0:00

Okay, so I'm just going to take you through

0:02

another case of, uh, renal infarcts as well.

0:05

I think it's an entity that occurs quite

0:07

frequently, and I think you should be

0:08

pretty aware of its imaging appearance.

0:10

So here's a 67-year-old with heart palpitations

0:13

and flank pain, and as we come down, we have

0:15

this just dramatic wedge of non-enhancing renal

0:19

parenchyma in that wedge-shaped distribution.

0:22

Notice that this is going to

0:23

be bilateral in nature as well.

0:25

We have a lower pole here and in the upper pole on

0:28

the right, and a few other smaller infarcts as well.

0:31

So this would be a typical

0:32

appearance of bilateral infarcts.

0:34

Patient has A-fib.

0:35

You're going to look at the heart.

0:37

Is the next part of your search pattern?

0:38

Should you have it on the study?

0:40

And in this patient, we found a thrombus

0:43

within the left atrial appendage.

0:46

This is a very hard location for our

0:48

referring clinicians to ultrasound.

0:50

It actually takes an esophageal echo

0:52

in order to get a good image of this.

0:53

It's very hard through the chest wall.

0:55

So if you see a thrombus in that location,

0:59

please highlight it to your referring clinicians.

1:01

It's a very important source of embolic disease.

1:05

Let's talk a little bit about a

1:07

sign you may encounter as well.

1:09

It's called the cortical rim sign.

1:11

I like anything that's rims,

1:12

the spinning rims of the tire.

1:14

So the cortical rim sign is just basically when you

1:16

have an infarct of the kidney, but you still have

1:19

enhancement of that just tiny amount of the capsule.

1:23

And that's because the capsular arteries of the kidneys

1:26

come off a little bit earlier off the renal arteries.

1:29

So as a result, when those emboli come

1:31

into the arcuate arteries and the such,

1:33

that artery is bypassed and can

1:35

still feed some blood to the capsule.

1:38

So if you see this rim of enhancement, don't misread

1:41

that as, uh, anything but a common enhancement

1:44

pattern in the setting of renal infarcts.

1:46

Let's go again.

1:47

Let's do another one.

1:48

Why not?

1:49

Here's a 54-year-old with right flank pain.

1:51

We have an arterial phase of imaging here.

1:53

You can see that the liver is in a early phase of

1:56

imaging, and the spleen is quite heterogeneous.

1:58

And as we come down.

2:00

We're going to see the celiac axis come off

2:02

and the SMA, and then we're going to see a renal

2:04

artery here with a unilateral large wedge

2:09

defect or infarct on just the right side.

2:12

Notice that the left side, we're going to go

2:14

all the way down, no infarct on the left.

2:17

So whenever you have a single sided renal

2:20

infarct, I suggest that you get a CTA.

2:22

That's because patients can have

2:25

unilateral renal artery dissections.

2:28

Notice this small little intimal

2:30

flap within that renal artery.

2:32

Um, these aren't that uncommon, and they're found

2:34

in the presence of the unilateral renal infarct.

2:38

It's a reason to even re interrogate those arteries.

2:41

In a patient who may have a portal venous phase,

2:42

I would always suggest just repeat the study.

2:45

You need to see if this is a dissection,

2:47

as in this case, because this would go on

2:49

to stent placement by your IR colleagues.

2:52

Here is a large defect in that kidney,

2:55

consistent with a beautiful renal infarct.

2:58

So renal artery dissections, frequently

3:00

unilateral, uh, cause unilateral infarcts.

3:03

Whenever you see a unilateral infarct,

3:05

do you want to raise the suspicion?

3:06

I mean, I guess if the patient had, like, AFib

3:08

and everything else, you'd be like, oh, well.

3:10

By nature, it just went to one side.

3:11

But otherwise, you want to look for these dissections.

3:14

They're associated with patients who have connective

3:16

tissue disorders, such as Ehlers-Danlos, types four.

3:20

I need the fibromuscular dysplasias.

3:21

But many times they're actually

3:23

just idiopathic or spontaneous.

3:25

I love the word idiopathic in medicine.

3:26

It just means like, who knows?

3:27

It just happens.

3:28

But they can just happen, and it can be a

3:30

cause for pretty significant flank pain.

3:33

These infarcts do hurt a lot, so patients

3:36

will come in with a unilateral flank

3:38

pain, and you'll want to interrogate that.

3:40

I like to write things when I can with

3:42

arterial and venous abnormalities.

3:44

Let's go on to this case.

3:46

This came in recently, and I was

3:47

looking at it with a resident.

3:48

This is a 56-year-old female

3:49

with left-sided flank pain.

3:51

As we come down, we're going to see

3:53

that this kidney is inflamed, right?

3:55

It is big.

3:56

It is poofy, comparatively to the contralateral side.

3:59

It's very hard to see the renal pelvis here.

4:02

We went all the way down on this case, the

4:04

ureter over here somewhere, and we did not see

4:07

a ureteric stone, so we were like, weird, weird,

4:09

like what's the ureter's kind of right in here.

4:11

This is actually a phlebolith in a gonadal vessel.

4:14

What's the cause of this enlarged kidney?

4:18

All right, no contrast.

