Regional right ventricular function and timing of contraction in healthy volunteers evaluated by strain‐encoded MRI

Purpose

To prospectively determine the feasibility and accuracy of strain‐encoded (SENC) magnetic resonance imaging (MRI) for the characterization of the right ventricular free wall (RVFW) strain and timing of contraction at 3.0 Tesla (3T) MRI.

Materials and Methods

In 12 healthy volunteers the RVFW was divided into three segments (anterior, lateral, and inferior) in each of three short‐axis (SA) slices (apical, mid, and basal) and into three segments (apical, mid, and basal) in a four‐chamber view. The study was repeated on a different day and interobserver and interstudy agreements were evaluated.

Results

Maximal systolic longitudinal strain values were highest at the apex and base, with a pronounced decrease in the medial segments (apex: –19.1% ± 1.4; mid: –17.4% ± 2; base: –19.4% ± 2.4, P < 0.001), and maximal systolic circumferential strain showed the highest values at the apex (apex: –18.1% ± 1.7; mid: –17.6% ± 1.2; base: –16.6% ± 0.9, P < 0.001). Peak systolic longitudinal and circumferential shortening occurred earliest at the apex compared to the mid‐ventricle and base. Excellent interobserver and interstudy correlation and agreement were observed.

Conclusion

The use of SENC MRI for the assessment of normal RV contraction pattern is feasible and accurate in 3T MRI. J. Magn. Reson. Imaging 2008;28:1379–1385. © 2008 Wiley‐Liss, Inc.     

Strain‐encoded MRI to evaluate normal left ventricular function and timing of contraction at 3.0 Tesla

Purpose

To define the reproducibility of strain‐encoded (SENC) magnetic resonance imaging (MRI) for assessment of regional left ventricular myocardial strain and timing of contraction in a 3T MRI system.

Materials and Methods

The study population consisted of 16 healthy subjects. SENC measurements were performed in three short‐axis (SA) slices (apical, mid, and basal) and three long‐axis (LA) views (two‐, three‐, and four‐chamber) for assessment of maximal transmural systolic strain and time to peak strain. To assess the interobserver and interstudy reproducibility, analysis of SENC MRI was performed by two independent observers who were blinded to each other's results and four studies were repeated on a different day.

Results

Maximal longitudinal strain was highest at the apex, as was maximal circumferential strain. Peak longitudinal strain occurred earliest at the base, as did peak circumferential strain. Interclass correlation coefficient between observers and repeated studies ranged from 0.92 to 0.98 (P < 0.001 for all).

Conclusion

The present study demonstrates the ability of SENC MRI to define regional left ventricular strain and the time sequence of regional strain. SENC MRI may represent a highly objective method for quantifying regional left ventricular function. J. Magn. Reson. Imaging 2009;29:799–808. © 2009 Wiley‐Liss, Inc.     

Strain‐encoded cardiac MR during high‐dose dobutamine stress testing: Comparison to cine imaging and to myocardial tagging

Purpose

To investigate regional strain response during high‐dose dobutamine stress cardiac magnetic resonance imaging (DS‐CMR) using myocardial tagging and Strain‐Encoded MR (SENC).

Materials and Methods

Stress induced ischemia was assessed by wall motion analysis, by tagged CMR and by SENC in 65 patients with suspected or known CAD who underwent DS‐CMR in a clinical 1.5 Tesla scanner. Coronary angiography deemed as the standard reference for the presence or absence of CAD (≥50% diameter stenosis) in all patients.

Results

SENC and conventional tagging detected abnormal strain response in six and five additional patients, respectively, who were missed by cine images and proved to have CAD by angiography (P < 0.05 for SENC versus cine, P = 0.06 for tagging versus cine and p = NS for SENC versus tagging). On a per‐vessel level, wall motion analysis on cine images showed high specificity (95%) but moderate sensitivity (70%) for the detection of CAD. Tagging and SENC yielded significantly higher sensitivity of 81% and 89%, respectively (P < 0.05 for tagging and P < 0.01 for SENC versus wall motion analysis, and p = NS for SENC versus tagging), while specificity was equally high (96% and 94%, respectively, P = NS for all).

