MR Technique Pelvis: How and Why We Do It

Introduction

My name is Antonio Westfield, and I have no disclosures.

We'll now cover some Mr. Technique.

Basically how we do it and why we do it at UCSF.

When Conrad gave me this topic, my first thought, oh great, this is gonna be easy.

And then I started thinking about it.

It's actually quite broad and complicated to make it short.

Now we can talk about rectal cancer, which was his talk, prostate cancer, which is my next talk.

Obstetrical, Yvonne, talk about that.

I decided to focus on gynecological imaging, which is along with prostate, the bulk of our volume.

And it's very important that now you know that there is no perfect single protocol.

There are many, many variations.

This is one example that we use, not perfect.

And the most important thing is that we have to tailor those protocols adapted to the clinical question that the clinicians, surgeons have.

What is the suspicion?

And then adapt your protocol to answer those questions.

Basic Protocol at UCSF

What do we do at UCSF?

Again, our basic protocol would be phase the array surface coil.

We will wrap it around with a Velcro in the patient.

We're gonna use saturation bands and those are placed anteriorly in the subcutaneous tissue in order to avoid ghosting artifact and also improves windowing 'cause it gets rid of the near field burnout area.

We use a respiratory compensation on our spin echo sequences.

And this obviously will minimize breeding artifacts and the motion artifact glucagon is something that can be very helpful, but you have to use it appropriately.

You can administer iv, you can do subcu or intramuscular as well.

One of the things to remember is that timing is crucial.

As you now give glucagon, you're gonna paralyze the bowel movement, the paralysis, but if you wait too long, you may actually get into a status in which peristalsis is increased and then you have much more artifact than you initially would have if you had not given it.

You have to give it just before the image that you wanna acquire, that you really want to have.

The peristalsis decreased our sequence.

We are gonna get a three plain faine echo T two without fat saturation.

So we get sagittal, coronal and axial in all patients.

We're gonna do an axial duo echo.

So we're gonna have a T one NPH phase and out phase diffusion weighted MR imaging.

Our high B value will be 800.

This is now open to discussion, but this is our protocol.

Then we acquire pre gad T one 3D spot greater echo images on both axial and sagittal plane.

Our dynamic images.

Following the contrast, typically are done on the sagittal plane.

For most of the patients, the reason is usually we're looking at the cervix and in the midterm, and that's a better plane to assess those.

But we'll also get image on the axial plane and we'll talk a little bit about that.

And every once in a while we'll invert that.

We might get the dynamic on the axial rather than on the sagittal.

T2 Fast Spin Echo Images

Why do we acquire the T two faine echo images?

For a few reasons. One of them, it's probably the best of the sequence to assess the anatomy.

And not only the normal anatomy, but the abnormal anatomy as well.

It's crucial that you think of the plane of acquisition as you are acquiring those images.

We use it to differentiate blood from fat.

It's one of the sequences we can use and we're gonna use it to assess fibrous tissues.

Fibrous tissues tend to be very dark on the T two 80 images and it's one of the things we can use to characterize lesions.

In addition, the amount of fibro tissue in the cervix is high, especially now just adjacent to the cervical canal.

And then going up the junctional zone, which is another reason we need to use good T two weight imaging.

Anatomy Assessment and Reporting

The anatomy, this is not reporting.

We'll provide a three plain diameter for the uterus.

So we measure the uterus in all of them.

We'll describe the uterine position and I'll show a little pictures.

Next, we will describe the endometrial cavity thickness and just remind ourselves that now this is not the best technique that's transvaginal ultrasound, but yet we do provide it when it's very prominent, very heterogeneous.

We can know guide the clinicians, perhaps even move to something else later.

But we do provide that thickness.

And then we describe the ovaries.

We don't really worry too much about describing dominant follicles, normal findings, we just say ovaries are normal or not.

And if they're not noal, then we'll describe it.

Uterine position, uterine position, verted or retroverted, fl and retroflex.

And often people ask, oh, I never remember which one is which.

The one way I came to remember is that if you have a V for retroverted, we are talking about the cervical vaginal angle.

So this angle right here, so this is an antivert uterus, this is a retroverted uterus.

And then the flax.

Now you can remember that it's the cervical fundal angle.

And then here you have a retroflex.

So the angle between the fundus and the cervix.

And this is an anti flexed plaintiff acquisition.

Plane of Acquisition

The plaintiff acquisition will depend on the clinical indication of the study.

If we're talking about malian duct anomalies, we'll do in one way cervical cancer, another way another.

What do we do? Malaria duct anomalies.

We try to get an oblique coronal of the uterus.

