Flip Angle and Inversion Time


by Joanne Santos


By definition a FLIP ANGLE:  is the rotation of the Net Magnetic Vector or NMV by a radiofrequency relative to the main magnetic field (Bo).

So what does that mean?

Hydrogen protons (or the nucleus) align with the main magnetic field (Bo) also known as longitudinal magnetization.  In order to acquire a signal from the body’s tissue the protons must be stimulated; a RF pulse (SE), or a gradient pulse (GRE) is used to excite the protons and move them toward the transverse plane or xy plane.  A NMV is used to measure the angle at which the protons are ‘flipped’.   This angle along with TR and TE will determine the contrast or weighting that differentiates one image from another i.e. PD, T1, T2, and T2*.

Spin Echo Imaging uses a 90° flip angle, with a 180° refocusing pulse applied by using a radiofrequency or RF pulse.  TR’s are much longer thus making SE sequences longer.   Traditional SE sequences rely on TR, TE and the amplitude of 90° to make one or more echoes to create images.

PD  WEIGHTING:        T1 WEIGHTING:                               T2 WEIGHTING:

TR-         Long                   TR-         Short                                     TR-         Long

TE-          Short                 TE-          Short                                     TE-          Long


Due to the application of greater amplitude RF pulses in SE sequences the body can warm to a point that would exceed the body’s core temperature, this is measured by Specific Absorption Rate (SAR).  Reducing the flip angle will keep the SAR down at appropriate FDA levels.   However, reducing the flip angle may greatly affect image contrast.

Gradient Echo Imaging uses small flip angles of less than 90°.  This means that the TR will be shorter which reduces scan time.  That is why GRE imaging is faster than SE imaging.

SMALL FLIP ANGLES:  Result in PD and T2* weighting, by reducing T1 weighting     

PD WEIGHTING:                                                                  T2* WEIGHTING:

FA – <40°                                                                                   FA- <40°

TR- Long TR, reduces T1                                                    TR-Long TR, reduces T1

TE-Short TE, reduces T2*, increases PD and T1       TE- Long TE,enhances T2*

 LARGE FLIP ANGLES:  Result in T1 imaging, by enhancing T1 weighting          


FA-          >50°                                                                                                       

TR-          Short TR, enhances T1

TE-           Short TE, reduces T2*


VARIABLE FLIP ANGLES:  Result in TOF imaging:  The flip angle can be increased slowly during the data acquisition of an image.  It starts by using a small flip angle that increases with each line of data acquisition.


By definition Inversion Time:  The time period between the initial 180° inversion pulse and the 90° excitation pulse in an IR pulse sequence

An Inversion Recovery Pulse Sequence acquires different contrast or weighting by adjusting the following parameters:  TR, TE, and TI (inversion time).    The TR has to be long to allow for full longitudinal recovery before the next pulse.  It can yield strong contrast between tissues that vary in T1 relaxation times.  An IR pulse sequence can also suppress fluid or fat.  Inversion times can also be measured as long or short.  A long TI is identified as 1700-2200ms, and a short TI is 100-180ms.  STIR sequences null the fat signal, and FLAIR sequences null the fluid signal.


T1 Weighting:                                         STIR:                                                      FLAIR:

TR-          Long                                    TR-          Long                                       TR-          Long

TE-           Short                                  TE-           Long                                       TE-          Long

TI-            Medium (300-700ms)  TI-            Short                                      TI-            Long



Lawrence N.T. MD, FACR (2005). Edison Imaging-JFK Medical Center, New Jersey Neuroscience      Institute, Edison, NJ; Seton Hall School of Graduate Medical Education, South Orange, NJ.  Retrieved from:  http://www.medscape.com/viewarticle/498295_2

McRobbie, D.W., et al (2007).  MRI from picture to proton 2nd ed.  Cambridge University Press.

Westbrook, C. (2008)  Handbook of MRI technique. 3rd ed.  Wiley-blackwell Publishing, U.K.





32 Responses to Flip Angle and Inversion Time

  1. Hi there mates, how is the whole thing, and what you want to say regarding this article, in my view its genuinely amazing for

  2. Hi there just wanted to give you a quick heads up.
    The words in your content seem to be running off the screen in Safari.
    I’m not sure if this is a formatting issue or something to do with browser compatibility but I figured I’d post
    to let you know. The layout look great though!

