MR-venography using manual flow augmentation in an open low field MR system

Abstract

To evaluate the feasibility of signal enhancement in the deep veins by means of manual compression of the calf (flow augmentation) as a new approach to MR venography in open configuration, low-field systems. 10 healthy volunteers underwent MR venography of the calf unconstrained and during short localized manual compression. Gradient recalled echo sequences (FLASH, FISP) with repeated single slice acquisition and first-order gradient motion refocussing were tested in four protocols with and without arterial presaturation slabs (scan time 2.2 - 5.0 s per slice). The effect on flow enhancement was rated by means of a signal score. Interventional accessories, particularly an in-room LCD screen, were required for interactive application of compression manoeuvres. Sequences with arterial presaturation slabs were superior to those without regardless of the longer acquisition times. Careful targeting of compression to the mid-time of data acquisition was crucial to obtain marked flow acceleration. Enhancement was best in the case of proximally applied calf compression. Signal improvement was consistently achieved in the proximal parts of the posterior tibial and peroneal veins, but was only seen in 4/10 volunteers in the distal part of the anterior tibial vein. Flow augmentation by means of manual calf compression is a simple and effective complementary approach to MR venography in open configuration, low field MR systems.