Reliability of pediatric ventricular function analysis by short-axis "single-cycle-stack-advance" single-shot compressed-sensing cines in minimal breath-hold time.

OBJECTIVES: Cardiovascular magnetic resonance (CMR) cine imaging by compressed sensing (CS) is promising for patients unable to tolerate long breath-holding. However, the need for a steady-state free-precession (SSFP) preparation cardiac cycle for each slice extends the breath-hold duration (e.g. for 10 slices, 20 cardiac cycles) to an impractical length. We investigated a method reducing breath-hold duration by half and assessed its reliability for biventricular volume analysis in a pediatric population. METHODS: Fifty-five consecutive pediatric patients (median age 12 years, range 7-17) referred for assessment of congenital heart disease or cardiomyopathy were included. Conventional multiple breath-hold SSFP short-axis (SAX) stack cines served as the reference. Real-time CS SSFP cines were applied without the steady-state preparation cycle preceding each SAX cine slice, accepting the limitation of omitting late diastole. The total acquisition time was 1 RR interval/slice. Volumetric analysis was performed for conventional and "single-cycle-stack-advance" (SCSA) cine stacks. RESULTS: Bland-Altman analyses [bias (limits of agreement)] showed good agreement in left ventricular (LV) end-diastolic volume (EDV) [3.6 mL (- 5.8, 12.9)], LV end-systolic volume (ESV) [1.3 mL (- 6.0, 8.6)], LV ejection fraction (EF) [0.1% (- 4.9, 5.1)], right ventricular (RV) EDV [3.5 mL (- 3.34, 10.0)], RV ESV [- 0.23 mL (- 7.4, 6.9)], and RV EF [1.70%, (- 3.7, 7.1)] with a trend toward underestimating LV and RV EDVs with the SCSA method. Image quality was comparable for both methods (p = 0.37). CONCLUSIONS: LV and RV volumetric parameters agreed well between the SCSA and the conventional sequences. The SCSA method halves the breath-hold duration of the commercially available CS sequence and is a reliable alternative for volumetric analysis in a pediatric population. KEY POINTS: • Compressed sensing is a promising accelerated cardiovascular magnetic resonance imaging technique. • We omitted the steady-state preparation cardiac cycle preceding each cine slice in compressed sensing and achieved an acquisition speed of 1 RR interval/slice. • This modification called "single-cycle-stack-advance" enabled the acquisition of an entire short-axis cine stack in a single short breath hold. • When tested in a pediatric patient group, the left and right ventricular volumetric parameters agreed well between the "single-cycle-stack-advance" and the conventional sequences.

Quantification of left ventricular interstitial fibrosis in asymptomatic chronic primary degenerative mitral regurgitation.

BACKGROUND: The optimum timing of surgery in asymptomatic patients with chronic severe primary degenerative mitral regurgitation (MR) remains controversial, and further markers are needed to improve decision-making. There are limited data that wall stress is increased in MR and may result in ventricular fibrosis. We investigated the hypothesis that chronic volume overload in MR is a stimulus for myocardial fibrosis using T1-mapping cardiac MRI. METHODS AND RESULTS: A cross-sectional study of 35 patients (age 60 ± 14 years) with asymptomatic moderate and severe primary degenerative MR (mean effective regurgitant orifice area, 0.45 ± 0.25 cm)(2) with no class I indication for surgery were compared with age and sex controls. Subjects were studied with cardiopulmonary exercise testing, echocardiography, and cardiac MRI. Longitudinal and circumferential myocardial deformation was reduced with MR when left ventricular ejection fraction (67% ± 10%) and N-terminal pro B Natriuretic peptide (126 [76-428] ng/L) were within the normal range. Myocardial extracellular volume was increased (0.32 ± 0.07 versus 0.25 ± 0.02, P<0.01) and was associated with increased left ventricular end-systolic volume index (r=0.62, P<0.01), left atrial volume index (r=0.41, P<0.05) but lower left ventricular ejection fraction (r=-0.60, P<0.01), longitudinal function (mitral annular plane systolic excursion, r=-0.46, P<0.01), and peak VO2 max (r=-0.51, P<0.05). In a multivariable regression model, left ventricular end-systolic volume index and left atrial volume index were independent predictors of extracellular volume (r(2)=0.42, P<0.01). CONCLUSIONS: Patients with asymptomatic MR demonstrate a spectrum of myocardial fibrosis associated with reduced myocardial deformation and reduced exercise capacity. Future work is warranted to investigate whether left ventricle fibrosis affects clinical outcomes.

Breathhold time-resolved three-directional MR velocity mapping of aortic flow in patients after aortic valve-sparing surgery.

PURPOSE: To evaluate the utility of breathhold time-resolved three-directional MR velocity mapping for quantifying the restoration of normal flow patterns in patients after aortic valve-sparing surgery. MATERIALS AND METHODS: Breathhold time-resolved three-directional MR velocity mapping was performed on 13 patients with aortic valve-sparing surgery. Ten healthy volunteers and 12 patients with ascending aortic aneurysm underwent the same MR examination for comparison. Aortic laminar flow, turbulent flow, and the presence of vortical flow in the sinuses of Valsalva were semiquantitatively assessed and statistically compared between the three groups of subjects. RESULTS: The average score of laminar flow in the ascending aorta for patients with surgery was not significantly different from that of volunteers (P=0.210), but was significantly greater than that of patients with aneurysm (P<0.01). The average score of turbulent flow in patients with surgery was significantly smaller than that of patients with aneurysm (P<0.01). The presence of systolic vortical flow in the sinuses of Valsalva for patients with surgery was not significantly different from that of healthy volunteers (P=0.405) and patients with aneurysm (P=0.238). CONCLUSION: Breathhold time-resolved three-directional MR velocity mapping allows for quantifying flow patterns in the aortic root and ascending aorta. Normal laminar flow in the ascending aorta and vortical flow in the sinuses of Valsalva can be restored in patients after aortic valve-sparing surgery.