0:02

Hello and welcome to Noon Conferences hosted by MRI Online.

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In response to the changes happening around the world

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right now, and the shutting down of in-person

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events, we have decided to provide free daily

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noon conferences to all radiologists worldwide.

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Today we're joined by Dr. Mukesh Harishinghani.

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He is a professor of radiology at Harvard Medical

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School and director of Abdominal MRI at the

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Massachusetts General Hospital in Boston, Massachusetts.

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In addition, he serves as the director and Clinical—

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of Clinical Discovery Program Center for Molecular

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Imaging Research at Mass Gen and has been the

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section editor of GU Radiology for the AJR.

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He has published over 150 peer-reviewed papers and

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edited five textbooks in the field of radiology.

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A reminder that there will be time at the

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end of this hour for a Q&A session.

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Please use the Q&A feature to ask all of your questions,

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and we'll get to as many as we can before our time is up.

0:46

That being said, thank you so much for

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joining us today. Dr. Harisinghani,

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I will let you take it from here.

0:51

Thank you, Ashley.

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Uh, good afternoon to the folks in the US,

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and a good day to the rest of you guys.

0:57

Uh, so today, um, what we are going to do is, uh, go over

1:00

some of the MR applications as they pertain to diseases of

1:04

the bladder, specifically bladder cancer, and also look at

1:08

how MR can be useful in assessment of the female urethra.

1:12

So we're going to talk about anatomy and technique,

1:14

and then, as I said, discuss the clinical utility

1:17

in these two, uh, specific, um, uh, anatomy areas.

1:23

So starting with the bladder, if you, from

1:25

a perspective, this is the, a sagittal

1:29

diagrammatic representation of a male pelvis.

1:31

And this is a corresponding, uh, sagittal

1:33

T2-weighted MR. And here is a sagittal.

1:37

Diagrammatic of a female pelvis, and

1:41

this is a corresponding MRI T2 image.

1:44

So the bladder is the most distal

1:46

conduit of the, uh, you know, the, uh.

1:51

Urinary system, where the two ureters sort of

1:53

bring and, and, um, accumulate urine

1:57

before, uh, the urine goes down into the urethra.

2:00

So it's the most distal part of the,

2:02

uh, collecting system in, in, in men.

2:05

It sits right on top of the prostate.

2:07

This patient has an enlarged, uh, prostate.

2:09

These are the seminal vesicles.

2:11

And it's retropubic in location.

2:13

Uh, this yellow line in the, uh, in the diagram

2:17

is a depiction of the peritoneal reflection.

2:21

So, as you can see from here, it's typically the superior and

2:24

a part of the anterior wall of the bladder that is covered

2:27

with the peritoneum lining, but the rest of the bladder

2:29

essentially is extraperitoneal and is surrounded by fat.

2:33

Same in the female pelvis, you know, and for when

2:36

we talk about the female pelvis, we like to

2:39

compartmentalize the, um, uh, the pelvic organs.

2:42

So the bladder and the urethra

2:43

fall in the anterior compartment.

2:45

The uterus, uh, the cervix, and the

2:47

vagina fall in the middle, and the rectum,

2:50

the anal canal, fall in the, uh,

2:52

in the posterior compartment.

2:54

So similarly, in, in the female pelvis, there

2:56

is peritoneal reflection on the superior and

2:59

part of the anterior aspect of the, uh, bladder.

3:03

And this is just to kind of

3:04

emphasize the peritoneal reflection.

3:06

This is a patient who sustained an intraperitoneal,

3:10

um, rupture of the bladder during surgery.

3:13

And you can see in this cystogram image on a

3:15

CT there is filling out the peritoneal space.

3:18

So, uh, you have to keep in mind that the dome and

3:21

the superior margin of the bladder is lined by peritoneum.

3:26

Uh, moving on to the layers of the bladder, and if, uh, sort

3:30

of one starts looking from the inside of the bladder towards

3:33

the outside and, and looking from a histologic perspective.

3:38

The innermost lining is the epithelium,

3:41

which is, uh, transitional cells.

3:43

In the case of the bladder, underlying the urothelium

3:46

is what we refer to as a subepithelial connective

3:49

tissue, which is comprised of the lamina propria.

3:53

Beyond the lamina propria is a smooth muscle,

3:56

which is the, um, the detrusor muscle.

3:59

Uh, this is an involuntary muscle that, um,

4:02

is key in terms of contracting the bladder

4:04

and expelling the urine into the urethra.

4:07

And also this is the most important, uh,

4:09

structure that we pay attention to on MR

4:12

in terms of bladder cancer, uh, staging.

4:15

Um, as I mentioned earlier, the extraperitoneal

4:18

aspect of the bladder on, on, on the sides,

4:21

anteriorly and posteriorly, is, uh, surrounded by fat.

4:26

Uh, before we, uh, talk about translating the anatomy to MR,

4:30

it is important to realize that the thickness of the bladder

4:34

wall is dependent on how distended the bladder is.

4:38

So if the bladder is collapsed, it can be as high as eight

4:41

millimeters, and if it is, you know, full and, and, and

4:44

distended, the bladder wall can be around two millimeters.

4:48

And, and this becomes an important point when we talk about

4:50

technique on how, um, we do, uh, MR of the urinary bladder.

4:56

So looking at the T1-weighted images in terms

4:58

of the, the bladder, uh, this is a T1-weighted

5:01

image, axial image without fat saturation.

5:04

This is a T1-weighted axial image with fat saturation.

5:08

And, and on the non-fat side, you can see the

5:10

urine is dark, as it is a T1-weighted sequence.

5:13

The, the fat that surrounds the bladder is

5:15

bright, um, and, uh, you essentially cannot see

5:20

much in way of the bladder wall because there is

5:22

not a lot of contrast differentiation between

5:26

the, the bladder lumen and the surrounding of the bladder.

5:29

But once you apply fat saturation, you can nicely

5:31

lay out the, um, the muscle layer of the bladder,

5:35

which has similar signal intensity to the, um,

5:38

to the skeletal muscle in the, in the pelvis.

5:42

When we move to T2-weighted sequences, that's

5:44

where you can nicely see the, um, uh, the dark

5:47

signal of the detrusor muscle of the bladder.

5:50

Urine is bright, as you would

5:52

expect on a T2-weighted sequence.

5:54

And because this is a turbo or a fast spin echo, uh,

5:57

fat that surrounds the bladder is also very bright.

6:00

Uh, this is a little bit more distended.

6:02

And again, you can see the low signal intensity of the, um.

6:06

Of the detrusor muscle in the bladder.

6:08

Now when, uh, the images are acquired with, uh, higher

6:11

resolution, you can sometimes see two bands, uh, two,

6:15

uh, hypointense, or dark bands on the T2-weighted sequences.

6:19

And in this, um, patient, you can

6:21

actually see a glimpse of that.

6:22

The most innermost layer is a

6:24

little bit darker than the rest.

6:25

And that's the compact, um, arrangement of the

6:28

detrusor muscle fibers that you can sometimes see.

6:31

It's actually best seen on the low b-value

6:34

diffusion-weighted sequences.

6:36

And here you can nicely see this inner dark

6:38

line that is immediately, um, surrounding

6:42

the, uh, the, uh, uh, urine in the lumen.

6:44

And beyond that, the signal is a little bit brighter.

6:48

So just keep that in mind that sometimes you can

6:50

have these two, uh, uh, two distinct, uh, appearances

6:54

of the, uh, detrusor muscle in the bladder wall.

6:58

Now in terms of technique, um, it's a, um, you know,

7:02

as, as is done with most other pelvic MRIs, you use phased

7:05

array coils because those are the ones that give you

7:07

the, the best, uh, possible SNR for imaging the pelvis.