Conclusion

Both the direct color‐coded visualization of strain on CMR images and the generation of additional visual markers within the myocardium with tagged CMR represent useful adjuncts for DS‐CMR, which may provide incremental value for the detection of CAD in humans. J. Magn. Reson. Imaging 2009;29:1053–1061. © 2009 Wiley‐Liss, Inc.     

Strain‐encoded (SENC) magnetic resonance imaging to evaluate regional heterogeneity of myocardial strain in healthy volunteers: Comparison with conventional tagging

Purpose

To evaluate the ability of strain‐encoded (SENC) magnetic resonance imaging (MRI) for regional systolic and diastolic strain analysis of the myocardium in healthy volunteers.

Materials and Methods

Circumferential and longitudinal peak systolic strain values of 75 healthy volunteers (35 women and 40 men, mean age 44 ± 12 years) were measured using SENC at 1.5T. MR tagging was used as the reference standard for measuring regional function. Diastolic function was assessed in the 10 youngest (24 ± 8 years) and 10 oldest (62 ± 5 years) subjects.

Results

Peak strain values assessed with SENC were comparable to those obtained by MR tagging, showing narrow limits of agreement (limits of agreement ?5.6% to 8.1%). Regional heterogeneity was observed between different segments of the left ventricle (LV) by both techniques (P < 0.001). Longitudinal strain obtained by SENC was also heterogenous (P < 0.001). Interestingly, no age‐ or gender‐specific differences in peak systolic strain were observed, whereas the peak rate of relaxation of circumferential strain rate was decreased in the older group.

Conclusion

SENC is a reliable tool for accurate and objective quantification of regional myocardial systolic as well as diastolic function. In agreement with tagged MRI, SENC detected slightly heterogeneous myocardial strain within LV segments. J. Magn. Reson. Imaging 2009;29:99–105. © 2008 Wiley‐Liss, Inc.

     

Does the amplatzer septal occluder device alter ventricular contraction pattern? A ventricular motion analysis by MR tagging

Purpose:

To assess by cardiovascular magnetic resonance (CMR) and CMR tagging if the Amplatzer Septal Occluder affects right ventricular (RV) and left ventricular (LV) motion pattern.

Materials and Methods:

Sixteen consecutive patients with significant atrial septal defect (ASD) and nine consecutive patients with persistent foramen ovale (PFO) as controls were studied before and a median of 14 days after defect closure by an Amplatzer occluder. By CMR end‐diastolic (EDV) and end‐systolic (ESV) RV and LV volumes were determined. Aortic and pulmonary artery flow was measured for assessment of left‐to‐right shunt (Qp/Qs). By CMR tagging circumferential strain and radial shortening, maximal rotation and torsion were measured,

Results:

In ASD patients RV‐EDV and RV‐ESV decreased (P < 0.05). LV‐EDV and LV‐ESV increased after ASD closure (P < 0.005). Qp/Qs dropped from 1.8 to 1.0 (P < 0.001). PFO patients showed no ventricular volume change after PFO closure. In ASD patients circumferential strain and radial shortening and maximal rotation of the RV decreased by ASD closure (P < 0.01). In LV only maximal rotation at the base and apex decreased significantly (P < 0.05). Torsion remained constant. In PFO patients no tagging parameter changed after defect closure.

Conclusion:

The Amplatzer occluder itself does not change the ventricular contraction pattern. All volume and myocardial deformation changes were caused by ventricular loading shifts. J. Magn. Reson. Imaging 2012;35:949–956. © 2012 Wiley Periodicals, Inc.     

Real-time imaging of regional myocardial function using fast-SENC.

A technique for fast imaging of regional myocardial function using a spiral acquisition in combination with strain-encoded (SENC) magnetic resonance imaging (MRI) is presented in this paper. This technique, which is termed fast-SENC, enables scan durations as short as a single heartbeat. A reduced field of view (FOV) without foldover artifacts was achieved by localized SENC, which selectively excited the region around the heart. The two images required for SENC imaging (low- and high-tuning) were acquired in an interleaved fashion throughout the cardiac cycle to further shorten the scan time. Regional circumferential contraction and longitudinal shortening of both the left ventricle (LV) and right ventricle (RV) were examined in long- and short-axis views, respectively. The in vivo results obtained from five human subjects and five infarcted dogs are presented. The results of the fast-SENC technique in a single heartbeat acquisition were comparable to those obtained by conventional SENC in a long acquisition time. Therefore, fast-SENC may prove useful for imaging during stress or arrhythmia.     

