Rationale and Objectives
To evaluate intra- and inter-observer variability of right ventricular (RV) functional parameters as evaluated by cardiac magnetic resonance imaging (MRI) in patients with acquired heart disease (AHD), and to identify factors associated with an increased variability.
Materials and Methods
Sixty consecutive patients were enrolled. Right and left ventricular (LV) volumes, ejection fraction, and mass were determined from short-axis cine sequences. All analyzes were performed twice by three observers with various training-degree in cardiac MRI. Intra- and inter-observer variability was evaluated. The impact on variability of each of the following parameters was assessed: observer’s experience, basal and apical slices selection, end-systolic phase selection, and delineation.
Results
Mean segmentation time ranged 9.8–19.0 minutes for RV and 6.4–9.2 minutes for LV. Variability of RV functional parameters measurement was strongly influenced by previous observer’s experience: it was two to three times superior to that of LV, even for the most experienced observer. High variability in the measurement of RV mass was observed. For both ventricles, selection of the basal slice and delineation were major determinants of variability.
Conclusion
As compared to LV, RV function assessment with cardiac MRI in AHD patients is much more variable and time-consuming. Observer’s experience, selection of basal slice, and delineation are determinant.
Introduction
The assessment of right ventricular (RV) function is essential in cardiac diseases and its prognostic value was reported in both ischemic and nonischemic cardiomyopathies . Contrary to the left ventricle, the right ventricle is often considered difficult to evaluate with current imaging techniques, mainly because of its complex motion and geometry . Cardiac magnetic resonance imaging (MRI) is the reference method of RV functional evaluation, for both clinical and research purposes . Previous studies stated that variability of RV function as estimated by cardiac MRI was comparable to that of the left ventricle . However, some of these results were obtained with long processing times (up to 45 minutes) incompatible with routine practice . Moreover, most published studies have evaluated the RV function variability either in healthy volunteers or in patients with congenital heart disease . On contrary, few studies have evaluated variability in patients with acquired heart disease (AHD). Most of them comprised limited sample size and were limited to a specific disorder . Consequently, the extension of those published results to clinical practice is questionable. Furthermore, to our knowledge, previous reports did not evaluate the factors associated with an increased variability, particularly the effect of cardiac MRI experience and processing steps .
The aim of this study was to evaluate intra- and inter-observer variability of RV functional parameters as evaluated by cardiac MRI in patients with AHD, and to identify factors associated with an increased variability.
Materials and methods
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Patients
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Cardiac MRI Protocol
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Cardiac MRI Analysis
Observers
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RV and LV function assessment
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End-diastole (ED) and end-systole (ES) definitions
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Definition of basal slices
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Definition of apical slices
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Endocardial and epicardial delineation
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Image Processing
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Statistical Analysis
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Results
Processing Time
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Table 1
Processing Times
Observer 1 (3 Years’ Experience) Observer 2 (1 Year of Experience) Observer 3 (No Experience) RV LV_P_ value RV vs. LV RV LV_P_ value RV vs. LV RV LV_P_ value RV vs. LV Measure 1 13.4 ± 3.9 7.8 ± 2.4 <.001 19.0 ± 4.0 9.2 ± 2.2 <.001 11.0 ± 2.8 7.9 ± 2.4 <.001 Measure 2 10.5 ± 1.9 6.4 ± 1.8 <.001 14.9 ± 3.1 7.0 ± 2.1 <.001 9.8 ± 2.5 7.0 ± 2.1 <.001P value measure 1 vs. 2 <.001 <.001 <.001 <.001 .03 .04
LV, left ventricle; RV, right ventricle.
Data are expressed in minutes ± standard deviation.