So we're trying to get as much of a coronal plane of the uterus as we can.

And obviously we won't be able to do it perfectly, but we adapt the angle to try to get as much as possible.

And then we get through axle and through sagittals of the pelvis.

This is what we would attempt to do in a case like this and why we do it.

The reason we do that is it allows us to have a better view of the fundus of the uterus, the presence of myometrium, the identification of the cavities or horns that we can identify.

And if we're lucky, we can get all of this in a single image and have a very clear view of what this look uterus looks like.

For cervical cancer. We'll always acquire an axial view, a true axial of the cervix.

And then we acquired through Corona and through sagittal of the pelvis itself.

The reason we do that is one of the main goals of this study is to determine if there's parameter extension or not.

And with a true axial view of the cervix, we can make that assessment quite clear.

Here is a large tumor and we can see the stromal ring of the cervix interrupted.

There is parameter extension.

If you have an oblique view, you'll create situations in which you will have a partial volume averaging.

You may suspect parameter extension that doesn't really exist.

And then for most of the other acquisitions we'll do through three orthogonal plane of the pelvis.

So through axial and sagittal.

And just wanna show two normal examples of the uterus.

You have a sense of anatomy.

We have the junctional zone, which is contiguous with the stromal ring of the cervix.

Myometrium with a slightly higher signal intensity and then much higher that of the endometrium sagittal plane, a different patient coronal plane of the uterus.

I mentioned that we use it to assess fat before.

This is just one example in which we have a T two weight image that shows a maxo mass with high signal intensity.

This could be fat, it could be no something else.

It could be just fluid.

Here's a fat high signal and when you compare it to a fat image, you can see that sat out.

That's fat. And then this is another example.

For the second reason to get these T two weight images, fibrous tissue and a lesion, we have a left NAL mass that's very low in signal intensity, that's typical for a fibroma.

T1 Dual Echo Fast Spin Echo Images

T one 3D duac echo fast sparked greater than echo images.

Again, we're gonna use it to distinguish blood and fat.

There are two ways to do it.

We can compare it to a fat suppressed image or we can look at the India ink artifact on the outer phase image.

And then we also use this for susceptibility artifact in a few cases.

Here, we have a T one enphase com and compared to a post GA image.

And now when you look at this you can see that there's no lesions with high signal intensity on T one.

There's fat saturation here in the post contrast.

These didn't go away on the in phase.

Both of them have high signal fat and the lesion didn't go away.

It's fat. Same thing as I showed you before with the T two 80 image.

This is what we can do when you're looking at the outer phase or the opposed phase compared to the endphase.

Here we have this dark line that surrounds organs that have water and adjacent fat.

This is the India ink artifact.

And that happens because you're in the interface of both of them.

So you have a signal void.

We have the at NEXO mass, the has high signal intensity.

This is ovarian tissue right here, high signal intensity right there.

If this was an interface of water and fat, we should have a in the in card effect in this area here we don't, that's not fat, that's an endometrioma.

And then this is another woman with this woman had known endometriosis now and had gross material.

That's why we were doing this study.

But it illustrates now the susceptibility artifact.

We can see now the blooming of many many small implants related to endometriosis.

And now we find it very helpful.

When you do identify it, it's very helpful.

It's not something that you see all the time, but when you do, it really helps.

Diffusion Weighted Imaging

Diffusion weighted imaging.

I'm glad Bashir is not here 'cause he'll almost certainly disagree 'cause he is the real expert in this.

But there are a couple of things that you have to remember first as a sequence by itself it's not that helpful.

It's much better when you actually using in conjunction with something else.

And the reasons there's a lot of overlap.

Benign lesions can restrict.

I mentioned ovarian lesions here can restrict and that alone no won't allow you to make a diagnosis of malignant disease.

Yet if you have something that has intermediate signal on T two, it's not very dark, it's not read cyst, it enhances maybe fast and it has restricted diffusion, then yes, that's helpful.

That's very likely to be a malignant lesion.

You have to use it in combination with other sequences in order to take the information out of it that is of value.

Is it helpful in endometriosis? It may be.

Some people suggest using it. In all cases we use it.

It's sort of a free, but it doesn't take a lot of time to do it.

And I'll show you an example so you have a sense of how it works.

And we use it in cervical cancer end endometrial cancer again as an adjunct sequence rather than the main stream.

This is an example, you probably remember this case I showed you before.

That's the T one with fat sat and you can see that the these two lesions here didn't lose the signal.

That was endometriomas two endometriomas.

And here we have the diffusion weighted MR image and you can see there's a lot of signal there.

There was restricted diffusion but they were benign.

