Regional Motion Patterns Research Articles

Kinematic motion representation in Cine-MRI to support cardiac disease classification

ABSTRACT Cine-MRI sequences provide detailed information about anatomical and movement of heart, covering one full periodic cycle, which result fundamental to support diagnosis and follow personalised treatments. From such sequences, expert cardiologists can estimate cardiac performance index manually delineating shapes, and evaluating temporal geometrical changes. This patterns nevertheless are subject to proper manual delineations of ventricles and restrict the analysis to standard dynamic index, losing sight-hidden dynamic relationships that could be related with certain cardiac diseases. This work introduces a motion cardiac descriptor that fully describes kinematic heart patterns computed from local velocity fields, along the cycle. Firstly, velocity field is recovered among consecutive basal slices, which thereafter are characterised with differential kinematics, such as velocity, acceleration, divergence, and among others. Then, a regional multiscale partition allows to recover regional motion patterns, coding incidence motion measures as kinematic occurrence histograms. The set of regional motion patterns form a motion descriptor that fully describes heart dynamic and allows to automatically classify cardiac pathologies. The motion descriptor was evaluated over two different datasets, achieving averages accuracies of (45 cases, 4 conditions) and (100 cases, 5 conditions) mapped to a Random Forest Classifier, and over a set of Cine-MRI volumes achieved an average accuracy of among four pathologies.

Characterization of motion patterns by a spatio-temporal saliency descriptor in cardiac cine MRI

Background and objective: Abnormalities of the heart motion reveal the presence of a disease. However, a quantitative interpretation of the motion is still a challenge due to the complex dynamics of the heart. This work proposes a quantitative characterization of regional cardiac motion patterns in cine magnetic resonance imaging (MRI) by a novel spatio-temporal saliency descriptor. Method: The strategy starts by dividing the cardiac sequence into a progression of scales which are in due turn mapped to a feature space of regional orientation changes, mimicking the multi-resolution decomposition of oriented primitive changes of visual systems. These changes are estimated as the difference between a particular time and the rest of the sequence. This decomposition is then temporarily and regionally integrated for a particular orientation and then for the set of different orientations. A final spatio-temporal 4D saliency map is obtained as the summation of the previously integrated information for the available scales. The saliency dispersion of this map was computed in standard cardiac locations as a measure of the regional motion pattern and was applied to discriminate control and hypertrophic cardiomyopathy (HCM) subjects during the diastolic phase. Results: Salient motion patterns were estimated from an experimental set, which consisted of 3D sequences acquired by MRI from 108 subjects (33 control, 35 HCM, 20 dilated cardiomyopathy (DCM), and 20 myocardial infarction (MINF) from heterogeneous datasets). HCM and control subjects were classified by an SVM that learned the salient motion patterns estimated from the presented strategy, by achieving a 94% AUC. In addition, statistical differences (test t-student, p<0.05) were found among groups of disease in the septal and anterior ventricular segments at both the ED and ES, with salient motion characteristics aligned with existing knowledge on the diseases. Conclusions: Regional wall motion abnormality in the apical, anterior, basal, and inferior segments was associated with the saliency dispersion in HCM, DCM, and MINF compared to healthy controls during the systolic and diastolic phases. This saliency analysis may be used to detect subtle changes in heart function.

Effects of ventricular insertion sites on rotational motion of left ventricular segments studied by cardiac MR

Obtaining new details for rotational motion of left ventricular (LV) segments using velocity encoding cardiac MR and correlating the regional motion patterns to LV insertion sites. Cardiac MR examinations were performed on 14 healthy volunteers aged between 19 and 26 years. Peak rotational velocities and circumferential velocity curves were obtained for 16 ventricular segments. Reduced peak clockwise velocities of anteroseptal segments (i.e. Segments 2 and 8) and peak counterclockwise velocities of inferoseptal segments (i.e. Segments 3 and 9) were the most prominent findings. The observations can be attributed to the LV insertion sites into the right ventricle, limiting the clockwise rotation of anteroseptal LV segments and the counterclockwise rotation of inferoseptal segments as viewed from the apex. Relatively lower clockwise velocities of Segment 5 and counterclockwise velocities of Segment 6 were also noted, suggesting a cardiac fixation point between these two segments, which is in close proximity to the lateral LV wall. Apart from showing different rotational patterns of LV base, mid ventricle and apex, the study showed significant differences in the rotational velocities of individual LV segments. Correlating regional wall motion with known orientation of myocardial aggregates has also provided new insights into the mechanisms of LV rotational motions during a cardiac cycle. LV insertion into the right ventricle limits the clockwise rotation of anteroseptal LV segments and the counterclockwise rotation of inferoseptal segments adjacent to the ventricular insertion sites. The pattern should be differentiated from wall motion abnormalities in cardiac pathology.

Improved method for quantification of regional cardiac function in mice using phase-contrast MRI.

Phase-contrast magnetic resonance imaging is a technique that allows for characterization of regional cardiac function and for measuring transmural myocardial velocities in human hearts with high temporal and spatial resolution. The application of this technique (also known as tissue phase mapping) to murine hearts has been very limited so far. The aim of our study was to implement and to optimize tissue phase mapping for a comprehensive assessment of murine transmural wall motion. Baseline values for regional motion patterns in mouse hearts, based on the clinically used American Heart Association's 17-segment model, were established, and a detailed motion analysis of mouse heart for the entire cardiac cycle (including epicardial and endocardial motion patterns) is provided. Black-blood contrast was found to be essential to obtain reproducible velocity encoding. Tissue phase mapping of the mouse heart permits the detailed assessment of regional myocardial velocities. While a proof-of-principle application in a murine ischemia–reperfusion model was performed, future studies are warranted to assess its potential for the investigation of systolic and diastolic functions in genetically and surgically manipulated mouse models of human heart disease. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.

108 Accelerated 3D tagging to assess left ventricular dyssynchrony in patients with sub-acute myocardial infarctions

Cardiac resynchronization therapy (CRT) proved success-ful in larger patient populations. However, individualresponsiveness to CRT is not yet highly predictable.Around 30% of patients do not appear to benefit fromCRT [1]. Accurate measurement of dyssynchrony couldhelp in discriminating CRT responders from non-responders. Individual responsiveness of patients couldbe improved with the knowledge of temporally resolved,regional motion patterns. The acquisition of multi-sliceMR tagging data [2] covering the whole heart in short- andlong axis orientations is associated with long acquisitiontimes and prone to slice misregistration. A novel acceler-ated 3D tagging acquisition scheme [3,4] allows assessingdetailed 3D motion patterns of the entire left ventricle(LV) in only three breath-holds. Accordingly, the methodis easily integrated into a clinical protocol including volu-metric, perfusion and viability measurements.The 3D tagging technique was applied to quantify LV dys-synchrony in patients with sub-acute myocardial infarc-tions as a model causing dyssynchrony relative to healthycontrols. Features of three-dimensional motion patternswere correlated with the presence of scar tissue as meas-ured with late enhancement images.