Identification and further differentiation of subendocardial and transmural myocardial infarction by fast strain-encoded (SENC) magnetic resonance imaging at 3.0 Tesla

Objectives

To investigate whether subendocardial and transmural myocardial infarction can be identified and differentiated using the peak circumferential and longitudinal strains measured by fast strain-encoded (SENC).

Methods

Nineteen patients with ischemic heart diseases underwent imaging with fast SENC and late gadolinium enhancement (LGE) MRI at 3?T. Fast SENC measurements were performed in three short-axis slices (basal, mid-ventricular and apical levels) and one long-axis view (four-chamber) to assess peak longitudinal and circumferential systolic strains.

Results

All patients showed myocardial infarction with an average of 7 positive LGE segments. A total of 304 segments for longitudinal strains (LS) and 114 segments for circumferential strains (CS) could be analysed. Positive LGE segments showed lower peak CS and LS compared with the no LGE segments (P?P?P?=?0.03), but no significant difference in LS between them (P?=?0.64).

Conclusions

Fast SENC can identify old myocardial infarction and differentiate subendocardial from transmural infarction.     

Real-time MR imaging of myocardial regional function using strain-encoding (SENC) with tissue through-plane motion tracking

PURPOSE: To implement real-time myocardial strain-encoding (SENC) imaging in combination with tracking the tissue displacement in the through-plane direction. MATERIALS AND METHODS: SENC imaging was combined with the slice-following technique by implementing three-dimensional (3D) selective excitation. Certain adjustments were implemented to reduce scan time to one heartbeat. A total of 10 volunteers and five pigs were scanned on a 3T MRI scanner. Spatial modulation of magnetization (SPAMM)-tagged images were acquired on planes orthogonal to the SENC planes for comparison. Myocardial infarction (MI) was induced in two pigs and the resulting SENC images were compared to standard delayed-enhancement (DE) images. RESULTS: The strain values computed from SENC imaging with slice-following showed significant difference from those acquired without slice-following, especially during systole (P < 0.01). The strain curves computed from the SENC images with and without slice-following were similar to those computed from the orthogonal SPAMM images, with and without, respectively, tracking the tag line displacement in the strain direction. The resulting SENC images showed good agreement with the DE images in identifying MI in infarcted pigs. CONCLUSION: Correction of through-plane motion in real-time cardiac functional imaging is feasible using slice-following. The strain measurements are more accurate than conventional SENC measurements in humans and animals, as validated with conventional MRI tagging.     

Mechanical dyssynchrony or myocardial shortening as MRI predictor of response to biventricular pacing?

Purpose

To investigate whether mechanical dyssynchrony (regional timing differences) or heterogeneity (regional strain differences) in myocardial function should be used to predict the response to cardiac resynchronization therapy (CRT).

Materials and Methods

Baseline mechanical function was studied with MRI in 29 patients with chronic heart failure. Using myocardial tagging, two mechanical dyssynchrony parameters were defined: the standard deviation (SD) in onset time (T_onset) and in time to first peak (T_peak,first) of circumferential shortening. Electrical dyssynchrony was described by QRS width. Further, two heterogeneity parameters were defined: the coefficient of variation (CV) in end‐systolic strain and the difference between peak septal and lateral strain (DiffSLpeakCS). The relative increase in maximum rate of left ventricle pressure rise (dP/dt_max) quantified the acute response to CRT.

Results

The heterogeneity parameters correlated better with acute response (CV: r = 0.58, DiffSLpeakCS: r = 0.63, P < 0.005) than the mechanical dyssynchrony parameters (SD(T_onset): r = 0.36, SD(T_peak,first) r = 0.47, P = 0.01, but similar to electrical dyssynchrony (r = 0.62, P < 0.001). When a heterogeneity parameter was combined with electrical dyssynchrony, the correlation increased (r > 0.70, P_incr < 0.05).