4:19

Now, I will tell you this is for

4:21

heroes only, but it's still fun.

4:22

I wanted to show you how you can make this diagnosis.

4:25

Look at the renal vein on the right.

4:26

It's really small and delicate.

4:28

That's the normal renal vein.

4:30

The renal vein on the right is pretty

4:31

short because the IVC is on the right side.

4:34

That's why, if you are a transplant surgeon, I gotta

4:37

tell you, you're going to get in there, you're going to

4:38

get into the scrum, you're going to try to get yourself

4:39

the left kidney because the left renal vein is much

4:43

larger, and that's a much easier anastomosis for you.

4:45

So they will, they will battle that out.

4:47

Look at this patient, this renal vein on

4:50

the left has an anatomic variant, which is

4:52

that it goes behind the aorta that occurs.

4:55

That's a pretty common variant,

4:56

but look at this renal vein.

4:58

See how enlarged it is?

4:59

See how dense the internal structure is here.

5:02

So I thought, you know, that looks like renal

5:04

vein thrombosis to me, and that is an entity

5:07

that can cause enlargement of the kidney.

5:09

It's an outflow.

5:10

Obstruction, we've talked about it in the GI tract.

5:12

Whenever you can't get blood out, whatever

5:14

is proximal to it, it's going to swell up.

5:16

Build fluid.

5:18

So, you know, the next thing I did, I was like, you

5:19

know what, let's get a CT scan of the abdomen and pelvis

5:23

with contrast. I felt like I could make

5:25

the diagnosis, but I need to prove it to

5:27

those who, who are looking more closely.

5:29

And here, as we come down, we see that the

5:31

nephrogram on the left is a bit delayed.

5:33

We have increased pressures somewhere in.

5:36

System here of this kidney because we have a cortical

5:39

medullary phase on the left as opposed to the right.

5:42

The right renal vein is nicely enhancing

5:44

homogeneously, and here we see a very large thrombus,

5:48

complete thrombosis of the left renal vein and

5:50

going into the IVC by just a tiny amount there.

5:54

So this is an anatomic variant of a

5:57

retroaortic renal vein with thrombosis.

6:00

We could make that diagnosis kind of,

6:02

or try to, by looking at the renal veins

6:05

for symmetry on our I-minus studies.

6:07

If we don't have any cause for why a

6:09

kidney looks angry, it's one of the reasons

6:11

why you may interrogate that further.

6:13

So this is, um, a beautiful example

6:15

where contrast really helped us out.

6:18

Um, and this is left renal vein thrombosis.

6:21

Oh, and coronal, I can't help myself.

6:23

Um, shows that thrombosis going into the IVC as well.

6:26

So renal vein thrombosis, not that common.

6:29

Um, tends to be in patients with hypercoagulability.

6:32

Uh, this is probably from this variant, and the patient

6:35

might have been hypercoagulable for another reason.

6:38

Very high incidence in nephrotic syndromes.

6:41

More common on the left than the right

6:42

because of that length of renal vein.

6:44

Um, there will be a filling defect here.

6:46

You're going to have enlargement of the kidney.

6:48

You're going to have a bit of delayed nephro.

6:50

'Cause now the venous system is

6:52

engorged and not allowing that normal

6:54

contrast flow through your nephrons.

6:56

You're going to have stranding around the

6:58

kidney, similar to what you would have in.

7:00

Other inflammatory states such as pyelonephritis,

7:03

but here it's really evident that you need

7:05

to make this diagnosis whenever possible.

7:06

It's also another reason why so nice to have contrast

7:09

if there is question about whether or not, uh, renal

7:13

stones are really that high on the differential.

7:15

I think that if you looked at this patient's history.

7:17

I don't think you would have put 95%

7:19

confidence interval in having a renal stone.

7:21

So that probably should have been done

7:22

with contrast to begin with, though

7:24

goodness knows we have run out of contrast.

7:26

So who knows?

7:27

There is also a very high risk of pulmonary

7:29

embolism in these cases because of the increased

7:31

blood flow through the renal collecting system.

7:34

So when I protocol this off the I-minus, I just told

7:37

them to get a contrast-enhanced CT scan of the abdomen

7:41

and pelvis, and I added a pulmonary embolism protocol.

7:43

Knowing that that may be a high incidence and.

7:46

As some concern there.

7:48

So here we've taken you through.

7:50

Both arterial and venous problems of the kidney,

7:53

including embolic disease, which is very common,

7:56

unfortunately, to the kidneys, and those little nephrons

7:58

don't stand a chance when they don't have blood flow.

8:01

So you'll get those just really dramatic

8:03

wedge-type of infarcts within them.

8:05

If it's a unilateral infarct in a kidney, even if you

8:08

have a portal venous phase, I would highly suggest

8:10

getting an arterial phase to look for those very.

8:13

Subtle dissections of the renal artery, uh, that can

8:16

take the patient to a stent or something very dramatic.

8:19

Renal vein thrombosis, though not very common, can

8:22

be seen when you have expansion of the renal vein,

8:25

and there is a high likelihood of pulmonary embolism

8:28

in these cases, so that will take you through both

8:31

the arterial and venous imaging of the kidneys.