7:12

Uh, you want to be as thin as possible, and

7:14

typically the, the, the section slice thicknesses

7:17

vary between three to four millimeters.

7:20

You want to have a matrix size, um, that gives

7:23

the highest possible resolution as possible.

7:26

And then, as I mentioned earlier, in terms of bladder

7:28

distension, you don't want this where the bladder

7:31

is totally collapsed, where you really cannot assess

7:33

what's going on in the wall, and you don't want the

7:35

bladder to be overtly distended, as is the case in

7:38

this instance, because distending the bladder thins

7:42

out the bladder wall and makes, again, assessment difficult.

7:46

Number one.

7:46

Number two is, um, if the patient, um, you know, has

7:50

a massively distended bladder, they are increasingly,

7:53

um, uh, uncomfortable at the time of the MR exam.

7:56

And that can lead to motion

7:58

artifacts and, and create problems.

8:00

And so what you typically do is

8:02

you have the patient, um, uh, void.

8:06

Uh, as soon as they check in for their MR

8:08

exam, and by the time they get their paperwork

8:10

and are put on the scanner, there is adequate

8:12

distention of the bladder for you to make the, uh,

8:15

the, the relevant, uh, findings.

8:19

One other note of caution is if the patient has

8:22

had a recent, uh, transurethral resection, um,

8:26

and a biopsy, you have to wait for two weeks.

8:28

Uh, and the reason for that is, um, you can, um,

8:32

have hemorrhage, uh, which can be a, a, you know,

8:36

create confounding issues in terms of bladder staging.

8:40

Uh, it can also be, uh, not very comfortable, uh, because

8:43

the patient, if they are bleeding into the lumen, may

8:46

have a, um, desire to, uh, pass urine much faster.

8:51

And so, you know, that may lead to discomfort.

8:53

So that's the reason why you need to wait for two weeks.

8:55

If the patient has had just a routine office cystoscopy,

8:58

you want to wait for two to three days because,

9:01

uh, because of the Foley catheterization and also

9:04

because of the procedure itself, there may be some

9:06

luminal air if you do it right after the procedure.

9:09

And that luminal air can sometimes create problems, uh,

9:13

when you're doing diffusion sequences in terms of artifacts.

9:16

So you have to wait for two to three days,

9:19

uh, after the, uh, office cystoscopy.

9:23

Now let's look at the, the protocol itself.

9:25

Uh, when we are talking about protocol,

9:27

we start with a triplanar scout.

9:29

Uh, and this is basically to get a bearing of the

9:32

area of coverage, and you want to typically go from

9:35

the, um, uh, L5–S1 junction or the aortic

9:38

bifurcation down to a few centimeters below the level

9:42

of the pubic symphysis. That typically will cover,

9:45

cover most of the, uh, bladder and allow us to get

9:48

uh, images that are relevant to, uh,

9:52

to looking at the, uh, urinary bladder.

9:54

Once you do the, um, the triplanar, uh, scout or

9:58

the localizers, you do a large field of view, um, uh,

10:03

coronal HASTE or a, um, single-shot fast spin echo.

10:07

These are, uh, T2-weighted, uh, sequences

10:10

that are relatively motion insensitive.

10:12

The reason to do these, um, large FOV is to basically

10:16

look at kidneys because, you know, if you have

10:18

bladder cancer, that can sometimes obstruct the

10:21

ureters and give rise to secondary hydronephrosis.

10:24

Um, also to make sure that there is

10:26

no congenital absence of kidneys.

10:29

Uh, and also this gives us a good way of looking

10:31

at the retroperitoneum in terms of looking at

10:34

adenopathy, which is beyond the confines of the pelvis.

10:37

A word of caution when you are looking at these, uh,

10:40

HASTE images, these, um, uh, whether it's single-shot or

10:45

HASTE, um, uh, motion-insensitive T2-weighted sequences

10:48

are extremely, uh, susceptible to motion in the fluid.

10:52

And so, as you can see in this bladder,

10:54

any kind of urine motion is perceived

10:56

as, um, a signal loss, and sometimes this

10:59

motion can appear or mimic, uh, focal

11:02

masses, as you can see in this patient.

11:04

But on the axial fat-sat T2, there's

11:06

actually nothing in that location.

11:08

So keep that caveat in mind when

11:10

you are looking at these sequences.

11:12

Do not end up calling these, uh, filling

11:14

defects or, uh, or actual, uh, lesions.

11:18

Once we do the large field-of-view HASTE, we,

11:20

um, subsequently acquire the main sequences.

11:23

These are the triplanar, uh, turbo or fast

11:26

spin-echo T2-weighted sequences that are

11:28

acquired in axial, coronal, and sagittal planes.

11:31

And these are truly the, um, you know,

11:32

the primary, uh, means of identifying

11:36

the detrusor muscle and also looking at, uh,

11:39

tumors and, and what are their characteristics.

11:42

Um, these are done typically without fat saturation because

11:45

you want to, um, have the contrast noise between the

11:48

surrounding fat and the bladder wall itself to, uh, look

11:52

for, uh, uh, what the tumor is doing, uh, to the bladder

11:56

wall itself, and whether it's extending beyond the wall.

11:59

So that's, those are sort of the, uh, the, um,

12:02

the primary sequences for staging, if you

12:04

will, and those are acquired in three planes.

12:07

Once you do the triplanar T2s, you acquire diffusion.

12:09

And typically, uh, you know, we at our institution acquire

12:13

three B values: low B value of 50, which is essentially

12:16

a, a, uh, T2-weighted sequence, an intermediate value

12:21

of around 400, and then a, a higher B value of 800.

12:25

And then you calculate an ADC. Now, in terms

12:28

of DWI, a couple of pointers, um, uh, one thing

12:32

you have to remember is as you progressively

12:34

go up on your B values, you are losing signal.

12:37

And, and one way of, uh, counteracting that is by increasing

12:41

your number of excitations or number of signal averages.

12:45

Uh, and most vendors allow you to vary the number of

12:48

averages between the low B value and the high B value.

12:50

So once you go to the high B value, it’s

12:53

important to bump up your, uh, signal averages

12:56

so that you get good signal intensity and you’re

12:58

able to see the, um, the anatomy a little bit better.

13:02

The other is, um, this is, uh, as you can

13:04

see, this is a relatively higher resolution

13:06

compared to what you see in routine DWI.

13:08

And this is a, a specific kind of, uh, DWI, which

13:12

is, uh, commercially called FOCUS on

13:16

the GE systems and ZOOMit on the Siemens system.

13:19

And these are spatially tailored excitation

13:22

pulses, um, with a decreased FOV in the phase-encoding

13:26

direction that leads to higher-resolution images.

13:29

And if you have the ability to do that, then you should

13:31

try and use those because they clearly give a much better

13:34

image of the bladder than you would with regular DWI.

13:37

This patient, incidentally, has a

13:38

small biopsy of the bladder wall.

13:42

After you do the DWI, you move on to

13:44

the gadolinium-enhanced, um, uh, images.

13:47

And so you start with a scout, uh, or

13:50

rather the non-contrast T1-weighted fat-

13:53

saturated image, uh, that gives you, um,

13:56

a, a, uh, sort of a baseline to assess for enhancement.

14:01

And then you do dynamic-enhanced, um, sequences.

14:04

You start at 30 seconds and typically do about

14:06

three to four runs, and it is very important that

14:09

you perform subtractions once you, um, uh, acquire

14:13

the, um, dynamic, uh, sequences.

14:17

Uh, we, in addition to the fat-

14:19

saturated T1 that is done before

14:21

gadolinium administration,

14:22

we also do an axial quick gradient-echo T1,

14:26

uh, as part of the, uh, uh, as part

14:31

of the, uh, 3D gradient-echo series.

