syngo TWIST Protocols
Author: Gerhard Laub
Siemens Medical Solutions, USA
Date: Apr 29, 2009
Time-resolved contrast-enhanced MR angiography creates a series of 3D images during the passage of a contrast agent. The principle clinical application is to demonstrate dynamic vascular events such as arterial-venous malformations, fistulas, shunts, and many congenital diseases. Additionally, this method is ideal for demonstrating non-symmetric filling defects typical in pulmonary diseases and peripheral atherosclerotic diseases. Another clinical application is to determine the optimal bolus arrival time for conventional, high-resolution contrast-enhanced MR angiography techniques, a.k.a. the “bolus timing test” technique. In general, time-resolved methods provide improved temporal resolution (faster) with some compromise in spatial resolution (detail) as compared to conventional MR angiography techniques, although these compromises are often acceptable from a clinical perspective, especially when assessing dynamic vascular events.
This comprehensive syngo TWIST Users Guide describes the basics of the TWIST principle. The given acquisition strategies have been clinically optimized to consider the clinical requirements for spatial and temporal resolution, optimal PAT factors, and coil combinations. No distinction was made between 1.5T and 3T. Each of the clinical applications offer protocols for high temporal resolution and high spatial resolution:
- Head (intracranial)
- Carotid (aortic arch and carotids)
- Thorax (pulmonary, aorta, and subclavians)
- Abdomen (aorta, renals, and iliacs)
- Thigh (runoff thighs)
- Calf (runoff calves and feet)
- Hand (extremity)
Since higher acceleration factors (PAT) generally require more coil elements and RF channels, the protocols are also organized according to RF configuration:
- PAT 2 + 08 channels
- PAT 3 + 18/32 channels
Appendix 1 of the syngo TWIST Users Guide contains a more detailed discussion of optimized clinical protocols.
Appendix 2 contains a more detailed discussion of the sequence implementation and caveats.
1Not for distribution in the U.S.
The information presented in MAGNETOM Flash is for illustration only and is not intended to be relied upon by the reader for instruction as to the practice of medicine.
Any health care practitioner reading this information is reminded that they must use their own learning, training and expertise in dealing with their individual patients. This material does not substitute for that duty and is not intended by Siemens Medical Solutions to be used for any purpose in that regard.
The treating physician bears the sole responsibility for the diagnosis and treatment of patients, including drugs and doses prescribed in connection with such use. The Operating Instructions must always be strictly followed when operating the MR System.