
67
The exception to this is intracranial masses that are involving the skull
68
or skull base where an extra perennial extension is being sought.
69
So the most common situation for this to be performed would be a base of skull meningiomas
70
or cerebellopontine angle masses where potential for extracranial spread is present.
71
Moving on to T2 weighted sequences, fat suppression can be performed as part of a gradient echo
72
sequence where the intention is not particularly to fat suppress but to make it more susceptible to paramagnetic effects.
73
And we'll talk about that more in a second.
74
Or more commonly in the orbit or base of skull, to examine structures that are otherwise closely related to fat.
75
This would be commonly the case in the orbits where the extraocular muscles and optic nerve are surrounded by fat.
76
and thus examining for abnormal signal within either of those structures is much more easily performed with the attenuation of fat.
77
The situation in intracranial imaging that this would be useful for would be to look for a CSF leak, for example.
78
Susceptibility-weighted sequences represent a number of different sequences that share the propensity to have signal loss due to paramagnetic or diamagnetic effects.
79
So calcium or blood product will result in dark signal or black signal.
80
The newer sequences such as SWI, susceptibility weighted imaging, are exquisitely sensitive to very small amounts of such materials.
81
In this example of a patient that has familiar autosomal dominant multiple cavernoma syndrome,
82
we can see numerous large black areas.
83
If you were to look at T1 or T2 weighted sequences, these abnormalities would be much smaller than the ones here.
84
And this phenomenon is called blooming, where the signal loss extends beyond the anatomical confines of the lesion.
85
And this is due to the fact that paramagnetic or diamagnetic materials distort the magnetic field locally beyond their margins.
86
Susceptibility-weighted imaging at higher field strengths is particularly sensitive.
87
An earlier and still widely used susceptibility-sensitive sequence is gradient echo imaging, but there are a number of others.
88
They probably deserve their own column, but as I'm going to run out of room, we're going to put them under the T2 weighted column, as many of these are T2 star weighted.
89
The next column is diffusion weighted imaging, which really encompasses two main sequences.
90
What we commonly refer to as DWI, or diffusion weighted imaging, or isotropic imaging, or T2 weighted imaging are different synonyms for this,
91
and ADC, or apparent diffusion coefficient.
92
The DWI sequence is really quite a dirty sequence made up of both true diffusion information and T2 information.
93
And examining the DWI on its own can lead you to erroneously interpret high signal as representing true abnormal restricted diffusion,
94
when in fact what you're seeing is so-called T2 shine-through.
95
The underlying principles as to why T2 shine-through exists and the exact relationship between DWI and ADC is well beyond this talk,
96
but I will be creating a separate talk to just examine DWI
97
because I think it's a very important and often misunderstood sequence.
98
An extension of diffusion is diffusion tensor imaging which allows tractography
99
whereby the fact
100
that water molecules' motion is restricted along white matter tracks enables
101
the tracking of white matter tracks from one part of the brain to the other
102
and here we can see white matter tracts crossing from one
103
frontal lobe across the corpus callosum to the other frontal lobe as well as extending posteriorly.
104
Although tractography is relatively frequently performed in academic institutions, it's still not really mainstream.
105
Its role is largely research based but it is finding increasing roles in operative planning.
106
Moving on to our next column of types of sequences, we're moving to flow sensitive sequences.
107
These encompass MR angiography which is usually performed without intravenous contrast and relies on blood bringing with it signal.
108
These can be shown just as a stack of very thin images and
109
because there is little background for the vessels to be localized
110
against it can be difficult to know exactly where one is on a single image.
111
Thus often these images are shown as MIPS in this case of a young patient with a vein of galen malformation, and these can of course be surface shaded.
112
MR venography can be performed similarly to MR angiography or also by other techniques such as phase contrast,
113
and can be used to image dural venous sciases and cerebral veins.
114
Here we can see thrombosis or occlusion of the posterior part of the superior sagittal sinus.
115
And the same principles as phase contrast venography can be employed
116
to look at the pulsatile flow of CSF in the cisterns and the aqueduct as shown here.
117
This can be particularly useful if aqueduct stenosis needs to be excluded
118
or if hyperdynamic flow of normal pressure hydrocephalus needs to be evaluated.
119
And on to the last column of miscellaneous sequences which includes MR spectroscopy
120
performed very routinely as part of particularly brain tumour or mass workup.
121
A functional MRI where we can image specific parts of the brain being activated during motor or verbal or memory tasks.
122
And lastly, MR perfusion, which has really become now routine in assessment of tumours and neurodegenerative conditions.
123
So that rounds out the different sequences that we have available to us in performing imaging of the brain and intracranial content.
124
Some of these, however, are not used terribly frequently and have only very specific applications,
125
particularly fat-suppressed T2, where most of the time this is performed for extracranial pathology,
126
DTI tractography, CSF flow studies,
127
and functional MRI, which only have very specific indications and most frequently performed in academic centres only.
128
If you want to get into a little bit more about different types of sequences, this is an excellent radiographics article which you can access by following this bit.ly link.