14:34

And, and the reason for that is you get a little more, um,

14:37

uh, a better delineation of the, um, you

14:41

know, of the bladder and its surroundings.

14:42

And it's a useful sequence, but there are some

14:45

institutions that may choose not to do this

14:48

and just rely on the, um, the pre-contrast run

14:50

as their primary, uh, T1-related sequence.

14:53

And that's fine.

14:54

Now, when you're looking at the, um, gadolinium-enhanced

14:57

series, uh, a couple of pointers again. The

15:00

first one is it's important to decide on which

15:02

plane are you going to do the dynamic images.

15:04

So,

15:05

if the tumor is located in the, uh, the dome or the

15:08

superior wall of the bladder, or the inferior wall,

15:12

as is the case here, then you may want to do it.

15:15

Sagittal is fine, as is the case being done

15:17

here, but if the tumor is located on the right

15:20

or left lateral wall, then it's very important

15:22

you either use axial or you use coronal.

15:26

You do not want to use sagittal as your dynamic

15:28

series because then it is difficult to assess

15:31

the relationship between the enhancement of the

15:34

tumor and the adjacent bladder wall if you do a sagittal image.

15:37

So again, keep in mind that the techs need to

15:40

be trained to kind of understand the difference in

15:43

terms of when they would, uh, when they would opt for,

15:47

uh, a sagittal or a coronal or axial dynamic series.

15:51

So that's sort of, in a nutshell, the, uh, protocol.

15:55

And, um, so then the next question is, where is bladder MR

15:59

most useful?

16:00

And the answer is in the imaging

16:02

and staging of bladder cancers.

16:03

And in order to understand that, it's

16:05

important to understand what happens, uh,

16:07

when a patient who presents with hematuria.

16:10

And so if you have somebody who presents with hematuria,

16:13

um, with or without urinary frequency, pelvic pain, or weight

16:17

loss, and there is a high index of suspicion that this

16:20

patient has bladder cancer, those patients typically undergo

16:23

an office cystoscopy to, you know, take a look, and then, um,

16:28

once something is found on the office cystoscopy, those

16:31

patients get transurethral resection of the bladder tumor

16:33

for staging, and then that's where you combine it with,

16:37

uh, with, uh, radiologic assessment, primarily MR.

16:42

Uh, to help you out in terms of staging the bladder cancer.

16:45

So the question is, you know, if it's, if you are doing

16:49

a TURBT, why do you need the radiologic assessment?

16:52

So, we'll, we'll, um, explore

16:55

that, uh, question a little bit.

16:57

So if you look at bladder cancer, most bladder

16:59

cancers are urothelial cell carcinomas,

17:01

and they can be divided into two subtypes.

17:04

You have the low-grade papillary lesions, and

17:06

you have the high-grade papillary lesions.

17:08

If the lesions are high grade, they can be non–muscle

17:11

invasive, which means they’re primarily confined to the,

17:14

uh, to the lumen, uh, and the, um, and the mucosa,

17:20

the lamina propria, and they can be muscle invasive,

17:23

in which case they are involving the detrusor muscle.

17:26

So here is an example of what a papillary

17:29

bladder tumor looks like on a cystoscopy assessment.

17:32

This is a, this is what the normal urothelium looks

17:35

like, and this is what the papillary, uh, tumor looks

17:38

like on histopathology when one does the, uh, sampling.

17:43

So the question is, why is it important to distinguish low-

17:45

and high-grade and, and muscle versus non–muscle invasive?

17:48

And the reason is, if you are having a muscle-invasive

17:52

cancer, then, uh, these patients typically do worse.

17:56

Uh, they, uh, if you have a muscle-invasive cancer,

17:59

it, it has aggressive growth and can lead to

18:01

nodal and, and subsequently distant metastasis.

18:06

So, as I mentioned to you, if the way, um, these patients

18:10

are diagnosed and staged is you do, the patient is brought,

18:13

uh, into the, um, uh, into the, uh, procedural room.

18:18

And then under anesthesia they do a transurethral resection

18:22

of the bladder, uh, where, um, following a cystoscopy,

18:26

you, um, try and resect the tumor, and the goal is to try

18:29

and get down to the muscle so that you have enough tissue

18:33

to conclusively, uh, prove or disprove the fact that

18:36

there is muscle invasion or, uh, muscle invasion or not.

18:40

If there is, uh, involvement of the muscle, then you

18:42

know that there is muscle invasion, and these patients

18:45

typically will get cystectomy with adjuvant therapy.

18:47

Whereas if it is non–muscle invasive, then a TURBT

18:51

can be therapeutic, and they can then just be

18:53

monitored with routine office, uh, cystoscopies.

18:57

So this is what I meant when, in terms of muscle

18:59

invasion, you need cystectomy with adjuvant therapy.

19:02

Now it’s important to realize that it’s contingent on

19:06

the fact that the person who is performing the, uh,

19:08

procedure, um, is able to not only, um, remove the

19:13

cancer, but also extend fairly down into the muscle

19:17

to be absolutely certain there is no muscle invasion.

19:20

Now, depending on the experience of the

19:22

operator and also where the tumor is located,

19:25

you can actually end up understaging

19:27

the cancer in about 25% of the cases.

19:30

And you can see that can be a problem.

19:31

It can be a problem because then if you, uh,

19:35

underestimate and take that as a fact, then

19:39

you are missing out on the muscle invasion.

19:41

And these patients who would normally get cystectomy.

19:44

With, uh, adjuvant therapy are then just being observed.

19:47

And, you know, the tumor in that duration can spread.

19:49

So that's the problem, and that's

19:51

where MR can be a useful compliment.

19:53

Two TURBT in terms of making sure

19:57

that there is truly no muscle invasion.

19:59

So it really comes down to the question of

20:01

question of is there muscle invasion or not?

20:03

And, and MR can and can truly be very helpful there.

20:08

So if you look at the schematic of, uh, bladder cancer,

20:11

staging, um, what you are trying to do is basically look at

20:16

tumors that are superficial tumors, which means they are

20:20

primarily confined to the mucosa,

20:21

extend to the lamina propria.

20:24

And you want to distinguish these from

20:26

those that are involving the muscle.

20:28

And so, T one disease is disease that, uh, is confined

20:33

to the, uh, mucosa and to the lamina propria or sub,

20:36

sub, uh, uh, mucosal connective tissue, and T two

20:40

disease is disease that extends into the detrusor muscle.

20:43

And those that extend into the detrusor muscle are

20:46

then, uh, divided into those with less than, um,

20:50

half of the, uh, detrusor circumference involved,

20:53

and greater than, uh, 50% of the, of the

20:57

wall of the detrusor or wall of the bladder

20:59

with the detrusor muscle involvement.

21:02

T three disease is when tumor extends beyond the bladder

21:04

wall into the adjacent fat, and T four disease is

21:07

when

21:07

disease extends beyond the bladder, through

21:10

the fat into the adjacent pelvic organs.

21:13

But really the, the goal of MR is to try and

21:15

distinguish those that are involving the

21:18

detrusor muscle versus those that are not.

21:22

And so, uh, this is, you know, just to kind of

21:26

emphasize when we do MR in these patients, you

21:29

have better localization, you have a better

21:32

differentiation of T one from T two cancers.

21:35

In addition to the, there are two other, um,

21:37

areas where MR can prove helpful, and the first

21:40

one is in the, in the setting of treatment.

21:42

And here is the other big one where MR is routinely used

21:45

in terms of looking at tumors within bladder, diabetic limb.

21:48

And we'll, we'll dwell into that on why that's,

21:50

um, that's becoming an important indication for.

