4Dflow-VP-Net: A deep convolutional neural network for noninvasive estimation of relative pressures in stenotic flows from 4D flow MRI.

PURPOSE: To estimate relative transvalvular pressure gradient (TVPG) noninvasively from 4D flow MRI. METHODS: A novel deep learning-based approach is proposed to estimate pressure gradient across stenosis from four-dimensional flow MRI (4D flow MRI) velocities. A deep neural network 4D flow Velocity-to-Presure Network (4Dflow-VP-Net) was trained to learn the spatiotemporal relationship between velocities and pressure in stenotic vessels. Training data were simulated by computational fluid dynamics (CFD) for different pulsatile flow conditions under an aortic flow waveform. The network was tested to predict pressure from CFD-simulated velocity data, in vitro 4D flow MRI data, and in vivo 4D flow MRI data of patients with both moderate and severe aortic stenosis. TVPG derived from 4Dflow-VP-Net was compared to catheter-based pressure measurements for available flow rates, in vitro and Doppler echocardiography-based pressure measurement, in vivo. RESULTS: Relative pressures calculated by 4Dflow-VP-Net and in vitro pressure catheterization revealed strong correlation (r2 = 0.91). Correlations analysis of TVPG from reference CFD and 4Dflow-VP-Net for 450 simulated flow conditions showed strong correlation (r2 = 0.99). TVPG from in vitro MRI had a correlation coefficient of r2 = 0.98 with reference CFD. 4Dflow-VP-Net, applied to 4D flow MRI in 16 patients, showed comparable TVPG measurement with Doppler echocardiography (r2 = 0.85). Bland-Altman analysis of TVPG measurements showed mean bias and limits of agreement of -0.20 ± 2.07 mmHg and 0.19 ± 0.45 mmHg for CFD-simulated velocities and in vitro 4D flow velocities. In patients, overestimation of Doppler echocardiography relative to TVPG from 4Dflow-VP-Net (10.99 ± 6.77 mmHg) was observed. CONCLUSION: The proposed approach can predict relative pressure in both in vitro and in vivo 4D flow MRI of aortic stenotic patients with high fidelity.

Calculation of Mitral Valve Area by Continuity Equation Using Velocity-Time Integral From Mitral Valve Orifices After Mitral Clip.

BACKGROUND: This study investigates the hemodynamics of a dual-orifice mitral valve after mitral valve clip closure (MVCC) in patients with functional and nonfunctional mitral regurgitation (MR). If inflow velocity-time integral (VTi) of both orifices is equal, then the standard continuity equation can be applied to calculate the total mitral valve area (MVA). METHODS AND RESULTS: Adults undergoing MVCC placement were prospectively enrolled. With transesophageal echocardiography (TEE), the vena contracta (VC) of the medial and lateral mitral valve (MV) orifices were determined using color-flow Doppler and dual MV orifice areas were calculated. Valve orifices were classified as large vs small based on VC diameters. Continuous-wave Doppler measurements from both orifices were obtained. Forty-nine patients with severe MR (functional, n = 18) were enrolled. The VTi, mean gradient, peak gradient, and mean velocity of the larger vs smaller orifice were not significantly different, irrespective of MR etiology (P=nonsignificant). There was no difference in these parameters between large and small orifice regardless of MR mechanism (P=nonsignificant). There were no differences in the means of MVA as derived from either large or small VTi-derived and VC-derived areas (P=nonsignificant). CONCLUSIONS: Mitral valve inflow hemodynamics were the same regardless of the size differences between the large and small orifices. Therefore, total MVA can be calculated using the continuity equation in patients irrespective of MR mechanism. This allows for a derivation of total MVA at the time of MVCC placement to evaluate for mitral stenosis.

Beneficial Cardiac Structural and Functional Adaptations After Lumbosacral Spinal Cord Epidural Stimulation and Task-Specific Interventions: A Pilot Study.