129
Thanks for your attention and I look forward to meeting many of you in person and many more of you online shortly.
130
We believe very strongly that access to quality medical education
131
should not be restricted by your personal wealth or that of your institution or that of your country.
132
And so that is the reason why we have created these courses and are making them available for free in 115 countries.
133
So I would like to thank all of the rest of you for supporting us and for making these viable.
アプリをダウンロード
流暢に話すために必要なすべて
AI発音採点文ごとに採点
IPA練習すべての音をマスター
単語学習自分の単語帳を作る
単語ゲーム遊びながら覚える
✨ おすすめ動画
C11
4 文
Ambr®️ 250 High Throughput Perfusion Product Tutorial - Learn with Sartorius
Business EnglishUniversity StudentsWorking Adults
C16
64 文
Expand your perception. Change your life. | Dr. Jill Bolte Taylor
Business EnglishUniversity StudentsWorking Adults
C11
506 文
Analyzing Statements of Cash Flows 1 (2025 CFA® Level I Exam – FSA – Learning Module 4)
Business EnglishUniversity StudentsWorking Adults
C12
72 文
Blood Flow Through the Heart (Made Easy in 5 Minutes!)
Business EnglishUniversity StudentsWorking Adults
C12
111 文
2025 Pathology Review: Practical Updates in Breast, Gastrointestinal and Genitourinary Pathology
Business EnglishUniversity StudentsWorking Adults
C14
123 文
Introduction to Diminsionality Reduction (a.k.a. Manifold Learning)
Business EnglishUniversity StudentsWorking Adults
C12
51 文
How to do ACTIVE RECALL Effectively? (4 Techniques worked for me)
Business EnglishUniversity StudentsWorking Adults
C11
153 文
In 9 minutes, you’ll understand breathwork better than 99% of the planet
Business EnglishUniversity StudentsWorking Adults
C25
127 文
Intro to Scanning Electron Microscopy (SEM)
Business EnglishUniversity StudentsWorking Adults
C12
181 文
FREE CCNA 200-301 course // Complete Practical CCNA (v1.1 2025 Course) with real equipment
Cambridge Exam PrepBusiness EnglishUniversity Students
B23
149 文
يجب أن تعرف هاذا على الأوميغا 3 !!
Business EnglishUniversity StudentsWorking Adults
C11
218 文
Introduction to Marketing: The Marketing Mix
Business EnglishUniversity StudentsWorking Adults
MRI脳画像シーケンスの学習コンテキスト
このビデオは、MRIの基本的な脳画像シーケンスについて説明したもので、放射線医学の入門講座として役立ちます。講師はFrank Gaillardで、T1強調画像やT2強調画像、FLAIR、拡散強調画像などの基本的な概念を、臨床例を交えながら分かりやすく解説しています。医学用語が多いですが、日常的なコミュニケーションにも応用できるフレーズや発音のポイントが隠れています。
日常会話に使える5つのフレーズ
- "make sure that we're all on the same page"：「みんなが同じ理解度にあるようにする」。会議や説明の前に使えるフレーズで、相手の理解を確認するときに便利です。
- "a great deal of material"：「大量の資料・内容」。「今日はa great deal of materialを扱います」というように、多くの情報を話すときに使えます。
- "in contrast"：「対照的に」。二つのものを比較するときに、「Aは〇〇です。In contrast、Bは△△です」と使います。
- "the exception to this is"：「この例外は」。一般的なルールを説明した後、例外を述べるときに便利です。
- "moving on to"：「次に移る」。話題を変えるときに、「Moving on to the next point」と使います。
YouTubeでの英語学習：シャドーイングのステップバイステップガイド
このビデオは医学用語が多いため、シャドーイング（shadow speech）の難易度は中程度ですが、以下の方法で効果的に練習できます。まず、英語シャドーイングの基本として、ビデオを10秒ずつ区切り、講師の発音やイントネーションを真似て繰り返します。医学用語は発音が難しいので、一つ一つの単語を分解して発音を確認しましょう。次に、shadowing siteなどを使って、テキストと音声を同期させながら練習すると、リズムを掴みやすくなります。さらに、「in contrast」「moving on to」などのフレーズは、日常会話でも使えるので、重点的に練習してください。YouTubeで英語学習をする際は、スピードを落として繰り返すことが重要で、1日10分でも継続すると、発音とリスニング力が大幅に向上します。shadow speakのコツは、「聞いて即座に真似る」ことです。慣れるまで時間がかかりますが、少しずつ進めると必ず成果が出ます！
この動画の文法
話し手がよく使っている文型を、動画の実際の表現とともに紹介します。
| 文型 | 動画での表現 |
|---|---|
| 受動態 be + 過去分詞 — 誰がするかより、何が起きるかに焦点を当てる | is expected · been examined · are built |
| 現在完了形 have/has + 過去分詞 — 過去の出来事が今も関係している | that's been examined · has been attenuated · has remained |
| 関係詞節 who / which + 節 — 人や物について情報を加える | change which has · angiography which is · perfusion, which has |
シャドーイングとは？英語上達に効果的な理由
シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。