21:55

Now, if you look at the, um, you know, the, the

21:57

literature in the last, uh, uh, four or five years,

22:00

uh, in bladder cancer, there has been an increasing

22:03

number of articles on RADS being proposed as a, uh,

22:08

unified reporting schema of, uh, for bladder cancer.

22:12

And I think, uh, at, at first glance, this looks

22:15

a little complicated, but, um, you know, it's

22:18

along the lines of RADS for prostate cancer.

22:21

This is, uh, a useful way of kind of looking at, uh,

22:25

bladder tumors and being able to answer the question.

22:28

So, we are not going to dwell into this today, but what

22:29

I'm going to try and do is distill the key points from the

22:33

RADS, uh, uh, reporting schema so that you can, um, you

22:37

know, you can start using, um, and make the relevant,

22:41

uh, um, or make the relevant observations and staging.

22:47

And so the bottom line for this, this whole schema, is to

22:50

detect and confidently diagnose, uh, muscle invasion.

22:55

And so, so what are some of the pointers when

22:57

you're looking at MR. The first pointer is to

22:59

make sure that you look at all the sequences.

23:02

This is very important, uh, with bladder cancer.

23:04

I told you that T2-weighted are the, uh, T2-

23:07

weighted sequences are the primary, uh, sequences.

23:10

But that does not mean you just look at the T2.

23:12

You also need to make sure you look

23:14

at the enhanced images and the DWI.

23:16

And, and typically when I'm looking at these cases, I'm

23:19

looking at it sort of four on one where, you know, I have

23:23

the T2-weighted sequences on, on the top left panel.

23:26

The, the, uh, diffusion-weighted on the top right panel,

23:30

the post-enhanced on the bottom left, and then the off-

23:33

axis, either a sagittal or a coronal plane on the bottom right.

23:37

And just to emphasize why that's needed is if

23:39

you look at the anatomy of the bladder wall.

23:42

From the urothelium to the detrusor muscle.

23:44

And you look at the various sequence types, you can

23:47

see that each part of the bladder wall is emphasized

23:49

on, on a different sequence type, slightly different.

23:52

And so if you combine the information from all the

23:55

sequences, you know, you can enhance your accuracy of, of

23:58

better detecting the tumors and better staging the cancer.

24:01

Uh, just to show you some examples, this

24:03

is a patient, um, with hematuria again,

24:06

with, uh, diagnosed, uh, bladder cancer on.

24:10

Office cystoscopy.

24:11

And if you're looking at the T2-weighted sequence here, uh,

24:14

the urine is bright, uh, you can see the nice outline and

24:17

the detrusor muscle, and it's not very easy to spot the tumor.

24:20

Sometimes these tumors, you know, may be a little bit

24:23

hyperintense, and the contrast-to-noise between the

24:26

cancer and the, and the bright urine may not be as apparent.

24:29

Here is, uh, looking at the low and high b-value,

24:32

you can nicely see that there is the outline of the

24:35

tumor on the right lateral bladder wall with a stalk.

24:38

Uh, which is relatively dark, and again, against

24:42

a backdrop of the enhanced, uh, uh, urine.

24:45

In the, um, in the post-gadolinium-enhanced axial images,

24:49

you can nicely see the outline of the papillary, uh, cancer.

24:52

So again, emphasizing the fact you

24:54

need to look at all the sequences.

24:56

Here is another example of a patient

24:58

who pre, who presented with hematuria.

25:01

If you look at the axial T2-weighted sequence,

25:03

there is mild asymmetry of the ureters.

25:05

It's very difficult to know where the cancer is.

25:08

If you look at the, uh, DWI, um, uh, high b-value, you

25:12

can see that there is, uh, increased signal as seen in

25:15

the, uh, left lateral bladder wall extending into the

25:18

ureter, which is seen much better on this, uh, slice.

25:22

And again, those corresponding areas show early enhancement.

25:25

Typically what cancer does is it enhances earlier

25:28

than the normal structures, and this was biopsy-

25:30

proven to be, um, high-grade, uh, TCC involving

25:33

the bladder extending into the, uh, ureter.

25:35

So again, the, the take-home message is to

25:39

make sure you look at all the sequences to, um.

25:42

Uh, to, uh, not only diagnose, but also stage the, uh,

25:47

uh, the, uh, I'm sorry, this is to stage, the, um, so the

25:52

next important thing about the RADS is to look for a stalk.

25:56

Now this is a very important, um.

25:59

Uh, point in terms of, um, uh, taking the

26:02

principles of RADS and, um, and applying it.

26:05

So what does, what is a, what, what does a stalk mean?

26:09

So the stalk is made up of loose connective tissue,

26:11

and it connects the cancer to the bladder wall.

26:14

So this is what it looks like.

26:15

Here is the outline of the bladder.

26:16

This is the papillary tumor.

26:18

And you can see this.

26:20

Area that is, uh, highlighted in the yellow

26:23

circle is the, um, is the, uh, is the stalk

26:28

that connects the cancer to the bladder wall.

26:31

So when you have the presence of a stalk with no

26:33

bladder wall, uh, thickening, it's a good sign.

26:36

It usually tells you that there is no

26:38

extension into the muscle, and typically

26:40

those tumors are non-muscle-invasive cancers.

26:43

So to show you some examples, now it's important to realize

26:47

that, uh, I mentioned to you the fi, the stalk is typically

26:51

composed of fibrous tissue, so majority of the cases,

26:54

the stalk is going to be dark on T2-weighted sequences.

26:58

And so in about 40% of the patients, the stalk is dark.

27:02

On T2, it can be isointense in about 30% and

27:06

can be hyperintense in about 20% of the cases.

27:09

So just keep that in mind.

27:10

The, the majority are dark, but you know, sometimes

27:13

you have to look on the other sequences if it's iso

27:16

and, and may not be easy to detect.

27:18

So here is an example of a large

27:20

polypoid lesion in the bladder.

27:22

You can see the stalk in the, um, uh, that is

27:25

emanating from the wall, extending into the cancer,

27:27

into the, uh, tumor, which is dark on T2.

27:30

It's also seen on the DWI images, and here is

27:33

the coronal depiction of the same, uh, stalk.

27:36

Um, and so again, presence of a stalk without

27:39

adjacent bladder wall thickening is a good sign.

27:41

It typically tells you there is

27:43

likely no bladder involvement.

27:45

On the enhanced images, there is some enhancement along

27:47

the mucosal lining, which can happen with bladder,

27:49

especially because they incite some inflammation

27:52

in the bladder wall adjacent to the cancer.

27:56

Here is another example of a stalk that is bright on T2.

27:59

So remember, this is the next most common type.

28:01

So here again, a large papillary tumor on the axial.

28:05

You can see the tumor.

28:06

Um, the, the stalk is, um, high in signal intensity in the

28:10

T2, uh, much better seen on the fat-saturated T2.

28:13

You can see the bright signal of the stalk.

28:16

And here is it on gadolinium, where the, the,

28:19

uh, stalk has enhanced, um, uh, is enhancing

28:23

a little bit different than the, the tumor.

28:25

And on delayed retains the contrast,

28:27

which typically fibrous tissue will do.

28:29

And lastly, this is an example of a

28:31

stalk that is, um, isointense on T2.

28:35

So when you look at the T2-weighted sequences, you

28:37

can see the signature of the normal bladder wall.

28:40

Uh, you are seeing a, a papillary cancer on

28:42

the right lateral posterior wall, but you

28:45

don't see a stalk on the T2-weighted sequences.

28:47

And as I mentioned, you have to look

28:49

at all the sequences, and on the T2.

