Free-breathing 3D late gadolinium enhancement imaging of the left ventricle using a stack of spirals at 3T.

PURPOSE: To develop navigator-gated free-breathing 3D spiral late gadolinium enhancement (LGE) imaging of the left ventricle at 3T and compare it with conventional breath-hold 2D Cartesian imaging. MATERIALS AND METHODS: Equivalent slices from 3D spiral and multislice 2D Cartesian acquisitions were compared in 15 subjects in terms of image quality (1, nondiagnostic to 5, excellent), sharpness (1-3), and presence of artifacts (0-2). Blood signal-to-noise ratio (SNR), blood/myocardium contrast-to-noise ratio (CNR), and quantitative sharpness were also compared. RESULTS: All 3D spiral scans were completed faster than an equivalent 2D Cartesian short-axis stack (85 vs. 230 sec, P < 0.001). Image quality was significantly higher for 2D Cartesian images than 3D spiral images (3.7 ± 0.87 vs. 3.4 ± 1.05, P = 0.03) but not for mid or apical slices specifically. There were no significant differences in qualitative and quantitative sharpness (95% confidence interval [CI]: 1.91 ± 0.67 vs. 1.93 ± 0.69, P = 0.83 and 95% CI: 0.41 ± 0.07 vs. 0.40 ± 0.09, P = 0.25, respectively), artifact scores (95% CI: 0.16 ± 0.37 vs. 0.40 ± 0.58, P = 0.16), SNR (95% CI: 121.5 ± 55.3 vs. 136.4 ± 77.9, P = 0.13), and CNR (95% CI: 101.6 ± 48.4 vs. 102.7 ± 61.8, P = 0.98). Similar enhancement ratios (0.65 vs. 0.62) and volumes (13.8 vs. 14.1cm(3) ) were measured from scar regions of three patients. CONCLUSIO: Navigator-gated 3D spiral LGE imaging can be performed in significantly and substantially shorter acquisition durations, although with some reduced image quality, than multiple breath-hold 2D Cartesian imaging while providing higher resolution and contiguous coverage.

Magnetic resonance imaging of vein wall thickness in patients with Behçet's syndrome.

OBJECTIVES: Vascular disease is a serious complication of Behçet's syndrome (BS), occurring in up to 20% of subjects. Superficial thrombophlebitis, deep vein thrombosis, and arterial aneurysm formation are the most common manifestations. Venous thrombosis is thought to result from vessel wall inflammation. This work investigated the potential usefulness of high resolution magnetic resonance imaging (MRI) to identify inflammation in the venous walls in BS subjects. METHODS: Seven healthy control (HC) subjects and five BS subjects were scanned with 3T MRI (Siemens Skyra). A standard MRI sequence was adapted for use in the venous system. Metronome guided breathing generated a regular respiratory variation of venous blood velocity. The vein wall imaging was triggered at an appropriate delay after the metronome. The popliteal vein was imaged. Vein wall images were ranked based on wall thickness and signal enhancement by two blinded, experienced observers. RESULTS: Popliteal vein rank scores were found to be significantly increased in BS versus HC subjects by the first observer (p(Observer 1)=0.025, p(Observer2)=0.07) and also averaging both observers (p=0.05). The repeated images of each subject gave a degree of variability in results, potentially from drifting response to metronome guidance over the 10 minute scan. CONCLUSIONS: MR imaging can detect increased vein wall thickness in BS subjects compared to healthy controls. Variable response to the metronome-guided breathing requires further development.

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

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 35 s, 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 short-term 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 time-averaged 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.