Table 5:

Previous evaluations in the literature of accelerated 4D flow. Second column lists “conventional” comparison method first, if applicable, and acceleration technique to be evaluated second. SR=spatial resolution, tempRes = temporalresolution

Study and Population	MRI Acquisitions	Main Relevant Findings
Current study n=20 healthy volunteers (mean age 38.3 [22-70] years) n=11 patients with aortic valve disease	1.5T: Aortic Acquisition Navigator-gated cartesian 4D flow with retrospective gating and ReCAR: SR=2.4-2.5 × 3.5-5.0 × 3.3-3.8mm^3 Temp Res: 40.0-45.3 ms Acquisition Time: 7.7 ± 3.6 min k-t accelerated cartesian 4D flow with retrospective gating, ReCAr, and CS reconstruction: SR=2.4-2.5 × 3.5-5.0 × 3.3-3.8Mm3 Temp Res: 38.5-44.5 ms Acquisition Time: 1.9 ± 0.3 min	Peak Velocity: Volunteers: −16 to −10 % underestimation Patients: Peak Flow: Volunteers: −10.1 to −0.9% underestimation
Gu et al, AJNR 200531 n=6 (3 patients, 3 volunteers) all had contrast except one Flow phantom with controllable flow rate	1.5T Venc = 20 cm/s Intracranial acquisition Cartesian 4D Flow: acquired SR=0.95×0.95× 2.00 mm3 TR/TE = 6.6 ms/18 ms Acquisition time= 7 min 22 sec unsure of R PC VIPR acquired SR = 0.63×0.63×0.63 mm3 TR/TE = 7.57/17.34 ms Acquisition time varied from 3:50 to 7:30 min depending on FOV and number of radial projections	Flow validation resulted in R2 = 0.99 in vitro and R2=0.97 in vivo, but this was involving comparison to 2D PC. PC-VIPR had a 6% underestimation in phantom flow with known flow rates. Direct comparison to 4D flow MRI focused on qualitative evaluation
Hsiao Radiology 201222 n = 34 (mean 6, range 10 month to 21 years)	1.5T Venc = 120-350 cm/s whole heart variable-density Poisson disk k-space undersampling: acceleration 1.4×1.4 to 2.2×2.2 (ky-kz); SR = 1.02×1.34×2.30 mm3 temporal res: 31 to 86 ms Acquisition time: 5-15 min Reconstruction: <3 hours offline 1-SPIRiT	may facilitate more reliable detection and characterization of intracardiac shunts and valve regurgitation
Schnell et al, MRM 201437 n=10 volunteers mean age 28.4 years	3T Venc = 150 cm/s looked at 12 and 32 channel receiver coils Navigator-gated Cartesian 4D flow with prospective triggering: SR= 2.1×2.5×2.5 mm^3 tempRes = 40.0 ms GRAPPA accelerated R= 2 n(net acceleration = 1.6) k-t accelerated cartesian 4D flow with prospective triggering: matched imaging parameters k-t acceleration rates: 3,5,8 (net acceleration = 2.8, 4.2, 6.3)	Quantification at aortic root, mid AAo, mid arch, proximal DAo. Differences from GRAPPA R=2 peak flow was significantly different for R=5 and R=8 R = 5: Peak flow: −5.3 to −3.7% R=8: peak flow: −12.0% to −8.0% Peak velocity was only significantly different for R=8: −7.4% at root, −12.0% at DAo p<0.03 net flow similar for all methods
Giese et al. JCMR 201432 n=6 for flow measurements	1.5T: Intracardiac: Venc = 200 cm/s for volunteers, Venc = 120-400 cm/s for patients Navigator-gated, retrospectively gated, k-t PCA-accelerated 3D PC: nominal acceleration of 8, 11 and 7, SR=2.5×2.5×2.5 mm3 (volunteers), 1.26-2.31×1.4-2.31, 1.72-2.31 mm3 (pediatric patients) temporal resolution = 35.6 ±5.3 ms, Acquisition time: 5.6 min for volunteers, 3.6 to 7.1 for others,	Volunteers: interested in AAO, MPA, RPA, LPA, SVC; stroke volume/net flow: 5.6± 14.9% difference from 2D flow peak flow: −5.1±7.5% from 2D CHD: 1.6±4.8 mL difference underestimation in net flow,
