Aortic relative pressure components derived from four-dimensional flow cardiovascular magnetic resonance.
OBJECTIVE
To describe the assessment of the spatiotemporal distribution of relative aortic pressure quantifying the magnitude of its three major components.


METHODS
Nine healthy volunteers and three patients with aortic disease (bicuspid aortic valve, dissection, and Marfan syndrome) underwent 4D-flow CMR. Spatiotemporal pressure maps were computed from the CMR flow fields solving the pressure Poisson equation. The individual components of pressure were separated into time-varying inertial ("transient"), spatially varying inertial ("convective"), and viscous components.


RESULTS
Relative aortic pressure is primarily caused by transient effects followed by the convective and small viscous contributions (64.5, 13.6, and 0.3 mmHg/m, respectively, in healthy subjects), although regional analysis revealed prevalent convective effects in specific contexts, e.g., Sinus of Valsalva and aortic arch at instants of peak velocity. Patients showed differences in peak transient values and duration, and localized abrupt convective changes explained by abnormalities in aortic geometry, including the presence of an aneurysm, a pseudo-coarctation, the inlet of a dissection, or by complex flow patterns.


CONCLUSIONS
The evaluation of the three components of relative pressure enables the quantification of mechanistic information for understanding and stratifying aortic disease, with potential future implications for guiding therapy.
Department of Biomedical engineering, Division of Imaging Sciences, The Rayne Institute, Kings College School of Medicine, United Kingdom; Department of Computer Science, University of Oxford, United Kingdom.
Pablo
P
Lamata
Alex
A
Pitcher
Sebastian
S
Krittian
David
D
Nordsletten
Malenka M
MM
Bissell
Thomas
T
Cassar
Alex J
AJ
Barker
Michael
M
Markl
Stefan
S
Neubauer
Nicolas P
NP
Smith
D000328:Adult; D001011:Aorta / Q000503:physiopathology*; D001018:Aortic Diseases / Q000175:diagnosis / Q000503:physiopathology*; D062186:Arterial Pressure; D001783:Blood Flow Velocity / Q000502:physiology; D001795:Blood Pressure Determination / Q000379:methods; D003326:Coronary Circulation; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
aorta; blood pressure; cardiac magnetic resonance imaging; hemodynamics; noninvasive pressure estimation