Cardiac myocyte atrophy and the resulting decreases to the left ventricular mass and dimensions are well documented in spinal cord injury. Therapeutic interventions that increase preload can increase the chamber size and improve the diastolic filling ratios; however, there are no data describing cardiac adaptation to chronic afterload increases. Research from our center has demonstrated that spinal cord epidural stimulation (scES) can normalize arterial blood pressure, so we decided to investigate the effects of scES on cardiac function using echocardiography. Four individuals with chronic, motor-complete cervical spinal cord injury were implanted with a stimulator over the lumbosacral enlargement. We assessed the cardiac structure and function at the following time points: (a) prior to implantation; (b) after scES targeted to increase systolic blood pressure; (c) after the addition of scES targeted to facilitate voluntary (i.e., with intent) movement of the trunk and lower extremities; and (d) after the addition of scES targeted to facilitate independent, overground standing. We found significant improvements to the cardiac structure (left ventricular mass = 10 ± 2 g, p < 0.001; internal dimension during diastole = 0.1 ± 0.04 cm, p < 0.05; internal dimension during systole = 0.06 ± 0.03 cm, p < 0.05; interventricular septum dimension = 0.04 ± 0.02 cm, p < 0.05), systolic function (ejection fraction = 1 ± 0.4%, p < 0.05; velocity time integral = 2 ± 0.4 cm, p < 0.001; stroke volume = 4.4 ± 1.5 ml, p < 0.01), and diastolic function (mitral valve deceleration time = -32 ± 11 ms, p < 0.05; mitral valve deceleration slope = 50 ± 25 cm s-1, p < 0.05; isovolumic relaxation time = -6 ± 1.9 ms, p < 0.05) with each subsequent scES intervention. Despite the pilot nature of this study, statistically significant improvements to the cardiac structure, systolic function, and diastolic function demonstrate that scES combined with task-specific interventions led to beneficial cardiac remodeling, which can reverse atrophic changes that result from spinal cord injury. Long-term improvements to cardiac function have implications for increased quality of life and improved cardiovascular health in individuals with spinal cord injury, decreasing the risk of cardiovascular morbidity and mortality.

Systolic and diastolic function in chronic spinal cord injury.

Individuals with spinal cord injury develop cardiovascular disease more than age-matched, non-injured cohorts. However, progression of systolic and diastolic dysfunction into cardiovascular disease after spinal cord injury is not well described. We sought to investigate the relationship between systolic and diastolic function in chronic spinal cord injury to describe how biological sex, level, severity, and duration of injury correlate with structural changes in the left ventricle. Individuals with chronic spinal cord injury participated in this study (n = 70). Registered diagnostic cardiac sonographers used cardiac ultrasound to measure dimensions, mass, and systolic and diastolic function of the left ventricle. We found no significant relationship to severity or duration of injury with left ventricle measurements, systolic function outcome, or diastolic function outcome. Moreover, nearly all outcomes measured were within the American Society of Echocardiography-defined healthy range. Similar to non-injured individuals, when indexed by body surface area (BSA) left ventricle mass [-14 (5) g/m2, p < .01], end diastolic volume [-6 (3) mL/m2, p < .05], and end systolic volume [-4 (1) mL/m2, p < .01] were significantly decreased in women compared with men. Likewise, diastolic function outcomes significantly worsened with age: E-wave velocity [-5 (2), p < .01], E/A ratio [-0.23 (0.08), p < .01], and e' velocity [lateral: -1.5 (0.3) cm/s, p < .001; septal: -0.9 (0.2), p < .001] decreased with age while A-wave velocity [5 (1) cm/s, p < .001] and isovolumic relaxation time [6 (3) ms, p < .05] increased with age. Women demonstrated significantly decreased cardiac size and volumes compared with men, but there was no biological relationship to dysfunction. Moreover, individuals were within the range of ASE-defined healthy values with no evidence of systolic or diastolic function and no meaningful relationship to level, severity, or duration of injury. Decreases to left ventricular dimensions and mass seen in spinal cord injury may result from adaptation rather than maladaptive myocardial remodeling, and increased incidence of cardiovascular disease may be related to modifiable risk factors.

Childhood cancer survivors: The integral role of the cardiologist and cardiovascular imaging.