28:51

And on the, sorry, on the high b-value diffusion,

28:54

you can see the restriction in the tumor and

28:57

the nice T2 and the nice, um, low-signal-

29:00

intensity, um, uh, stalk that is projecting into

29:04

the, um, and it's the reverse on the, on the ADC.

29:08

And here's the last example.

29:09

Same thing.

29:10

Um, isointense, um, stalk on T2-weighted, nicely seen

29:14

on the high b-value diffusion as low-signal intensity.

29:18

Uh, extending into the, uh, tumor.

29:21

So presence of a stalk without adjacent

29:23

bladder wall thickening, whether it's

29:24

hypo, or hyper, or iso, is a good sign.

29:27

And that can reliably help you in terms of, uh, telling

29:31

you that there is no adjacent muscle involvement.

29:34

So that's sort of the key, uh, pointers.

29:36

Now let's look at some examples.

29:37

So here's two different patients,

29:40

both presenting with hematuria.

29:42

And, um, in this instance, you can see

29:45

there is a tumor on the left lateral wall.

29:46

This is a T2-weighted coronal image.

29:48

You can see the prostate right here,

29:50

and in this case, you do see a stalk.

29:52

That is bright, T2 bright.

29:54

And, and again, this is primarily confined to the,

29:57

um, to the wall or, or the submucosa sometimes, or the,

30:02

uh, lamina propria, but there is no muscle involvement.

30:06

Um, here is another example.

30:07

This is, um, a gadolinium-enhanced image where you can

30:10

see some enhancement, early enhancement in the wall

30:13

and the primary tumor, but there is no extension

30:15

into the adjacent, uh, uh, adjacent muscle.

30:20

Now T2a is, um, uh, tumors that go into

30:24

the detrusor muscle, but involve less than

30:26

half the, uh, thickness of the detrusor muscle.

30:29

So here are, here is an example of a patient where

30:31

you can clearly see there is a polypoid lesion

30:33

projecting into the, uh, in from the left lateral wall.

30:38

There is some bladder wall thickening and there is no stalk

30:41

either on the diffusion or on the T2a, uh, sequence.

30:44

So bladder wall thickening with, you know, some, um,

30:47

extension into the, into the adjacent detrusor muscle, as

30:51

you're seeing on this high b-value image where you can

30:53

see that there is some projection into the, the muscle, and

30:56

there is clearly thickening of the detrusor muscle there.

30:59

And so that indicates that there is involvement,

31:00

though not the entire thickness is, is, uh, involved.

31:05

And here is a different patient.

31:06

Uh, this is gadolinium-enhanced, uh, series.

31:08

Again, you can see some inflammation

31:10

in the, in the, uh, urothelium.

31:12

Here is the tumor on the anterior wall and clearly

31:14

extending into the, uh, muscle layer, but not the

31:17

entire thickness of the, of the detrusor muscle.

31:21

T2b is when there is muscle

31:23

involvement involving the entire thickness.

31:25

So again, two different cases.

31:27

Here is a sagittal T2 sequence, where

31:28

you can see the evil gray.

31:30

Of the cancer that extends the

31:32

entire thickness of the muscle.

31:34

Different patient, little bit distension of the bladder.

31:37

Again, you don't want the bladder

31:38

to be more distended than this.

31:40

Uh, and then you start getting into errors.

31:43

So again, there is, uh, the same thing, the, the,

31:45

um, evil gray of the, uh, tumor extending the

31:49

entire thickness of the, uh, of the detrusor muscle.

31:53

Uh, here is another example where again, looking

31:56

at the, uh, multiparametric, uh, sort of approach

31:59

and, and all the sequences, you can see there is

32:01

a polypoid lesion, uh, in the right lateral wall.

32:05

Very close to the ureteric orifice, enhancing

32:08

early on, uh, restricting on diffusion.

32:10

And again, there is, um.

32:12

Thickness of the, um, muscle layer there

32:15

with lack of the normal dark signal.

32:17

And again, this left lateral wall

32:19

nicely shows that bilaminar appearance.

32:21

We spoke about the inner being a little bit darker than

32:23

the, the, the more, uh, lateral part of the detrusor.

32:27

Uh, you can sometimes see that very

32:28

nicely with the high-resolution images.

32:30

So this is, uh, also, um, a T2b with the

32:33

entire thickness of the muscle layer involved.

32:37

Now T3 is when disease extends beyond

32:40

the, uh, uh, detrusor into the adjacent fat.

32:43

So again, uh, in this instance, there is a large lesion.

32:47

Clearly there is extension into the adjacent fat.

32:50

A different patient on the axial image.

32:52

You can see there is tumor involvement

32:54

of the, uh, perivesical fat there.

32:57

And lastly, T4 disease, which is, uh, involvement of

33:00

pelvic sidewall, where you can see there is a large tumor

33:03

extending into the, uh, pelvic sidewall musculature.

33:06

And this is, um, uh, T4, uh, disease pattern

33:10

where there's involvement of the pelvic sidewall.

33:13

Um, one other attribute of MR, which

33:16

can be extremely beneficial to our, um.

33:19

urology colleagues is to find, uh, multiple cancers.

33:24

And so in this instance, you can see there are multiple,

33:26

um, uh, there's a large primary tumor that is, um,

33:31

uh, arising in the, um, uh, in the trigonal area.

33:35

It involves the ureteric orifice.

33:37

There is obstruction to the ureter, and there may be

33:39

another sort of satellite lesion present in the ureter.

33:43

But when you look on the diffusion, there

33:45

are multiple other foci scattered throughout

33:47

the, um, uh, remainder of the bladder.

33:50

In this instance, the enhanced images also show the

33:52

additional tumor foci on the T2

33:54

coronal also, I'm sorry, T2 axial.

33:56

You can see the additional foci.

33:57

So here, that's another sort of power of MR

34:01

in terms of helping, uh, and delineating the

34:04

tumor burden if there is multiple, uh, cancers

34:06

present in the, uh, in the, uh, in the bladder.

34:11

Now in terms of nodal, uh, drainage, uh, the, uh, the

34:16

primary or the regional nodes for bladder are essentially,

34:21

uh, they spread into, uh, three distinct groups.

34:24

The first is in the perivesical area,

34:26

so right adjacent to the bladder.

34:28

You can sometimes see small nodes.

34:31

And then the established nodal groups are the, um.

34:33

It spreads to the, um, the external iliac nodes, can spread

34:38

to the obturator nodes, and also the internal iliac nodes.

34:42

So internal iliac, obturator,

34:44

external iliac, and presacral nodes.

34:47

Those are the primary, um, drainage

34:50

pathway for bladder cancer.

34:52

And this is a patient who has external iliac, um,

34:55

uh, adenopathy that you're seeing in this instance.

34:59

If there is involvement of common iliac nodes,

35:01

common iliac nodes is the sort of second tier,

35:04

and they are considered distant metastasis.

35:07

Um, typically with bladder, it's a, uh, nodal

35:10

involvement is sequential, which means it typically

35:13

first goes to these, uh, pelvic sidewall nodes, which

35:16

are regional nodes, and then will spread to the, um.

35:20

Uh, to the common iliac nodes, which are non-

35:22

regional or are distant metastatic, uh, foci.

35:26

Occasionally it may skip, though not very common,

35:29

and that's the reason why we try and image

35:31

from the bifurcation all the way, uh, down.

35:34

Here is an example, coronal MR, showing external iliac

35:37

nodes leading up to common iliac, uh, uh, lymph nodes.

35:41

One other point about adenopathy is, you know,

35:44

bladder cancer can also cause distant mets,

35:46

uh, to, uh, to the lung, uh, to, to, uh, liver.

35:50

Um, typically patients who have nodal disease, they

35:54

still do better than those that have distant metastases,

35:57

and that's something to keep in mind as well.