    Hope you get the problem resolved soon. Thanks

  3. Have you ever thought about adding a little bit more than just your articles?
    I mean, what you say is important and everything.
    Nevertheless think about if you added some great graphics or videos to give your posts more, “pop”!

    Your content is excellent but with images and video clips, this website could certainly be one of
    the most beneficial in its field. Excellent blog!

  4. It’s going to be finish of mine day, however before ending I am reading this great article to
    improve my know-how.

  5. ハリコのケーキ入刀だけで5万とか8万とか、手作りのケーキは15万とか20万とか、もう暴力団も真っ青のチョーウルトラボッタクリ セカンドバージンという概念には驚いたな
    会場で上映された新郎新婦の出会いからの再現ドラマムービーには金かかってそうだったけど インターンの大学生なんかでも、何か勘違いしていて、大企業に入れば一生安泰で30歳で年収600万円、40歳で800万円、あわよくば1000万円とか本気で思っている人がいます。 お祝い メッセージ

    友情なんて、1万円で切れるのか、5万円で切れるのか、10万円で切れるのか、50万円で切れるのか、100万円で切れるのか、1000万円で切れるのか、その程度の差でしかないわ。 東北も朝晩涼しいです。★今日も1日を大切にがんばりましょうp(^-^)q カルティエ 結婚指輪
    それ以外にお祝いしたい人は別に出せばいいと思うんだ。 結婚は人生の墓場どころか地獄になる可能性もあるんだな…と思う

    So , pay your purchases in notes rather than placing them in your
    Visa card. In world of online marketing, article
    marketing is normally meant for advertising or marketing a product
    or even a website which is achieved by writing and submitting to several.

    結婚式 メッセージ 英語 結婚祝いプレゼント兄弟 Doctoral students discuss their dissertation proposal as portion of their
    qualifying exam. If you want typing to actual writing, that’s not a problem either.

  6. 高見ゆり says:

    AKBのお局様状態になってから 卒業って・・・・遅いわ

    The answer to writing an excellent paper is organization and making clear points.
    How could I ever believe as part of his people when they
    had moveable birthdays. 高見ゆり 二次画像まとめ Cause of death is usually the result of an autopsy, that is not done before the funeral in many instances.
    We make certain that we provide custom writing services on the lowest prices possible.

  7. The light bar itself must be functional in most kinds of weather, whether it is raining or snowing.
    LEDs are at least 80% more efficient and do not run through batteries as
    often. Led light bar waterproof Firstly, the sunshine emitting diodes can offer
    maximum brightness and lighting output on the lowest possible wattage and power consumption.

    You may use the Hi-Lo intensity variation to lower your energy whenever
    bright lights usually are not required. The
    back houses the 5 MP camera and led light bar Kenya flash, which much like Casio’s rugged phone tradition can back up as being a flashlight at the same time.

  8. ” NVRTitan also supports IE, Firefox (Windows version), and Safari browsers; windows and mac platforms are backed up by NVRTitan’s client application. A regular tv has a screen aspect ration of 4:3, (which is, the dimensions are four units wide by three units high) and its size is given as being a diagonal measure across the screen. Free online printable coupons olive garden

  9. Along using the demographics and pupil spending habits changing, so
    are some with the mind-sets of today’s students. If you have been in a profession, which
    is related to computer then you will need a computer or laptop to perform your
    official work in your home. Dell apple laptops college deals college students So
    in this article we’ll discuss the methods to learn laptop
    repairing and how is laptop repairing course useful to secure a job.

    All the pros are certified in laptop repair with the extensive experience.
    Commonly called MOOCs (Massive Open Online Courses), most of those do not
    offer college credit toward a diploma but offer a variety of classes to
    your mass quantity of individuals.

  10. Howdy this is kind of of off topic but I was wanting to know if
    blogs use WYSIWYG editors or if you have to manually code with
    HTML. I’m starting a blog soon but have no coding experience so I wanted to get guidance from
    someone with experience. Any help would be enormously appreciated!

  11. Hi, this weekend is pleasant in favor of me, as
    this moment i am reading this fantastic informative post here at my

  12. It is in reality a nice and helpful piece of info.
    I’m happy that you shared this useful info with us.
    Please keep us up to date like this. Thanks for

    Review my web site cialis prescription canada

  13. cost cialis says:

    Outstanding quest there. What happened after?
    Take care!