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Intra- and Inter-observer Variability
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Table 2
Intra-observer Variability of RV and LV Parameters
Observer 1 (3 Years’ Experience) Observer 2 (1 Year of Experience) Observer 3 (No Experience) RV LV RV LV RV LV EF (%) Mean 53.2 ± 11.4 55.3 ± 15.2 55.5 ± 11.5 52.9 ± 15.7 52.0 ± 10.6 54.8 ± 15.9 Mean difference −1.3 ± 4.1 −0.7 ± 3.0 −0.7 ± 6.5 0.5 ± 4.9 1.4 ± 10.5 −0.5 ± 5.9 CV 7.8 5.4 11.7 9.4 20.2 10.7 ICC 0.931 0.980 0.854 0.952 0.605 0.935 EDV index (mL/m 2 ) Mean 74.7 ± 19.2 95.0 ± 33.3 74.9 ± 19.8 95.2 ± 32.3 75.3 ± 21.8 93.2 ± 32.4 Mean difference 4.1 ± 7.0 1.2 ± 3.4 −2.4 ± 9.5 1.3 ± 5.9 0.7 ± 9.9 1.3 ± 6.3 CV 9.3 3.6 12.7 6.2 13.1 6.8 ICC 0.917 0.994 0.886 0.983 0.904 0.981 ESV index (mL/m 2 ) Mean 35.9 ± 16.5 46.2 ± 31.8 34.2 ± 16.2 48.7 ± 32.5 36.9 ± 17.0 45.5 ± 31.2 Mean difference 2.7 ± 4.3 1.3 ± 3.5 −0.6 ± 4.9 0.4 ± 4.4 −0.7 ± 6.1 0.7 ± 4.5 CV 12.0 7.6 14.4 9.1 16.7 10.0 ICC 0.955 0.993 0.955 0.991 0.937 0.989 Stroke V index (mL/m 2 ) Mean 38.8 ± 10.5 48.7 ± 12.4 40.9 ± 11.6 46.6 ± 12.1 38.6 ± 10.9 47.5 ± 13.1 Mean difference 1.4 ± 5.0 −0.1 ± 4.0 −1.5 ± 8.1 0.8 ± 7.5 1.2 ± 11.5 0.4 ± 6.9 CV 12.8 8.3 19.9 16.2 29.7 14.4 ICC 0.890 0.949 0.777 0.824 0.567 0.874 Mass index (g/m 2 ) Mean 27.2 ± 5.8 75.9 ± 19.3 23.4 ± 5.4 69.1 ± 17.2 30.0 ± 7.2 74.2 ± 18.4 Mean difference 2.5 ± 3.1 1.7 ± 3.2 1.6 ± 4.5 −0.1 ± 6.4 −0.2 ± 5.1 −0.1 ± 5.0 CV 11.3 4.2 19.2 9.2 17.1 6.7 ICC 0.785 0.983 0.672 0.935 0.779 0.965
CV, coefficient of variation, expressed as a percentage; EDV, end-diastolic volume; EF, ejection fraction; ESV, end-systolic volume; ICC, intraclass correlation coefficient; LV, left ventricle; RV, right ventricle; Stroke V, stroke volume.
Table 3
Inter-observer Variability of RV and LV Parameters
Obs1 vs. Obs2 Obs1 vs. Obs3 Obs2 vs. Obs3 RV LV RV LV RV LV EF (%) Mean 53.9 ± 11.3 54.0 ± 15.3 52.6 ± 10.8 54.7 ± 15.2 54.0 ± 10.8 53.8 ± 15.5 Mean difference 2.7 ± 7.2 −1.8 ± 4.5 −0.2 ± 9.3 0.4 ± 5.9 2.5 ± 9.9 −1.4 ± 5.8 CV 13.3 8.2 17.8 10.8 18.4 10.7 ICC 0.800 0.953 0.689 0.929 0.639 0.931 EDV index (mL/m 2 ) Mean 75.2 ± 19.6 95.7 ± 33.0 76.2 ± 20.5 94.7 ± 32.9 74.6 ± 21.1 94.8 ± 32.4 Mean difference −3.1 ± 8.9 0.2 ± 5.4 1.2 ± 9.9 1.8 ± 6.5 −1.9 ± 10.8 2.0 ± 6.6 CV 11.9 5.7 13.0 6.9 14.5 7.0 ICC 0.892 0.987 0.890 0.979 0.875 0.978 ESV index (mL/m 2 ) Mean 35.6 ± 16.1 47.9 ± 32.5 36.9 ± 16.4 46.4 ± 31.5 35.2 ± 16.4 47.4 ± 31.8 Mean difference −3.4 ± 5.9 1.9 ± 3.7 0.8 ± 6.7 1.0 ± 5.7 −2.6 ± 7.4 3.0 ± 6.1 CV 12.4 7.7 18.1 12.3 20.9 12.8 ICC 0.917 0.992 0.921 0.983 0.894 0.978 Stroke V index (mL/m 2 ) Mean 39.8 ± 11.4 47.8 ± 11.7 39.3 ± 10.8 48.2 ± 12.3 39.7 ± 11.4 47.4 ± 12.0 Mean difference 0.6 ± 7.3 −1.7 ± 6.1 0.3 ± 10.2 1.0 ± 7.0 1.0 ± 10.4 −0.7 ± 7.2 CV 18.4 12.7 26.0 14.5 26.2 15.1 ICC 0.814 0.867 0.636 0.849 0.658 0.838 Mass index (g/m 2 ) Mean 26.3 ± 6.0 72.9 ± 18.0 29.3 ± 6.7 75.4 ± 18.9 29.2 ± 6.5 71.6 ± 17.4 Mean difference −4.3 ± 5.0 −7.8 ± 7.2 −1.2 ± 6.2 2.6 ± 6.7 −1.5 ± 5.1 −5.1 ± 7.3 CV 18.9 9.9 21.2 8.8 17.5 10.2 ICC 0.540 0.848 0.638 0.932 0.713 0.881
CV, coefficient of variation, expressed as a percentage; EDV, end-diastolic volume; EF, ejection fraction; ESV, end-systolic volume; ICC, intraclass correlation coefficient; LV, left ventricle; Obs1, observer 1; Obs2, observer 2; Obs3, observer 3; RV, right ventricle; stroke V, stroke volume.