Dvorne et al, Radiology 201521 n=10 (7 liver patients, 3 healthy volunteers) Mean age 51 (30-70) years	1.5T Venc = 60 cm/s Abdominal acquisition Free-breathing, Navigator-gated Cartesian 4D Flow with prospective gating: acquired SR: 2.5×3.9×5.0 mm3 TempRes = 68.4 ms; R=2 GRAPPA Acquisition time= 11 min 21 sec (6 min 12 sec-20 min 37 sec) Accelerated Prospectively Gated 4D flow Spiral sampling with multiple breatholds Acquired SR = 2.5×2.5×5.0 TempRes = 66.2 ms R=6 Acquistion time: 18-25 s CS reconstruction	Quantified 18 major abdominal vessels: CS reconstruction took 3 hours per subject offline Flow: −2.8 to −38.8% change in flow (p<0.001)in CS compared to cartesian 4D flow Peak Velocity: −30.9 to 86% change compared to cartesian (p=0.024);
Zaman et al JMRI 201538 n=15 healthy subjects (mean 26.5, 22-48 years, 10M), 8 patients with surgically repaired aortic coarctation (4M, 30.5 years, range 22-37 years).	3T: Aorta acquisition free-breathing retrospectively-gated, cartesian, SENSE 4D flow: R = 1.6, SR=2.5×2.5×2.5 mm3 Temporal Resolution = 50-55 ms Acquisition time: 25.2 min Free-breathing, prospectively gated 4D flow with k-t BLAST: R=5, SR=2.5×2.5×2.5 temp res 45-60 ms (5.5 min)	Reference was 2D PC using SENSE: no significant differences in flow, velocity, or stroke volume values for any of the 4D flow pulse sequences compared to the reference
Cheng et al, Nature 201736 n=6 (3F) age 3 days to 15 years, pediatric patients	1.5/3T, Venc=100-250 cm/s Whole heart acquisition 4D flow with intrinisic butterfly navigators, Vrad sampling, and CS: SR=0.9-2.1×0.8-2.0×1.4-3.0 mm3 TR/TE=1.7-1.8 ms/ 4.0-5.8 ms Acquisition time: 7:14 to 10:34 min	Comparison of patients found lower average flow that varies throughout time in XD flow recon (~0.25 L/min) compared to conventional (~0.35 L/min) but also improved image sharpness and decreased velocity standard deviations in XD flow.
Bollache et al, MRM 201833 n=20 (10 volunteers, mean age 61 [31-77] years; 10 patients with aortic disease, mean age 60 [44-74] years; in-vitro: pulsatile 3D printed aortic flow phantom with aortic coarctation	1.5 T Aortic acquisition Venc = 150/150-250 cm/s (volunteers/patients) Navigator-gated Cartesian 4D flow with prospective triggering: acquired SR =3.1×2.1×2.6 mm3 (is it acquried) TempRes = 38.4-39.2 ms Acquisition time (average): 11:56-12:47 k-t accelerated cartesian 4D flow with prospective triggering and varying samping patterns (R=5): Volunteers: acquiredSR: 3.4×2.3×2.6-3.3 and 4.5×2.3×2.6-3.8 mm3 tempRes: 67.2 ms Acquisition time: 3:00 min Patients: acquired SR: 3.4×2.3×2.8-3.0 mm3 TempRes = 65.6 ms Acquisition time: <2:30 min	differences from GRAPPA R=2 In vitro: Peak Velocity: −22 to −0.8% Peak Flow: −4.0 to 4.2% Net flow: −2.0 to 11% Healthy Volunteers: Peak Velocity: −18 to 6.4% PeakFlow: −15.0 to 3.0 % Net flow: −17.0 to 2.9% Patients: Peak Velocity: −5.0 to −3.8% Peak Flow: −4.1 to − 3.8% Net Flow: 4.4 to 5.8%