0:01

There have been several multi-institutional

0:03

studies looking at the value of thrombolysis and

0:06

thrombectomy in patients suspected of having a stroke.

0:10

The neurology stroke world has embraced a

0:14

software package called the RAPID analysis

0:17

package, and I'd like to demonstrate what that

0:21

avails you of when you have that as

0:24

part of your CT perfusion package.

0:28

So this is the RAPID analysis of the previous

0:31

case that I just had previously gone over in the

0:35

individual who had right-side hemiparesis

0:37

with aphasia and had a left frontal ER stroke.

0:43

This is the analysis of the cerebral blood flow, and

0:46

as I mentioned, the neurology community has embraced

0:51

the value of CBF less than 30% volume as what they

0:56

look at for determining whether or not the patient

0:59

would benefit from thrombolysis or thrombectomy.

1:03

So we report a CBF less than 30%

1:06

volume of, in this case, four ccs.

1:09

And this is demonstrated as the yellow signal

1:15

in these brain images on the RAPID analysis.

1:19

So in the interpretation portion of your

1:22

report, you would say the CBF less than 30%

1:27

volume of brain tissue involved was four ccs.

1:31

The next thing that one looks at is the Tmax.

1:35

So as I mentioned, the value that

1:37

neurology has consolidated around is

1:40

a Tmax greater than six-second volume.

1:43

So in this case, it's six ccs.

1:46

This is usually, again, color-coded so that

1:49

the greenish area here at six seconds and

1:52

to eight seconds is seen on your imaging.

1:56

The blue area, which is a larger volume, as

2:00

you can see, is the 26 ccs of the four seconds.

2:03

But what is reported to neurology is the volume at Tmax,

2:08

six seconds.

2:09

The value of having these different thresholds is that

2:13

although this is what they're using to make therapeutic

2:16

decisions, the four-second does show that there is

2:20

additional area that is potentially ischemic at risk.

2:25

And then there are these indices.

2:28

So, as you can see, we do have additional volumes

2:31

that you can use for the CBF, up to 34% or 38%.

2:36

And then CBV is cerebral blood volume.

2:38

This is no longer used for the

2:41

decision-making on whether to do

2:43

thrombolysis or thrombectomy.

2:45

The final thing that is looked at is the mismatch ratio.

2:49

So, in this case, we had a CBF

2:52

volume less than 30% of four ccs.

2:55

We had the Tmax volume of greater

2:58

than six seconds, representing six ccs.

3:01

Which represents a mismatch ratio of 1.5.

3:05

Again, neurology and stroke teams have

3:08

consolidated around a mismatch ratio of 1.2.

3:12

If the mismatch ratio is greater than 1.2, then it seems

3:17

as if there is value in doing the thrombolysis/thrombectomy

3:21

in order to improve the patient's outcome.

3:27

In a stroke case, so were you to have the rapid analysis

3:31

as part of your evaluation on CT perfusion imaging,

3:37

these are the numbers that you would report,

3:39

that being the CBF volume less than 30%,

3:43

the Tmax greater than six seconds, and the

3:46

mismatch ratio as part of the formal report.

3:50

And this is with this rapid analysis.