NetForum uses cookies to ensure that we give you the best experience on our website. If you continue to use the site, we'll assume that you are happy to receive these cookies on the NetForum website. Read about our cookies.
NetForum Community
Learn. Share. Optimize.
Log in | Sign up now | Submit content | Contact
Go to similar content

1.5T TRANCE lower legs

ExamCard
Geerts, Liesbeth Philips Healthcare
Kramer, Joyce Philips Healthcare

15T TRANCE lower legs

Download
Login is required to download ExamCards.

ExamCard purpose

TRANCE (TRiggered Angiography Non Contrast Enhanced) is a technique for imaging arteries and veins without contrast agents. This ExamCard is intended for the lower legs. SENSE 2 is used for speed up.

 

TRANCE protocols are 3D TSE sequences with cardiac triggering. Visualizing arteries only requires two separate scans with triggering in different cardiac phases. In systole arterial blood is flowing fast. This causes dephasing of signal and leads to flow voids, so arteries will be black with systolic triggering. In diastole blood flow in arteries is slow. The signal will not dephase, so arteries will be bright on diastolic scans. Subtracting these scans results in a 3D data set with arteries only.

 

To obtain veins only, a 3D TSE protocol with STIR is scanned with systolic triggering. STIR gives extra background suppression as fat and bones will also be suppressed. With systolic triggering the arteries are black. Result is a dataset with veins only, no subtraction needed.

 

A QFlow scan is performed to determine the appropriate trigger delay times for systolic and diastolic triggering.

ExamCard overview

TRANCE_LowerLeg_11_1_3
Scan 1Survey
Scan 2Ref_SBC
Scan 32D_QF
Scan 4Diastole
Scan 5Systole
Scan 6Systole veins

ExamCard images

TRANCE diastole Bright arteries and bright veins. 
Resolution is 1.88x2.08x2.00mm.TRANCE systole Black arteries and bright veins. 
Resolution is 1.88x2.08x2.00mm.
TRANCE diastole
TRANCE systole
Bright arteries and bright veins. Resolution is 1.88x2.08x2.00mm.
Black arteries and bright veins. Resolution is 1.88x2.08x2.00mm.
MIP TRANCE arteries MIP of the subtraction: diastole-systole. Because veins and background have the same signal intensity in both images, these are subtracted out. What remains is an image with arteries only.MIP TRANCE systole veins STIR is used for extra background suppression. 
Resolution is 1.88x2.08x2.00mm.
MIP TRANCE arteries
MIP TRANCE systole veins
MIP of the subtraction: diastole-systole. Because veins and background have the same signal intensity in both images, these are subtracted out. What remains is an image with arteries only.
STIR is used for extra background suppression. Resolution is 1.88x2.08x2.00mm.

Patient preparation

Position the patient is supine, feet first on the table. The lower legs can be supported with the MobiTrak device to prevent motion. The phase encoding direction is LR, so put the the legs closely together, so that a smaller FOV can be used, which means shorter scan times.

 

The SENSE Body coil is used on the lower legs to get extra signal and to enable use of SENSE. Alternatively, the 16-channel XL Torso coil can be used.

 

VCG leads need to be attached to the VCG electrodes on the chest. 
TRANCE in the lower legs cannot be performed with PPU triggering.

Post-processing / analysis

The QFlow data needs to be analyzed to determine the trigger delay times. This can be done in the QFlow package. If you do not have a QFlow package, you can draw a ROI on an artery in the PCA/P images in Gyroview. Propagate this to all phases and look at the intensity curve.

 

To obtain a dataset with arteries only, scan 4 and 5 need to be subtracted. This can be done with  ImageAlgebra. To obtain bright arteries (comparable to CE-MRA) you have to subtract diastole-systole.

 

Note: In order to be able to subtract scans, their FOV, coverage and

           resolution must be exactly the same.

 

The subtracted dataset can be further processed with VolumeView. For bright arteries, you can make Maximum Intensity Projections (MIP). 

 

TRANCE systole veins with STIR (scan 6) can directly be processed in VolumeView to obtain MIPs of the veins.  

Tips and tricks

The QFlow scan is required to determine the appropriate trigger delay times. Position the QFlow scan on the right or on the left calf, in the center of the preferred FOV.

  • Diastolic trigger delay in general can be put to "longest".
  • Systolic trigger delay: take the moment with highest flow as systolic trigger delay. This is usually between 150 and 350 ms.

 

Check whether the acquired resolution and the scan percentage on the info-page are similar to what you asked for. You may need to adjust the TSE factor to obtain the desired resolution and scan percentage.

 

Avoid patient motion at any time. If the patient moves between scans 4 and 5, subtraction will not be perfect.

 

Do not forget to check that resolution (matrix, FOV and rectangular FOV) is exactly the same for scans 4 and 5.

 

Veins are easily compressed, resulting in signal loss. To prevent compression try to keep the calfs hanging freely and bend the knees a little.

QFlow, axial in center of the right leg This QFlow data is processed in QFlow package. The green lines are added to give you directions for appropriate trigger delay times.
QFlow, axial in center of the right leg
This QFlow data is processed in QFlow package. The green lines are added to give you directions for appropriate trigger delay times.


This content has been made possible by NetForum Community.
Share this on: Share your link in twitter Share your link in facebook Share your link on LinkedIn Print Rate this article: Log in to vote

 
Rating:
Votes:
0
Views:
7463
Added:
Nov 27, 2007

Rate this:
Log in to vote
 

ExamCard
Achieva 1.5T, Intera 1.5T
Release 1, Release 11, Release 12, Release 2
mra, Peripheral MRA, Vascular
 

Clinical News
Best Practices
Case Studies
Publications and Abstracts
White Papers
Web seminars and Presentations
ExamCards
Protocols
Application Tips and FAQ
Training
Try an Application
Business News
Case Studies
White Papers
Web Seminars and Presentations
Utilization Services
Contributing Professionals
Contributing Institutions
Become a Contributor