    Look at my web page cost cialis

  14. Turn Your Dell Inspiron 15 Into A High Performing Machine Things to help keep into your mind
    in selecting the most effective gaming laptop under $1000.
    There aren’t any serious PC games which use touchscreens and having
    one would only cause smudges. Dell Inspiron 15 Battery Problems inspiron 15 bios

  15. Amino acids will be the building blocks of protein of which tresses are basically
    made up. You may either have vitamin E inside your diet or apply that as hair mask.
    Biotin Shampoo psoriasis All goods are created from paraben-free formulas
    and don’t contain harsh chemical additives that you will normally find with more than the counter hairdressing

    Women because they enter perimenopause as early because the mid thirties experience significant thinning hair.
    You can consult to your doctor in the event of hair fall problem to get
    rid of it.

  16. He also includes a mouse that may earn him points as part of
    his game and help him level up. It’s even truer for gamers who’ve to spend their very own money.

    Jite gaming mouse This is really because mice are often short-sighted animals and follow the identical path for transferring any room.

    On the full, gaming mouse Kinzu
    mouse in various mouse pad can move smoothly, in rapid some very generous, dodge process
    quicker also. Be certain to read the review if you are considering purchasing
    this gaming mouse.

  17. 高見ゆり says:


    Events and information that’s connected towards the Jammu Kashmir news
    are not just politically important and also appear on important list internationally.

    高見ゆり 高見侑里 胸 A strong Jupiter gives
    wealth, religious inclination and gains from govt.

  18. These are large country restaurants with absolutely huge barrels of cider that the name
    is derived. Wrecker light bars, have additional rear work
    lights, tail and brake lights. How to mount led light bar for jeep liberty light bar on roof rack The other attraction in this corner
    from the park was obviously a walk through haunted house called El Pasaje Maldito.

    Compression gaskets and UV resistant domes can also be part from the construction from
    the mini light bars. In fact, some mini light bars have split center color sections where you can create flashing patterns in multiple
    colors inside the middle and inside the ends.

  19. With the release with the 92-inch Mitsubishi 3D HDTV with even larger models on the horizon the
    size of your respective screen is currently,
    a lot more than ever, dependant on your budget. Opting for the HDTV format or plan will
    not mean that one could actually benefit from your
    better image if you don’t have the required tv. Small diy hdtv antenna If you might be not too
    sure wherever the tv tower is, you’d much better choose
    multidirectional antenna.

    Be jack digital hdtv outdoor antenna TV installation or home theatre installation, you can be
    assured with antenna Sydney. It’s just a foot tall with the adjustable antenna part herniated twenty inches, this thing takes
    significantly less space and appearance a lot better than your average group of rabbit ears.

  20. You can tell what access point the consumer is trying to connect with by correlating the bssids with the bottom with all the bssids with the top.
    Direc – TV installation necessitates following basic components.

    The media device includes software to your computer that will locate all of the
    media files about the hard drive exactly like Windows
    Media Center Software. If you want to figure out the way to find your wifi extender without access to router password without difficulty, just read below
    for many quick instruction. Netgear wifi extender unable to
    join network I also get five to ten more local networks from people’s homes or businesses which
    might be just not available with all the notebook wireless device during my Hewlett Packard notebook

  21. This is her technique of telling you that she is going to be
    having sexual climax very shortly. Devoting 1 day or several days
    to simply one color during a period is a fun approach to help preschoolers learn their colors.
    How to squirt Meet Lauren Luke, a make-up artist, who used with You – Tube to acquire across to
    millions of girls all within the world along with
    her beauty products, tips and tricks.

    Once you could have gotten her attention by letting on with
    the life you are able to approach her about going out to
    have an evening about the town. Real people sell real things,
    plus Lauren Luke’s case, she sells fabulous stuff.

    Economy news that individuals watch on TV just to get something to talk with their friends later
    apparently aren’t of great value. different (http://www.karenranieri.com) how to make a girl squirt It is actually difficult having to deal
    with a person that abuses you and in many cases more so
    in the event the person is often a part of one’s family.

  22. None from the purely mechanical home security cameras bunnings and burglar home security systems have even one ounce of ‘loyalty’ built straight
    into them. purposeful a part of a security systems plan is really a great and functional idea.

    Home security products These cameras are wired to security televisions
    from the business itself, therefore, the cameras may be monitored by security, if desired.

