JPH0399631A - Magnetic resonance imaging apparatus - Google Patents
Magnetic resonance imaging apparatusInfo
- Publication number
- JPH0399631A JPH0399631A JP1235676A JP23567689A JPH0399631A JP H0399631 A JPH0399631 A JP H0399631A JP 1235676 A JP1235676 A JP 1235676A JP 23567689 A JP23567689 A JP 23567689A JP H0399631 A JPH0399631 A JP H0399631A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- frequency pulse
- signal
- imaging apparatus
- resonance imaging
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000002595 magnetic resonance imaging Methods 0.000 title claims description 13
- 230000005284 excitation Effects 0.000 claims abstract description 11
- 238000005259 measurement Methods 0.000 claims description 4
- 238000003384 imaging method Methods 0.000 abstract description 18
- 238000000034 method Methods 0.000 abstract description 4
- 238000005070 sampling Methods 0.000 abstract description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000523 sample Substances 0.000 description 3
- 238000005481 NMR spectroscopy Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001208 nuclear magnetic resonance pulse sequence Methods 0.000 description 2
- 230000017531 blood circulation Effects 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000002592 echocardiography Methods 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
Landscapes
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は核磁気共鳴現象を利用した断層像撮影装置（以
下ｒＭＲＩＪと言う）に係り、特に縦緩和時間及び横緩
和時間を強調した２つの画像を同時に映像化する際に有
効なイメージング方θ；に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a tomographic imaging apparatus (hereinafter referred to as rMRIJ) that utilizes nuclear magnetic resonance phenomena, and particularly relates to a tomographic imaging apparatus that utilizes nuclear magnetic resonance phenomena. This invention relates to an effective imaging method θ when images are visualized simultaneously.
マグネティク・レゾナンス・イン・メデイスン・６、第
１７５頁から第１９３頁、１９８８年（Ｍａｇｎｅｔｉ
ｃ Ｒｅ５ｏｎａｎｃｅ ｉｎ Ｍｅｄｉｃｊｎｅ、
６． Ｉ’７５１９３、 ］９８８）および第１３回ｌ
」本磁気共鳴医学会人会寄稿集、第１９６頁 １９８９
年かられかるように、高速撮影法は縦緩和時間を強調し
た画像を得ることは容易であるが、横緩和時間を強調し
た画像を得ることは是かしい。高速撮影法において、撮
影対象領域の緩和時間に対して極端に短い繰り返し時間
で撮影を行うと、高周波パルスによる励起直後及び次の
高周波パルスの直前に信−８が生じる。この２つの信号
は、それぞれ違った生体情報は反映しており、特に、高
周波パルス直前の信号は、生体の横緩和時間を強く反映
している。この信号を使って画像を作ると横緩和時間強
調画像が得られる。また、高周波パルス直後の信号は、
縦緩和時間を反映しているため、この信シ」・からは、
縦緩和時間強調画像を得ることかできる。Magnetic Resonance in Medicine 6, pp. 175-193, 1988.
c Re5onance in Medicjne,
6. I'75193, ]988) and the 13th l
"Magnetic Resonance Medical Society Contribution Collection, p. 196, 1989
As shown in 2010, high-speed imaging makes it easy to obtain images with emphasis on longitudinal relaxation time, but it is not advisable to obtain images with emphasis on transverse relaxation time. In high-speed imaging, when imaging is performed with an extremely short repetition time relative to the relaxation time of the region to be imaged, signal 8 occurs immediately after excitation by a high-frequency pulse and immediately before the next high-frequency pulse. These two signals reflect different biological information, and in particular, the signal immediately before the high-frequency pulse strongly reflects the transverse relaxation time of the biological body. When an image is created using this signal, a transverse relaxation time-enhanced image is obtained. In addition, the signal immediately after the high-frequency pulse is
Since it reflects the longitudinal relaxation time, this belief is
Longitudinal relaxation time-enhanced images can be obtained.
