Intracardiac flow - where we are and where we want to be
Malenka Bissell1

1Leeds Insitute of Cardiovascular and Metabolic Medicine, Division of Biomedical Imaging, University of Leeds, Leeds, United Kingdom

Synopsis

Flow is an important consideration in cardiology. Intra-cardiac flow profiles and energetics are thought to play an important part in ischaemic heart disease, cardiomyopathies and congenital heart disease. Current gold standard for cardiac function is ejection fraction calculation. Recent advances in cardiac 4D flow MRI may now offer novel, more sensitive imaging biomarkers for cardiac function. This presentation will provide an overview of current parameters used, limitations of the technique and explore measurements for clinical use.

Target audience

Those interested in clinical potential of intra-cardiac flow measurements

Objectives

  • To review parameters that we can currently analyse
  • To explore what we would like to measure
  • To reflect on current limitations of the technique

Purpose

Flow is an important consideration in cardiology. Leonado Da Vinci already described the importance of flow for valve closure over 500 years ago1. Recent advances in cardiac MRI now allow us to study flow in more detail than ever before. Intra-cardiac flow profiles and energetics are thought to play an important part in ischaemic heart disease, cardiomyopathies, congenital heart disease and pulmonary hypertension. Current gold standard for cardiac function is ejection fraction calculation. 4D flow MRI may offer novel, more sensitive bioimaging markers for cardiac function.

Methods

Time resolved 4D flow MRI acquires flow images in 3 directions and 1 magnitude image within the prescribed acquisition slab2. Recent advances in sequence development now allow whole heart acquisition in less than 10 minutes.

Results

Initial analysis focused on the left ventricle. Here, particle tracing is used to divide the blood flow into 4 component to assess efficiency of flow3,4. Kinetic energy can either be calculated within these 4 components, globally or in different anatomical areas (such as base, mid and apex)5. Vortex visualisation and quantification is used to characterise mitral inflow, especially in congenital heart disease6,7. Another important advantage of 4D flow MRI analysis includes valve tracking allowing more precise quantification of mitral function8. Most of the above analysis parameters are now also being evaluated in the right ventricle9.

Discussion

The analysis options discussed are potential novel imaging biomarkers to assess cardiac function. To evaluate the clinical applicability of these, longitudinal and outcome linked studies are necessary.

Acknowledgements

No acknowledgement found.

References

1. Bissell MM, Dall'armellina E, Choudhury RP. Flow vortices in the aortic root: in vivo 4D-MRI confirms predictions of Leonardo da Vinci. Eur Heart J. 2014;

2. Dyverfeldt P, Bissell M, Barker AJ, Bolger AF, Carlhall CJ, Ebbers T, Francios CJ, Frydrychowicz A, Geiger J, Giese D, Hope MD, Kilner PJ, Kozerke S, Myerson S, Neubauer S, Wieben O, Markl M. 4D flow cardiovascular magnetic resonance consensus statement. J Cardiovasc Magn Reson. 2015; 17: 72-015-0174-5.

3. Eriksson J, Bolger AF, Ebbers T, Carlhall CJ. Four-dimensional blood flow-specific markers of LV dysfunction in dilated cardiomyopathy. Eur Heart J Cardiovasc Imaging. 2013; 14: 417-424.

4. Stoll VM, Loudon M, Eriksson J, Bissell MM, Dyverfeldt P, Ebbers T, Myerson SG, Neubauer S, Carlhall CJ, Hess AT. Test-retest variability of left ventricular 4D flow cardiovascular magnetic resonance measurements in healthy subjects. J Cardiovasc Magn Reson. 2018; 20: 15-018-0432-4.

5. van der Geest RJ, Garg P. Advanced Analysis Techniques for Intra-cardiac Flow Evaluation from 4D Flow MRI. Curr Radiol Rep. 2016; 4: 38-016-0167-7. Epub 2016 May 20.

6. Elbaz MS, Calkoen EE, Westenberg JJ, Lelieveldt BP, Roest AA, van der Geest RJ. Vortex flow during early and late left ventricular filling in normal subjects: quantitative characterization using retrospectively-gated 4D flow cardiovascular magnetic resonance and three-dimensional vortex core analysis. J Cardiovasc Magn Reson. 2014; 16: 78-014-0078-9.

7. Elbaz MS, van der Geest RJ, Calkoen EE, de Roos A, Lelieveldt BP, Roest AA, Westenberg JJ. Assessment of viscous energy loss and the association with three-dimensional vortex ring formation in left ventricular inflow: In vivo evaluation using four-dimensional flow MRI. Magn Reson Med. 2017; 77: 794-805.

8. Kamphuis VP, van der Palen RLF, de Koning PJH, Elbaz MSM, van der Geest RJ, de Roos A, Roest AAW, Westenberg JJM. In-scan and scan-rescan assessment of LV in- and outflow volumes by 4D flow MRI versus 2D planimetry. J Magn Reson Imaging. 2018; 47: 511-522.

9. Fredriksson AG, Svalbring E, Eriksson J, Dyverfeldt P, Alehagen U, Engvall J, Ebbers T, Carlhall CJ. 4D flow MRI can detect subtle right ventricular dysfunction in primary left ventricular disease. J Magn Reson Imaging. 2016; 43: 558-565.

Proc. Intl. Soc. Mag. Reson. Med. 26 (2018)