IMPORTANCE: With 80% of childhood cancer survivors (CCS) alive 30 years after diagnosis, preventable causes of death, such as cardiovascular disease resulting from initial cancer therapy, becomes an important metric. This leads to a more pronounced role for cardiologists in the care of CCS. OBSERVATIONS: While routine cardiovascular screening has been traditionally performed by the hematologist/oncologist or primary care provider, our understanding of cardiovascular disease in CCS has advanced. The measurement of left ventricular ejection fraction (LVEF) can now be complemented with additional assessments of strain, LV mass, right ventricular function, diastolic function, valve function, the pericardium, coronary perfusion, and biomarkers. Risk factor modification, prophylaxis, and timing of treatment are also critical. CONCLUSIONS AND RELEVANCE: Early cardiovascular screening and treatment in asymptomatic CCS can be nuanced and complex. As a result, there is a renewed opportunity for the cardiologist to play an integral role in the care of CCS. KEY POINTS: Question/Purpose: Review cardiovascular disease and the role of the cardiologist in the care of asymptomatic childhood cancer survivors (CCS). FINDINGS: Cardiovascular care in CCS benefits from a multi-faceted approach that does not overly rely on LVEF. Meaning: Adequate screening and treatment of cardiovascular disease in asymptomatic CCS may often be optimized by the involvement of a cardiologist.

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.

Two-dimensional strain echocardiography-derived left ventricular ejection fraction, volumes, and global systolic dyssynchrony index: Comparison with three-dimensional echocardiography.

BACKGROUND: Three-dimensional (3D) echocardiography is the most accurate echocardiographic method for ventricular chamber quantification. It is unclear how two-dimensional (2D) techniques perform against 3D technology and whether 2D methods can be extrapolated to obtain 3D data. METHODS: Retrospective review of transthoracic echocardiography was performed, with comparison of ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), and 2D strain-derived global longitudinal strain (GLS) and synchrony index. RESULTS: One-hundred patients were identified. Using 3D echocardiography as reference standard, good correlation was noted with 2D strain-derived EF (r = 0.89, P < 0.01) and with 2D standard biplane EF (r = 0.90, P < 0.01) and similarly for EDV (r = 0.84 and r = 0.81, respectively, both P < 0.01). Two-dimensional strain-derived EDV by 8% and 2D biplane-derived EDV underestimated by 8% (P < 0.01). In relation to 3D EF, 2D strain underestimated by 2% and 2D standard biplane overestimated by 2% (P < 0.01). There was a negative correlation between GLS and 3D EF (r = 0.84, P = 0.001). On multivariate analysis, 3D EF could be derived from 2D strain [3D EF = 34.345 + (0.125 * EDV) + (-0.289 * ESV) + (-1.141 * GLS)]. Three-dimensional echocardiography-derived synchrony parameter (ie, standard deviation from mean time to minimum systolic volume from 16 subvolumes) did not correlate with 2D strain-derived synchrony index (r = 0.171). CONCLUSIONS: Two-dimensional standard biplane and 2D strain EF and EDV strongly correlate with 3D EF and EDV. Although 2D methods are predictive of 3D findings, over- and underestimations may occur. Three-dimensional echocardiography should be used when available.

The evolution of apical hypertrophic cardiomyopathy: Development of mid-ventricular obstruction and apical aneurysm 11 years after initial diagnosis.

Asian hypertrophic cardiomyopathy (AHCM) is a rare variant of hypertrophic cardiomyopathy (HCM) that is more prevalent in the Asian population. There is significant overlap between AHCM, mid-cavitary obstruction, and apical aneurysms. Although more benign compared to HCM, the course of AHCM is not clearly defined. We present an interesting case of an African American male with known AHCM who develops symptomatic mid-cavitary obstruction and apical aneurysm 11 years after initial diagnosis.

A curious case of an absent left atrial appendage.

The left atrial appendage (LAA) in the setting of non-valvular atrial fibrillation (NVAF) is the predominant location for intracardiac thrombus formation. An absent LAA is a very rare congenital cardiac anomaly. We present a case of a 79-year-old female with NVAF, high CHADS2VASC2 score, and high bleeding risk who presented for elective Watchman™ left atrial appendage closure device implant. A pre-procedural transesophageal echocardiography showed an absent LAA. This finding was confirmed with cardiac computed tomography and a left atrial angiogram. The patient was discharged on medical therapy with close outpatient follow-up.

