4D left ventricular resultant wall motion and blood flow assessed by phase-shift velocity mapping at high-field 3T MRI.

BACKGROUND: Contractility and elasticity of the myocardium are important variables for detecting anomalies that may influence pump function. It is important to assess both wall motion and blood flow to detect regional left ventricular (LV) dysfunction and abnormal flow patterns. This study discusses four-dimensional (4D) phase-contrast magnetic resonance imaging (MRI) for simultaneous quantification and visualization of LV wall motion and blood flow. METHODS: In thirteen healthy subjects, a three-directional retrospective cardiac triggered phase-shift velocity mapping technique was used to acquire velocity data of the LV throughout the cardiac cycle. All short-axis slices of the LV wall were segmented in six sectors of 60° starting from the anterior hinge point between the right and left ventricles, from base to apex. Velocity data in resultant, radial, circumferential and longitudinal directions were calculated and presented as coloured three-directional vectors. RESULTS: Our findings showed a reduction in maximum wall velocities from base to apex, whereas for the radial and circumferential directions no significant differences were noted (13·1 ± 2·7 and 13·0 ± 2·9 cm s-1 , respectively. P = 0·9). The longitudinal maximum velocities (21·0 ± 0·6 cm s-1 ) were significantly higher than the radial and circumferential components (P = 0·002). We found that the inclination angle of the resultant blood flow was changed towards the left ventricular outflow tract during systole. CONCLUSIONS: Using this 4D MRI velocity mapping technique, we present an improved method for quantification and visualization of ventricular wall velocities in the radial, circumferential and longitudinal directions, as well as for the intracavity blood flow.

Assessment of coronary flow reserve in the coronary sinus by cine 3T-magnetic resonance imaging in young adults after surgery for tetralogy of Fallot.

This study aimed to evaluate CFR by assessing blood flow in the coronary sinus and systemic endothelial function measured by FMD of the brachial artery in an open prospective study of 10 control subjects and 10 patients (ages, 15-25 years) who have undergone surgical TOF repair. Reduced ventricular function, impaired exercise capacity, and ventricular arrhythmia have been proposed as risk factors for sudden cardiac death after surgical repair of TOF. Some of this may be related to impaired myocardial perfusion. A 3.0T GE Signa Excite scanner was used to achieve phase-contrast, velocity-encoding cine magnetic resonance imaging in the coronary sinus before and during infusion with adenosine (0.14 mg/kg/min). FMD was measured in the brachial artery before arterial occlusion and 5 min afterward. The TOF group demonstrated significantly higher volumetric blood flow in the coronary sinus (282 ± 63 ml/min) than the normal control subjects at rest (184 ± 57 ml/min) (P = 0.006). During adenosine infusion, this difference disappeared. The CFR was 2.00 ± 0.43 in the control group and 1.19 ± 0.34 in the TOF group (P = 0.002). No correlation between FMD and CFR was observed in the study group (r (s) = 0.61, n = 8, P = 0.15). This study showed a reduced CFR due to a higher blood flow of the subject at rest in the TOF group. This reduced CFR may disable a normal adaptation to increased oxygen demand during exercise and increase myocardial vulnerability to reduced blood supply postoperatively for TOF patients with coronary heart disease.