A segmented k-space velocity mapping protocol for quantification of renal artery blood plow during breath-holding
✍ Scribed by C. Thomsen; M. Cortsen; L. Söndergaard; O. Henriksen; F. Ståhlberg
- Book ID
- 102907268
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 855 KB
- Volume
- 5
- Category
- Article
- ISSN
- 1053-1807
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Two Important prerequisites for MR velocity mapping of pulsatile motion are synchronization of the sequence execution to the time course of the flow pattern and robustness toward loss of signal in complex flow fields. Synchronization is normally accomplished by using either prospective ECG triggering or so‐called retrospective gating. However, if the studied vessel moves periodically in space as a result of respiratory motion, as in the case of renal arteries, a second synchronization with respect to the vessel motion in space may be necessary. One method to overcome this problem is to use the segmented k‐space technique, in which the entire data acquisition can be made within a breath‐hold by the sampling of several phase‐encoding lines within a small time window during each heart cycle. The aim of this study was to investigate the performance of a segmented k‐space velocity mapping protocol for renal artery flow determination. The protocol uses 16 phase‐encoding lines per heart beat during 16 heart cycles and gives a temporal velocity resolution of 160 msec. Comparison with a conventional ECG‐triggered velocity mapping protocol was made in phantoms as well as in volunteers. In our study, both methods showed sufficient robustness toward complex flow in a phantom model. In comparison with the ECG technique, the segmentation technique reduced vessel blurring and pulsatility artifacts caused by respiratory motion, and average flow values obtained in vivo in the left renal artery agreed between the two methods studied. Although presently hampered by a relatively low temporal resolution, velocity mapping with k‐space segmentation In combination with breath‐holding will benefit from future increased gradient quality, and we assume that in the future the method will become an attractive choice for noninvasive renal artery flow determination.