Frequent premature atrial contractions impair left atrial contractile function and promote adverse left atrial remodeling.

OBJECTIVES: This study assessed if frequent premature atrial contractions (PACs) were associated with decreased left atrial (LA) strain and adverse remodeling. BACKGROUND: Left atrial dysfunction and enlargement increases risk of stroke. If frequent PACs cause LA dysfunction and remodeling, PAC suppressive therapy may be beneficial. METHODS: Inclusion criteria were age ≥18 years and sinus rhythm. Exclusion criteria were atrial fibrillation or any etiology for LA enlargement. Hundred and thirty-two patients with frequent PACs (≥100/24 hours) by Holter were matched to controls. Speckle tracking strain of the left atrium was performed from the 4-chamber view. Strain measurements were LA peak contractile, reservoir and conduit strain and strain rates. RESULTS: In the frequent PAC vs control group, PACs were more frequent (1959 ± 3796 vs 28 ± 25/24 hours, P < .0001). LA peak contractile strain was reduced in the group with frequent PACs vs controls (-7.85 ± 4.12% vs -9.33 ± 4.45%, P = .006). LA peak late negative contractile strain rate was less negative in the frequent PAC vs control group (-0.63 ± 0.27 s-1 vs -0.69 ± 0.32 s-1 , P = .051). LA reservoir and conduit strain and strain rates did not differ. LA volume index (LAVI) was larger in the frequent PAC vs control group (26.6 ± 7.8 vs 24.6 ± 8.8 mL/m2 , P < .05). Frequent PACs were an independent predictor of reduced LA peak contractile strain and reduced LA peak late negative contractile strain rate. CONCLUSIONS: Patients with frequent PACs have reduced LA peak contractile strain and strain rates and larger LAVI compared to controls. Frequent PACs are an independent predictor of reduced LA peak contractile strain and strain rate. These findings support the hypothesis that frequent PACs impair LA contractile function and promote adverse LA remodeling.

Echocardiographic Assessment of Cardiotoxic Effects of Cancer Therapy.

Patients with cancer can present with difficult management issues, as the medicine can sometimes cause sequelae destructive to healthy tissue. As this population lives longer, cardiotoxic effects are beginning to emerge, but the early recognition of this signal can prove difficult, with too late a recognition leading to lifelong cardiac impairment and dysfunction. Cardio-oncology can bridge this difficulty, and echocardiography and its newer imaging abilities are proving efficacious in this population. This article will address common sequelae of cardiotoxic treatment regimens and offer recommendations for echocardiographic surveillance. We recommend echocardiography, preferably three-dimensional and strain imaging, to monitor for cardiotoxic myocardial effects before, during, and after chemotherapy with cardiotoxic drug regimens, particularly anthracycline derivatives. A reduction in left ventricular (LV) global longitudinal strain in all patients, or reduction in LV global circumferential strain or global radial strain in patients at intermediate to high risk for cardiotoxicity, despite normal LV ejection fraction warrants a clinical assessment on the benefits of continuing cardiotoxic chemotherapeutic agents. Lifelong surveillance using echocardiography for cardiotoxicity and radiation-related valvular, pericardial, and coronary artery disease is prudent.

Risk of Recurrent Neurologic Stroke or Transient Ischemic Attack in Patients with Cryptogenic Stroke and Intrapulmonary Shunt.