通常の高速法は高周波パルス直後の信号を使い縦緩和時
間強調画像を撮影しているが、最近、高周波パルス直前
の信とを使い横緩和時間強調画像を撮影する試みがなさ
れている。しかし、同時に２つの信号を取り込み映像化
したと言う発表はなＬ’。The normal high-speed method uses the signal immediately after the high-frequency pulse to capture a longitudinal relaxation time-enhanced image, but recently, attempts have been made to capture a transverse relaxation time-enhanced image using the signal immediately before the high-frequency pulse. However, there has been no announcement that two signals were captured and visualized at the same time.
・記したように通常の高速撮影υ、技術では、高周波パ
ルス直後の信号と高周波パルス直前の信号を同一の位相
エンコードプロジェクション内にサンプリングし一回の
撮影で縦緩和時間を強調した画像と横緩和時間を強調し
た画像を同時に得るという配慮がされておらず、それら
の緩和時間を強調した画像を得るには、異なる２つの撮
影パルスシーケンスが必要となるという問題がある。・As mentioned above, with normal high-speed imaging υ technology, the signal immediately after the high-frequency pulse and the signal immediately before the high-frequency pulse are sampled in the same phase encode projection, and in a single imaging, an image with emphasis on the vertical relaxation time and a horizontal relaxation time are obtained. There is no consideration given to simultaneously obtaining images with emphasis on time, and there is a problem in that two different imaging pulse sequences are required to obtain images with emphasis on their relaxation times.
本発明の目的は高周波パルス直後の信号と高周波パルス
直前の信号を同一の位相エンコードプロジェクション内
にサンプリングし、−度の撮影で、縦緩和時間を強調し
た画像と横緩和時間を強調した画像を同時に得るように
した磁気共鳴イメージ一
ング装置を提供することにある。The purpose of the present invention is to sample the signal immediately after the high-frequency pulse and the signal immediately before the high-frequency pulse in the same phase encode projection, and simultaneously produce an image with an emphasis on the longitudinal relaxation time and an image with the emphasis on the transverse relaxation time by imaging at -degrees. An object of the present invention is to provide a magnetic resonance imaging apparatus that can obtain magnetic resonance imaging.
本発明によれば、高周波パルス印加直後に生じる信号と
次の高周波パルス印加直前に生じる信号が同一の位相エ
ンコードプロジェクション内に８１測される。According to the present invention, a signal occurring immediately after application of a high-frequency pulse and a signal occurring immediately before application of the next high-frequency pulse are measured within the same phase encode projection.
高周波パルス印加直後の信号−と次の高周波パルス印加
直前の信号とを同一・の位相エンコードプロジェクショ
ン内に計測するようにしているので、１回の撮影で縦緩
和時間を強調した画像と横緩和時間を強調した画像の２
枚を得ることができる。Since the signal immediately after the application of a high-frequency pulse and the signal immediately before the application of the next high-frequency pulse are measured within the same phase encode projection, a single image captures an image that emphasizes the longitudinal relaxation time and an image that emphasizes the horizontal relaxation time. Image 2 highlighting
You can get one.
第１図に本発明の一実施例であるＭＲＩ装置の構成概要
を示すブロック図を示す１１図によりいて１０］は、均
一な静磁場を発生させる磁石、１０２は被検体内で核磁
気共鳴を生じさせるための高周波磁場を発生させる励起
システ１１．１０：３は、被検体から発生する電磁波を
受信し検波した後、Ａ／［〕変換する受信システ１１．
１０４は、磁場の強さをＸ、Ｙ、７．方向にそれぞれ独
立に線形に変化させることが可能な傾斜磁場発生システ
ム、１０５は、計測システムからの配４測データを基に
画像再生に必要な各種演算を行う画像処理システム、１
０６は、」−記構酸における各システムの動作タイミン
グをコントロールするシーケンス制御システム、１０７
は、高周波の送受信に使用するプローブ、］０８は、オ
ペレーションを行う操作卓である。FIG. 1 is a block diagram showing an outline of the configuration of an MRI apparatus according to an embodiment of the present invention. 10] is a magnet that generates a uniform static magnetic field; An excitation system 11.10:3 that generates a high-frequency magnetic field to generate a high-frequency magnetic field receives and detects electromagnetic waves generated from a subject, and then converts the electromagnetic waves to A/[].