Conclusion

Regional heterogeneity in myocardial shortening correlates better with response to CRT than mechanical dyssynchrony, but should be combined with electrical dyssynchrony to improve prediction of response beyond the prediction from electrical dyssynchrony only. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.     

Right ventricular regional function using MR tagging: Normals versus chronic pulmonary hypertension

Right ventricular (RV) regional function, in both normal and diseased states, is not well characterized. Using 1D MR myocardial tagging, RV and septal intramyocardial segmental shortening was noninvasively measured in ten healthy subjects and in seven patients with chronic pulmonary hypertension. The normal RV free wall regional shortening was not uniform. A pattern of increasing RV free wall short-axis shortening was found from the RV outflow tract to the RV apex, and a more complex pattern of RV free wall long-axis shortening was observed. Both regional short- and long-axis shortening were globally reduced in pulmonary hypertension patients, with the greatest decreases in the RV outflow tract and in the basal septal wall region. Regional RV function can be quantitatively evaluated using MR tagging to determine the impact of chronic pulmonary hypertension on RV performance.     

Myocardial 3D strain calculation by combining cine displacement encoding with stimulated echoes (DENSE) and cine strain encoding (SENC) imaging

Three‐dimensional (3D) strain maps of the myocardium provide a coordinate‐system–independent quantification of myocardial deformation and kinematics. We combine two MRI techniques, displacement encoding with stimulated echoes (DENSE) and strain encoding (SENC), to fully formulate a 3D strain map in a single slice of myocardium. The method utilizes 2D DENSE in‐plane displacement measurements in two adjacent slices in conjunction with a single SENC through‐plane strain measure to calculate the 3D strain tensor. Six volunteers were imaged and the technique demonstrated 3D strain measures in all volunteers that are consistent with those reported in the literature from 3D tagging. The mean peak strain (± standard deviation [SD]) for six healthy volunteers for the first, second, and third principal strains are 0.42 ±0.11, –0.10 ±0.03, and –0.21 ±0.02, respectively. These results show that this technique is capable of reliably quantifying 3D cardiac strain. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Real-time fast strain-encoded magnetic resonance imaging to evaluate regional myocardial function at 3.0 Tesla: comparison to conventional tagging

PURPOSE: To compare the utility of the real-time technique fast strain-encoded magnetic resonance imaging (fast-SENC) for the quantification of regional myocardial function to conventional tagged magnetic resonance imaging (MRI). MATERIALS AND METHODS: Healthy volunteers (N = 12) and patients with heart failure (N = 7) were examined using tagged MRI and fast-SENC at 3.0T. Circumferential strain was measured using fast-SENC in six endo- and six subepicardial regions in the basal-, mid-, and apical-septum and the basal-, mid-, and apical-lateral wall from the four-chamber view. These measurements were plotted to tagging, in corresponding myocardial segments. RESULTS: Peak systolic strain (Ecc) and early diastolic strain rate (Ecc/second) acquired by fast-SENC correlated closely to tagged MRI (r = 0.90 for Ecc and r = 0.91 for Ecc/second, P < 0.001 for both). Both fast-SENC and tagging identified differences in regional systolic and diastolic function between normal myocardium and dysfunctional segments in patients with heart failure (for fast-SENC: Ecc = -21.7 +/- 2.7 in healthy volunteers vs. -12.8 +/- 4.2 in hypokinetic vs. 0.6 +/- 3.8 in akinetic/dyskinetic segments, P < 0.001 between all; Ecc/second = 104 +/- 20/second in healthy volunteers vs. 37 +/- 9/second in hypokinetic vs. -16 +/- 15/second in akinetic/dyskinetic segments, P < 0.001 between all). Quantitative analysis was more time-consuming for conventional tagging than for fast-SENC (time-spent of 3.8 +/- 0.7 minutes vs. 9.5 +/- 0.7 minutes per patient, P < 0.001). CONCLUSION: Fast-SENC allows the rapid and accurate quantification of regional myocardial function. The information derived from fast-SENC during a single heartbeat seems to be superior or equal to that acquired by conventional tagging during several heart cycles and prolonged breathholds.     