BACKGROUND AND PURPOSE: Cardio-embolic phenomenon is believed to underlie a significant proportion of cryptogenic strokes. We recently showed that intrapulmonary shunt (IPS) was associated with cryptogenic stroke and transient ischemic attack (TIA). We hypothesized that patients with prior cryptogenic stroke or TIA that had an IPS were at a higher risk for recurrent ischemic events. METHODS: The population included subjects with cryptogenic cerebrovascular accident (CVA) or TIA. Inclusion criteria were age ≥18 years, sinus rhythm, and clinically indicated transesophageal echocardiography (TEE). Exclusion criteria were hemorrhagic CVA, septal defect, and patent foramen. Patients were followed from index TEE. RESULTS: Of 71 patients, 8 were lost to follow-up. A total of 23 patients had and 40 were without IPS. Average follow-up duration was 38.3 ± 19.2 months. Groups were similar at baseline. There was no significant difference in the recurrence of ischemic CVA or TIA in the IPS versus non-IPS groups (0% vs. 7.5%; P = NS). There was no difference between the incidence of hemorrhagic CVA in the IPS and non-IPS groups (4.3% vs. 5.0%; P = NS). The proportion of patients on warfarin in the IPS group was significantly higher compared to the non-IPS group (17.4% vs. 0%; P < 0.05). CONCLUSIONS: Patients with IPS and cryptogenic stroke or TIA did not have a higher recurrence of ischemic cerebral events. Warfarin was significantly higher at follow-up in the IPS compared to the non-IPS group, which may explain these findings. A study randomizing patients with IPS and cryptogenic stroke or TIA to warfarin or no warfarin would be of great interest.

4D spiral imaging of flows in stenotic phantoms and subjects with aortic stenosis.

PURPOSE: The utility of four-dimensional (4D) spiral flow in imaging of stenotic flows in both phantoms and human subjects with aortic stenosis is investigated. METHODS: The method performs 4D flow acquisitions through a stack of interleaved spiral k-space readouts. Relative to conventional 4D flow, which performs Cartesian readout, the method has reduced echo time. Thus, reduced flow artifacts are observed when imaging high-speed stenotic flows. Four-dimensional spiral flow also provides significant savings in scan times relative to conventional 4D flow. RESULTS: In vitro experiments were performed under both steady and pulsatile flows in a phantom model of severe stenosis (one inch diameter at the inlet, with 87% area reduction at the throat of the stenosis) while imaging a 6-cm axial extent of the phantom, which included the Gaussian-shaped stenotic narrowing. In all cases, gradient strength and slew rate for standard clinical acquisitions, and identical field of view and resolution were used. For low steady flow rates, quantitative and qualitative results showed a similar level of accuracy between 4D spiral flow (echo time [TE] = 2 ms, scan time = 40 s) and conventional 4D flow (TE = 3.6 ms, scan time = 1:01 min). However, in the case of high steady flow rates, 4D spiral flow (TE = 1.57 ms, scan time = 38 s) showed better visualization and accuracy as compared to conventional 4D flow (TE = 3.2 ms, scan time = 51 s). At low pulsatile flow rates, a good agreement was observed between 4D spiral flow (TE = 2 ms, scan time = 10:26 min) and conventional 4D flow (TE = 3.6 ms, scan time = 14:20 min). However, in the case of high flow-rate pulsatile flows, 4D spiral flow (TE = 1.57 ms, scan time = 10:26 min) demonstrated better visualization as compared to conventional 4D flow (TE = 3.2 ms, scan time = 14:20 min). The feasibility of 4D spiral flow was also investigated in five normal volunteers and four subjects with mild-to-moderate aortic stenosis. The approach achieved TE = 1.68 ms and scan time = 3:44 min. The conventional sequence achieved TE = 2.9 ms and scan time = 5:23 min. In subjects with aortic stenosis, we also compared both MRI methods with Doppler ultrasound (US) in the measurement of peak velocity, time to peak systolic velocity, and eject time. Bland-Altman analysis revealed that, when comparing peak velocities, the discrepancy between Doppler US and 4D spiral flow was significantly less than the discrepancy between Doppler and 4D Cartesian flow (2.75 cm/s vs. 10.25 cm/s), whereas the two MR methods were comparable (-5.75 s vs. -6 s) for time to peak. However, for the estimation of eject time, relative to Doppler US, the discrepancy for 4D conventional flow was smaller than that of 4D spiral flow (-16.25 s vs. -20 s). CONCLUSION: Relative to conventional 4D flow, 4D spiral flow achieves substantial reductions in both the TE and scan times; therefore, utility for it should be sought in a variety of in vivo and complex flow imaging applications.

Impact and predictors of noncircular left ventricular outflow tract shapes on estimating aortic stenosis severity by means of continuity equations.