104 indicates the strength of the magnetic field by X, Y, 7. A gradient magnetic field generation system 105 capable of linearly changing each direction independently is an image processing system 1 that performs various calculations necessary for image reproduction based on the four-way measurement data from the measurement system.
06 is a sequence control system that controls the operation timing of each system in the structure, 107
08 is a probe used for transmitting and receiving high frequency waves, and 08 is a console for performing operations.
第２図に、定常歳差運動（ＳＳＦＰ）により生じる信１
」を小ず。Figure 2 shows the signal 1 caused by steady state precession (SSFP).
” small.
本発明を実施するパルスシーケンスの一実施例を第３図
から第６図に示す。第３図が、高周波パルスの前後に生
じる２つの信号を同一の位相エンコードプロジェクショ
ン内にサンプリングするシーケンスである。撮影領域を
３０１でスライス選択し３］１の高周波パルスで励起す
る。３０２゜３０３は、３０１でスライス方向に乱され
た位相を戻すためのものである。撮影領域の縦緩和時間
に対し、極端に短い繰り返し時間（Ｔｅ）で励起のだめ
の高周波パルス（３１１）を印加し、高周波パルスによ
る励起直後に生じる信号を３０６と３０７の両極性傾斜
磁場によりエコーとして集め、３０９でＡ、 ／ Ｄサ
ンプリンタする。さらに、高周波パルスによる励起直前
に生じる信号を３３０７と３０８の両極性傾斜磁場によ
りエコーとして集め、３１０でＡ／Ｄサンプリングする
。この過程を３０’１，３０５の同一の位相エンコード
プロジェクション内に計測する。また、３０５は、３０
４による位相回りを元に戻すように；３０７］ど１１１
ドＩ（の逆極性（＃ｉ斜磁場として印加ずろ、、：（０
４と：ｌ ０５の位相エンコードプロジェクションを変
えながら、４１１号をｉｉｌ １ｌｌｌｌ Ｌ像再構成
すると、３０９てサンプリングした信号からは縦緩和時
間強調画像が、３１０でサンプリングした信号からは横
緩和時間強調画像が得られる。An example of a pulse sequence implementing the present invention is shown in FIGS. 3 to 6. FIG. 3 is a sequence for sampling two signals occurring before and after a high frequency pulse into the same phase encode projection. Slices of the imaging region are selected at 301 and excited with a high frequency pulse at 3]1. 302 and 303 are for restoring the phase disturbed in the slice direction in 301. A high-frequency pulse (311) for excitation is applied with an extremely short repetition time (Te) to the longitudinal relaxation time of the imaging region, and the signal generated immediately after excitation by the high-frequency pulse is converted into an echo by bipolar gradient magnetic fields 306 and 307. Collect and use A,/D Sunprinter at 309. Further, signals generated just before excitation by the high-frequency pulse are collected as echoes by bipolar gradient magnetic fields 3307 and 308, and A/D sampled at 310. This process is measured within the same phase encode projection 30'1, 305. Also, 305 is 30
To restore the phase rotation due to 4; 307] Do 111
Reverse polarity of (#i) applied as oblique magnetic field, :(0
When reconstructing the il 1llll L image of No. 411 while changing the phase encoding projection of 4 and :l 05, the signal sampled at 309 becomes a vertical relaxation time-enhanced image, and the signal sampled at 310 becomes a transverse relaxation time-enhanced image. is obtained.
第４図は、両極性傾斜磁場によって生じる傾斜磁場の１
次モーメン１−を零にするシーケンスである。第３図の
３０６と３０７及び３０７と２３０８のような両極性磁
場を印加すると、スピンの動きを時間で展開したときの
１次の項、つまり速度の項が位相回りを起こす。この時
の速度に応じた位相回りの比例定数を１次モーメン１へ
と呼ぶ。１次モーメン１へにより血流や体動のような速
度をもたらすものは全て位相回りを起こしアーチファク
１〜どなって現われる。これを零にするには、印加順序
を逆にした両極性傾斜磁場を１次モーメントを発生させ
る両極性傾斜磁場に連続して印加してやればよい。それ
をほどこしたものが／１．０１〜４０９の傾斜磁場印加
のパターンである。このような状態を位相不感という。Figure 4 shows the gradient magnetic field generated by the bipolar gradient magnetic field.
