Whole-heart four-dimensional flow can be acquired with preserved quality without respiratory gating, facilitating clinical use: a head-to-head comparison

Abstract

BackgroundRespiratory gating is often used in 4D-flow acquisition to reduce motion artifacts. However, gating increases scan time. The aim of this study was to investigate if respiratory gating can be excluded from 4D flow acquisitions without affecting quantitative intracardiac parameters.MethodsEight volunteers underwent CMR at 1.5 T with a 5-channel coil (5ch). Imaging included 2D flow measurements and whole-heart 4D flow with and without respiratory gating (Resp(+), Resp(−)). Stroke volume (SV), particle-trace volumes, kinetic energy, and vortex-ring volume were obtained from 4D flow-data. These parameters were compared between 5ch Resp(+) and 5ch Resp(−). In addition, 20 patients with heart failure were scanned using a 32-channel coil (32ch), and particle-trace volumes were compared to planimetric SV. Paired comparisons were performed using Wilcoxon’s test and correlation analysis using Pearson r. Agreement was assessed as bias ± SD.ResultsStroke volume from 4D flow was lower compared to 2D flow both with and without respiratory gating (5ch Resp(+) 88 ± 18 vs 97 ± 24.0, p = 0.001; 5ch Resp(−) 86 ± 16 vs 97.1 ± 22.7, p < 0.01). There was a good correlation between Resp(+) and Resp(−) for particle-trace derived volumes (R2 = 0.82, 0.2 ± 9.4 ml), mean kinetic energy (R2 = 0.86, 0.07 ± 0.21 mJ), peak kinetic energy (R2 = 0.88, 0.14 ± 0.77 mJ), and vortex-ring volume (R2 = 0.70, −2.5 ± 9.4 ml). Furthermore, good correlation was found between particle-trace volume and planimetric SV in patients for 32ch Resp(−) (R2 = 0.62, −4.2 ± 17.6 ml) and in healthy volunteers for 5ch Resp(+) (R2 = 0.89, −11 ± 7 ml), and 5ch Resp(−) (R2 = 0.93, −7.5 ± 5.4 ml), Average scan duration for Resp(−) was shorter compared to Resp(+) (27 ± 9 min vs 61 ± 19 min, p < 0.05).ConclusionsWhole-heart 4D flow can be acquired with preserved quantitative results without respiratory gating, facilitating clinical use.Electronic supplementary materialThe online version of this article (doi:10.1186/s12880-015-0061-4) contains supplementary material, which is available to authorized users.

Scan–rescan reproducibility of diastolic left ventricular kinetic energy, viscous energy loss and vorticity assessment using 4D flow MRI: analysis in healthy subjects

“…They found a strong correlation between the KE measurements in both scans. The current study differs from the study by Kanski et al [24] in that we used the same protocol for both scans. In the current study, moderate-strong correlation was found between KE measurements in both scans.…”

“…Therefore, reliability and reproducibility of KE measurements from 4D flow MRI in a repeated scan setting remains largely unknown. Kanski et al [24] compared mean KE and peak KE between two scans (with and without respiratory gating) with the aim to evaluate the impact of respiratory gating on KE measurements. They found a strong correlation between the KE measurements in both scans.…”

Comparison of fast acquisition strategies in whole‐heart four‐dimensional flow cardiac MR: Two‐center, 1.5 Tesla, phantom and in vivo validation study

“…These studies have not only used different acceleration methods, but also different flow‐encoding schemes (symmetric, asymmetric, Hadamard 4‐point encoding, 5‐point‐encoding or multipoint encoding), different field‐strengths (mainly 1.5T/3T systems), different scan parameters (field of view, spatio‐temporal resolution) and not necessarily with intra‐cardiac assessment for quality and consistency of flow. Vendor‐specific acceleration techniques have been investigated by several research groups to investigate consistency and reliability of intra‐cardiac flow assessment using 4D flow cardiac MR. One of these studies used GRAPPA (20), three studies used EPI, two studies L1‐SPIRiT, two studies compared k‐t BLAST acceleration and SPGR (SENSE) acceleration, and one study used SPGR (SENSE) …”

Comparison of respiratory motion suppression techniques for 4D flow MRI

“…Others have indicated that 4D Flow MRI‐based quantification of flow volumes , intracardiac pathlines visualization , and total kinetic energy in the left atrium can be performed without respiratory motion suppression. Unfortunately, the Kanski study included only eight subjects and thus the lack of significant differences between gated and nongated data may be due to underpowered statistics.…”