Imaging three‐dimensional myocardial mechanics using navigator‐gated volumetric spiral cine DENSE MRI

A navigator‐gated 3D spiral cine displacement encoding with stimulated echoes (DENSE) pulse sequence for imaging 3D myocardial mechanics was developed. In addition, previously described 2D postprocessing algorithms including phase unwrapping, tissue tracking, and strain tensor calculation for the left ventricle (LV) were extended to 3D. These 3D methods were evaluated in five healthy volunteers, using 2D cine DENSE and historical 3D myocardial tagging as reference standards. With an average scan time of 20.5 ± 5.7 min, 3D data sets with a matrix size of 128 × 128 × 22, voxel size of 2.8 × 2.8 × 5.0 mm³, and temporal resolution of 32 msec were obtained with displacement encoding in three orthogonal directions. Mean values for end‐systolic mid‐ventricular mid‐wall radial, circumferential, and longitudinal strain were 0.33 ± 0.10, ?0.17 ± 0.02, and ?0.16 ± 0.02, respectively. Transmural strain gradients were detected in the radial and circumferential directions, reflecting high spatial resolution. Good agreement by linear correlation and Bland‐Altman analysis was achieved when comparing normal strains measured by 2D and 3D cine DENSE. Also, the 3D strains, twist, and torsion results obtained by 3D cine DENSE were in good agreement with historical values measured by 3D myocardial tagging. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Right ventricular outflow tract obstruction as a confounding factor in the assessment of the impact of pulmonary regurgitation on the right ventricular size and function in patients after repair of tetralogy of Fallot

Purpose:

To compare right ventricular (RV) size and function between patients with combined pulmonary regurgitation (PR) plus RV outflow tract (RVOT) obstruction (RVOTO) and patients with isolated PR.

Materials and Methods:

Consecutive individuals with significant PR (PR fraction ≥20%) after tetralogy of Fallot (TOF) repair who underwent cardiovascular magnetic resonance (CMR) were included. Patients with additional hemodynamic abnormalities (residual ventricular septal defect, extracardiac shunt, and/or more than mild regurgitation at a valve other than the pulmonary valve) were excluded. Significant RVOTO was defined as peak gradient across RVOT ≥30 mmHg.

Results:

Significant differences between patients with combined PR+RVOTO (n = 9) and isolated PR (n = 33) were observed in RV end‐diastolic volume (138.6 ± 25.1 vs. 167.0 ± 34.6 mL/m², P = 0.02, respectively), RV end‐systolic volume (65.0 ± 9.6 vs. 92.7 ± 26.2 mL/m², P = 0.003), and RV ejection fraction (RVEF) (52.8 ± 3.7 vs. 45.0 ± 6.4%, P = 0.001). Both PR and peak RVOT gradient were independent predictors of RV size.

Conclusion:

Patients with combined PR+RVOTO had smaller RV volumes and higher RVEF when compared with patients with isolated PR. The confounding effect of RVOTO on RV size and function needs to be considered in CMR studies evaluating patients after TOF repair. J. Magn. Reson. Imaging 2011;33:1040–1046. © 2011 Wiley‐Liss, Inc.     

Left ventricular diastolic function in type 2 diabetes mellitus is associated with myocardial triglyceride content but not with impaired myocardial perfusion reserve

Purpose:

To study myocardial perfusion reserve and myocellular metabolic alterations indicated by triglyceride content as possible causes of diastolic dysfunction in patients with type 2 diabetes mellitus, preserved systolic function, and without clinically evident coronary artery disease.

Materials and Methods:

Patients with type 2 diabetes mellitus (n = 42) underwent cardiac magnetic resonance (CMR) for quantification of 1) myocardial contractility by strain‐encoded MR (SENC); 2) myocardial triglyceride content by proton magnetic resonance spectroscopy (¹H‐MRS); and 3) myocardial perfusion reserve during pharmacologic hyperemia. Age‐matched healthy volunteers (n = 16) also underwent CMR to acquire normal values for myocardial strain and perfusion reserve.