This is a sequence in which the next moment 1- is made zero. When bipolar magnetic fields such as 306 and 307 and 307 and 2308 in FIG. 3 are applied, the first-order term when the spin movement is expanded over time, that is, the velocity term, causes a phase rotation. The proportionality constant around the phase depending on the speed at this time is called the first-order moment 1. Anything that increases the velocity of the first-order moment 1, such as blood flow or body movement, causes a phase shift and appears as artifacts 1 to 1. In order to make this zero, it is sufficient to apply a bipolar gradient magnetic field in which the application order is reversed in succession to the bipolar gradient magnetic field that generates the first moment. The resulting pattern is a gradient magnetic field application pattern of /1.01 to 409. This state is called phase insensitivity.
４］−〇は擬似信号をディフェイズさせるための傾斜磁
場である。また、スライス軸においても位相不感とする
ことができる。4]-0 is a gradient magnetic field for dephasing the pseudo signal. Further, the slice axis can also be made phase insensitive.
第５図に本発明を三次元イメージングに適用したシーケ
ンスを示す。FIG. 5 shows a sequence in which the present invention is applied to three-dimensional imaging.
本発明は、以」こ説明したように構成されているので以
下に記載されるような効果を奏する。Since the present invention is configured as described below, it produces the effects described below.
１回の撮影で、縦緩和時間を強調した画像と、横緩和時
間を強調した画像の２枚を得ることができる９さらに、
高速法を利用するため、撮影時間も短縮できる。また、
位相不感シーケンスを使用すれば、横緩和時間の長く、
流れている領域の撮影もアーチファクトなく撮影できる
。With one shooting, two images can be obtained, one with the vertical relaxation time emphasized and the other with the horizontal relaxation time emphasized9.Furthermore,
Since the high-speed method is used, the imaging time can also be shortened. Also,
By using phase-insensitive sequences, the transverse relaxation time is long;
You can also take pictures of flowing areas without artifacts.
【図面の簡単な説明】
第１図は、本発明のイメージング方法が適用される磁気
共鳴イメージング装置（ＭＨＩ）の構成を示すブロック
ダイヤグラム、第２図は、撮影領域の縦緩和時間に対し
、極端に短い繰り返し時間で高周波パルスを印加した場
合に起こる定常歳差運動（Ｓ Ｓ Ｆ Ｐ）により生じ
る信号、第３図は、本発明の磁気共鳴イメージング装置
の一実施例、第４図は本発明の磁気共鳴イメージング装
置のもう一つの実施例、第５図は、本発明の磁気共り！
；５イメージング装置の更にもう一つの実施例である。
１０１− ｔｉｌ＆石、］ ０２−ｍｈｌｄシステム、
１０３−受信システム、１０４・・・傾斜磁場発生シス
テム、１０５・画像処理システ１１．１−０６・・シー
ケンス制御システム、１０７・プローブ、１．０８−操
作卓。[Brief Description of the Drawings] Fig. 1 is a block diagram showing the configuration of a magnetic resonance imaging apparatus (MHI) to which the imaging method of the present invention is applied, and Fig. 2 shows extreme Signals generated by steady state precession (S S F P) that occurs when a high-frequency pulse is applied with a short repetition time to Another embodiment of the magnetic resonance imaging apparatus, FIG. 5, shows the magnetic resonance imaging system of the present invention!
;5 is yet another embodiment of the imaging device. 101- til&stone,] 02-mhld system,
103-Reception system, 104... Gradient magnetic field generation system, 105. Image processing system 11.1-06.. Sequence control system, 107. Probe, 1.08- Operation console.