36:01

Now, um, as I mentioned, the two other areas is

36:04

post-treatment and cancer arising in a ileal conduit.

36:08

Cancer in an ileal conduit can arise because an ileal conduit

36:10

can lead to urinary stasis and chronic inflammation.

36:13

And so it's about 10% of cases, you know,

36:16

that an ileal conduit can develop, uh, cancer.

36:19

The reason why it's important because these diverticula

36:21

can have a narrow neck, and if they, this is a patient,

36:25

who doesn't have cancer but had had a bladder

36:28

diverticulum that was totally missed on

36:30

cystoscopy because of the narrow neck.

36:32

And this may be a challenge for

36:34

the, um, cystoscopies to identify.

36:36

And so that's another area where MR can be helpful

36:39

in terms of delineating the diverticulum if there

36:41

is cancer that's hiding within the diverticulum.

36:45

Uh, one other important, uh, anatomy fact to keep in mind

36:48

is that the detrusor muscle is absent in the diverticulum.

36:51

And so,

36:53

if you have a tumor that is present in the diverticulum,

36:55

that is, um, equal to a muscle-invasive, invasive

36:59

cancer, and, and very often when you have tumors

37:03

present in the, uh, diverticulum, they usually

37:06

invade the perivesical fat at the time of diagnosis,

37:09

and therefore, they typically have worse prognosis.

37:12

So, just to show you an example, this is a

37:14

posterior diverticulum, large diverticulum

37:16

that is arising from the bladder.

37:18

And again, you can see how narrow the neck is.

37:20

There's a large tumor that fills the, uh,

37:22

lumen, and it's showing early enhancement,

37:24

uh, within the, uh, within the cancer.

37:28

This is another example of a large posterior

37:30

diverticulum with the tumor seen along the left

37:33

lateral wall showing early enhancement and, and, and

37:36

restricted diffusion on the high, uh, b-value images.

37:42

Uh, this is, uh, sort of the power of MR

37:44

in terms of looking at response to therapy.

37:47

And so on the left is the pretreatment scan showing

37:50

the T2 and the gadolinium-enhanced images.

37:52

And this is after undergoing, uh,

37:55

treatment, uh, with chemotherapy.

37:57

You can see there is dramatic shrinkage in the

37:59

size of the cancer, and there is relative, um,

38:02

a relatively absent early enhancement in the tumor.

38:05

And so you can sort of follow the, um, uh, the,

38:08

uh, the tumors after treatment in terms of, um,

38:12

uh, what their size is and what the extent of the

38:15

cancer is, uh, uh, once the treatment is done.

38:20

So that was in a nutshell in terms of looking at bladder.

38:22

We now spend the, you know, last, um, uh, 10

38:26

minutes or so looking at the female urethra.

38:29

Um, MR can be extremely helpful in assessing

38:32

the female urethral region and the normal

38:35

anatomy, if you look at the axial and the sagittal

38:38

images essentially is comprised of four rings.

38:41

So you have the inner bright or hyperintense, um.

38:44

Uh, uh, um, a ring which is basically,

38:48

um, the inner lumen that represents, um,

38:51

uh, that represents urine or secretions.

38:55

Beyond that, you have a dark ring, uh, that

38:57

represents the inner, um, mucosal layer.

39:01

And then beyond that, you have a bright ring, which is,

39:03

um, is the high-signal intensity of the middle submucosal layer.

39:08

And then after that is the, is the final dark

39:11

ring, which is enhancing vascularized, um, um, uh,

39:16

outer muscle layer, uh, that represents a smooth

39:19

muscle layer that surrounds the, um, the urethra.

39:22

So those are sort of the four rings you see in, in

39:24

the female urethra on the T2-weighted sequence.

39:28

The clinical condition that we commonly

39:31

can identify in, in on with MR in the

39:34

female urethra, female urethral diverticulum.

39:37

And typically what happens in this instance is

39:39

you have periurethral glands that can get obstructed.

39:42

There is abscess formation, which ruptures

39:44

into the urethra, and that's ultimately what

39:47

leads the formation of the diverticulum.

39:49

Typically, these are young, uh, patients between the

39:52

ages of 20 and 40, and they, they will present with

39:55

urinary symptoms of dysuria, urgency, or, or incontinence.

40:00

So this is what a classic urethral

40:01

diverticulum looks like on MR.

40:03

Here is the axial coronal, uh, T2-weighted sequence,

40:06

and this is the post-gadolinium-enhanced axial image.

40:09

So you can see there is a, um.

40:11

A semicircular, uh, sort of horseshoe-shaped, uh,

40:14

T2-bright, um, lesion that surrounds the urethra.

40:17

Here on the coronal, you can see it's sort of evenly

40:20

distributed on either side of the, uh, of the short urethra.

40:24

Uh, there is no enhancement within

40:26

the lumen, 'cause it's fluid filled.

40:27

There is enhancement surrounding, um, 'cause

40:30

there, there's inflammation in the wall.

40:32

And that's sort of the typical pattern of appearance.

40:34

Now, you can have complications within the urethra.

40:38

They can bleed, uh, within the urethral diverticulum.

40:41

They can bleed, they can get infected, they can have

40:44

stone formation, or they can, uh, if long standing with

40:48

inflammation, can have tumor, uh, development within these.

40:52

So here is an example of a patient with, uh,

40:54

fluid, fluid level, likely as a result of

40:57

perhaps old hemorrhage or, or prior infection.

41:01

This is slightly eccentric.

41:03

You can see this is a urethra.

41:04

This, unlike the prior case where

41:06

there was even distribution.

41:07

This is slight eccentric in location, and you can see

41:10

the urethra in, uh, periurethral tissue enhancing here.

41:13

And this is the outline on the diverticulum

41:15

on the axial gadolinium-enhanced image.

41:19

These are, uh, axial and, uh, sagittal images

41:22

in a patient with a longstanding diverticulum.

41:24

So you can see from the size of the diverticulum.

41:27

This patient has developed stones within the, uh,

41:30

uh, urethral diverticulum, and the same is seen

41:32

on the coronal image as multiple stones that are

41:35

filling the lumen of the, um, of the urethral lumen.

41:40

Um, as I said, if there's longstanding

41:42

inflammation, uh, you can develop tumors.

41:45

They are extremely rare, the most, and if

41:48

they do happen, the most common subtype

41:51

that you see is a squamous, uh, subtype.

41:53

And this is what it looks like.

41:54

So here is the sagittal image.

41:57

You can see that there is a, um.

41:59

A, uh, diverticular lumen, but unlike the other cases

42:04

I showed you where there was bright signal or fluid

42:06

that filled the diverticulum, in this case, there is soft

42:09

tissue that is filling the diverticulum, and this tissue

42:12

is enhancing on the post-gadolinium-enhanced images.

42:15

And when you see this, you need to

42:16

start getting worried about cancer.

42:18

And this was squamous cell carcinoma.

42:21

This is a more, um, uh, severe case of

42:24

squamous cell where there is a large tumor.

42:27

This almost looks like a prostate.

42:28

This is actually a female patient.

42:31

There is a large cancer that fills the

42:32

entire lumen of the diverticulum and showing

42:34

enhancement and marked restricted diffusion.

42:37

And this was a large squamous cell, uh,

42:40

uh, tumor within a, within a, uh, periurethra.

42:45

Now, one, uh, point to keep in mind is, um.

42:48

Sometimes in the periurethral location, especially

42:52

retropubic, uh, in, in, in, in, at, uh, uh, location, you

42:56

can see enhancing soft tissue as you're seeing in this case.

43:00

And this is a patient who had ovarian cancer,

43:03

mets, had undergone bilateral salpingo-oophorectomy,

43:06

hysterectomy, and also debulking surgery.

