MR phase‐contrast velocity mapping methods for measuring venous blood velocity in the deep veins of the calf

Abstract

Purpose: To evaluate the feasibility of using un-gated, real-time MRI for venous blood velocity mapping in the calf, comparing an interleaved spiral k-space sequence (ISP) against a standard segmented gradient echo sequence (GRE). Materials and Methods:A flow phantom with a variable flow-rate was scanned using both GRE and ISP sequences for an in vitro comparison. Seven subjects were scanned prone, performing metronome guided breathing, using the (externally triggered) segmented GRE and real-time ISP sequences. The segmented GRE acquisition duration was 2.5 mins (22 guided respiratory cycles) and the ISP sequence ran continuously for 35s, 4 full guided respiratory cycles. Mean velocity from each of the deep veins was measured and peak mean velocity, peak flow rate and cumulative volume flow over a respiratory cycle compared between sequences.Results: The two sequences compared well both in vitro and in vivo. The real-time ISP sequence showed shortterm variations in mean velocity superimposed on the respiratory induced flow, which were averaged out using the segmented GRE sequence. Conclusion:Real-time ISP provides comparable timeaveraged flow results to the standard sequence with additional information on real-time flow variations and so could be used for further investigation into venous blood flow in the lower leg.

Efficient and reproducible high resolution spiral myocardial phase velocity mapping of the entire cardiac cycle

“…Using spirals potentially allows large reductions in scan time while maintaining spatial and temporal resolution. Spiral PVM has been applied to measuring blood flow velocity (for example in the heart [21,22], the coronary arteries [23], renal arteries [24] and deep veins in the calf [25]) but it has not previously been applied to measuring myocardial velocities.…”

Detection of infragenual arterial disease using non–contrast‐enhanced MR angiography in patients with diabetes

“…FSD‐SSFP exploits the different blood flow velocities in arteries and veins to maintain high arterial blood signal while suppressing venous blood signal. As blood flow velocity difference between arteries and veins diminishes in patients (either slow arterial flow or fast venous flow) , venous contamination may occur. On the other hand, residual soft tissue signal arises primarily from the signal difference between bright‐artery and dark‐artery measurements.…”

Magnetic resonance venous velocity mapping during intermittent pneumatic compression of the calf and foot

“…However, this realtime MR VM technique has been validated against conventional phase-contrast MRI. 10…”

“…No systematic method was adopted but the inter-observer variability of this approach has been published. 10 The ROI positions and sizes were copied to the corresponding velocity maps using CMR Tools image analysis software (Cardiovascular Imaging Solutions Ltd, London, UK). The ROI was adjusted for each individual image, in order to cover small translational shifts resulting from bulk motion of the leg during cuff inflation and also any cross-sectional area changes of the measured veins during each compression cycle.…”