Claims (1)
起したスピンに位相変化を与える位相エンコード磁場を
印加する手段と、傾斜磁場を印加しながら信号を計測す
る手段とを備え、前記励起から信号計測までの手順を位
相エンコードを変化させながら繰り返し行う磁気共鳴イ
メージング装置において、励起させた特定部位の縦緩和
時間に対し短い繰り返し時間で励起のための任意角度の
高周波パルスを印加し、その高周波パルスによる励起直
後に生じる信号と次の高周波パルスの直前に生じる信号
を同一の位相エンコードプロジェクション内に計測する
ことを特徴とする磁気共鳴イメージング装置。 ２、特許請求の範囲第１項記載の装置において、各々の
信号を得るために、逆極性の傾斜磁場を周波数エンコー
ド磁場の前後に印加することを特徴とする磁気共鳴イメ
ージング装置。 ３、特許請求の範囲第２項記載の装置において、両極性
傾斜磁場によつて生じる傾斜磁場の１次モーメントを零
にして計測することを特徴とする磁気共鳴イメージング
装置。 ４、特許請求の範囲第１項記載の装置において、スライ
ス選択用の傾斜磁場に対し逆極性の傾斜磁場をその前後
に印加することを特徴とする磁気共鳴イメージング装置
。 ５、特許請求の範囲第１項記載の装置において、本来得
ようとする信号以外に生じる擬似信号を除去するため、
スライス軸に位相を乱すためのデイフエイズ用傾斜磁場
を印加することを特徴とする磁気共鳴イメージング装置
。[Claims] 1. A means for exciting spins in a specific region of a sample, a means for applying a phase encoding magnetic field that changes the phase of the excited spins, and a means for measuring a signal while applying a gradient magnetic field. In a magnetic resonance imaging apparatus that repeats the steps from excitation to signal measurement while changing the phase encode, a high-frequency pulse at an arbitrary angle for excitation is applied in a short repetition time relative to the longitudinal relaxation time of the specific excited region. A magnetic resonance imaging apparatus characterized in that a signal generated immediately after excitation by the high-frequency pulse and a signal generated immediately before the next high-frequency pulse are measured within the same phase encode projection. 2. A magnetic resonance imaging apparatus according to claim 1, characterized in that gradient magnetic fields of opposite polarity are applied before and after the frequency encoding magnetic field in order to obtain each signal. 3. A magnetic resonance imaging apparatus according to claim 2, characterized in that measurement is performed with the first moment of the gradient magnetic field generated by the bipolar gradient magnetic field set to zero. 4. A magnetic resonance imaging apparatus according to claim 1, characterized in that a gradient magnetic field of opposite polarity to the gradient magnetic field for slice selection is applied before and after the gradient magnetic field. 5. In the device according to claim 1, in order to remove a pseudo signal that occurs in addition to the signal that is originally intended to be obtained,
A magnetic resonance imaging apparatus characterized in that a gradient magnetic field for diffusing is applied to a slice axis to disturb the phase.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1235676A JPH07110272B2 (en) | 1989-09-13 | 1989-09-13 | Magnetic resonance imaging equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1235676A JPH07110272B2 (en) | 1989-09-13 | 1989-09-13 | Magnetic resonance imaging equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0399631A true JPH0399631A (en) | 1991-04-24 |
| JPH07110272B2 JPH07110272B2 (en) | 1995-11-29 |
Family
ID=16989555
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1235676A Expired - Fee Related JPH07110272B2 (en) | 1989-09-13 | 1989-09-13 | Magnetic resonance imaging equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07110272B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005096929A1 (en) * | 2004-04-05 | 2005-10-20 | Fukuyama, Hidenao | Magnetic resonance imaging device and magnetic resonance imaging method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5957147A (en) * | 1982-09-27 | 1984-04-02 | Yokogawa Hokushin Electric Corp | Method and apparatus for inspection utilizing nuclear magnetic resonance |
-
1989
- 1989-09-13 JP JP1235676A patent/JPH07110272B2/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5957147A (en) * | 1982-09-27 | 1984-04-02 | Yokogawa Hokushin Electric Corp | Method and apparatus for inspection utilizing nuclear magnetic resonance |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005096929A1 (en) * | 2004-04-05 | 2005-10-20 | Fukuyama, Hidenao | Magnetic resonance imaging device and magnetic resonance imaging method |
| US7511490B2 (en) | 2004-04-05 | 2009-03-31 | Shin-ichi Abe | Magnetic resonance imaging apparatus and magnetic resonance imaging method |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07110272B2 (en) | 1995-11-29 |
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