Results:

Stress CMR procedures were successfully performed in all subjects, and no regional inducible perfusion defects were observed in type 2 diabetes mellitus patients. Diastolic strain rate and myocardial perfusion reserve were significantly impaired in patients with type 2 diabetes mellitus compared to control subjects (P < 0.001 for both). Interestingly, impaired diastolic function in type 2 diabetes mellitus was not associated with impaired myocardial perfusion reserve (r = 0.12, P = NS). Conversely a significant association was observed between diastolic dysfunction and myocardial triglyceride content (r = ?0.71, P < 0.001), which proved to be independent of age, gender, diabetes duration, blood pressure, and fasting blood glucose.

Conclusion:

Myocardial steatosis may represent an early marker of diabetic heart disease, triggering subclinical myocardial dysfunction irrespective of myocardial perfusion reserve. J. Magn. Reson. Imaging 2012;35:804–811. © 2011 Wiley Periodicals, Inc.

     

Automated estimation of aortic strain from steady‐state free‐precession and phase contrast MR images

The strain values extracted from steady‐state free‐precession (SSFP) and phase contrast (PC) images acquired with a 1.5T scanner on a compliant flow phantom and within the thoracic aorta of 52 healthy subjects were compared. Aortic data were acquired perpendicular to the aorta at the level of the pulmonary artery bifurcation. Cross sectional areas were obtained by using an automatic and robust segmentation method. While a good correlation (r = 0.99) was found between the aortic areas extracted from SSFP and PC sequences, a lower correlation (r = 0.71) was found between the corresponding aortic strain values. Strain values estimated using SSFP and PC sequences were equally correlated with age. Interobserver reproducibility was better for SSFP than for PC. Strain values in the ascending and descending aorta were better correlated for SSFP (r = 0.8) than for PC (r = 0.65) and fitted with the expectation of a larger strain in the ascending aorta when using SSFP. The spatial and temporal resolutions of the acquisitions had a minor influence upon the estimated strain values. Thus, if PC acquisitions can be used to estimate both pulse wave velocity and aortic strain, an additional SSFP sequence may be useful to improve the accuracy in estimating the aortic strain. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

MRI evaluation of right ventricular pressure overload in chronic obstructive pulmonary disease

In chronic obstructive pulmonary disease (COPD), the development of pulmonary hypertension is common. This study was performed to assess the signs of right ventricular (RV) pressure overload and RV failure in COPD. In 8 COPD patients without primary cardiac disease, RV wall thickness, mass, and end-diastolic volume were measured by cardiac-triggered cine MRI. MR phase-contrast velocity quantification was used to measure stroke volume and the patterns of flow into and out of the RV. Data of patients were tested versus those of a control group matched for age (n = 8). Results showed that the RV wall thickness was increased (.6 ± 0.1 vs 0.4 ± 0.1 cm, P < .001). RV mass was increased (67 ± 11 vs 57 ± 5 g, P < .005). RV stroke volume was decreased (57 ± 13 vs 71 ± 13 ml, P < .01), but RV ejection fraction was not different. In the main pulmonary artery flow, the quotient of acceleration time divided by ejection time was decreased (33 ± 5% vs 38 ± 4%, P < .05), which is indicative of pulmonary hypertension. In conclusion, this MRI protocol provides a tool to assess the effects of RV pressure overload in COPD before heart failure has become manifest.     

Early onset of retrograde flow in the main pulmonary artery is a characteristic of pulmonary arterial hypertension

Purpose:

To evaluate if early onset of retrograde flow in the main pulmonary artery is a characteristic of pulmonary arterial hypertension (PAH).

Materials and Methods:

Fifty‐five patients with suspected pulmonary hypertension (PH) underwent right‐sided heart catheterization and retrospectively ECG‐gated MR phase‐contrast velocity quantification in the main pulmonary artery. Pulmonary hypertension was defined by a mean pulmonary artery pressure being larger than 25 mmHg. The onset time of the retrograde flow relative to the cardiac cycle duration (Relative Onset Time = ROT) was compared with mean pulmonary artery pressure.

Results:

By the catheterization, 38 patients were identified as having PAH. The ROT for these PAH patients was significantly different from those found in the 17 non‐PH subjects (0.14 ± 0.06 versus 0.37 ± 0.06, P < 0.001). The mean pulmonary artery pressure was related to the ROT (r² = 0.62, P < 0.001) and could be estimated from the ROT with a standard deviation of 11.7 mmHg. With a cutoff value of 0.25, the ROT distinguished PAH patients from non‐PH subjects.

