Translating principles of quality control to cardiovascular magnetic resonance: assessing quantitative parameters of the left ventricle in a large cohort

Figures

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  Figure 1. Flowchart of data selection. Abbreviations: CMR, cardiac magnetic resonance; LV EF, left ventricular ejection fraction; LV EDV, left ventricular end-diastolic volume; LV SV, left ventricular stroke volume; LVM, left ventricular mass.

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  Figure 2. Quality control charts scheme explained by means of a moving median (MM) chart of left ventricular stroke volume (LV SV) values. The green curve shows the MM with a window of 750. The horizontal black line shows the median of all LV SV values. The red dashed lines show the tolerance interval boundaries. The area under the curve is colored green or red, to show that the curve is inside and outside of the tolerance interval respectively. A box is drawn into the plot, which transfers the reader to a zoom on the right side of the figure. The zoomed figure shows the drift inside the curve with an arrow.

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  Figure 3. Flowchart of quality control procedure. The examination procedure can be divided into multiple steps with varying processing locations. All these steps may have an impact on the result of the examination. Abbreviations: CMR, cardiac magnetic resonance; LV, left ventricle.

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  Figure 4. Simulated phantom dataset with a demonstration of the proposed method. (a) Bi-modal distribution of simulated LV SV values. (b) 20,000 random samples of the LV SV dataset were drawn and concatenated to simulate a stationary time series. (c) The data from (b), where 5 ml have been added to the last 10,000 samples to demonstrate a sudden and permanent change in the setup. No perceptual difference is visible. (d) The moving median of the data shown in (b) with different window sizes. Lines in different shades of blue represent aggregations of window sizes ranging from 100 to 1000. Red dashed lines indicate the tolerance interval (e) The moving median of the data shown in (c) with different window sizes. Lines in different shades of blue represent aggregations of window sizes ranging from 100 to 1000. Red dashed lines indicate the tolerance interval. The box with black borders indicates the area of drift. (f) Zoom in to the area of (e) containing the drift. The exclamation mark notes a potential alarm that could be issued by the system. Abbreviations: LV SV, left ventricular stroke volume; MM, moving median; * shows the alert of window 250; ** shows the alert for window size 750.

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  Figure 5. Moving median (MM) time series plots of age, weight, body-mass-index (BMI) and body-surface-area (BSA) (split by men and women) using windows of sizes 750 and 250. Gray and white background indicates time frames of staff rotation. The blue lines in every subplot represent the male population and the orange lines the female population. The faded lines represent a window size of 250 and the fully colored lines a window size of 750.

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  Figure 6. Time-dependent analysis of key parameters in relation to tolerance intervals. Tolerance intervals are marked as black dashed lines for each LV function parameter. Gray and white background indicates time frames of staff rotation. The orange line represents a window size of 250 and the green line a window size of 750. Abbreviations: MM, moving median; LV EF, left ventricular ejection fraction; LV ESV, left ventricular end-systolic volume (computed using LV EDV and LV SV); LV EDV, left ventricular end-diastolic volume; LV SV, left ventricular stroke volume; LVM, left ventricular mass.