How to Learn MRI An Illustrated Workbook

Exercise 15: Maximum Intensity Projection (MIP) Images Teaching Points: • Learn how to reconstruct a 3D Image. • Learn how to measure the renal artery diameter. • Learn how to measure kidney length and parenchymal thickness. • Learn about Renal Artery Blood-Flow Graph.

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Part I: Reconstructing a 3D Image Go to Browser. Highlight the name of the patient and the sequence you want to reconstruct, and then click 3D MIP on the Applications. Four windows will appear on the screen showing the image on 3D, Axial, Sagittal, and Coronal views. For the plane to appear on the upper right hand window, change the Axial View to Oblique and click the Rotating Plane tool on the left hand side of the screen (Fig 15.2). Position the plane to the angle of your choice in order to view the vessel clearly.

Applications LV-MTERIC Volume Viewer Reformat ReportCARD CV Flow MASS Analysis+ Add/Sub 3D MIP

More... Fig 15.1 3D MIP Application

Make sure that the upper left hand window is in 3D view, and then click the Rotating box tool (Fig 15.2). The box that will appear on the window that will allow you to rotate the image at different angles for easier reconstruction (Fig 15.3). Fig 15.2 Window images of 3D MIP 605270 left @ 256 2 185786 left @ 5122

March 4 7:23 PM

Disk 32% full ECG MISSING

Idle

iLinq 4237/4/26 28/28 Sent: 4236/10 (DYNACAD61)

Removed Series 4234/9

Volume Viewer 2 - Voxtool 6.4.52o

New Protocol

Additional Guides

Layout Presets Angle

Options/More...

Rotate/ Translate S

I

A

P

L

3D Tools Display Tools Filming Tools Save/Recall

Close

R

2 Fig 15.3 Rotating the 3D image 605270 left @ 256 2 185786 left @ 5122

March 4 7:23 PM

Disk 32% full The patient comfort level has returned to normal

Idle

iLinq 4237/4/26 28/28 Sent: 4236/10 (DYNACAD61)

Removed Series 4234/9

Volume Viewer 2 - Voxtool 6.4.52o

New Protocol

Additional Guides

Layout Presets Angle

Click the 3D tools and select the Cutting pair of scissors tool to start defining the region (Fig 15.4).

Fig 15.4 Region Cut Definition screen Layout Presets Angle

Options/More...

Rotate/ Translate SI

AP

3D Tools

Clear

Start Edit

LR

Auto Select

Display Tools

Cut Inside

Option

Filming Tools Save/Recall

button on the image of interest, continue by holding the left mouse button down

Threshold Close Remove Objects Advance Processing

Close

25examinations

Cut Outside

Undo

Keep Object

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Click on the image to start defining the region. Highlight the region that you want to eliminate using the left button of the mouse (Fig 15.5). Click Cut Inside to get rid of that region (Fig 15.4).

Fig 15.5 Cutting the region

On the window of the image, click the right button of the mouse and select Save Image. Click close to exit.

4 Fig 15.6 Newly Reconstructed Renal Arteries

To retrieve the reconstructed image, go to Browser and look for PJN, the name of your new image. Click Viewer on the right side of the window to see the image.

Part II: Measuring the Diameter of the Renal Artery Go to Browser. Select the patient’s name and the Axl 3D PC sequence then 3D MIP. Go to Display Tools and then click Double arrowhead tool (Fig 15.7a). On the Distance window, click Measure then projection 2D. Then close it to start measuring (Fig 15.7b). Fig 15.7 Measure distance (a) Display Tools

(b) Distance window

Distance

3D Tools

To measure a distance, click on an image with the left mouse button to depost points

Display Tools Filming Tools Save/Recall

!

!

Measure

projection (2D)

Display

on one viewport

Display

on one slice

Along

straight line

Close

Preferences

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! Click found at the top of the Axial window screen, then start depositing the point on one side of the right renal artery to the other side of the vessel to measure the diameter (Fig 15.8). Diameter thickness will be displayed in mm.

Fig 15.8 Measuring Renal Artery Diameter

!

To save the image, click the right button of the mouse and select Save Image. Click Close to exit. Do the same for the left renal artery.

Part III: Measuring Kidney Length and Parenchymal Thickness Go to Browser. Select the patient’s name and the Sagittal T1 sequence then 3D MIP. Go to Display Tools and then click Double arrowhead tool (Fig 15.7a). On the Distance window, click Measure then projection 2D. Then close it to start measuring (Fig 15.7b).

! Click found at the top of the Sagittal window screen, then choose the slice with the largest kidney by sliding the scroll bar on the side. Start depositing the point on the upper pole of the one side of the right renal artery to the other side of the vessel to measure the diameter (Fig 15.8). Diameter thickness will be displayed in mm. Draw a line from the upper end of the kidney all the way to the lower end. Kidney length will be displayed at the bottom of the screen.

Fig 15.9 Measuring kidney length

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To measure parenchymal thickness on the other hand using the same image, draw a line on the upper, mid, and lower poles (Fig 15.10). Measurement of each pole is displayed accordingly.

Part IV: Renal Artery Blood-Flow Graph Go to Browser. Highlight the name of the patient and the Sagittal 2D Cine PC (RT) sequence, and then click CV Flow on the Applications.

Fig 15.10 Measuring parenchymal thickness (upper, mid, and lower poles)

Fig 15.11 CV Flow Application

Applications LV-MTERIC Volume Viewer Reformat ReportCARD CV Flow MASS Analysis+ Add/Sub 3D MIP

More...

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! Click the vessel.

on the Mode section, then click on the right renal artery to automatically outline the countour of

Fig 15.12 Outline vessel contour Object R1 R2 R3 R4 PROF

Mode

UNDO

Select Full Automatic under Contour Detection to automatically outline the contour on all the slides (Fig 15.13a). To display the blood-flow curve, click Views then select Flow Curve (Fig 15.13b). Fig 15.12 Outline vessel contour (a) Contour Detection

(b) Views

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Fig 15.14 Right Renal Artery Blood-Flow Curve

FLOW Results Graph

Show:

Volume

0

R2

R3

R4

AutoUpdate

Flow Volume

[ml/s] -3.0

R1

20

40

60

80

100

4.90 ml/beat (-3184 ml/min)

-3.5 -4.0 -4.5 -5.0 -5.5 -6.0 -6.5 -7.0 -7.5 -8.0 0

200

400

600

800

1000

Trigger delay [ms]

The flow in ml/beat is found on the top part of the curve. Do the same for the left renal artery using the Sagittal 2D Cine PC (LT) sequence.

Suggested Readings: http://books.google.com/books?id=T_KNSWU4uz4C&pg=PA246&dq=maximum+intensity+p rojection&ei=WM51S43dLqOEywSXzN1H&cd=1#v=onepage&q=maximum%20intensity%20 projection&f=false http://cjasn.asnjournals.org/cgi/content/full/2/1/38 http://radiology.rsna.org/content/211/2/337.abstract http://www.medscape.com/viewarticle/437305_2