Conclusion:

Early onset of retrograde flow in the main pulmonary artery is a characteristic of pulmonary arterial hypertension and is visible by standard MR phase‐contrast velocity quantification. J. Magn. Reson. Imaging 2011;33:1362–1368. © 2011 Wiley‐Liss, Inc.     

Right ventricular dyssynchrony in pulmonary hypertension: Phase analysis using FDG-PET imaging

Background

Right ventricular (RV) performance in patients of pulmonary hypertension (PH) requires optimal assessment. The objective of this study is to develop phase analysis using ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging as a feasible tool for evaluation of RV dyssynchrony in PH.

Methods and Results

Fifty-four PH patients with well-characterized hemodynamic parameters were enrolled. All subjects performed FDG-PET imaging for RV phase analysis and RV function evaluation. Two-dimensional echocardiography with speckle tracking analysis was conducted to obtain RV time to peak systolic strain (PSST) as a comparison. The median contraction delay difference between RV middle free wall and septum measured by PET phase analysis (RVPD_PET) was 20.12° (interquartile range, 4.99°-30.10°). The median difference of PSST between RV middle free wall and middle septal wall (RVPD_Echo) measured by echocardiography was 43.98° (interquartile range, 6.25°-72.00°). RVPD_PET was well correlated with RVPD_Echo (r = 0.685, P < .001). RV phase standard deviation (RVSD) and histogram bandwidth (RVBW) derived from PET phase histogram were significantly correlated with cardiac index, RV ejection fraction, 6-minute walking distance, and serum N-terminal pro B-type natriuretic peptide (NT-proBNP) (RVSD: r = ?0.532, P < .001; r = ?0.551, P < .001; r = ?0.544, P < .001; r = 0.404, P < .01; respectively, RVBW: r = ?0.492, P < .001; r = ?0.466, P < .001; r = ?0.544, P < .001; r = 0.349, P = .01, respectively), while there were no significant correlations between RVSD and RVBW with hemodynamic parameters (right atrial pressure, right ventricular systolic pressure, right ventricular end-diastolic pressure, mean pulmonary artery pressure, and total pulmonary resistance).

Conclusions

Contraction delays between RV free wall and septum in PH measured by phase analysis and speckle tracking echocardiography were well correlated. RV dyssynchrony measured by phase analysis of FDG-PET was significantly related to RV dysfunction. Phase analysis of FDG-PET is feasible to evaluate RV mechanical dyssynchrony in patients of PH.

     

组织速度显像技术定量估测先天性心脏病右心室容量负荷过重时右心室功能

目的：探讨组织多普勒显像技术对先天性心脏病(先心病)右心室容量负荷过重时右心室功能评估价值。方法：采集18例正常儿童，28例房间隔缺损(ASD)患者和14例Amplatzer介入治疗后患者心尖四腔心右室长轴切面和腹部剑突下右室短轴切面组织多普勒图像，应用室壁运动速度定量分析技术测量长轴方向右室侧壁基底段、中段、室间隔基底段、短轴方向右室游离壁中段收缩期平均峰值速度(V)、平均峰值应变率(SR)和平均峰值应变(S)并进行比较。28例ASD患者行右心导管检查测定右室等容收缩期最大压力上升速率(max dp/dt)作为右室收缩性能的金标准。结果：ASD长轴方向右室侧壁基底段、中段收缩期V、SR、S均与正常对照组比较差异有显著性意义。室间隔基底段室壁运动速度指标也高于正常，但差异无显著性意义。短轴切面右室游离壁中段收缩期V、SR和S与正常比较差异无显著性意义。14例ASD介入治疗后右室侧壁基底段、中段V、SR和S明显下降。与dp/dt相关分析表明，右室壁基底段和中段V、SR和S与dp／dt显著相关(基底段r分别是0．3398；0．4315；0．7055；中段r分别是0．3051；0．3692；0．5081)。结论：组织速度显像技术可定量估测先心病右室室壁运动功能，长轴方向右室侧壁基底段、中段收缩期平均峰值应变是无创性定量估测右室收缩功能的良好指标。