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Variability of Ejection Fraction Related to Each Processing Steps
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Table 4
Intra-observer Variability of RV and LV Ejection Fraction Related to the Selection of the Same Basal/Apical Slice and End-systolic Phase during the Two Measurements
Observer 1 (3 Years’ Experience) Observer 2 (1 Year of Experience) Observer 3 (No Experience) RV LV RV LV RV LV All measurements_n_ (%) 60 (100) 60 (100) 60 (100) 60 (100) 60 (100) 60 (100) Mean (%) 53.2 ± 11.4 55.3 ± 15.2 55.5 ± 11.5 52.9 ± 15.7 52.0 ± 10.6 54.8 ± 15.9 Mean difference (%) −1.3 ± 4.1 −0.7 ± 3.0 −0.7 ± 6.5 0.5 ± 4.9 1.4 ± 10.5 −0.5 ± 5.9 CV (%) 7.8 5.4 11.7 9.4 20.2 10.7 ICC 0.931 0.980 0.854 0.952 0.605 0.935 Same basal slice selected_n_ (%) 44 (73) 44 (73) 34 (57) 37 (62) 38 (63) 39 (65) Mean (%) 52.5 ± 12.3 56.0 ± 15.4 55.1 ± 13.7 55.9 ± 15.3 50.9 55.7 ± 16.0 Mean difference (%) −0.8 ± 3.3 −0.2 ± 2.1 0.3 ± 3.6 0.6 ± 3.3 0.7 ± 6.7 0.9 ± 4.1 CV (%) 6.4 3.7 6.6 6.0 13.1 7.3 ICC 0.962 0.991 0.966 0.976 0.807 0.967 Same apical slice selected_n_ (%) 44 (73) 48 (80) 41 (68) 44 (73) 28 (47) 40 (67) Mean (%) 54.6 ± 10.7 55.3 ± 15.1 54.6 ± 11.2 50.2 ± 17.0 52.1 ± 10.5 54.2 ± 17.0 Mean difference (%) −1.3 ± 4.2 −0.5 ± 2.7 0.3 ± 5.6 0.2 ± 4.8 1.2 ± 8.5 −0.5 ± 5.9 CV (%) 7.6 4.9 10.3 9.6 16.3 10.8 ICC 0.922 0.984 0.884 0.962 0.720 0.943 Same systolic phase selected_n_ (%) 48 (80) 48 (80) 36 (60) 36 (60) 21 (35) 21 (35) Mean (%) 54.5 ± 10.4 55.7 ± 15.7 58.4 ± 9.6 55.2 ± 13.2 53.7 ± 9.0 55.9 ± 17.4 Mean difference (%) −1.4 ± 4.1 −0.6 ± 3.2 −0.2 ± 6.1 0.3 ± 5.5 1.6 ± 7.8 1.0 ± 3.9 CV (%) 7.5 5.7 10.4 9.9 14.5 7.1 ICC 0.919 0.979 0.823 0.920 0.686 0.974 Same basal/apical slices and ES phase selected_n_ (%) 25 (42) 27 (45) 15 (25) 16 (27) 5 (8) 9 (15) Mean (%) 54.9 ± 11.6 58.3 ± 14.6 57.2 ± 11.5 55.2 ± 12.3 53.8 ± 3.5 50.7 ± 18.9 Mean difference (%) −0.7 ± 2.9 0.1 ± 1.8 0.1 ± 3.8 0.6 ± 3.4 −2.9 ± 4.5 2.4 ± 3.1 CV (%) 5.4 3.1 6.6 6.1 8.5 6.1 ICC 0.968 0.993 0.951 0.964 0.355 0.980
CV, coefficient of variation, expressed as a percentage; EF, ejection fraction; ES, end systole; ICC, intraclass correlation coefficient; LV, left ventricle; RV, right ventricle.