Determining aortic stenosis (AS) severity is clinically important. Calculating aortic valve (AV) area by means of the continuity equation assumes a circular left ventricular outflow tract (LVOT). The full impact of this assumption in calculating AV area is unknown. Predictors of noncircular LVOT shape in patients with AS are undefined. In 109 adult patients with AS who underwent multiplanar transesophageal echocardiography, we calculated AV area by means of the standard continuity method and by a modified method involving planimetric LVOT area. We found 54 circular, 37 horizontal-oval, 8 vertical-oval, and 10 irregular LVOTs. Area derived by direct planimetry correlated better with the modified than the standard continuity method (r=0.89 vs r=0.85; both P=0.0001). Valve areas of patients with mild, moderate, or severe AS by planimetry were more often mischaracterized with use of the standard than modified method (29 vs 18; P <0.0001). Horizontal-oval AV area derived by planimetry (1.28 ± 0.55 cm(2)) was underestimated by the standard method (1.05 ± 0.47 cm(2); P=0.001), but not by the modified method. Congenital AV morphology and low cardiac index were the only multivariate predictors of horizontal-oval shape. Low cardiac index was the only predictor of noncircular shape. More than half our patients with AS had noncircular LVOTs. Using the modified method reduces mischaracterizations of AS severity. Congenital AV morphology and low cardiac index predict horizontal-oval or noncircular shape. These data suggest the value of direct LVOT measurement to calculate AS severity in patients who have congenital AV or a low cardiac index.

4D UTE flow: a phase-contrast MRI technique for assessment and visualization of stenotic flows.

PURPOSE: Inaccuracy of conventional four-dimensional (4D) flow MR imaging in the presence of random unsteady and turbulent blood flow distal to a narrowing has been an important challenge. Previous investigations have revealed that shorter echo times (TE) decrease the errors, leading to more accurate flow assessments. METHODS: In this study, as part of a 4D flow acquisition, an Ultra-Short TE (UTE) method was adopted. UTE works based on a center-out radial k-space trajectory that inherently has a short TE. By employing free induction decay sampling starting from read-out gradient ramp-up, and by combining the refocusing lobe of the slice select gradient with the bipolar flow encoding gradient, TEs of ≈1 msec may be achieved. RESULTS: Both steady and pulsatile flow regimes, and in each case a range of Reynolds numbers, were studied in an in-vitro model. Flow assessment at low and medium flow rates demonstrated a good agreement between 4D UTE and conventional 4D flow techniques. However, 4D UTE flow significantly outperformed conventional 4D flow, at high flow rates for both steady and pulsatile flow regimes. Feasibility of the method in one patient with Aortic Stenosis was also demonstrated. CONCLUSION: For both steady and pulsatile high flow rates, the measured flow distal to the stenotic narrowing using conventional 4D flow revealed more than 20% error compared to the ground-truth flow. This error was reduced to less than 5% using the 4D UTE flow technique.

Tissue Doppler imaging optical flow (TDIOF): a combined B-mode and tissue Doppler approach for cardiac motion estimation in echocardiographic images.

The quantitative analysis of cardiac motion from echocardiographic images helps clinicians in the diagnosis and therapy of patients suffering from heart disease. Quantitative analysis is usually based on tissue Doppler imaging (TDI) or speckle tracking. These methods are based on two techniques which to a large degree are independent: the Doppler phenomenon and image sequence processing. Herein, to increase the accuracy of the speckle tracking technique and to cope with the angle dependence of TDI, a combined approach dubbed tissue Doppler imaging optical flow (TDIOF) is proposed. TDIOF is formulated based on the combination of B-mode and Doppler energy terms minimized using algebraic equations and is validated on simulated images, and in vivo data. It was observed that the additional Doppler term is able to increase the accuracy of speckle tracking, compared to two popular motion estimation and speckle tracking techniques (Horn-Schunck and block matching methods). This observation was more pronounced when noise was present. The magnitude and angular error for TDIOF applied to simulated images, when comparing estimated motion with ground-truth motion, were 15% and 9.2°/frame, respectively. As an additional validation, echocardiography-derived strains were compared to tagged MRI-derived myocardial strains in the same subjects. The correlation coefficient (r) between the TDIOF-derived radial strains and tagged MRI-derived radial strains value was 0.83 (P < 0.001). The correlation coefficient ( r) for the TDIOF-derived circumferential strains compared to the tagged MRI-derived circumferential strains was 0.86 (P < 0.001). The comparison of TDIOF-derived and block matching speckle tracking and Horn-Schunck optical flow strain values using student t-test demonstrated superiority of TDIOF (95% confidence interval, P < 0.001).