    You can remodel you gutter based around the gutters nj security-enhanced homes have.
    The security alarm agencies are installing the surveillance cameras
    and detectors in most places in your house or company.

  23. Subsequently, the wireless home alarm notifies you whenever an unauthorized individual
    intrudes your private property or building. Their security systems are recognized from the
    security industry, and specifically around California.
    home alarm systems georgia alarm systems Today people want no clutter, therefore, the preferred options are of course wireless systems.

    You need to look at special attention and care while selecting a security alarm.
    If you desire the whole DIY wireless home alarm installation to get easy then an invisible alarm system could well be best.

  24. The last tip – DO NOT try & write anything back for your Canon EOS Rebel camera (memory card) before
    you found the missing pictures. IP wireless cameras are
    well suited for their ease of use and installation; they could be accessed via a
    secure wireless transmission, treatment of need for
    wires completely. fujifilm waterproof camera quicksnap camera equipment You can effortlessly adjust intensity
    & brightness of your image on this camera.

    The card should go in smoothly, whether it doesn’t,
    there exists a reason for it – perhaps you’re attempting to insert it into you got it the wrong way.
    You must also look at obtaining a weatherproof or even waterproof

  25. しかもCD買えば一人何票も投票できる仕組みで選挙とか言うし

    Natural news may be the place for your latest and the majority updated information. ほんだつばさ
    本田翼 gto There is
    solution to much happening to cover in this one little article.

  26. 意味もなくコンスタントに再生回数が伸びていくもんなんですね(棒)

    I am devoted to further my education for the reason that I think my questions are
    yet to been answered. 13番さんのあな 二次もれ Price hikes already
    have begun to bite According to research by Goldman Sachs,
    in some instances bauxite price rises have previously begun to bite.

  27. Leather is the best materials for a recliner sofa as
    it can be easy to completely clean and is very resilient.
    Consider these points carefully before purchasing a sofa so that
    you’ll be able to make an informed decision that you won’t
    regret. You could also have suitable sleeper sofa jacksonville nc
    sofa sheets to produce your sleep about the sofas additional comfy.

    From every one of these foam mattress is considered
    as best option with good flexibility for the frequent and regular
    use of sofa bedding. If you are afraid you are going to forget their precise color, have a digital
    picture of the room and make camera sofa shopping,

  28. Also Mayweather made Hatton step above his natural weight to battle him where by Pacquiao fought him from the division he was
    best pocket pussy try recognized for.

    It appears as if no matter how good you might be at aiding people for the reason that department, the tax collectors are even better.
    Pocket pussy make A vibrator will be the perfect gift for couples for you their lovemaking experience soaring to a
    totally new level.

    The optimum settings could change because your a higher level excitement
    builds. The jackets along with the hoodies include the popular elements over the kids.

  29. An intriguing discussion is worth comment. I believe that you need to
    write more about this subject matter, it may not be a taboo subject but typically people do not discuss such issues.
    To the next! Kind regards!!

    Also visit my page buy generic cialis online canada

  30. Hello would you mind sharing which blog platform you’re working
    with? I’m going to start my own blog soon but I’m having a tough time choosing between BlogEngine/Wordpress/B2evolution and Drupal.
    The reason I ask is because your design seems different then most
    blogs and I’m looking for something completely unique.
    P.S Sorry for getting off-topic but I had to ask!

    Look into my webpage – cialis generic pharmacy

  31. In comparison, companies distributing or retailing good quality cctv dvr pc cms software download surveillance systems are more likely to supply quick as well as free delivery services.
    The capabilities and reputation in the wireless CCTV camera may be put towards the test in mere about every
    part of society and contains always come forth with nothing but praises.
    Elec® 4ch cctv dvr motion detection security system In earlier days of
    CCTV technology you do not have much choice but to select an analog
    DVR to record surveillance data.

    Closed Circuit Television (CCTV) is made over 60 years ago and
    continues to evolve into the most reliable camera around
    the consumer market. CCTV methods are 1 of the old and popular safety systems that men and women today
    are employing currently.

  32. Hi there to all, the contents present at this website are actually
    amazing for people experience, well, keep up the good work fellows.

    Look into my web-site generic viagra canada

Leave a Reply

Your email address will not be published.


* Copy This Password *

* Type Or Paste Password Here *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>