43:10

And in those patients, uh, sometimes you can get

43:13

recurrences, and when they do happen, they can happen at

43:16

the level of the vaginal fornix or also in this location.

43:19

And this was, um, you know, a patient who

43:22

had undergone surgery for ovarian carcinoma

43:25

and came back with elevated CA-125.

43:28

And this was biopsy-proven to be ovarian cancer,

43:30

metastatic, retropubic in location.

43:32

So that's the other thing to keep in mind.

43:35

And last couple of minutes I want to spend

43:37

on, um, you know, one, uh, important aspect.

43:40

Uh, a lot of patients, uh, with, um, female

43:44

patients with urinary symptoms, uh, undergo,

43:48

uh, periurethral bulking agent instillation.

43:51

And you know, the, the common ones that are used

43:53

are collagen and, and other inert substances.

43:57

And the goal is to try and, uh, improve their symptoms.

44:01

It's important for us to know this, uh, entity

44:03

and beware, and also, um, sort of look for it

44:07

in the patient's, um, uh, medical records.

44:11

If.

44:15

Uh, the appearance of periurethral bulking agent

44:18

instillation on imaging can look very similar to a diverticulum,

44:22

and we have seen many instances where they have been

44:24

wrongly called a periurethral diverticulum or malignancy.

44:27

So it's important, you know, to, to, to

44:29

ensure that you don't make that error.

44:33

Now typically when, uh, when collagen or any other

44:36

inert substances are instilled, they, the, the substance is

44:39

avascular and typically will have low signal, uh,

44:42

or low density on CT, as you're seeing in this case.

44:45

As you can see, it's surrounding,

44:46

this is the urethra right here.

44:47

It is surrounding the urethra, as you would expect, a diverticulum

44:50

to be, and the key is it doesn't show any enhancement.

44:54

On MR, it's the same, um, it's the same appearance.

44:58

Um, if it's acute, which means the instillation

45:01

has been done in the last, uh, few months, it'll

45:04

be, uh, high water content and be hyperintense.

45:07

But as, as time progresses, it

45:09

can become iso- to hypointense.

45:11

But the key is there is no enhancement in this,

45:14

uh, in this, um, uh, uh, imaging appearance.

45:19

So this is what it looks like on MR.

45:20

And again, you're seeing this semilunar

45:23

area of instillation surrounding the

45:24

urethra, which shows no enhancement.

45:26

And again, if I had just shown you this

45:28

gadolinium-enhanced image,

45:30

you would've, uh, called this a urethral diverticulum.

45:33

So pay attention to the history.

45:36

Do not make this error if there has been

45:37

instillation of, um, of bulking agent periurethrally.

45:41

Make sure you, you make the right call

45:43

and do not mistakenly call this

45:45

either a periurethral diverticulum or, or tumor.

45:49

And this is the last case I wanted to show you.

45:51

Here is an axial T2, and this

45:53

is a gadolinium-enhanced image.

45:55

And as we go, scroll through the axial T2-weighted

45:58

sequence, you can see in the right lateral bladder,

46:01

there appears to be sort of an ill-defined, uh, lesion.

46:04

This is a patient who presented with hematuria and,

46:08

um, you know, sort of not, not very well delineated,

46:12

looks like it's projecting into the bladder lumen.

46:15

And, uh, as we scroll down, you can see this linear,

46:18

uh, dark signal intensity area, which is coming

46:21

in from anteriorly, uh, from the abdominal wall

46:24

through the, uh, level of the pubic, uh, or superior

46:27

to the level of the pubic bone, which will become

46:28

important in terms of delineating the history.

46:31

And so that's what is seen on the T2.

46:34

And as we move down, you can

46:35

again see a little bit of, um, uh,

46:39

soft tissue mass, if you will, uh, extending from that, uh,

46:43

perivesical location down into the region of the urethra.

46:46

And if you look at the enhanced images,

46:51

there is a little bit of peripheral

46:53

enhancement, but nothing seen within the, um,

46:57

within the actual, uh, bulk of the, uh,

47:00

uh, the, uh, visualized, uh, lesion.

47:03

And so this patient, uh, underwent cystoscopy, and

47:05

all that was seen on cystoscopy were blood clots.

47:09

There was some, um, irregularity seen on

47:11

the right bladder wall, which was biopsied,

47:14

and it came back as granulation tissue.

47:16

There was no cancer that was evident.

47:19

So what is going on here?

47:21

And so this is a patient who has undergone

47:23

urethral sling with vaginal mesh, uh, surgery

47:26

for, uh, you know, for, uh, symptoms.

47:31

And, and, you know, just to kind of show you

47:33

the, the appearance, this is sort of where

47:35

the mesh is installed along with the sling.

47:37

So this linear line that we were seeing on

47:39

the T2-weighted sequence is part of the, um,

47:43

is part of the sling.

47:44

We cannot see the mesh on, uh, on MR.

47:47

So that's not, um, easy to delineate.

47:50

Now, sometimes with these meshes, they can lead

47:53

to chronic inflammatory response, which can

47:56

erode through the bladder, as was happening here.

47:59

That's what was causing the hematuria, and this is not cancer.

48:02

So again, history is key.

48:04

Look for signs of, uh, these, um, augmentation procedures

48:08

if they have been mentioned in the, uh, in the history.

48:10

For you to make the relevant call on MR. So I think in

48:14

conclusion, um, MR can be a useful, uh, aid and a complement

48:18

to TURBT for bladder cancer staging, as we went through.

48:22

Uh, it can also be extremely useful

48:24

in, um, assessment of the female urethra.

48:28

Uh, the role of MR is still evolving in bladder

48:30

cancer, and volume is gradually ramping up.

48:33

Uh, RADS can be a useful way of, uh, you know, having a, um,

48:38

sort of a, uh, simplified way of communicating the findings.

48:42

It looks a little complex, you know, when you look at it,

48:45

but the bottom line is you're looking for extension into the

48:48

bladder muscle and presence or absence of a, uh, a stalk.

48:53

And I think as we get much better and faster

48:56

with MR, it probably will become the primary

48:58

modality of choice in assessment of the bladder.

49:03

I'll end here, and if there are questions,

49:05

I'll be happy to, um, to, uh, to answer.

49:11

Perfect.

49:12

Thank you so much.

49:12

Uh, before we move into the Q&A, on behalf

49:14

of MRI Online, I wanted to thank all of you for

49:15

participating in this noon conference and remind

49:17

you that it will be made available on MRIOline.com,

49:20

in addition to all previous noon conferences.

49:22

And join us tomorrow; we'll be joined by Dr. Petra Lewis

49:24

for a noon conference on MRI-guided breast biopsies.

49:28

Dr. Ani, I do see some questions in the Q&A feature

49:30

for you, if you want to open that up.

49:33

Thanks, Ashley.

49:34

So, um, I'm going to, so the first was, could you

49:37

enumerate standard terms of bladder anatomy,

49:39

example, trigone, lateral wall, et cetera?

49:42

So, as I showed you, the trigonal area is basically the

49:45

area that is present between the two, uh, ureteric orifices.

49:49

Um, you know, it's, um, important to sort of match

49:53

the terms to what the urologist sees on cystoscopy.

49:56

Um, if you can do the call, so anterior, posterior,

50:00

and lateral walls are fairly easy, and trigone is basically

50:02

an area which is present between the two ureters.

50:05

Uh, let's see.

50:07

The next question is, must all bladder masses have a stalk?

50:11

And the answer is no.

50:12

As I mentioned, if, um, clearly if this is, um, a high-

50:16

grade tumor that is extending into the bladder, uh, into

50:19

the detrusor muscle, then that is not going to show a stalk.