Table 5
Inter-observer Variability of RV and LV Ejection Fraction Related to the Selection of the Same Basal/Apical Slice and End Systolic Phase during the Two Measurements
Obs1 vs. Obs2 Obs1 vs. Obs3 Obs2 vs. Obs3 RV LV RV LV RV LV All measurements_n_ (%) 60 (100) 60 (100) 60 (100) 60 (100) 60 (100) 60 (100) Mean (%) 53.9 ± 11.3 54.0 ± 15.3 52.6 ± 10.8 54.7 ± 15.2 54.0 ± 10.8 53.8 ± 15.5 Mean difference (%) 2.7 ± 7.2 −1.8 ± 4.5 −0.2 ± 9.3 0.4 ± 5.9 2.5 ± 9.9 −1.4 ± 5.8 CV (%) 13.3 8.2 17.8 10.8 18.4 10.7 ICC 0.800 0.953 0.689 0.929 0.639 0.931 Same basal slice selected_n_ (%) 24 (40) 38 (63) 26 (43) 26 (43) 14 (23) 38 (63) Mean (%) 51.4 ± 14.3 53.7 ± 16.9 52.5 ± 12.3 56.1 ± 14.9 51.1 ± 11.6 54.9 ± 14.4 Mean difference (%) 3.8 ± 3.6 −1.6 ± 3.4 −2.5 ± 4.7 −0.4 ± 3.3 3.8 ± 4.3 −1.0 ± 4.0 CV (%) 7.1 6.3 9.0 5.8 8.4 7.3 ICC 0.937 0.977 0.914 0.977 0.891 0.960 Same apical slice selected_n_ (%) 21 (35) 36 (60) 24 (40) 41 (68) 15 (25) 29 (48) Mean (%) 55.8 ± 9.9 50.1 ± 17.1 51.2 ± 11.5 53.1 ± 16.3 56.2 ± 8.8 48.0 ± 16.1 Mean difference (%) 1.5 ± 8.4 −2.2 ± 4.4 −0.2 ± 8.9 −0.6 ± 5.8 2.9 ± 12.5 −0.8 ± 5.3 CV (%) 15.1 8.8 17.3 10.8 22.3 11.0 ICC 0.700 0.960 0.748 0.940 0.334 0.948 Same systolic phase selected_n_ (%) 34 (57) 34 (57) 25 (42) 25 (42) 22 (37) 22 (37) Mean (%) 52.7 ± 13.1 55.7 ± 15.4 51.1 ± 10.8 55.3 ± 17.2 52.4 ± 12.4 54.9 ± 16.1 Mean difference (%) 3.0 ± 6.4 −1.4 ± 4.9 2.1 ± 8.7 1.3 ± 4.8 4.9 ± 9.8 −3.3 ± 5.3 CV (%) 12.2 8.8 17.0 8.8 18.7 9.6 ICC 0.868 0.948 0.720 0.960 0.691 0.930 Same basal/apical slices and ES phase selected_n_ (%) 4 (7) 16 (27) 3 (5) 7 (12) 0 (0) 4 (7) Mean (%) 54.3 ± 16.0 49.4 ± 19.1 39.9 ± 13.9 61.1 ± 14.8 - 53.2 ± 17.8 Mean difference (%) 2.4 ± 3.0 −1.2 ± 3.9 −0.1 ± 6.5 1.2 ± 3.4 - −3.4 ± 3.7 CV (%) 5.5 7.8 16.4 5.6 - 7.0 ICC 0.976 0.979 0.927 0.974 - 0.966
CV, coefficient of variation, expressed as a percentage; EF, ejection fraction; ES, end-systole; ICC, intraclass correlation coefficient; LV, left ventricle; RV, right ventricle.
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Effect of Basal Slice Selection
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Effect of Apical Slice and ES Phase Selection
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Effect of Observer’s Delineation
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Discussion
Intra- and Inter-observer Variability
Effect of observer’s experience
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Effect of selection of basal slice
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Effect of selection of apical slice
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Effect of selection of ES phase
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Effect of observer delineation
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Processing Time
Effect of processing time on variability
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Differences between the processing times of right and left ventricles
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Clinical and Research Relevance
Clinical relevance
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Research relevance
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Limitations
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Conclusion
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References
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