Determination of the optimum number of cardiac cycles to differentiate intra-pulmonary shunt and patent foramen ovale by saline contrast two- and three-dimensional echocardiography.

INTRODUCTION: Patent foramen ovale (PFO) and intra-pulmonary shunt (IPS) are potential causes of stroke. The most optimum cardiac cycle cutoff for bubbles to appear in the left heart on saline contrast transthoracic echocardiography (TTE) as criteria to differentiate the 2 entities is unknown. METHODS: Ninety-five adult patients had saline contrast transesophageal echocardiography (TEE), two-dimensional (2D) and 3DTTE. Sensitivity and specificity of each cardiac cycle as cutoff to differentiate a PFO and IPS were obtained. RESULTS: Transesophageal echocardiography showed IPS in 28 and PFO in 15 patients. If bubbles appeared in the left heart within the first 4 cardiac cycles (the 4th cardiac cycle rule) as compared to alternate cutoffs, a PFO was most accurately diagnosed by both 2D and 3DTTE. Bubbles appearing at or after the 5th cardiac cycle most accurately determined an IPS. 3D versus 2DTTE had a trend for a higher sensitivity (61% vs. 36%, P = 0.06), but similar specificity (94% vs. 91%) for IPS. Accuracy of 3DTTE was 84% and 2DTTE was 75% (P = 0.08) for IPS. For PFO, 2DTTE sensitivity (87%) and specificity (98%) did not differ (P = NS) from that of 3DTTE sensitivity (73%) and specificity (100%). CONCLUSIONS: This study demonstrates for the first time that the 4th cardiac cycle rule differentiates PFO and IPS most optimally by 2D and 3DTTE. 3DTTE appears to have higher sensitivity for diagnosing IPS. These data suggest that 3DTTE is preferable when IPS is to be diagnosed. Both methods are similar for diagnosing PFO.

Intrapulmonary shunt is a potentially unrecognized cause of ischemic stroke and transient ischemic attack.

BACKGROUND: Ischemic stroke is a major cause of mortality and disability. Transient ischemic attack (TIA) is a harbinger of stroke. The etiology of stroke in as many as 40% of patients remains undetermined after extensive evaluation. It was hypothesized that intrapulmonary shunt is a potential facilitator of cerebrovascular accident (CVA) or TIA. METHODS: Patients undergoing clinically indicated transesophageal echocardiography were prospectively enrolled. Comprehensive multiplane transesophageal echocardiographic imaging was performed and saline contrast done to assess for intrapulmonary shunt and patent foramen ovale. RESULTS: Three hundred twenty-one patients with either nonhemorrhagic CVA (n = 262) or TIA (n = 59) made up the stroke group. Three hundred twenty-one age-matched and gender-matched patients made up the control group. Intrapulmonary shunt occurred more frequently in the stroke group (72 of 321) compared with the control group (32 of 321) (22% vs 10%, P < .0001). Intrapulmonary shunt was an independent predictor of CVA and/or TIA (odds ratio, 2.6; P < .0001). In subjects with cryptogenic CVA or TIA (n = 71), intrapulmonary shunt occurred more frequently (25 of 71) than in the control group (5 of 71) (35% vs 7%, P < .0001). Intrapulmonary shunt was an independent multivariate predictor of CVA or TIA in patients with cryptogenic CVA or TIA (odds ratio, 6.3; P < .005). CONCLUSIONS: These results suggest that intrapulmonary shunt is a potentially unrecognized facilitator of CVA and TIA, especially in patients with cryptogenic CVA and TIA. Future studies assessing the prognostic significance of intrapulmonary shunt on cerebral vascular event recurrence rates in patients after initial CVA or TIA would be of great interest.