50:24

For TCC, do you have to have, um,

50:27

multiple phases of enhancement?

50:30

And, and the answer is yes, because it's not so much,

50:33

you know, unlike in liver, where you are looking for

50:36

characterizing a lesion based on what the lesion does with

50:39

enhancement, in bladder cancer, what you're trying to do

50:43

is look for differential enhancement between the wall.

50:46

The, uh, and the tumor.

50:47

And so essentially what we are relying

50:49

on is early enhancement of the tumor

50:51

compared to the rest of the bladder wall.

50:52

So if you can, uh, temporally assess

50:56

that, in other words, you do early imaging

50:59

where you can only see the tumor enhancing.

51:01

And then as you gradually see enhancement of the,

51:03

uh, of the wall and then a little bit delayed,

51:06

where you have opacified urine, that kind of

51:08

also lays out the tumor, that can be helpful.

51:12

Uh, the answer to that is yes, it's

51:13

preferable to do multiple phases.

51:15

Um, uh, can we reliably differentiate less

51:19

or greater than 50% invasion by MR alone?

51:22

Um, and so again, you know, this is where,

51:25

um, looking at the presence or absence of

51:28

stalk, looking at all the sequences together.

51:31

In other words, diffusion, enhanced images, um, and as you

51:36

gain experience, you know, that becomes something that, um.

51:39

Uh, in, in terms of, uh, in terms of reported

51:43

accuracy, it's sort of quite variable now,

51:46

because we have just started doing these images.

51:48

Uh, the papers which are written by experienced, uh,

51:51

reviewers, you know, the accuracy is, uh, is close to 80%.

51:55

And there are others where they have shown lesser accuracy.

51:58

But again, it depends on technique, it

52:00

depends on, um, uh, adequate timing.

52:03

You don't want to be imaging too soon after

52:05

procedure because that can lead to false positives.

52:08

You also want to make sure that, uh, you acquire all

52:11

the, all the various sequence types so that you are

52:14

able to, um, you are able to, um, reliably stage.

52:19

Which one do you prefer, MR urography versus CT urography?

52:23

Again, we didn't talk about upper tract disease.

52:25

We are talking about basically bladder

52:27

cancer, uh, with upper tract disease.

52:30

Uh, uh, you know, clearly the goal there is not only

52:34

staging in the retroperitoneum, but also finding.

52:37

Additional lesions.

52:38

And in those cases, uh, preference is for hematuria

52:42

protocol CT or CT urogram rather than MR urogram.

52:47

How do you know if a tumor of the urethra, tumor arising from

52:50

the periurethral diameter, like in case shown by—Not sure.

52:55

I understand that, uh, that question.

52:58

Any role of MR avoiding retrograde urethrogram?

53:01

And the answer is, you know, I don't have experience.

53:03

And again, doing that in real time in, um,

53:07

in, um, in the scanner may be a challenge.

53:11

What is the signal intensity of the detrusor muscle?

53:13

As I showed you on T2, it's dark, and on, um, you

53:17

know, on gadolinium-enhanced images, it sort of gradually enhances,

53:21

as opposed to tumor, which shows early enhancement.

53:25

Does visualization of the stalk indicate

53:26

better prognosis and lower-grade neoplasm?

53:28

Yes.

53:29

If you have presence of a stalk, it usually means it

53:31

is, it is, uh, non-muscle-invasive, which typically

53:34

means it's, uh, lower in stage and likely lower grade.

53:37

Obviously, you cannot predict the histopathologic nature

53:40

of a, of a lesion, but it sort of implies that that

53:43

lesion is not deeply invading into the bladder wall.

53:48

All right.

53:48

Does the bladder

53:50

would be devoid of detrusor in other parts than the outlet?

53:53

So is there a bladder diverticulum arising from those parts?

53:55

Would it be poor prognosis?

53:57

So by definition, if you have a bladder diverticulum,

53:59

no matter which part of the bladder it arises from,

54:02

it is, it is considered to be, um, it's considered to

54:06

be devoid of detrusor muscle, and there is, and if you

54:09

have tumor, it is considered to be muscle-invasive.

54:11

Uh.

54:13

Does primary bladder amyloidosis pose,

54:15

pose any risk of development of neoplasm?

54:18

Um, you know, to be honest, I haven't seen too many

54:22

cases of primary bladder amyloidosis, so I don't think

54:24

I'll be able to answer that, uh, uh, that, uh, question.

54:30

Uh, this is a, a last one, differentiating

54:33

gadolinium enhancement of cystitis and cancer.

54:36

So I think that's a, that's a good point.

54:38

Uh, we, I didn't show you too many examples of, uh, you

54:42

know, cystitis glandularis or other sort of chronic,

54:44

uh, uh, or active, uh, inflammation in the bladder.

54:49

Um.

54:50

Typically, you know, when the patients do

54:52

come to us, they have a known diagnosis

54:54

of bladder cancer or an office cystoscopy.

54:56

So we are trying to stage them and not, uh, try

55:00

and, um, sort of make the primary, uh, diagnosis.

55:04

Um, typically when you have inflammation,

55:06

it affects the entire bladder.

55:07

It's going to be extremely unlikely that you have such

55:09

a diffuse, um, infiltrative bladder cancer, although

55:14

uncommon, can happen, but it'd be very unusual for it

55:16

to involve the entire circumference of the bladder.

55:19

So I guess that would be one way of differentiating,

55:22

um, if you mention muscle and stalk in the report with

55:27

staging, is it still required to mention wires?

55:30

So, you know, I have sort of given

55:32

you a, a, um, a sort of a, uh,

55:36

uh, you know, a nitty-gritty of what the RADS requires.

55:41

Um, clearly it doesn't replace the RADS.

55:43

It's merely sort of taking the

55:45

principles of RADS and simplifying it.

55:48

Uh, I would encourage you to read the RADS document

55:51

and see if you can implement that in our practice.

55:54

I think we still find it a little too cumbersome

55:56

to go through all those things, so we have sort of

55:58

tried to use this simplified approach to help us.

56:02

But I'm sure as the, um, you know, ideas get, um, uh,

56:06

get, um, you know, as the schema gets a little more

56:11

simpler, it'll probably become a norm, just like LI-RADS has.

56:16

Well, does MRI muscle invasion

56:17

correlate with histopathology?

56:19

I already mentioned the accuracy.

56:21

Uh, the reported accuracy on T2 and the

56:23

reported accuracy on, um, on, uh, enhanced

56:28

images have been, have been, uh, reported.

56:30

So for T2, it's, um, it's somewhere between, uh,

56:34

uh, between 40 and 75%.

56:37

And for DWI, it's somewhere between 50 and 85%.

56:40

So if you combine the two, uh, in, in terms of truly

56:44

complementary, um, fashion, you can, you know, uh, if your,

56:48

if your technique is right, you're doing it at the right time,

56:50

and your experience in looking at it, it can be close to 80%

56:53

in terms of, uh, making the call, uh, for assessment.

56:59

I think those are pretty much it.

57:01

Um, Ashley.

57:04

And we are close to the, uh, end of the hour.

57:06

So I'd like to, uh, take this

57:08

opportunity to thank everybody.

57:10

Hope everybody's staying safe, and, uh, I would

57:13

like to thank, uh, ProScan and MRI Online for

57:16

taking this endeavor to bring, uh, you know,

57:18

these wonderful lectures to a larger audience.

57:23

It too.

57:24

I thank you, Doctor, for your time today.

57:25

We really appreciate it.

57:26

Thanks.

57:28

This conference, again, will be made available online,

57:31

in addition to all online conferences complimentary.

57:33

You can follow us on social media at MRI Online for

57:36

updates and reminders on upcoming noon conferences.

57:38

Thanks, and have a wonderful day.