Dual-Venc acquisition for 4D flow MRI in aortic stenosis with spiral readouts.

BACKGROUND: Single Venc 4D flow MRI with Cartesian readout is hampered by poor velocity resolution and noise when imaging during diastole. Dual Venc acquisitions typically require the acquisition of two distinct datasets, which leads to longer scan times. PURPOSE/HYPOTHESIS: To design and develop a 4D Spiral Dual Venc sequence. The sequence allows for separate systolic and diastolic Venc s as part of a single acquisition with a prescribed switch time. The implemented sequence was hypothesized to be comparable to Cartesian 4D flow, but with increased velocity resolution in the diastolic phase and with better scan efficiency and reduced noise. STUDY TYPE: Prospective. POPULATION: The studied populations were two phantoms-a straight pipe with a stenotic narrowing and a phantom of the aortic arch which included a calcific polymeric valve-under both steady and pulsatile flows, six healthy volunteers, and eight patients with severe aortic stenosis (AS). FIELD STRENGTH/SEQUENCE: 1.5T, Dual Venc 4D flow with spiral readouts. ASSESSMENT: Data from the proposed sequence were compared with data from 4D Cartesian Dual Venc and Single Venc acquisitions. Noise was assessed from the acquired velocity data with the pump turned off and by varying Venc . Steady acquisitions were compared to the proximal slice of the lowest Single Venc acquisition. STATISTICAL TESTS: Steady flows were compared using relative-root-mean-squared-error (RRMSE). For in vivo flows and pulsatile in vitro flows, net flow for corresponding timepoints were compared with the Pearson correlation test (P < 0.01). RESULTS: For steady flows, RRMSEs for Single Venc s ranged from 17.6% to 19.4%, and 9.6% to 16.5% for Dual Venc s. The net flow correlation coefficient for the aortic arch phantom was 0.975, and 0.995 for the stenotic phantom. Normal volunteer and patient comparisons yielded a correlation of 0.970 and 0.952, respectively. in vitro and in vivo pulsatile flow waveforms closely matched. DATA CONCLUSION: The Dual Venc offers improved noise properties and velocity resolution, while the spiral trajectory offers a scan efficient acquisition with short echo time yielding reduced flow artifacts. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2020;52:117-128.

Echocardiographic Correlates of Mortality Among Cardiac Intensive Care Unit Patients With Cardiogenic Shock.

BACKGROUND: Prior studies have shown worse outcomes in patients with cardiogenic shock (CS) who have reduced left ventricular ejection fraction (LVEF), but the association between other transthoracic echocardiogram (TTE) findings and mortality in CS patients remains uncertain. We hypothesized that Doppler TTE measurements would outperform LVEF for risk stratification. METHODS: Retrospective analysis of cardiac intensive care unit patients with an admission diagnosis of CS and a TTE within 1 day of admission. Hospital survivors and inpatient deaths were compared, and multivariable logistic regression was used to analyze the associations between TTE variables and hospital mortality. RESULTS: We included 1,085 patients, with a median age of 69.5 (59.6, 77.5) years; 37% were females and 62% had an acute coronary syndrome. Most patients (66%) had moderate or severe left ventricular (LV) systolic dysfunction, and 48% had moderate or severe right ventricular (RV) systolic dysfunction. Hospital mortality occurred in 31%, and inpatient deaths had a lower median LVEF (29% vs. 35%, P < 0.001). Patients with mild or no LV or RV dysfunction were at lower risk of adjusted hospital mortality (P < 0.01). The LV outflow tract (LVOT) velocity-time integral (VTI) was the single best predictor of hospital mortality. After multivariable adjustment, both the LVEF and LVOT VTI remained strongly associated with hospital mortality (P < 0.001). CONCLUSIONS: Early comprehensive Doppler TTE can provide important prognostic insights in CS patients, highlighting its potential utility in clinical practice. The LVOT VTI, reflecting forward flow, is an important measurement to obtain on bedside TTE.