So there is overlap you have to use in conjunction with the other sequences.

But now if we had implants, maybe in other places, this would be one of the techniques we can use to identify those additional implants.

And this is just one example just to illustrate the fact that tumors and the uterus do restrict.

We had the diffusion weight at Ammar imaging, the A DC map, we can see very high signaling end endometrial cavity restricted diffusion.

This was a very large endometrial cancer.

It was already known the patient had had a biopsy.

And the reason we were doing this is to help with staging surgical planning.

Gadolinium-Enhanced Imaging

And we acquire also images before and after gadolinium.

And the main reason is to assess for tumors, neoplasms.

And in all of our cases we'll do subtraction and the subtractions are great tool, but you have to be careful with some pitfalls.

In many, many cases you'll be struggling to decide if there is enhancement.

You may be very minimal enhancement, you may be hidden because of adjacent signal you're struggling if you do subtraction.

Now those enhancement, those areas of enhancement will be, will really be highlighted for you and much easier to identify.

Now again, this is just a patient that had known and endometrial cancer and was getting this scan to assess for treatment and staging.

So we have an earlier phase and a little bit later phase.

And what I would like to point out here, sagittal views, when the cervix down here, fundus here, it's large uterus you can identify there is a ream of enhancement that's pretty well defined and very clear, smooth and you keep going around.

So here you have the mass that's enhancing.

This is the in theum that's not affected by the tumor.

And as you get up towards the posterior aspect of the body of the uterus, you notice that that line, that very smooth line disappears.

Now you have this ill-defined focal disruption here, which again seen on the later phase, you follow it up smoothly and then all of a sudden this is ill-defined slightly irregular.

So that's one of the signs of myometrial invasion.

Gadolinium does help assessing myometrial invasion.

This is just one example.

Every once in a while it's pretty obvious you don't need it, but it's highly recommended that you acquire it for the areas that are a little bit less obvious on the T two 80 images.

And then this other example.

This was a 55-year-old woman that had a suspicious at maxo mass and ultrasound.

So now we have a pre GA image here, we have this large mass, it has some bureau nodules and we acquire now in post GA images.

This is an axo and you're trying to struggle with their enhancement in this nodules, yes or no.

Now if you look at it, you may think there is, you're not quite sure this is a good case to apply subtraction.

So you do, Here it is.

So we have the post GA image here.

Now the subtraction here And now the first thing that probably pops to your eyes is that you have two large areas that are very bright on the subtraction adjacent to that nodule.

So there are a couple of possibilities here.

Maybe there was some tumor here that we weren't really identifying that is now enhancing.

And if that's, so that's now likely to be a malignant lesion.

But you have to be careful and remember is that the subtraction is not perfect.

You are acquiring images at different moments and a patients move, it may be peristalsis, it may be breeding, it may be that the patient just moved in the table couldn't stand there.

So this dotted line here shows the actual area of the overlap.

And as you can see, this in fact represents just the fluid that was present in that lesion in the pre GA image.

So that's not enhancement, that's a pitfall.

This turned out to be a cyst. Adeno fibroin.

So a benign lesion.

Flow Sensitive Sequences

And I wanna very briefly mention to you flow sensitive sequences.

There are different things you can do.

We use the gradient echo images for that and they'll pretty much use them as a problem solving tool in addition to the other uses of it.

Here is the post ga image of the pelvis.

This is just inferior, the bifurcation of the aorta.

And we look at the right common iliac artery.

We see this apparent feeling defect.

And the question then is this, no thrombus or not.

And the way to solve the problem then is to look at flow sensitive sequences.

Here's the great in echo, this is the auto phase.

Can see the India ink artifact surrounding the organs where the fat interface is and there's no filling defect there.

That was just some flow artifact.

This patient has no thrombosis.

Something to keep in mind if you do find something in the post GA image, you're not quite sure.

Contrast mixing. Now flow artifacts go to the flow sensitive sequence, take a look, do a run, and you can then establish the diagnosis.

If this was a true thrombus, you would see it there as well.

You can go fancier.

There are like velocity encoded CNY MRIs.

But for most of the applications in the pelvis, the greater neck can be to solve the problem.

Conclusion

This would be a short lecture.

In conclusion, just want you to know, and again, stress the fact that you can use mr, but you have to think of the question the clinician has.

Now are we looking for endometrioma?

Are we trying to stage cancers that for cervical cancer?

And you have to adapt your protocols.

Now remember, the in and out of phase fat sat are basic sequences, flow sensitive sequences.

The gadolinium in our case, we'd like to acquire them on the sagittal plane.

Thank you.